Geomorphic Studies of the Storm and Flood of 

November 3-5, 1985, in the Upper Potomac 

and Cheat River Basins in West Virginia and 

Virginia 

U.S. G EO LOG I CAL SURVEY BULLETIN 1 981 · 

Geomorphic Studies of the Storm and Flood of 

November 3-5, 1985, in the Upper Potomac 

and Cheat River Basins in West Virginia and 

Virginia 

ROBERT B. JACOBSON, Editor 

Chapters A through E are published as a 

single volume and are not available separately 

U.S. GEOLOGICAL SURVEY BULLETIN 1981 
U.S. DEPARTMENT OF THE INTERIOR 

BRUCE BABBITT, Secretary 

U.S. GEOLOGICAL SURVEY 

Dallas L. Peck, Director 

Any use of trade, product, or firm names 

in this publication is for descriptive purposes only 

and does not imply endorsement by the U.S. Government 

UNITED STATES GOVERNMENT PRINTING OFFICE: 1993 

For sale by 

U.S. Geological Survey, Map Distribution 

Box 25286, MS 306, Federal Center 

Denver, CO 80225 

Library of Congress Cataloging in Publication Data 

Geomorphic studies of the storm and flood of November 3-5, 1985, in the 

upper Potomac and Cheat River basins in West Virginia and Virginia I 

Robert B. jacobson, editor. 

p. cm.-(U.S. Geological Survey bulletin; 1981) "A multidisciplinary study 

of the geomorphic effects of a severe storm in a mountainous area of the 

Appalachians." 

Includes bibliographical references. 

1. Landslides-Potomac River Watershed. 2. Landslides-Cheat River Watershed (W.Va. and Pa.). 3. Severe storms-Appalachian Mountains. 

4. Floods-Potomac River Watershed. 5. Floods-Cheat River Watershed 

(W.Va. and Pa). 6. Geomorphology-Appalachian Mountains. I. Jacobson, Robert B. II. Series. 

QE75.B9 no. 1981 

[QE599.U5] 

557.3 s-dc20 

[551.3'07'0975491] 91-14451 

CIP 
CONTENTS 

[Letters designate the chapters] 

(A) Introduction: Geomorphic Studies of the Storm and Flood of November 3-5, 1985, 

in the Upper Potomac and Cheat River Basins, by Robert B. Jacobson 

(B) Meteorology of the Storm of November 3-5, 1985, in West Virginia and Virginia, 

by Stephen J. Colucci, Robert B. Jacobson, and Steven Greco 

(C) Landslides Triggered by the Storm of November 3-5, 1985, Wills Mountain 

Anticline, West Virginia and Virginia, by Robert B. Jacobson, John P. McGeehin, 

Elizabeth D. Cron, Carolyn E. Carr, John M. Harper, and Alan D. Howard 

(D) Depositional Aspects of the November 1985 Flood on Cheat River and Black Fork, 

West Virginia, by J. Steven Kite and Ron C. Linton 

(E) Flood Hydrology and Geomorphic Effects on River Channels and Flood Plains: The 

Flood of November 4-5, 1985, in the South Branch Potomac River Basin of West 

Virginia, by Andrew J. Miller and Douglas J. Parkinson 

Chapter A 

Introduction: Geomorphic Studies of the 

Storm and Flood of November 3-5, 1985, in 

the Upper Potomac and Cheat River Basins 

By ROBERT B. JACOBSON 

A multidisciplinary study of the geomorphic effects 

of a severe storm in a mountainous area of the 

Appalachians 

U.S. GEOLOGICAL SURVEY BULLETIN 1981 

GEOMORPHIC STUDIES OF THE STORM AND FLOOD OF NOVEMBER 3-5, 1985, IN 

THE UPPER POTOMAC AND CHEAT RIVER BASINS IN WEST VIRGINIA AND VIRGINIA 
II Contents 

CONTENTS 

Introduction Al 

Social Costs and Mitigation Issues Al 

The November 1985 Storm as a Geomorphic Experiment A2 

Geomorphic Effects of the 1985 Storm and Natural Hazard Mitigation A2 

Geomorphic Effects of the 1985 Storm and Long-Term Landscape 

Evolution A3 

References Cited A3 

PLATE 

1. Study area, drainage basin boundaries, and map of rainfall for November 3-5, 

1985 In pocket 
Introduction: Geomorphic Studies of the Storm and 

Flood of November 3-5, 1985, in the Upper Potomac 

and Cheat River Basins 

By Robert B. jacobson 

INTRODUCTION 

The heavy rains of November 3-5, 1985, produced 

record floods and extensive landsliding in the Potomac and 

Cheat River basins in West Virginia and Virginia (pl. 1). 

Although rainfall intensity was moderate, the storm covered 

a very large area and produced record floods for basins in 

the size range of 1000-10,000 km2

• In addition, thousands 

of landslides were triggered on slopes underlain by shale 

bedrock. The total social cost of the storm amounted to 70 

lives lost and an estimated $1.3 billion in damage to homes, 

businesses, roads, and productive land in West Virginia and 

Virginia (Federal Emergency Management Agency 

(FEMA) 1985a, b). These extreme costs were incurred 

despite the fact that the affected area is sparsely populated. 

To understand the origins and geomorphic effects of 

the 1985 storm, studies were undertaken by the U.S. 

Geological Survey, University of Maryland, West Virginia 

University, Cornell University, University of Virginia, The 

Johns Hopkins University, and Carleton College. Personnel 

were also consulted from the National Weather Service, 

Nuclear Regulatory Commission, U.S. Army Corps of 

Engineers, Soil Conservation Service, and Interstate Commission on the Potomac River basin. 

This cooperative effort serves to document the effects 

of the storm as an example of an extreme geomorphic event 

in the central Appalachian Mountains. The following chapters comprise observations and preliminary analyses for 

some of the observed phenomena. Subsequent publications 

by the contributors to this volume will expand the scope of 

this research. 

SOCIAL COSTS AND MITIGATION ISSUES 

Cataclysmic storms that trigger floods and landslides 

are rare on human time scales, and memory of the cataManuscript approved for publication February 22, 1991. 

strophic effects of storms appears to fade quickly. Despite a 

regional history of destructive floods in the central Appalachians, including well-publicized events in 1936, 1949, 

1955, 1969, and 1972, homes and businesses are concentrated in valley bottoms, and public awareness of flood and 

landslide hazards is low. Interagency reports following the 

1985 flood concluded that local and federal flood-plain 

management and disaster preventiveness programs have not 

been effective in reducing the risks to inhabitants of the 

region (FEMA, 1985a). When floodwaters swept through 

the narrow valleys of the Potomac and Cheat River basins 

November 4-6, 1985, inhabitants were ill prepared for the 

severity of the storm (FEMA, 1985a, p. 16). 

The storm and flood caused an estimated $1.3 billion 

in damages in West Virginia and Virginia, including 70 

deaths (FEMA, 1985a, b). In West Virginia, estimated 

damages totaled $577 million; 45 percent was to homes 

(9,000 homes, most of which were mobile homes in flood 

plains), 17 percent to agriculture, 20 percent to businesses, 

and 18 percent to public structures, primarily roads and 

bridges (FEMA, 1985a). In Virginia, estimated damages 

totaled $753 million; 62 percent was to private nonagricultural, 20 percent to agricultural, and 17 percent to public 

land and structures (FEMA, 1985b). Total disaster assistance from 14 federal agencies amounted to $285 million 

(Government Accounting Office, 1988). 

In the wake of the 1985 flood, interagency floodhazard mitigation reports stressed several key aspects of the 

problem of flooding in steep mountainous areas (FEMA, 

1985a, b). The primary factor that leads to loss of life is the 

inhabitants' lack of perception of the hazard of flash floods. 

Hazard perception is a particular problem in steep basins, 

where channels are normally dry or have small flows. 

Inhabitants are not aware that steep basins can produce 

heavy flows with high concentrations of sediment und 

debris. To increase perception of the hazards of flood-prone 

areas, the reports stressed increased implementation of 

flood-warning evacuation systems and public awareness 

campaigns. Other factors addressed were siting of structures 

Introduction: Geomorphic Studies of the Storm and Flood of Nov. 3-5, 1985 A1 
to avoid both inundation and erosional damage, design of 

bridges and highways to minimize impact of large, highenergy floods with high sediment loads, implementation of 

flood-control structures (both impoundments and protective 

levees), and restoration of stream channels and agricultural 

lands (FEMA, 1985a, b). 

THE NOVEMBER 1985 STORM AS A 

GEOMORPHIC EXPERIMENT 

Many of the mitigation strategies proposed for recovery from the 1985 event, and for dealing with similar events 

in the future, require understanding of the processes that 

create destructive floods and landslides in the central 

Appalachians. The meteorological conditions that lead to 

severe rainfall are poorly understood, and the recurrence 

frequencies of severe rainfall intensities and durations are 

only broadly predictable. Poor estimates of the recurrence 

frequencies of extreme floods stem from the fact that 

frequency analysis must rely on short historical flood 

records (most less than 50 yr). Landslide recurrence frequencies are mostly unknown. General models for geologic, geomorphic, and land-use controls on where flood 

and landslide damage occur do not exist, although evidence 

from many past floods indicates that the geomorphic effects 

of extreme storms are not randomly distributed on the 

landscape. No general strategy or methodology exists for 

adequately mapping flood and landslide hazards in the 

central Appalachian Mountains. 

Because the November 1985 storm and its effects 

were unusually well documented by stream gages, rain 

gages, and poststorm aerial photography, the cataclysmic 

event could be studied in detail. In the study area, the storm 

consisted of a large, fairly homogeneous area of precipitation that can be resolved with existing rain gage data (pl. 1). 

Colucci and others (chapter B, this volume) discuss the 

meteorological context of the 1985 storm. 

One of the main areas of high rainfall was located 

astride the Wills Mountain anticline, a structure that 

involves a variety of bedrock lithologies. Thus the influences of very different rocks and regoliths on landslide 

occurrence could be investigated along a well-defined 

rainfall gradient. Jacobson and others (chapter C, this 

volume) discuss the occurrence of landslides triggered by 

the 1985 storm. 

Substantial rain fell on both the Potomac and Cheat 

River basins. The Cheat River basin is in the nearly 

flat-lying sedimentary rocks of the Appalachian Plateau 

physiographic province, whereas most of the affected parts 

of the Potomac River basin are in the folded Valley and 

Ridge physiographic province. This varied physiography 

has permitted study of flood effects in basins with very 

different geologic controls on valley geometry, sediment 

supply, and hydrologic response. Kite and Linton (chapter 

D, this volume) discuss these effects in the Cheat River 

basin and Miller and Parkinson (chapter E, this volume) 

discuss flood effects in the Potomac River basin. 

Geomorphic Effects of the 1985 Storm and 

Natural Hazard Mitigation 

Geomorphologists seek to understand the landscape 

in terms of mechanics, magnitude, and frequency of erosional and depositional processes. These concepts are also 

critical to design of policies that can mitigate hazards of 

severe storms like the November 1985 event. 

Colucci and others (chapter B, this volume) analyzed 

the November 1985 storm event in terms of the size and 

recurrence of severe storms in the central Appalachians. 

They show that the 1985 storm resulted from a complex, but 

recognizable, series of meteorological events. Analysis of 

the genesis of the storm should be of use in future 

monitoring of meteorological conditions and should aid in 

prediction of severe rainfall. Simple frequency analysis of 

2-day rainfall totals yielded a range of recurrence intervals 

(for rainfall at a point) from 80 to nearly 300 yr. The 

constraints on the frequency analysis point to the need for 

more long-term rainfall data. This chapter also contains a 

description of how "flash floods" can be triggered by 

long-duration as well as intense, short-duration rainfall. 

Jacobson and others (chapter C, this volume) concentrate on magnitude and frequency of landslides, and the 

geologic, geomorphic, and land-use factors that control 

where landslides were triggered by the storm. Their results 

include ( 1) characterization of physical properties that were 

responsible for stability or instability of some regoliths, (2) 

evaluation of the bedrock, surficial geologic, land cover, 

and topographic factors that controlled where landslides 

occurred, (3) determination of the rainfall totals that triggered landslides on several regoliths, ( 4) determination of 

the relation between total rainfall and number of slope 

movements triggered, (5) construction of a statistical model 

for the recurrence frequency with which different areal 

densities of landslides can be expected in the future, and (6) 

evaluation of the influence of the considerable numbers of 

landslides that mobilized into debris flows and delivered 

sediment to streams to cause flood-related geomorphic 

changes. 

Evaluation of the sensitivity of slope stability to 

various combinations of bedrock geology, surficial geology, land cover, and topography is necessary for establishing land management policies concerned with minimizing 

erosion, sedimentation, and hazards. Data on the recurrence 

frequency of landslides are important to evaluate future 

hazards and sediment supply from landslides. Landslides 

were not a particular concern in FEMA (1985a, b) reports, 

presumably because they occurred mostly on agricultural 

and forested land rather than in populated areas. However, 

much of the damage from flooding was due to large deposits 

of sediment and debris, which possibly originated from 

A2 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W. Va., Va. 
landslides. Furthermore, in at least eight instances, debris 

flows reached stream channels and continued downstream, 

where their high bulk density could be expected to exert 

high shear stresses on channel beds and banks. The hypothesis that landslides may have contributed significantly to 

geomorphic changes in stream channels was tested by 

Jacobson and others, who found that landslides did have a 

measurable effect on these changes. 

Kite and Linton (chapter D, this volume) and Miller 

and Parkinson (chapter E, this volume) discuss where and 

how flood damage occurs in these steep mountain basins. 

The December 1985 interagency report on flood-hazard 

mitigation for West Virginia states, "The unprecedented 

flood waters affected both floodprone areas and areas that 

had not known serious flooding in the past ... " and that 

floodwater velocity, and not simply inundation, was 

responsible for much of the flood damage (FEMA, 1985a). 

Both chapters contain analyses of the hydraulic situations 

that created the most severe flood-plain erosion and deposition. Flow patterns and flow velocities were better than 

inundated area in predicting where the most severe floodplain erosion and associated deposition occurred. In certain 

hydraulic situations, floodwaters caused channel avulsion 

and severe lateral erosion of valley bottom sediments. 

Lateral erosion was effective in removing parts of alluvial 

terraces and fans, whose surfaces were far above the 

presumed 100-yr flood levels. Other low-lying areas of 

valley bottoms were covered by several meters of slowmoving floodwater but experienced insignificant deposition 

or erosion. These observations suggest that step-backwater 

modeling of 100-yr flood stages may not be the best method 

to measure potential hazards in steep headwater drainage 

basins. 

Kite and Linton's analysis of slack-water deposits 

from the 1985 storm illustrates the limitations of paleoflood 

hydrology in the central Appalachians. If calculation had 

been based on the altitudes of slack-water sediments deposited by the flood, the discharge of the 1985 flood on the 

Cheat River would have been significantly underestimated. 

The conclusions of these two chapters have implications for (1) where to place public facilities, roadways, and 

bridges in valley bottoms to minimize risk from highvelocity flows, (2) design criteria for flood control structures, (3) design criteria for wet floodproofing, (4) the 

potential" effects of upstream channelization on downstream 

hazards, and (5) the importance of valley-bottom land use in 

determining flood damage. 

Geomorphic Effects of the 1985 Storm and 

Long-Term Landscape Evolution 

The effects of the 1985 storm also provide information to construct models of long-term landscape evolution. 

The primary questions at issue in the central Appalachian 

Mountains are (1) the relative importance of rare and severe 

versus more common, low-magnitude geomorphiC events in 

sculpting the landscape and (2) the importance of 

the present -day climate versus the effects of ancient 

climates. 

Erosional and depositional features similar to those 

created by the 1985 event are replicated elsewhere in the 

landscape. Many debris flows from small landslides in 1985 

were deposited on colluvial wedges and debris fans; these 

features are composed of multiple layers from previous 

events, although the bulk of the deposits may date from the 

transition between the Pleistocene and Holocene (Jacobson 

and others, 1989a, b). Flows from a small number of large 

debris avalanches that were triggered high on ridgetops are 

similar to more extensive prehistoric debris deposits (see pl. 

1B, in Jacobson and others, chapter C, this volume). 

Similarly, prehistoric anastomosing channel patterns, channel avulsion scars, and levee and splay deposits attest to the 

fact that floods like the 1985 flood have occurred in the past 

in this area. Radiocarbon dates from two sites in Petersburg 

and Moorefield, W. Va., indicate that most of the existing 

sediment in the valley bottom is middle to late Holocene, 

but that islands and terraces of older sediments are also 

present (Jacobson and others, 1989a). In fact, most distinct 

features in the central Appalachian landscape are erosional 

or depositional features from processes similar to those 

triggered by the 1985 storm. From these observations, 

Jacobson and others (1989b) argued that rare, catastrophic, 

storm-generated events are the most effective in sculpting 

the central Appalachian landscape under the present-day 

climate, although extensive older deposits also attest to the 

importance of ancient climates. 

REFERENCES CITED 

Federal Emergency Management Agency, 1985a, Interagency 

flood hazard mitigation report in response to the November 7, 

1985, disaster declaration (West Virginia): Report FEMA743-DR-WV, 56 p. 

---1985b, Interagency flood hazard mitigation report for the 

Commonwealth of Virginia: Report FEMA-755-DRVirginia, 59 p. 

Government Accounting Office, 1988, Disaster assistanceResponse to West Virginia's November 1985 flood shows 

need for improvements: Report to Congressional Requesters 

GAO/RCED-88-5, 90 p. 

Jacobson, R.B., Linton, R.C., and Rubin, Meyer, 1989a, Alluvial 

stratigraphy of the Potomac River valley bottom near Petersburg and Moorefield, West Virginia: U.S. Geological Survey 

Open-File Report 89-485, 27 p., 14 pls. 

Jacobson, R.B., Miller, A.J., and Smith, J.A., 1989b, The role of 

catastrophic events in central Appalachian landscape evolution, in Gardner, T.W., and Sevon, W.D., eds., Appalachian 

geomorphology: Geomorphology, v. 2, p. 257-284. 

Introduction: Geomorphic Studies of the Storm and Flood of Nov. 3-5, 1985 A3 

Chapter B 

Meteorology of the Storm of 

November 3-5, 1985, in West Virginia 

and Virginia 

By STEPHEN j. COLUCCI, ROBERT B. JACOBSON, and 

STEVEN GRECO 

U.S. GEOLOGICAL SURVEY BULLETIN 1981 

GEOMORPHIC STUDIES OF THE STORM AND FLOOD OF NOVEMBER 3-5, 1985, IN 

THE UPPER POTOMAC AND CHEAT RIVER BASINS IN WEST VIRGINIA AND VIRGINIA 
II Contents 

CONTENTS 

Abstract Bl 

Introduction Bl 

Acknowledgments Bl 

Meteorological Factors Bl 

Antecedent Conditions B8 

Rainfall Distribution B9 

Duration, Intensity, and Frequency of Rainfall Bll 

Discussion B12 

References Cited B30 

FIGURES 

1. Schematic surface weather map, October 31 to November 5, 1985 B2 

2. Mid-tropospheric maps, October 31 to November 3, 1985 B3 

3. Temperature distribution maps, October 31 to November 3, 1985 BS 

4. Map showing positions of Hurricane and Tropical Storm Juan and the schematic 

500-mbar surface B7 

5. Map of temperature increase, 7 a.m., November 1, 1985 B8 

6. Rainfall map, October 1985 B9 

7. Histograms of rainfall records, Franklin and Spruce Knob, W. Va. BlO 

8. Rainfall map, November 3-5, 1985 B12 

9. Graphs showing representative hourly rainfall data, November 2-6, 1985 B27 

10. Graph of ratio of storm rainfall to estimated 100-yr rainfall B27 

11. Histograms of Franklin and Spruce Knob gage records B28 

12. Plots of exceedence probability of rainfall, Franklin and Spruce Knob 

gages B30 

TABLES 

1. Official NOAA rain gage network data, October and November 1-6, 1985 B13 

2. Nonofficial rainfall data from bucket surveys, November 1-6, 1985 B26 

3. Estimated recurrence intervals of peak rainfall B30 
Meteorology of the Storm of November 3-5, 1985, 

West Virginia and Virginia 

. 1n 

By Stephen J. Colucci, 1 Robert B. Jacobson,2 and Steven Greco3 

Abstract 

The storm of November 3-5, 1985, in the central 

Appalachian Mountains of West Virginia and Virginia 

resulted from a complex sequence of meteorological 

events. The stage was set by Hurricane Juan, which made 

landfall in the Gulf Coast on October 31. juan brought 

moisture northward up the Mississippi Valley; latent heat 

released by condensation aloft probably helped to render 

stationary a high-pressure anticyclone over southeastern 

Canada. A second low-pressure cyclone, moving north 

through the Southeastern United States, was blocked by 

the stationary anticyclone, intensifying a surface-pressure 

gradient that forced moist air from the Atlantic westward 

up the slope of the Appalachian Mountains. In the Cheat 

and Potomac River basins the resulting rainfall was of 

moderate intensity but of long duration. In Pendleton 

County, W. Va., the 1985 storm was the largest on record 

for durations from 24 to 72 h; the highest rainfall recurrence intervals were registered at durations of 24 to 48 h. 

Estimates of rainfall recurrence intervals from highly 

skewed records yield values ranging from 80 to 300 yr. 

INTRODUCTION 

Heavy rainfall during November 3-5, 1985, in West 

Virginia and Virginia produced extraordinary flooding and 

triggered thousands of landslides. Most of the damage 

occurred in the Cheat and Potomac River basins, although 

substantial damage was also recorded in the James River 

basin and smaller basins. The meteorological factors leading to the heavy rainfall are of interest in order to evaluate 

the frequency and spatial distributions of such storms in the 

Appalachian Mountains. This chapter discusses the meteorology of the storm, antecedent soil moisture conditions 

rainfall distribution, and frequency analysis of selected rai~ gage data in the Cheat and Potomac River basins. 

Manuscript approved for publication February 22, 1991. 1 Department of Soil, Crop and Atmospheric Sciences, Cornell 

University, Ithaca, NY 14853. 2 U.S. Geological Survey. 3 Department of Environmental Sciences, University of Virginia, 

Charlottesville, VA 22903. 

Acknowledgments 

We thank F. Richards and J.A. Smith of the National 

Weather Service for thoughtful reviews of this manuscript. 

We are grateful to T. Purkey, U.S. Soil Conservation 

Service, and S. Kite, West Virginia University, for use of 

their bucket-survey data. · 

METEOROLOGICAL FACTORS 

The heavy rainfall of November 3-5, 1985, was 

caused by a surface cyclone moving northeastward from the 

Gulf of Mexico along the southeastern Atlantic coastline 

toward a nearly stationary anticyclone over southeastern 

Canada (fig. 1). The surface pressure gradient between the 

cyclone and anticyclone centers increased from 9.3 x 10-3 

millibars per kilometer (mbarlkm) at 7 p.m. November 3 to 

18.4 X 10-3 mbar/km by 7 p.m. November 5. If the effects 

of surface friction are not taken into account, the horizontal 

surface winds are instantaneously proportional in magnitude 

to the pressure gradient and oriented perpendicular to the 

line connecting the low- and high-pressure centers, the low 

pressure occurring to the left. Therefore, the surface wind 

speed that was perpendicular to this line (which is roughly 

parallel to the Appalachian Mountains) theoretically doubled during this period. 

Precipitation is caused when rising moist air cools 

sufficiently to condense and form droplets large enough to 

fall to the surface. During the period under study, the moist, 

westward-moving air was transported upward over the 

mountains of Virginia and West Virginia and contributed to 

the substantial rainfall. Other mechanisms that might have 

contributed to this heavy rainfall include the ascent of warm 

moist air from the east over cold air trapped near the surface 

east of the mountains (typically observed with the arrangement of surface weather systems depicted in fig. 1) and (or) 

the ascent of air near the surface cyclone due to the 

ventilation of air aloft during intensification of the cyclone 

(that is, during the period of pressure fall at the cyclone 

center). 

Many factors may have influenced rainfall; therefore 

understanding the origin, behavior, and three-dimensional 

Meteorology of the Storm of Nov. 3-5, 1985, W. Va., Va. 81 
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WEST LONGITUDE, DEGREES 

Figure 1. Schematic surface weather map, October 31 to November 5, 1985. Positions of surface 

cyclone (L) and anticyclone (H), are marked for 7 p.m. EST with date and central pressure in 

millibars. 

structure of both the surface cyclone and the anticyclone 

will help explain the meteorological conditions that contributed to the flood. In the middle latitudes of the Northern 

Hemisphere, surface cyclones tend to be observed to the 

east of troughs aloft (relatively low height of the 500-mbar 

pressure surface in the middle troposphere), while surface 

anticyclones are found near ridges aloft (relatively high 

elevation of the 500-mbar pressure surface). A sequence of 

500-mbar maps preceding the event is presented in figure 2. 

The upper- level trough associated with the surface cyclone 

is observed at 7 a.m. November 3 over the lower Mississippi River Valley (fig. 2D), having moved eastward from 

western Mexico 24 h earlier (fig. 2C). Inspection of the 

500-mbar temperature maps for this case (fig. 3) reveals 

that the trough was a region of cold air relative to its 

surroundings. The ascent of air east of the trough caused air 

to expand and cool; hence the trough (and associated 

surface cyclone) moved generally eastward. 

The upper-level ridge associated with the surface 

anticyclone moved from the mid-Atlantic States at 7 a.m. 

October 31 (fig. 2A) to the Northeastern States 24 h later 

(fig. 2B) and finally merged with an upper-level ridge 

moving westward from over the Atlantic Ocean (fig. 2C). 

The merged ridge became stationary (compare figs. 2C and 

2D), accounting for the stationarity of the surface anticyclone. The stationarity of the upper-level ridge, a critical 

meteorological factor in this event, can be explained as 

follows. 

The upper-level ridge was warm relative to the 

surrounding air (fig. 3). Under ordinary conditions, the 

sinking (and thus compression and warming) of air parcels 

found east of the ridge would favor eastward displacement 

of the ridge and also of the surface anticyclone. Opposing 

the eastward displacement of the upper-level ridge is its 

westward drift due to the rotation of the Earth (the Coriolis 

effect). Also, since the ridge is a warm air mass, any 

processes that produce local atmospheric warming on the 

west side of the ridge would favor westward drift of the 

ridge. Temperatures at 500 mbar increased on the west side 

of the upper-level ridge during the period October 31 to 

November 5 (figs. 2, 3). Maximum warming was observed 

over northwestern Quebec, where 500-mbar temperatures 

increased from -30 oc on October 31 to -15 oc on 

November 2 (figs. 3A, C). 

This local warming may have caused the upper-level 

ridge to become stationary, or it may have been a conse82 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W. Va., Va. 
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(A) 7 a.m. October 31, (B) 7 a.m. November 1, (C) 7 a.m. ovember 2, and (D) 7 a.m. November 3. 

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Meteorology of the Storm of Nov. 3-5, 1985, W.Va., Va. 83 
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60 40 20 

WEST LONGITUDE, DEGREES 

Figure 3. Temperature distribution maps, October 31 to November 3, 1985. Shown are 500-mbar temperatures (degrees 

Celsius) at (A) 7 a.m. October 31, (B) 7 a.m. November 1, (Q 7 a .. m. November 2, and (D) 7 a.m. November 3. 

-18 

-22 -20 

-18 

-12 

-16 

-14 

"""q -8 ' 

'i' ~). . 

20 ~----~~~-~Q--~-~--·~~~~1~d~~~---~------~--------~--------~--·---10--~--------~~ 98 80 60 40 20 

WEST LONGITUDE, DEGREES 

Figure 3. Continued. 

Meteorology of the Storm of Nov. 3-5, 1985, W.Va., Va. 85 
. .. J=/.t··~ ~I ;)~. 'y~· ... . .. ~1 . I 

-24~ c ~ .<c-1.. vi-"~ < 

60 ~ ~ ~~~ ~~ ~ 

\~~~ . . ~ 

Cl) 

L.U 

c:::: 

L.U -28 ~\5 ~ (!) 

L.U 

0 -'-~~ '~~~ -~~'!. ~6 ·'"" 

-22 -20 

L.U' 

0 

II-

~ 

-1~ ~( Jl -24 

<( 40 _J -18 -16 -16 

::I: -18 Ic:::: 

0 

z ( -12 -14 

~~() -10 

..... ~ 

. -10 t:::,. ~ 

11 ). • -8 

I ~ \ 'p Q \ 0.. 0 I~ "" 20 

98 80 60 40 20 

WEST LONGITUDE, DEGREES 

Figure 3. Continued. 

60 

-30 . 

Cl) 

L.U . -24 

L.U 

c:::: 

(!) 

-16 

L.U 

0 

L.U' 

0 

~ 

I- -18 

I-

<( 40 _J 

::I: 

Ic:::: -16 . -22 

0 

z 

-12 

-6 

. -8 

20 ~'~--~--~----L-~-L---L----~~--------~----~~~-----L------~~ 

98 80 60 40 20 

WEST LONGITUDE, DEGREES 

Figure 3. Continued. 

86 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W. Va., Va. 
U) 

w 

w 

a: 

(!) 

w 

Cl 

w' 

Cl 

=> 

II-

<( 

....J 

:::c 

1-

a:: 

0 

z 

60 

40 -

20 

10/31, OOz 

/ 

10/31, OOz 

11/1, 12:00z 

120 100 80 60 40 20 0 

WEST LONGITUDE, DEGREES 

Figure 4. Positions of Hurricane and Tropical Storm juan (circled crosses) with dates and Greenwich (z) times (5 h before 

EST) and the position of the 5,460-m height contour at 500 mbar on October 31 and November 1 and 2, 1985. 

quence of the tendency for the ridge to drift westward due 

to the Coriolis effect. The possible impact of the Coriolis 

effect was evaluated with a diagnostic model that estimates 

the change in height of the 500-mbar surface (Holton, 

1979). Calculations showed that, in the 48-h period centered at 7 a.m. November 1, the Coriolis effect could have 

contributed approximately +40 m to the height change of 

the 500-mbar surface. This value is an order of magnitude 

smaller than the observed height increase of about 400 m 

between 7 a.m. October 31 and 7 a.m. November 2 (figs. 

2A, 2C). Assuming as a boundary condition that the 

Coriolis effect produced no change in the pressure or 

temperature of the surface weather systems, then the model 

calculation also implies a 2 °C increase over 48 h in the 

temperature of the 500-mbar surface over northwestern 

Quebec. This is much smaller than the observed 15 oc 

warming at 500 mbar during this period. Thus, the Coriolis 

effect does not appear to have contributed significantly to 

local warming, suggesting that the warming was primarily a 

cause, rather than a consequence, of the westward drift and 

the near stationarity of the upper-level ridge. 

The warm air over Quebec could have been produced 

locally by the release of heat from precipitating clouds, for 

example, or it could have been imported from a remote 

location. The northward migration of the -16 °C isotherm 

at 500 mbar from near the Great Lakes at 7 a.m. October 31 

(fig. 3A) to northeastern Canada at 7 a.m. November 2 (fig. 

3C) suggests the latter possibility. Note that 500-mbar 

winds, being parallel to the height contours, were from the 

south over this key region at 7 a.m. November 1 (fig. 2B) 

and 7 a.m. November 2 (fig. 2C). Farther to the south, a 

uniformly warm air mass existed within an upper-level 

trough over Louisiana at 7 a.m. October 31 (figs. 2A, 3A). 

Ordinarily, upper-level troughs are cold, but this one was 

associated with Hurricane Juan, situated on the Louisiana 

border. This storm, accompanied by substantial rainfall 

(Case, 1986) and attendant release of latent heat, subsequently moved inland, as illustrated in figure 4. This figure 

also schematically illustrates concurrent changes in the 

500-mbar patterns over North America an~ the Atlantic 

Ocean. 

A simple estimate of the heat released in the hurricane's precipitation is obtained by assuming that the heat 

Meteorology of the Storm of Nov. 3-5, 1985, W.Va., Va. 87 
en 

u..J 

u..J 

cc 

C!:l 

u..J 

0 

u..J~ 

60 

0 

::> 

II- 40 

<( 

.....J 

::I: 

Icc 

0 

z 

120 100 80 60 40 

WEST LONGITUDE, DEGREES 

Figure 5. Temperature increase (in degrees Celsius per 12 h) of air at 500 mbar due to precipitation at 7 a.m. on 

November 1. 

release is distributed in the vertical direction in proportion 

to total heating calculated as a residual in the thermodynamic energy equation (Holton, 1979). Heating from the 

vertically integrated precipitation is calculated with 

satellite-derived estimates of ground precipitation (Robertson, 1987). The heating thus obtained at 500 mbar is shown 

in figure 5 for 7 a.m. Novembe~ 1. The calculated heating 

maxima occur far from the region of the maximum 500-

mbar temperature increase over Quebec, suggesting thatprecipitation heating is not directly responsible for warming 

the Quebec upper-level trough. However, because the 

heating maximum near the Great Lakes is situated upwind 

from northwestern Quebec (compare figs. 2B and 5), the 

heat generated by precipitation over the Great Lakes could 

have been imported to northwestern Quebec. In fact, the 

maximum calculated heating rate near the Great Lakes 

(3.81 °CI12 h) corresponds exactly to the 15 °C/48 h 

warming observed over northwestern Quebec. This analysis 

suggests that heating from precipitation over the Great 

Lakes influenced the local warming over Quebec. 

The heavy rainfall of November 3-5 in West Virginia 

and Virginia therefore appears to be an indirect consequence of Hurricane Juan. The heat released in the rainfall 

was transported northward, thereby favoring westward 

(rather than eastward) displacement of a warm 500-mbar 

upper-level ridge. This movement, in tum, favored the 

stationarity of a surface anticyclone over southeastern 

Canada. In conjunction with a northward-moving surface 

cyclone, this stationary anticyclone caused an increase in 

the surface pressure gradient along the Appalachian Mountains, the flow of surface air up the mountains, and thus the 

heavy precipitation. 

This complex sequence of events was specific to this 

storm and is unlikely to repeat itself exactly. However, the 

general situation of a stationary surface anticyclone over 

southeastern Canada and surface cyclone over the Southeastern United States is a recurring blocking pattern that has 

been associated with other substantial rainstorms in the 

Eastern United States (Hirschboeck, 1987). 

ANTECEDENT CONDITIONS 

The rainfall of November 3-5 occurred at a time of 

year when leaves had fallen from the trees and ambient air 

temperatures were relatively low. As a result, evapotranspiration was probably minimally effective in removing 

antecedent soil moisture. 

Usually, October is a month of low soil moisture in 

the central Appalachians. No direct data exist on soil 

moisture for the period antecedent to the storm, but rainfall 

and streamflow data for October 1985 suggest that storage 

levels of soil moisture were moderate. Figure 6 shows 

88 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W.Va., Va. 
41 

N 

I 

0 25 50 MILES 

0 25 50 KILOMETERS 

C/) 

L.U 

L.U 

0::: 

(!) 

L.U 

0 39 L.U' 

0 

::> 150 II-

<( 

.....J 

:I: 

I- 100 0::: 

0 

z 

37 

82 

75 

( l 

1 

50 

80 

''100 

100 

~50 

PENNSYLVANIA 

~,, 50 

78 76 

WEST LONGITUDE, DEGREES 

Figure 6. Rainfall map for October 1985 (data from NOAA, 1986). 

rainfall during October 1985 for West Virginia and Virginia. In the Cheat and Potomac River basins, October 

rainfall was as much as 200 percent of normal at isolated 

rain gages, but most stations were only slightly above 

normal (normal values are calculated as the average for the 

years 1951-1980). Thirty-day rainfall totals for September 

and October at Spruce Knob and Franklin, W. Va., show 

that the 1985 totals were equaled or exceeded in more 

than half the years of record (fig. 7). Average streamflow 

for the month was also slightly above normal. At the South 

Branch Potomac River gage at Springfield, W. Va., in 

October 1985 the average streamflow was 125 percent of 

normal (Embree and others, 1987; S. Runner, personal 

communication). 

RAINFALL DISTRIBUTION 

The sequence of meteorological events described 

above produced large amounts of rainfall at moderate 

intensity and long duration. The isohyetal map for November 3-5 is shown in figure 8. This map was contoured from 

the official National Oceanic and Atmospheric Administration (NOAA) rain gage network (table 1) and shows the 

general spatial distribution and magnitude of the storm. 

Although the extremes of high and low precipitation from 

the storm are probably not recorded by the official gage 

network, data from bucket surveys in West Virginia do not 

disagree substantially with figure 8 (table 2). 

Figure 8 shows a large area of concentrated rainfall 

(totals exceeding 250 mm) dominating eastern West Virginia and western Virginia. Along the Blue Ridge in central 

Virginia, local orographic effects appear to have triggered 

intense convection, and total rainfall for the storm was in 

excess of 325 mm. Reconnaissance of the central Virginia 

area shortly after the storm revealed little flood and landslide damage, possibly because of the hydrologic and 

geomechanical stability of the particular rocks and regoliths 

under conditions of rainfall intensity and duration of this 

Meteorology of the Storm of Nov. 3-5, 1985, W. Va., Va. 89 
250 I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I T T T T T T T T T T T T T T I I I 

~ ~A - ffi 200 f---

1--

LJ..J 

~ 

:3 150 fQ I I I 

1945 1955 1965 

YEAR 

-

-

-

-

-

-

1975 1985 1995 

FRANKLIN 30-DAY RAINFALL, SEPTEMBER AND OCTOBER 

I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I 

250 f- -

~ 

c:: 

~ 200 fLU 

~ 

:3 150 f.-

~ 100 f- _J~ 

_J 

<( 

u.. 

z 

<( 

c:: 

50 f1--

0 I I I I I I 

1945 

~' 1955 1965 

-

-

-

-

-

-

-

-

~I -II II II Ill I I I I I I I 

1975 1985 1995 

YEAR 

SPRUCE KNOB 30-DAY RAINFALL, SEPTEMBER AND OCTOBER 

Figure 7. Rainfall records from gages at Franklin and Spruce Knob, W. Va. (A, B) 

Thirty-day duration rainfall during the months of September and October for the years 

of record. (C, D) Thirty-day duration rainfall for all months of the year (100-mm 

minimum cut off) (data from NOAA, 1986). 

storm. Alternatively, slopes and channels in the area may 

still be adjusted to the intense precipitation from Hurricane 

Camille in 1969 (Williams and Guy, 1973; Gryta and 

Bartholomew, 1989). 

The most dramatic flood and landslide damage in 

1985 was associated with the rainfall maximum located in 

eastern West Virginia (fig. 8). Rain-gage data recorded 

hourly illustrate the history of the storm. Rainfall intensities 

were not exceptional (fig. 9). The most rainfall for 1-h 

duration was only 38 mm/h, recorded at Hot Springs, Va. 

According to Hershfield (1961), 1-h rainfall intensities of 

this magnitude recur on the average approximately every 3 

yr in the central Appalachian Mountains. Due to the sparse 

network of hourly recording rain gages, it is likely that 

actual hourly intensities were greater than those recorded. 

Anecdotal accounts by residents, however, did not emphasize extreme intensities. 

Although intensities were only moderate, duration of 

rainfall was long. In eastern West Virginia the storm began 

late in the morning of November 4, peaked in the early 

evening, and continued into the morning of November 5. 

For durations up to 8 h, intensity was near 10 mm/h at many 

hourly recording gages and probably over much of the area. 

The main storm event was a little longer than 24 h in 

duration, ending by evening on November 5. Several rain 

gages also reported light rainfall preceding the event on 

November 3 and lasting into the evening of November 5 

(table 1). 

Rainfall in eastern West Virginia and western Virginia was concentrated in the headwaters of the Cheat and 

Potomac River basins. An isohyetal map for this area at 

larger scale is shown in plate 1 of Jacobson (chapter A, this 

volume). Although most of the rain fell on November 4, 

this map incorporates gage data over the period November 

810 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W.Va., Va. 
350 I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I 

C/) f- c -

a: 

L.U 280 1- r- -

L.U 

2: I- -

::::::i 210 

= r- -

2: I- -

~ 140 _.r r- -

....J 

<( f- - u.. 

z 70 I-- -

<! 

a: f- -

0 I I J .I I II I I I I I I I I 

1945 1955 1965 1975 1985 1995 

YEAR 

FRANKLIN 30-DAY RAINFALL 

350 

C/) 

a: 

L.U 280 1-

L.U 

2: 

::::::i 210 ....J 

2: 

~ 140 ....J-

....J 

<( 

u.. 

z 70 

<! 

a: 

0 

1945 1955 1965 1975 1985 1995 

YEAR 

SPRUCE KNOB 30-DAY RAINFALL 

Figure 7. Continued. 

3-5 in order to include all rain delivered as the storm moved 

across the area and to account for different reading times 

among gages. Peak rainfall recorded in this area for a 24-h 

period was 191 mm at Franklin, W. Va., and for a 48-h 

period was 241 mm at Upper Tract, W. Va. 

The rainfall was also spread over a large part of the 

mountainous region; an area in excess of 12,800 km2 

received more than 220 mm (Miller, 1990). 

DURATION, INTENSITY, AND FREQUENCY OF 

RAINFALL 

The storm of November 3-5, 1985, was remarkable 

for its moderate intensity and long duration. Depicted 

graphically in figure 10 is the ratio of recorded rainfall to 

rainfall of the 100-yr event for durations ranging from 1 h to 

7 days. Total rainfall of the 100-yr event is estimated from 

Hershfield ( 1961) and Miller ( 1964); because these data 

sources are fairly old, the plotting of the recorded data 

points with respect to the vertical axis may not be very 

accurate. However, of more interest is plotting with respect 

to the horizontal axis, which shows the relative importance 

of rainfall durations for a single storm. The 1985 storm was 

important over long time intervals, peaking in the 1- to 

2-day durations. 

Two representative rain gages in the South Branch 

Potomac River basin were chosen for frequency analysis 

because of their long records and locations near the main 

concentration of rainfall. The Franklin, W. Va. , gage began 

in 1949 and the Spruce Knob, W.Va., gage began in 1952. 

Histograms of rainfall totals for these gages for 1-, 2-, and 

4-day durations are shown in figure 11. 

At the Franklin gage the 1985 storm was the largest 

on record at all durations. The 1985 storm and three others 

(1949, 1954, and 1972) form a subset of events that are 

much greater in magnitude than the background events. 

Similarly, at the Spruce Knob gage, the 1985 and 1972 

storms are appreciably larger than the other events in the 

record. These subsets of large events result in hibhly 

skewed populations and suggest the possibility that the 

record consists of a mixed population of storms; the large 

events may result from meteorological processes that are 

quite different from the remainder of the events. Similar 

Meteorology of the Storm of Nov. 3-5, 1985, W.Va., Va. 811 
41 

N 

I 50 

100 PENNSYI~VANIA 

0 25 50 MILES 50 

·~ 

0 25 50 KILOMETERS 25 

(/) 150 UJ 

UJ 

c:::: 

~ 100 UJ 

0 39 '225 UJ~ 

0 

::) 75 II- 150 

<( 

-I 

:c 

I- \:VEST c:::: 

0 

z 

250, 

100 

75' 

:100, · 25tF VIRGINIA 

200 .:150"' 

100 '' 

125 

37 

82 80 78 76 

WEST LONGITUDE, DEGREES 

Figure 8. Rainfall map for November 3-5, 1985 (data from NOAA, 1986). 

mixed populations of rainfall and runoff events have been 

noted elsewhere in North America, especially where floods 

are generated by snowmelt and convective thunderstorms; if 

sufficient numbers of events exist for the constituent populations, then frequency, duration, and magnitude can be 

evaluated separately for different types of events, and more 

accurate models can be made (Waylen, 1985). 

With the limited number of large events in the Spruce 

Knob and Franklin records, an analysis based on mixed 

populations was not attempted. For this study the population was treated as homogeneous. The annual series of the 

1- and 2-day rainfall records were subjected to frequency 

analysis using log Pearson type III models with regional 

skew coefficients calculated from four neighboring gages. 

Frequency plots with the log Pearson type III model fitted 

with regional skew coefficients are shown in figure 12, and 

estimates of peak rainfall recurrence intervals are given in 

table 3. The recurrence intervals of the 2-day rainfall peak 

recorded at the Upper Tract gage were estimated from the 

Franklin model. 

The highly skewed distributions give a wide range of 

recurrence intervals for the rare, larger rainfalls, and for 

both gages the 1985 event falls outside the 95 percent 

confidence intervals. Using the models as the best available 

estimates, one would conclude that events of the magnitude 

of the 1985 storm event would recur on the average 

approximately every 80-300 yr. This estimate is in general 

agreement with estimates of the 100- to 500-yr recurrence 

intervals for flooding from this storm (Miller and Parkinson, chapter E, this volume). 

DISCUSSION 

The total rainfall, intensity, and duration of the storm 

are unique in the historical records of this part of the central 

Appalachians. The sequence of meteorological events 

812 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W.Va., Va. 
~ II) 

;-

0 

3 

0 

~ 

0 

--::r 

II) 

~ 0 

3 

s. 

z 

0 

~ 

w 

in 

... 

!.&> 

!J1 = 

~ 

p 

~ 

~ w 

Table 1. Official NOM rain gage network data, October and November 1-6, 1985 

Latitude Longitude 

arc arc October 

Station deg min deg min 1985 

180015 39 28 76 10 80.5 

180193 38 59 76 30 112.5 

180335 38 14 75 8 67.1 

180465 39 11 

180470 39 17 

180700 39 2 

180732 39 30 

181032 39 13 

181125 39 12 

181385 38 34 

76 40 

76 37 

76 53 

76. 23 

77 20 

77 1 

76 4 

63.0 

48.5 

69.9 

71.6 

105.9 

75.9 

45.7 

181530 39 39 77 29 96.0 

181750 39 13 76 4 78.0 

181862 39 15 76 56 76.2 

181995 38 59 76 57 65.3 

182060 39 39 76 10 41.9 

182215 37 59 75 52 110.0 

182282 39 38 78 45 105.9 

182325 38 56 77 7 91.7 

182335 39 16 77 14 85.1 

182523 38 53 75 48 56.1 

182770 39 40 77 33 80.8 

182906 39 41 77 18 77.0 

183348 39 25 77 26 88.9 

183355 39 24 77 22 104.4 

183415 39 40 78 56 142.7 

183675 38 58 76 

183975 39 39 77 

48 89.9 

44 96.5 

184030 39 42 78 11 102.1 

185080 38 32 77 0 129.8 

185111 39 6 76 54 81.8 

185832 39 35 79 22 112.8 

185865 38 26 76 43 111.8 

185894 39 36 79 5 121.9 

185985 39 16 75 52 63.8 

186350 38 54 76 59 88.4 

186620 39 24 

186770 38 41 

79 24 121.7 

76 40 105.2 

o.o 

1.0 

4.1 

o.o 

o.o 

0.8 

o.o 

2.5 

o.o 

2.3 

1.5 

0.0 

o.o 

3.6 

o.o 

3.3 

0.8 

7.6 

3.3 

o.o 

0.3 

1.3 

2.5 

1.8 

5.1 

1.0 

4.6 

3.0 

5.1 

o.o 

0.5 

7.9 

2.3 

o.o 

3.0 

3.0 

11.4 

2 

0.0 

0.3 

0.8 

0.0 

0.0 

0.5 

0.0 

0.3 

0.0 

0.0 

0.8 

0.5 

0.0 

0.3 

0.0 

0.3 

2.3 

1.0 

1.0 

0.0 

1.3 

0.0 

0.0 

1.3 

15.0 

0.5 

0.5 

1.8 

2.0 

1.3 

3.8 

5.6 

5.1 

o.o 

12.7 

6.6 

1.3 

4 

o.o 1.5 

0.5 20.6 

0.0 0.3 

2.8 

2.5 

0.0 

2.0 

1.8 

2.0 

0.0 

33.0 

0.8 

0.0 

0.3 

1.0 

0.5 

7.9 

1.3 

2.0 

0.8 

5.1 

17.8 

11.4 

1.8 

14.0 

1.5 

17.3 

30.0 

7.1 

1.8 

8.9 

4.6 

3.8 

0.5 

5.1 

14.0 

16.0 

24.1 

30.5 

23.9 

8.1 

14.2 

33.0 

6.6 

61.5 

3.0 

17.0 

19.8 

0.0 

13.5 

37.6 

29.7 

24.1 

4.6 

34.3 

41.1 

25.9 

17.8 

57.9 

26.7 

25.9 

21.8 

33.8 

36.8 

17.8 

21.8 

40.6 

0.5 

23.4 

39.6 

19.0 

November 1985 

3-4 4-5 

Maryland 

6.6 5.1 1.5 8.1 

7.1 10.9 21.1 27.7 

9.4 2.0 0.3 9.7 

4.3 

8.1 

14.5 

26.9 

19.6 

10.2 

5.6 

38.6 

6.6 

14.5 

15.5 

10.9 

1.3 

31.8 

12.2 

21.6 

4.3 

62.2 

13.2 

20.6 

20.3 

83.6 

12.7 

18.5 

39.9 

6.4 

o.o 

65.5 

4.1 

70.1 

6.9 

30.5 

66.5 

10.2 

0.8 

0.3 

3.0 

9.9 

2.3 

0.0 

6.9 

2.5 

0.8 

2.5 

4.1 

5.8 

5.8 

1.3 

1.3 

2.5 

0.0 

5.8 

2.5 

6.4 

15.2 

3.0 

2.8 

2.0 

0.5 

0.3 

o.o 

15.2 

o.o 

6.4 

4.3 

4.3 

2.3 

1.5 

26.9 

33.0 

23.9 

10.2 

16.0 

35.1 

6.6 

94.5 

3.8 

17.0 

20.1 

1.0 

14.0 

45.5 

31.0 

26.2 

5.3 

39.4 

58.9 

28.4 

38.6 

38.4 

35.1 

33.8 

43.2 

12.2 

100.1 

9.7 

31.5 

35.3 

10.9 

14.7 

69.3 

41.9 

45.7 

8.9 

96.5 

54.4 

37.3 46.5 

19.6 38.1 

71.9 141.5 

28.2 39.4 

43.2 44.5 

51.8 61.7 

40.9 40.1 

38.6 36.8 

26.7 83.3 

26.4 25.9 

44.5 110.7 

1.0 7.4 

28.4 53.8 

53.6 106.2 

35.1 29.2 

5-6 3-5 4--6 3--6 

11.7 8.1 13.2 13.2 

18.0 28.2 38.6 39.1 

11.4 9.7 11.7 11.7 

5.1 

8.4 

17.5 

36.8 

21.8 

10.2 

12.4 

31.2 

41.1 

38.4 

37.1 

35.6 

45.2 

12.2 

29.2 

38.9 

41.4 

45.0 

36.1 

43.2 

19.1 

32.0 

41.4 

41.4 

47.0 

37.8 

45.2 

19.1 

1--6 

13.2 

40.4 

16.5 

32.0 

41.4 

42.7 

47.0 

40.6 

45.2 

21.3 

41.1 133.1 102.6 135.6 137.9 

7.4 10.4 10.4 11.2 11.7 

17.0 31.5 34.0 34.0 34.0 

19.6 

16.8 

7.1 

33.0 

13.5 

24.1 

35.6 39.4 39.6 

11.9 16.8 17.8 

15.2 20.6 21.1 

77.2 70.6 78.5 

43.2 43.2 44.5 

47.8 48.3 50.3 

43.4 

17.8 

24.6 

81.5 

53.1 

54.6 

4.3 9.7 8.9 9.7 9.7 

68.1 101.6 102.4 107.4 109.0 

15.7 72.1 56.9 74.7 75.9 

26.9 57.9 52.8 64.3 66.8 

35.6 39.9 53.3 55.1 58.2 

86.6 155.4 144.5 158.5 

15.5 40.9 42.2 43.7 

20.6 61.7 46.5 63.8 

40.4 91.7 62.2 92.2 

178.6 

45.2 

68.8 

97.0 

6.6 47.2 40.4 47.5 54.6 

0.0 38.6 36.8 38.6 39.9 

80.8 92.2 98.6 107.4 111.8 

4.1 30.5 25.9 30.5 43.9 

76.5 114.6 117.1 120.9 128.3 

11.2 7.9 11.7 12.2 12.2 

34.8 58.9 58.2 63.2 79.0 

68.8 120.1 108.5 122.4 

11.7 45.2 30.7 46.7 

132.1 

59.4 
~ 

"" 

C1 

~ 

3 

0 

""l 

"'C 

::r 

;::;-

~ c 

Q. 

;:;· 

~ 

~ 0 

3 

Ill 

:::J 

Q. 

.., 

0 

0 

Q. 

0 

-

z 

0 

~ 

w 

y. 

..... 

I.C 

,?1 = 

~ 

< f 

~ 

Table 1. Official NOM rain gage network data, October and November 1-6, 1985-Continued 

Station 

186844 

186915 

187272 

187330 

187705 

187806 

188000 

188005 

188065 

188380 

latitude longitude 

deg 

39 

38 

39 

38 

39 

38 

38 

38 

39 

38 

arc arc 

min deg min 

38 76 42 

20 76 25 

2 77 15 

13 75 41 

6 77 6 

43 76 11 

22 75 35 

20 75 31 

31 79 8 

14 75 23 

October 

1985 

75.7 

103.4 

91.7 

56.6 

83.6 

52.1 

60.7 

48.3 

188877 39 23 

189030 39 27 

189070 38 52 

189140 38 29 

189440 39 33 

189750 39 20 

76 34 

77 11 

76 47 

75 50 

76 58 

76 52 

140.0 

115.3 

84.3 

77.5 

117.1 

60.7 

72.9 

69.6 

360022 

360106 

360130 

360140 

360355 

360409 

360457 

360475 

360482 

360488 

360560 

360656 

360738 

360763 

360785 

360821 

360861 

360865 

360867 

360868 

361004 

40 32 79 

40 39 75 

40 18 78 

40 30 78 

40 39 79 

41 40 79 

40 50 76 

40 46 80 

40 46 77 

40 23 75 

40 46 75 

39 56 77 

40 26 79 

40 16 77 

40 23 76 

40 9 79 

40 24 79 

41 48 78 

41 57 78 

41 57 78 

41 9 79 

49 69.9 

26 50.0 

19 63.8 

28 95.0 

59 39.4 

2 39.1 

30 47.8 

19 44.5 

9 76.2 

37 63.2 

44 39.1 

15 49.3 

9 84.1 

22 40.6 

2 38.4 

2 80.8 

52 54.9 

38 54.9 

39 82.6 

44 102.9 

5 63.8 

o.o 

2.8 

3.0 

1.5 

3.3 

0.0 

0.5 

0.8 

1.0 

5.6 

o.o 

0.0 

1.5 

0.5 

0.0 

o.o 

0.0 

o.o 

1.0 

0.0 

2.3 

24.1 

o.o 

0.0 

o.o 

0.0 

0.0 

o.o 

0.0 

0.0 

0.0 

0.0 

o.o 

o.o 

0.0 

o.o 

0.0 

2 

0.0 

3.0 

1.3 

o.o 

0.8 

0.0 

o.o 

4.3 

10.2 

0.0 

0.0 

7.6 

0.8 

0.3 

0.0 

0.0 

0.5 

0.0 

4.1 

o.o 

13.5 

13.5 

o.o 

0.0 

2.8 

0.0 

o.o 

0.0 

0.0 

o.o 

0.0 

5.6 

0.8 

6.1 

4.1 

10.2 

0.3 

1.3 

1.8 

2.5 

0.8 

1.8 

0.0 

0.0 

0.8 

7.6 

1.3 

3.8 

5.1 

1.3 

0.0 

2.0 

2.5 

11.9 

0.0 

18.8 

10.9 

55.9 

55.9 

0.0 

14.2 

32.3 

0.0 

o.o 

3.0 

11.9 

4.6 

0.0 

8.9 

10.9 

15.7 

5.1 

29.2 

12.4 

4 

32.3 

14.7 

26.7 

9.4 

44.5 

7.9 

6.6 

11.7 

47.5 

8.1 

17.3 

12.7 

18.5 

6.1 

13.5 

17.3 

7.1 

1.0 

3.0 

3.3 

6.9 

4.6 

3.0 

4.3 

90.9 

7.9 

19.6 

16.0 

16.8 

2.8 

14.5 

20.3 

Pennsylvania 

0.0 

0.3 

o.o 

9.9 

0.0 

8.1 

0.8 

1.0 

5.3 

4.3 

10.2 

0.5 

3.0 

3.8 

4.3 

2.8 

54.6 33.3 1.0 

4.6 20.1 2.5 

21.1 26.9 0.3 

33.0 24.9 4.6 

41.4 2.5 1.0 

38.4 13.0 7.9 

4.3 9.1 6.4 

38.1 50.0 8.1 

11.2 10.7 0.0 

1.3 27.2 2.5 

o.o 13.0 11.9 

48.0 35.1 9.9 

25.9 9.9 9.4 

36.1 20.8 3.3 

o.o 24.1 3.8 

9.7 16.5 6.6 

53.3 30.5 1.3 

7.9 9.9 1.8 

19.0 7.1 7.9 

11.7 6.4 0.5 

33.3 4.3 0.5 

November 1985 

3-4 

33.5 

16.5 

29.2 

10.2 

46.2 

7.9 

6.6 

12.4 

55.1 

9.4 

21.1 

17.8 

19.8 

6.1 

15.5 

19.8 

66.5 

4.6 

39.9 

43.9 

97.3 

94.2 

4.3 

52.3 

43.4 

1.3 

0.0 

51.1 

37.8 

40.6 

o.o 

18.5 

64.3 

23.6 

24.1 

40.9 

45.7 

4-5 

39.4 

15.7 

29.7 

12.7 

51.3 

12.4 

9.7 

16.0 

138.4 

16.0 

36.8 

28.7 

35.3 

8.9 

27.9 

37.6 

87.9 

24.6 

48.0 

57.9 

43.9 

51.3 

13.5 

88.1 

21.8 

28.4 

13.0 

83.1 

35.8 

56.9 

24.1 

26.2 

83.8 

17.8 

26.2 

18.0 

37.6 

5--{, 

7.1 

1.3 

3.0 

13.2 

6.9 

12.7 

3.8 

5.3 

96.3 

12.2 

29.7 

16.5 

19.8 

6.6 

18.8 

23.1 

34.3 

22.6 

27.2 

29.5 

3.6 

20.8 

15.5 

58.2 

10.7 

29.7 

24.9 

45.0 

19.3 

24.1 

27.9 

23.1 

31.8 

11.7 

15.0 

6.9 

4.8 

3-5 

40.6 

17.5 

32.3 

13.5 

53.1 

12.4 

9.7 

16.8 

146.1 

17.3 

40.6 

33.8 

36.6 

8.9 

30.0 

40.1 

99.8 

24.6 

66.8 

68.8 

99.8 

107.2 

13.5 

102.4 

54.1 

28.4 

13.0 

86.1 

47.8 

61.5 

24.1 

35.1 

94.7 

33.5 

31.2 

47.2 

50.0 

4--{, 

39.4 

16.0 

29.7 

22.6 

51.3 

20.6 

10.4 

17.0 

143.8 

20.3 

47.0 

29.2 

38.4 

12.7 

32.3 

40.4 

88.9 

27.2 

48.3 

62.5 

45.0 

59.2 

19.8 

96.3 

21.8 

31.0 

24.9 

93.0 

45.2 

60.2 

27.9 

32.8 

85.1 

19.6 

34.0 

18.5 

38.1 

3--{, 

40.6 

17.8 

32.3 

23.4 

53.1 

20.6 

10.4 

17.8 

151.4 

21.6 

50.8 

34.3 

39.6 

12.7 

34.3 

42.9 

100.8 

27.2 

67.1 

73.4 

100.8 

115.1 

19.8 

110.5 

54.1 

31.0 

24.9 

96.0 

57.2 

64.8 

27.9 

41.7 

96.0 

35.3 

39.1 

47.8 

50.5 

1--{, 

40.6 

23.6 

36.6 

24.9 

57.2 

20.6 

10.9 

22.9 

162.6 

27.2 

50.8 

41.9 

41.9 

13.5 

34.3 

42.9 

101.3 

27.2 

72.1 

73.4 

116.6 

152.7 

19.8 

110.5 

56.9 

31.0 

24.9 

96.0 

57.2 

64.8 

27.9 

47.2 

96.8 

41.4 

43.2 

57.9 

50.8 
~ ~ 

;-

0 

a 

Q 

~ 

0 

...... 

-::r 

~ 

~ 0 

3 

S.· 

z 

0 

~ 

w 

jn 

... 

<J:> 

!J1 = 

~ 

; 

~ 

~ (J1 

Table 1. Official NOM rain gage network data, October and November 1-6, 1985-Continued 

Station 

361033 

361080 

361087 

361105 

361139 

361212 

361255 

361301 

361342 

361350 

361354 

361377 

361480 

361485 

361505 

361519 

361534 

361591 

361705 

361719 

361726 

361737 

361749 

361773 

361790 

361806 

361833 

361881 

362013 

362108 

362116 

362183 

362190 

362221 

362260 

362343 

latitude longitude 

arc arc October 

deg min deg min 1985 

40 

40 

39 

40 

40 

41 

40 

41 

39 

39 

39 

40 

41 

41 

40 

41 

41 

39 

18 

31 

57 

23 

51 

39 

35 

31 

52 

51 

56 

9 

3 

12 

37 

1 

44 

59 

79 59 

75 12 

78 39 

80 26 

79 55 

76 51 

78 42 

77 27 

75 37 

79 35 

77 38 

79 54 

77 56 

79 26 

75 39 

78 27 

78 32 

75 52 

39 48 79 

41 44 80 

39 60 79 

40 4 75 

41 20 79 

40 30 ·eo 

41 55 79 

41 50 78 

41 44 77 

40 41 79 

40 58 76 

40 18 79 

40 5 75 

40 8 79 

40 10 79 

40 18 75 

41 11 78 

41 24 76 

22 

17 

36 

19 

13 

5 

38 

4 

7 

12 

37 

20 

33 

24 

52 

8 

54 

35 

67.8 

53.3 

113.0 

75.2 

61.0 

55.1 

51.8 

43.2 

43.2 

83.1 

52.8 

46.5 

40.9 

59.9 

39.6 

48.0 

61.5 

57.4 

77.5 

83.8 

63.0 

44.7 

77.5 

56.9 

89.9 

58.4 

41.1 

56.1 

34.8 

146.1 

47.8 

64.8 

55.1 

61.5 

54.4 

46.7 

o.o 

o.o 

2.3 

o.o 

0.3 

0.0 

o.o 

17.8 

17.8 

0.0 

7.1 

o.o 

0.0 

0.3 

0.0 

0.3 

o.o 

o.o 

o.o 

o.o 

0.0 

0.0 

o.o 

o.o 

o.o 

o.o 

o.o 

o.o 

o.o 

o.o 

o.o 

0.3 

2.3 

o.o 

0.3 

o.o 

o.o 

0.0 

1.8 

1.3 

1.0 

o.o 

o.o 

0.0 

0.0 

0.5 

0.5 

2.8 

o.o 

0.3 

o.o 

o.o 

0.0 

0.0 

2.5 

o.o 

1.3 

o.o 

0.0 

15.2 

6.1 

o.o 

0.0 

o.o 

o.o 

4.6 

0.0 

2.5 

6.6 

0.0 

2.5 

0.0 

0.0 

0.0 

11.4 

15.2 

16.3 

0.0 

7.9 

7.9 

0.0 

11.7 

18.8 

14.0 

0.0 

11.4 

o.o 

5.1 

5.3 

1.0 

11.7 

13.2 

11.4 

o.o 

11.4 

33.3 

8.6 

7.1 

o.o 

7.1 

o.o 

21.3 

1.3 

10.4 

10.9 

0.0 

11.9 

0.0 

4 

74.9 

8.1 

34.8 

41.4 

35.1 

14.5 

15.7 

15.7 

o.o 

32.8 

17.8 

53.3 

0.0 

55.1 

0.0 

24.9 

19.6 

14.7 

17.8 

14.0 

25.4 

0.0 

50.3 

32.5 

35.6 

14.7 

10.9 

26.9 

10.7 

33.0 

38.1 

17.0 

49.5 

o.o 

15.7 

3.3 

30.5 

14.5 

55.4 

63.5 

42.7 

9.7 

23.6 

23.6 

25.9 

36.8 

30.2 

39.4 

o.o 

19.0 

15.5 

8.1 

8.6 

13.5 

35.1 

99.6 

22.9 

36.1 

10.2 

0.5 

35.6 

6.4 

10.2 

5.6 

7.1 

3.0 

5.1 

16.8 

12.7 

25.1 

0.8 

6.4 

November 1985 

0.3 

0.5 

8.4 

3.3 

0.8 

3.8 

7.9 

7.9 

5.6 

11.7 

0.5 

1.8 

0.0 

0.5 

12.4 

2.3 

3.8 

0.3 

10.4 

18.0 

10.2 

2.5 

1.8 

0.0 

2.0 

2.5 

6.4 

4.6 

7.1 

22.6 

0.0 

10.2 

0.5 

o.o 

o.o 

6.1 

3-4 

74.9 

8.1 

46.2 

56.6 

51.3 

14.5 

23.6 

23.6 

0.0 

44.4 

36.6 

67.3 

0.0 

66.5 

0.0 

30.0 

24.9 

15.7 

29.5 

27.2 

36.8 

0.0 

61.7 

65.8 

44.2 

21.8 

10.9 

34.0 

10.7 

54.4 

39.4 

27.4 

60.5 

0.0 

27.7 

3.3 

4-5 

105.4 

22.6 

90.2 

104.9 

77.7 

24.1 

39.4 

39.4 

25.9 

69.6 

48.0 

92.7 

0.0 

74.2 

15.5 

33.0 

28.2 

28.2 

52.8 

113.5 

48.3 

36.1 

60.5 

33.0 

71.1 

21.1 

21.1 

32.5 

17.8 

36.1 

43.2 

33.8 

62.2 

25.1 

16.5 

9.7 

5-6 

30.7 

15.0 

63.8 

66.8 

43.4 

13.5 

31.5 

31.5 

31.5 

48.5 

30.7 

41.1 

0.0 

19.6 

27.9 

10.4 

12.4 

13.7 

45.5 

117.6 

33.0 

38.6 

11.9 

0.5 

37.6 

8.9 

16.5 

10.2 

14.2 

25.7 

5.1 

26.9 

13.2 

25.1 

0.8 

12.4 

3-5 

105.4 

22.6 

101.6 

120.1 

94.0 

24.1 

47.2 

47.2 

25.9 

81.3 

66.8 

106.7 

0.0 

85.6 

15.5 

38.1 

33.5 

29.2 

64.5 

126.7 

59.7 

36.1 

71.9 

66.3 

79.8 

28.2 

21.1 

39.6 

17.8 

57.4 

44.4 

44.2 

73.2 

25.1 

28.4 

9.7 

4-6 

105.7 

23.1 

98.6 

108.2 

78.5 

27.9 

47.2 

47.2 

31.5 

81.3 

48.5 

94.5 

0.0 

74.7 

27.9 

35.3 

32.0 

28.4 

63.2 

131.6 

58.4 

38.6 

62.2 

33.0 

73.2 

23.6 

27.4 

37.1 

24.9 

58.7 

43.2 

43.9 

62.7 

25.1 

16.5 

15.7 

3-6 

105.7 

23.1 

110.0 

123.4 

94.7 

27.9 

55.1 

55.1 

31.5 

93.0 

67.3 

108.5 

0.0 

86.1 

27.9 

40.4 

37.3 

29.5 

74.9 

144.8 

69.9 

38.6 

73.7 

66.3 

81.8 

30.7 

27.4 

44.2 

24.9 

80.0 

44.4 

54.4 

73.7 

25.1 

28.4 

15.7 

1-6 

105.7 

23.1 

114.0 

124.7 

96.0 

27.9 

55.1 

72.9 

49.3 

93.5 

74.9 

111.3 

0.0 

86.6 

27.9 

40.6 

37.3 

29.5 

77.5 

144.8 

71.1 

38.6 

73.7 

81.5 

87.9 

30.7 

27.4 

44.2 

24.9 

84.6 

44.4 

57.2 

82.6 

25.1 

31.2 

15.7 
~ 

0'1 

~ II) 

0 

3 

~ "C 

::r 

;:;-

~ c 

Q.. 

;;· 

~ 

r.I'J 

8" 

3 

Qj 

~ 

Q.. 

"TT 

0 

&. 

S, 

z 

0 

~ 

w 

jn 

... 

I.C 

= .?1 

?f 

f 

~ 

Table 1. Official NOM rain gage network data, October and November 1-6, 1985-Continued 

latitude longitude 

arc arc October 

Station deg min deg min 1985 

362470 40 28 78 44 75.7 

362537 39 

362629 41 

362671 41 

362682 42 

362942 40 

363018 41 

49 77 16 53.8 

30 78 14 67.1 

52 75 16 52.3 

5 80 11 132.1 

43 79 30 38.4 

7 75 44 69.6 

363028 41 23 79 49 79.0 

363056 41 1 75 54 63.0 

363130 41 44 77 38 48.5 

363158 41 

363211 41 

49 79 27 

39 77 40 

78.5 

48.5 

363311 41 34 78 36 60.5 

363321 40 6 75 47 51.1 

363343 40 33 80 13 56.9 

363394 41 15 75 27 32.8 

363437 40 14 75 26 52.8 

363503 39 47 79 55 53.3 

363526 41 25 80 22 82.8 

363632 40 33 75 59 26.4 

363662 39 48 76 59 

363699 40 13 76 51 

363758 41 29 75 10 

364008 41 23 75 26 

364019 39 50 76 20 

364043 41 37 75 19 

364047 40 5 75 50 

364076 40 12 75 47 

364166 40 6 77 18 

364190 39 49 78 44 

364214 40 36 79 7 

364325 41 30 80 28 

364385 

364432 

364481 

364611 

40 20 78 55 

41 41 78 48 

39 59 78 43 

40 49 79 32 

364672 40 54 75 32 

364727 41 13 75 3 

37.3 

34.0 

31.0 

59.4 

27.9 

84.1 

37.3 

59.9 

27.9 

109.7 

68.1 

79.5 

67.6 

72.9 

98.8 

62.5 

39.6 

69.9 

0.0 

0.0 

0.0 

0.0 

o.o 

0.0 

o.o 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.5 

0.0 

0.0 

o.o 

o.o 

0.0 

0.0 

o.o 

0.0 

o.o 

o.o 

0.0 

0.0 

0.0 

o.o 

3.0 

o.o 

0.0 

0.0 

0.0 

2.5 

0.0 

0.0 

o.o 

2 

0.0 

0.0 

0.0 

o.o 

16.3 

0.3 

o.o 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.5 

o.o 

0.0 

1.5 

1.3 

0.0 

0.0 

o.o 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

2.8 

0.0 

5.6 

2.0 

0.0 

7.6 

o.o 

0.0 

o.o 

8.1 

23.9 

3.6 

0.0 

5.8 

5.8 

0.0 

14.5 

0.0 

7.6 

8.6 

4.3 

4.1 

0.0 

14.0 

o.o 

0.0 

4.3 

17.0 

o.o 

0.0 

5.3 

0.0 

0.0 

0.0 

o.o 

0.0 

0.0 

o.o 

9.9 

10.7 

10.4 

14.5 

8.9 

20.3 

7.4 

0.0 

0.3 

4 

18.8 

46.2 

21.6 

o.o 

57.9 

48.8 

0.0 

24.9 

0.8 

26.7 

22.4 

33.8 

23.1 

o.o 

39.9 

o.o 

o.o 

44.7 

19.3 

0.3 

11.7 

17.5 

o.o 

o.o 

o.s 

o.o 

o.o 

0.3 

29.2 

30.7 

23.4 

11.4 

8.6 

21.3 

39.4 

55.9 

o.o 

o.o 

27.7 

15.7 

4.6 

6.9 

49.3 

14.7 

7.1 

53.1 

11.9 

10.4 

29.5 

12.2 

7.1 

34.0 

41.9 

41.1 

27.7 

53.3 

52.3 

15.0 

20.8 

4.1 

11.9 

20.3 

13.0 

9.9 

25.4 

44.5 

31.8 

42.7 

8.4 

96.3 

22.4 

7.6 

34.3 

0.0 

15.7 

19.8 

November 1985 

6.9 

3.8 

1.3 

11.9 

1.5 

2.3 

11.4 

11.4 

16.3 

3.8 

14.7 

5.1 

2.3 

7.6 

2.5 

6.9 

3.0 

o.o 

11.9 

6.6 

8.6 

o.o 

10.7 

13.0 

7.9 

0.0 

13.2 

7.1 

12.7 

3.3 

6.4 

15.0 

1.8 

3.8 

o.o 

o.o 

5.6 

19.0 

3--4 

26.9 

70.1 

25.1 

o.o 

63.8 

54.6 

o.o 

39.4 

0.8 

34.3 

31.0 

38.1 

27.2 

0.0 

53.8 

o.o 

0.0 

49.0 

36.3 

0.3 

11.7 

22.9 

0.0 

0.0 

o.s 

o.o 

0.0 

0.3 

29.2 

40.6 

34.0 

21.8 

23.1 

30.2 

59.7 

63.2 

o.o 

0.3 

4-5 

46.5 

62.0 

26.2 

6.9 

107.2 

63.5 

7.1 

78.0 

12.7 

37.1 

51.8 

46.0 

30.2 

34.0 

81.8 

41.1 

27.7 

98.0 

71.6 

15.2 

5-6 

34.5 

19.6 

5.8 

18.8 

50.8 

17.0 

18.5 

64.5 

28.2 

14.2 

44.2 

17.3 

9.4 

41.7 

44.5 

48.0 

30.7 

53.3 

64.3 

21.6 

32.5 29.5 

21.6 4.1 

11.9 22.6 

20.3 33.3 

13.5 20.8 

9.9 9.9 

25.4 38.6 

44.7 51.6 

61.0 44.5 

73.4 46.0 

31.8 14.7 

107.7 111.3 

31.0 24.1 

29.0 11.4 

73.7 34.3 

55.9 o.o 

15.7 21.3 

19.8 38.9 

3--5 

54.6 

85.9 

29.7 

6.9 

113.0 

69.3 

7.1 

92.5 

12.7 

44.7 

60.5 

50.3 

34.3 

34.0 

95.8 

41.1 

27.7 

102.4 

88.6 

15.2 

32.5 

26.9 

11.9 

20.3 

13.5 

9.9 

25.4 

44.7 

61.0 

83.3 

42.4 

118.1 

45.5 

37.8 

94.0 

63.2 

15.7 

20.1 

4-6 

53.3 

65.8 

27.4 

3--6 

61.5 

89.7 

31.0 

1--6 

61.5 

89.7 

31.0 

18.8 18.8 18.8 

108.7 114.6 130.8 

65.8 71.6 71.9 

18.5 18.5 18.5 

89.4 103.9 103.9 

29.0 

40.9 

66.5 

51.1 

32.5 

41.7 

84.3 

48.0 

30.7 

29.0 

48.5 

75.2 

55.4 

36.6 

41.7 

98.3 

48.0 

30.7 

29.0 

48.5 

75.2 

55.4 

36.6 

41.7 

99.3 

48.0 

30.7 

98.0 102.4 103.9 

83.6 100.6 101.9 

21.8 21.8 21.8 

41.1 

21.6 

22.6 

33.3 

21.3 

9.9 

38.6 

51.8 

73.7 

76.7 

38.1 

122.7 

32.8 

32.8 

73.7 

55.9 

21.3 

38.9 

41.1 

26.9 

22.6 

33.3 

21.3 

9.9 

38.6 

51.8 

73.7 

86.6 

48.8 

133.1 

47.2 

41.7 

94.0 

63.2 

21.3 

39.1 

41.1 

26.9 

22.6 

33.3 

21.3 

9.9 

38.6 

51.8 

73.7 

92.5 

48.8 

138.7 

49.3 

41.7 

104.1 

63.2 

21.3 

39.1 
~ 1'1) 

;-

0 

0 

~ s. 

;. 

1'1) 

~ 0 

3 

0 

-

z 

0 

~ 

~ ... 

I.C 

00 

~ 

~ 

<:: 

! 

~ 

~ 

'! 

Table 1. Official NOAA rain gage network data, October and November 1-6, 1985-Continued 

latitude longitude 

arc arc October 

Station deg min deg min 1985 

364763 40 3 76 17 

364778 

364853 

364896 

364934 

364972 

364983 

40 7 

40 54 

40 20 

40 50 

41 41 

41 52 

76 26 

77 13 

76 28 

75 43 

76 43 

78 39 

364992 40 35 77 35 

365050 41 39 80 26 

365109 41 7 77 27 

365160 41 3 75 30 

365212 40 27 79 29 

365344 40 50 76 8 

365381 40 24 77 56 

365390 39 49 75 25 

365408 40 45 79 2 

365470 41 22 74 42 

365606 41 38 80 10 

365651 41 13 80 14 

365662 39 50 77 54 

365686 39 47 79 3 

365790 40 53 77 29 

365817 41 6 76 34 

365902 40 39 80 23 

365915 41 50 75 52 

366042 40 8 79 33 

366126 40 22 76 18 

366151 40 37 79 43 

366194 40 9 74 57 

366233 41 1 80 22 

366289 39 44 76 30 

366297 40 29 77 8 

366310 40 12 79 38 

366370 40 7 75 21 

366508 

366622 

366681 

366689 

39 48 

41 55 

40 23 

40 48 

76 3 

76 18 

75 30 

75 37 

42.2 

30.5 

51.1 

49.0 

39.4 

50.5 

70.9 

39.9 

62.2 

51.8 

63.0 

45.7 

70.1 

63.8 

38.6 

60.5 

47.5 

69.6 

49.5 

92.7 

101.9 

46.5 

37.3 

55.4 

48.3 

62.7 

25.4 

62.0 

43.2 

43.4 

52.8 

49.8 

54.4 

46.5 

57.7 

55.6 

43.4 

55.4 

o.o 

o.o 

o.o 

o.o 

o.o 

o.o 

0.0 

o.o 

o.o 

o.o 

0.0 

o.o 

o.o 

o.o 

o.o 

0.5 

o.o 

o.o 

0.0 

2.5 

4.3 

1.3 

o.o 

0.3 

o.o 

o.o 

o.o 

o.o 

0.0 

o.o 

o.o 

o.o 

3.6 

0.0 

o.o 

o.o 

0.0 

o.o 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

o.o 

5.3 

0.8 

2.3 

o.o 

1.5 

0.0 

0.0 

0.0 

1.8 

0.0 

0.0 

0.8 

15.2 

9.1 

0.0 

0.0 

0.0 

o.o 

1.3 

o.o 

0.3 

0.0 

o.o 

o.o 

0.0 

14.2 

0.0 

0.0 

o.o 

0.0 

0.0 

1.3 

0.3 

11.7 

1.0 

0.0 

0.0 

9.9 

33.0 

11.7 

22.6 

0.0 

12.4 

o.o 

6.1 

0.0 

11.7 

0.0 

19.3 

18.0 

43.2 

6.1 

7.1 

0.0 

8.1 

0.0 

20.6 

0.0 

9.4 

0.0 

16.3 

0.8 

13.0 

43.2 

0.0 

0.3 

0.0 

0.0 

o.o 

4 

0.5 

1.3 

25.1 

1.0 

0.0 

9.9 

17.0 

31.2 

7.9 

12.2 

0.0 

39.4 

o.o 

38.9 

8.1 

24.1 

0.0 

17.3 

24.4 

27.9 

23.6 

19.3 

6.9 

31.2 

0.3 

30.2 

5.1 

52.3 

3.0 

30.0 

5.8 

15.5 

11.4 

0.0 

0.3 

6.1 

1.0 

26.4 

12.2 

10.7 

22.9 

11.4 

9.1 

12.2 

11.2 

8.9 

95.3 

16.5 

24.6 

6.4 

14.0 

17.5 

27.9 

8.4 

o.o 

75.7 

70.4 

10.2 

80.3 

14.5 

7.6 

49.0 

11.7 

12.7 

11.4 

26.7 

26.2 

33.0 

33.8 

12.7 

3.8 

31.0 

16.5 

17.3 

11.9 

11.9 

November 1985 

6.4 

4.8 

2.8 

8.1 

16.5 

9.7 

6.9 

0.0 

14.0 

0.0 

8.4 

4.6 

14.2 

12.2 

0.0 

4.6 

0.0 

18.5 

10.7 

0.0 

10.2 

12.7 

8.9 

5.6 

4.6 

6.6 

o.o 

1.3 

0.0 

10.4 

8.4 

2.0 

1.0 

2.5 

3.8 

2.0 

2.5 

2.5 

3-4 4-5 

1.8 12.7 

1.5 11.9 

36.8 48.0 

2.0 12.4 

0.0 9.1 

9.9 22.1 

26.9 28.2 

64.3 40.1 

19.6 103.1 

34.8 28.7 

0.0 24.6 

51.8 45.7 

0.0 14.0 

45.0 56.4 

8.1 36.1 

35.8 32.5 

0.0 o.o 

36.6 93.0 

42.4 94.7 

71.1 38.1 

29.7 103.9 

26.4 33.8 

6.9 14.5 

39.4 80.3 

0.3 11.9 

50.8 42.9 

5.1 16.5 

61.7 79.0 

3.0 29.2 

46.2 63.0 

6.6 39.6 

28.4 28.2 

54.6 15.2 

o.o 31.0 

0.5 

6.1 

1.0 

26.4 

16.8 

23.4 

13.0 

38.4 

5--{i 

18.5 

15.5 

25.7 

19.6 

25.7 

21.8 

18.0 

8.9 

109.2 

16.5 

33.0 

10.9 

28.2 

29.7 

27.9 

13.0 

o.o 

94.2 

81.0 

10.2 

90.4 

27.2 

16.5 

54.6 

16.3 

19.3 

11.4 

27.9 

26.2 

43.4 

42.2 

14.7 

4.8 

33.5 

20.3 

19.3 

14.5 

14.5 

3-5 4--{i 

14.0 19.1 

12.2 16.8 

59.7 50.8 

13.5 20.6 

9.1 25.7 

22.1 31.8 

38.1 35.1 

73.2 40.1 

114.8 117.1 

51.3 28.7 

24.6 33.0 

58.2 50.3 

14.0 28.2 

62.5 68.6 

36.1 36.1 

44.2 37.1 

0.0 o.o 

112.3 111.5 

112.8 105.4 

81.3 38.1 

110.0 114.0 

40.9 46.5 

14.5 23.4 

88.4 85.9 

11.9 16.5 

63.5 49.5 

16.5 16.5 

88.4 80.3 

29.2 29.2 

79.2 73.4 

40.4 48.0 

41.1 30.2 

58.4 16.3 

31.0 33.5 

17.0 

23.4 

13.0 

38.4 

20.6 

25.4 

15.5 

40.9 

3--{i 

20.3 

17.0 

62.5 

21.6 

25.7 

31.8 

45.0 

73.2 

128.8 

51.3 

33.0 

62.7 

28.2 

74.7 

36.1 

48.8 

o.o 

130.8 

123.4 

81.3 

120.1 

53.6 

23.4 

94.0 

16.5 

70.1 

16.5 

89.7 

29.2 

89.7 

48.8 

43.2 

59.4 

33.5 

20.8 

25.4 

15.5 

40.9 

1--{i 

20.3 

17.0 

62.5 

21.6 

25.7 

31.8 

45.0 

78.5 

129.5 

53.6 

33.0 

64.3 

28.2 

74.7 

36.1 

51.1 

0.0 

130.8 

124.2 

99.1 

133.6 

54.9 

23.4 

94.2 

16.5 

71.4 

16.5 

89.9 

29.2 

89.7 

48.8 

43.2 

77.2 

33.5 

20.8 

25.4 

15.5 

40.9 
~ 

= 

C"l 

~ 

3 

0 

-ti 

:r 

r;· 

~ c 

c.. 

;· 

~"' 

f.l'l 

S" 

3 

$» 

:l 

c.. 

'TI 

0 

0 

c.. 

s. 

z 

0 

~ 

w 

I 

.:n 

.... 

I.C 

00 

.:n 

?E 

; 

~ 

Table 1. Official NOM rain gage network data, October and November 1-6, 1985-Continued 

Latitude Longitude 

arc arc October 

Station deg min deg min 1985 

366721 41 5 

366762 41 24 

366889 39 53 

366916 40 54 

366927 40 7 

79 41 57.9 

75 14 32.8 

75 14 39.1 

78 5 30.2 

75 30 50.3 

366955 

366993 

367029 

367103 

367167 

40 2 

40 30 

77 18 

80 13 

41 44 75 27 

41 49 78 17 

40 39 78 33 

367229 40 56 79 17 

367310 41 52 77 52 

367312 40 26 78 0 

367322 40 22 75 56 

367409 41 20 77 44 

367477 41 25 

367578 40 33 

78 45 

75 43 

367727 41 47 76 7 

367728 41 56 79 4 

367730 41 50 77 28 

367735 40 47 79 14 

367782 40 31 

367846 40 12 

79 33 

78 15 

367863 

367931 

367942 

367978 

368057 

368073 

368145 

368184 

368203 

368244 

40 41 79 40 

40 46 76 52 

40 1 79 18 

40 48 76 33 

41 12 76 8 

40 3 77 31 

41 19 78 6 

41 3 80 4 

41 51 78 29 

39 60 79 5 

368308 39 51 77 30 

368379 39 52 76 52 

368388 40 13 75 13 

368449 40 48 77 52 

368469 41 24 78 1 

54.9 

57.7 

58.2 

51.3 

63.5 

74.9 

50.8 

60.2 

20.1 

36.3 

67.1 

37.8 

39.9 

84.6 

27.9 

58.4 

58.7 

65.5 

54.6 

36.8 

53.3 

35.1 

27.7 

45.7 

81.5 

50.5 

52.3 

80.0 

65.5 

52.8 

54.4 

40.9 

48.8 

3.8 

o.o 

0.0 

o.o 

o.o 

0.0 

0.0 

0.0 

o.o 

0.0 

0.0 

0.0 

0.0 

0.0 

0.5 

0.0 

o.o 

0.0 

0.0 

0.0 

0.0 

0.0 

0.3 

o.o 

o.o 

0.0 

0.0 

0.0 

0.0 

0.0 

1.3 

0.0 

0.8 

0.0 

0.0 

o.o 

1.3 

o.o 

3.8 

o.o 

0.0 

o.o 

o.o 

0.0 

13.0 

0.0 

o.o 

0.5 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

o.o 

0.0 

0.0 

0.0 

8.9 

0.0 

0.5 

0.0 

0.0 

0.0 

0.0 

0.8 

0.0 

16.0 

0.0 

3.6 

0.0 

0.0 

o.o 

0.0 

o.o 

11.4 

0.0 

o.o 

17.8 

o.o 

4.3 

40.1 

0.0 

5.1 

10.4 

10.7 

0.0 

6.4 

o.o 

8.9 

6.4 

0.5 

0.0 

10.2 

0.0 

8.1 

15.7 

6.1 

10.4 

3.8 

0.0 

0.0 

0.0 

18.8 

5.8 

27.9 

5.8 

6.4 

4.3 

0.0 

0.0 

2.5 

4.8 

4 

20.8 

o.o 

9.7 

14.2 

9.4 

51.6 

43.7 

0.5 

11.2 

16.5 

41.4 

23.6 

22.9 

0.8 

20.8 

23.6 

1.5 

3.0 

32.0 

27.9 

32.3 

44.7 

24.1 

53.3 

16.3 

o.o 

3.3 

2.0 

32.8 

35.1 

57.9 

16.0 

14.7 

43.2 

10.7 

0.0 

30.2 

32.3 

31.8 

14.7 

15.2 

5.1 

25.1 

35.1 

1.8 

14.2 

7.4 

10.2 

9.1 

9.7 

21.6 

20.6 

9.7 

3.8 

22.9 

22.4 

17.8 

11.4 

6.9 

8.9 

47.8 

21.8 

3.0 

24.6 

5.3 

5.6 

21.8 

10.4 

10.2 

9.7 

34.3 

61.5 

31.2 

31.5 

20.3 

10.2 

November 1985 

1.8 

11.9 

0.3 

0.0 

1.3 

18.8 

o.o 

13.2 

4.1 

6.1 

1.0 

3.6 

11.9 

5.1 

6.1 

0.8 

3.3 

2.8 

13.7 

15.2 

2.8 

0.0 

2.8 

1.0 

10.4 

14.0 

9.1 

4.8 

0.0 

5.8 

1.3 

5.6 

3.8 

13.7 

7.4 

0.0 

8.6 

3.3 

3-4 

32.3 

o.o 

9.7 

32.0 

9.4 

55.9 

83.8 

0.5 

16.3 

26.9 

52.1 

23.6 

29.2 

0.8 

29.7 

30.0 

2.0 

3.0 

42.2 

27.9 

40.4 

60.5 

30.2 

63.8 

20.1 

o.o 

3.3 

2.0 

51.6 

40.9 

85.9 

21.8 

21.1 

47.5 

10.7 

0.0 

32.8 

37.1 

4-5 

52.6 

14.7 

24.9 

19.3 

34.5 

86.6 

45.5 

14.7 

18.5 

26.7 

50.5 

33.3 

44.5 

21.3 

30.5 

27.4 

24.4 

25.4 

49.8 

39.4 

39.1 

53.6 

71.9 

75.2 

19.3 

24.6 

8.6 

7.6 

54.6 

45.5 

68.1 

25.7 

49.0 

104.6 

41.9 

31.5 

50.5 

42.4 

5-6 

33.5 

26.7 

15.5 

5.1 

26.4 

53.8 

1.8 

27.4 

11.4 

16.3 

10.2 

13.2 

33.5 

25.7 

15.7 

4.6 

26.2 

25.1 

31.5 

26.7 

9.7 

8.9 

50.5 

22.9 

13.5 

38.6 

14.5 

10.4 

21.8 

16.3 

11.4 

15.2 

38.1 

75.2 

38.6 

31.5 

29.0 

13.5 

3-5 

64.0 

14.7 

24.9 

37.1 

34.5 

4-6 

54.4 

26.7 

25.1 

19.3 

35.8 

90.9 105.4 

85.6 45.5 

14.7 27.9 

23.6 22.6 

37.1 32.8 

61.2 51.6 

33.3 36.8 

50.8 56.4 

21.3 26.4 

39.4 36.6 

33.8 28.2 

24.9 27.7 

25.4 28.2 

59.9 63.5 

39.4 54.6 

47.2 41.9 

69.3 53.6 

18.0 74.7 

85.6 76.2 

23.1 29.7 

24.6 38.6 

8.6 17.8 

7.6 12.4 

73.4 54.6 

51.3 51.3 

96.0 69.3 

31.5 31.2 

55.4 52.8 

109.0 118.4 

41.9 49.3 

31.5 31.5 

53.1 59.2 

47.2 45.7 

3-6 

65.8 

26.7 

25.1 

37.1 

35.8 

109.7 

85.6 

27.9 

27.7 

43.2 

62.2 

36.8 

62.7 

26.4 

45.5 

34.5 

28.2 

28.2 

73.7 

54.6 

50.0 

69.3 

80.8 

86.6 

33.5 

38.6 

17.8 

12.4 

73.4 

57.2 

97.3 

37.1 

59.2 

122.7 

49.3 

31.5 

61.7 

50.5 

1-6 

73.4 

26.7 

25.1 

37.1 

35.8 

109.7 

98.6 

27.9 

27.7 

43.7 

62.2 

36.8 

62.7 

26.4 

46.0 

34.5 

28.2 

28.2 

73.7 

54.6 

50.0 

78.2 

81.0 

87.1 

33.5 

38.6 

17.8 

12.4 

74.2 

57.2 

114.6 

37.1 

63.5 

122.7 

49.3 

31.5 

63.0 

50.5 
~ 

~ 

~ 

a 

0 

~ 

0 

-:;. 

~ 

~ 0 

3 

0 

-

z 

0 

~ 

w 

in 

... 

1.0 

,?1 = 

~ 

p 

~ 

~ 

1.0 

Table 1. Official NOAA rain gage network data, October and November 1-6, 1985-Continued 

Station 

368560 

368570 

368596 

368692 

368758 

368763 

368873 

368888 

368893 

368905 

368959 

369022 

369042 

369050 

369115 

369128 

369298 

369318 

369367 

369385 

369408 

369464 

369490 

369507 

369655 

369702 

369705 

369714 

369728 

369823 

369933 

369950 

369995 

440021 

440135 

latitude longitude 

arc arc October 

deg min deg min 1985 

40 

40 

41 

41 

40 

40 

41 

41 

41 

41 

41 

40 

41 

39 

41 

40 

41 

40 

6 

29 

0 

57 

47 

51 

29 

38 

11 

45 

47 

40 

54 

55 

19 

36 

51 

11 

39 54 

41 18 

41 42 

39 58 

39 58 

41 35 

40 44 

41 14 

41 20 

40 28 

41 15 

40 3 

39 55 

40 7 

40 28 

36 40 

36 54 

78 

76 

75 

75 

75 

75 

79 

79 

75 

76 

76 

78 

79 

79 

79 

79 

79 

80 

57 

11 

11 

36 

59 

59 

26 

42 

25 

25 

47 

13 

49 

43 

39 

33 

9 

11 

80 10 

78 29 

77 16 

75 38 

75 40 

79 24 

79 24 

75 53 

75 44 

78 12 

76 55 

78 32 

76 45 

76 43 

75 27 

81 58 

80 44 

78.0 

35.8 

52.3 

57.9 

68.3 

71.1 

89.7 

86.6 

44.5 

36.8 

50.8 

71.1 

75.4 

73.2 

63.0 

52.3 

74.7 

57.7 

45.0 

51.8 

38.9 

51.8 

42.4 

70.9 

53.1 

42.2 

48.8 

60.2 

46.5 

107.7 

39.6 

39.6 

48.0 

66.8 

69.9 

440166 37 6 79 18 94.2 

440187 37 18 78 2 104.9 

2.3 

0.0 

o.o 

o.o 

o.o 

o.o 

0.0 

o.o 

o.o 

0.0 

o.o 

o.o 

o.o 

0.0 

o.o 

0.3 

o.o 

0.3 

o.o 

0.0 

o.o 

o.o 

o.o 

0.0 

o.o 

o.o 

o.o 

o.o 

0.0 

1.3 

o.o 

o.o 

o.o 

o.o 

0.0 

5.3 

11.7 

2 

10.7 

0.0 

0.0 

0.0 

0.0 

o.o 

0.3 

0.0 

0.0 

0.0 

0.0 

o.o 

0.0 

0.5 

14.2 

0.8 

0.0 

1.3 

2.3 

0.0 

0.0 

0.0 

0.0 

0.0 

0.8 

0.0 

0.0 

0.3 

0.0 

0.0 

0.0 

o.o 

0.0 

22.6 

9.4 

72.9 

38.1 

14.0 

0.0 

0.0 

0.0 

0.0 

0.0 

11.7 

9.7 

0.0 

0.0 

o.o 

0.0 

9.1 

11.9 

30.5 

7.9 

8.4 

20.6 

11.4 

5.8 

0.0 

0.0 

0.0 

9.7 

7.6 

0.0 

0.0 

5.3 

8.9 

10.7 

1.3 

o.o 

0.0 

1.3 

0.0 

29.5 

8.1 

4 

20.8 

0.0 

0.0 

0.0 

0.0 

0.0 

35.3 

23.6 

0.0 

5.3 

18.0 

0.0 

13.7 

31.5 

36.6 

50.5 

33.3 

43.4 

59.4 

22.6 

16.5 

o.o 

32.5 

31.5 

43.2 

1.3 

0.8 

27.9 

11.7 

7.6 

13.2 

21.1 

8.4 

13.5 

11.9 

23.1 

41.7 

35.6 

10.4 

10.7 

0.0 

51.6 

33.5 

6.4 

20.3 

12.7 

44.7 

65.0 

7.1 

8.1 

33.5 

10.4 

19.6 

10.7 

3.0 

7.9 

18.0 

14.2 

32.0 25.4 

7.1 58.4 

6.4 10.9 

o.o 28.4 

Virginia 

26.7 36.6 

5.1 60.5 

47.5 

184.2 

41.4 

15.2 

November 1985 

0.5 

28.7 

7.4 

5.3 

9.7 

11.4 

6.4 

16.8 

10.9 

8.9 

5.1 

5.6 

20.1 

11.2 

0.5 

3.8 

10.4 

2.8 

2.8 

6.6 

9.7 

3.0 

3.3 

5.1 

3.3 

5.1 

8.4 

7.1 

o.o 

2.3 

7.1 

6.9 

2.8 

9.7 

0.0 

0.0 

2.8 

3-4 

34.8 

0.0 

o.o 

0.0 

0.0 

0.0 

47.0 

33.3 

0.0 

5.3 

18.0 

0.0 

22.9 

43.4 

67.1 

58.4 

41.7 

64.0 

70.9 

28.4 

16.5 

0.0 

32.5 

41.1 

50.8 

1.3 

0.8 

33.3 

20.6 

42.7 

8.4 

6.4 

0.0 

27.9 

5.1 

77.0 

192.3 

4-5 

28.4 

13.2 

21.1 

8.4 

13.5 

11.9 

58.4 

65.3 

35.6 

15.7 

28.7 

0.0 

65.3 

65.0 

42.9 

70.9 

46.0 

88.1 

124.5 

29.7 

24.6 

33.5 

42.9 

51.1 

53.8 

4.3 

8.6 

46.0 

25.9 

57.4 

65.5 

17.3 

28.4 

63.2 

65.5 

88.9 

199.4 

5---ti 3-5 

8.1 42.4 

41.9 13.2 

28.4 21.1 

13.7 8.4 

23.1 13.5 

23.4 11.9 

29.5 70.1 

58.4 74.9 

46.5 35.6 

19.3 15.7 

15.7 28.7 

5:6 0. 0 

71.6 74.4 

44.7 77.0 

6.9 73.4 

24.1 78.7 

23.1 54.4 

47.5 108.7 

67.8 135.9 

13.7 35.6 

17.8 24.6 

36.6 33.5 

13.7 42.9 

24.6 60.7 

14.0 61.5 

8.1 4.3 

16.3 8.6 

25.1 51.3 

14.2 34.8 

27.7 

65.5 

17.8 

31.2 

46.2 

60.5 

68.1 

66.8 

17.3 

28.4 

64.5 

65.5 

41.4 118.4 

18.0 207.5 

4---{i 

29.0 

41.9 

28.4 

13.7 

23.1 

23.4 

64.8 

82.0 

46.5 

24.6 

33.8 

5.6 

85.3 

76.2 

43.4 

74.7 

56.4 

90.9 

127.3 

36.3 

34.3 

36.6 

46.2 

56.1 

57.2 

9.4 

17.0 

53.1 

25.9 

59.7 

72.6 

24.1 

31.2 

72.9 

65.5 

88.9 

202.2 

3---ti 

42.9 

41.9 

28.4 

13.7 

23.1 

23.4 

76.5 

91.7 

46.5 

24.6 

33.8 

5.6 

94.5 

88.1 

73.9 

82.6 

64.8 

111.5 

138.7 

42.2 

34.3 

36.6 

46.2 

65.8 

64.8 

9.4 

17.0 

58.4 

34.8 

70.4 

73.9 

24.1 

31.2 

74.2 

65.5 

118.4 

210.3 

1---ti 

55.9 

41.9 

28.4 

13.7 

23.1 

23.4 

76.7 

91.7 

46.5 

24.6 

33.8 

5.6 

94.5 

88.6 

88.1 

83.6 

64.8 

113.0 

141.0 

42.2 

34.3 

36.6 

46.2 

65.8 

65.5 

9.4 

17.0 

58.7 

34.8 

71.6 

73.9 

24.1 

31.2 

96.8 

74.9 

196.6 

260.1 
= 

~ 

0 

C1 

~ 

3 

Q 

-a 

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~ c 

c.. 

;:;· 

~ 

f.l'l 

0 

3 

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s. 

z 

Q 

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w 

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I.C 

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Table 1. Official NOM rain gage network data, October and November 1-6, 1985-Continued 

Latitude 

arc 

Station deg min 

440243 37 22 

440327 37 45 

440385 36 40 

440551 37 21 

440670 39 9 

440720 38 31 

440766 37 11 

440792 37 6 

440993 37 42 

441082 37 3 

441136 37 33 

441209 37 5 

441259 36 48 

441322 37 2 

441585 37 4 

441593 38 2 

Longitude 

arc October 

deg min 1985 

78 50 88.1 

77 29 122.2 

75 55 83.8 

79 31 76.5 

77 59 151.1 

78 26 

80 25 

243.1 

74.7 

81 6 59.4 

78 18 121.9 

78 56 81.3 

78 33 121.4 

81 20 54.6 

80 59 94.5 

77 57 160.5 

78 42 62.5 

78 31 124.7 

15.2 

23.4 

6.9 

3.8 

6.9 

71.1 

2.0 

7.6 

10.4 

3.0 

18.8 

7.1 

8.9 

16.8 

6.4 

28.2 

2 

97.0 

9.9 

7.1 

35.8 

5.1 

67.3 

2.5 

14.2 

36.8 

51.6 

45.7 

6.1 

25.4 

40.6 

71.1 

52.1 

441606 36 50 78 28 106.2 10.2 54.9 

441614 36 49 79 24 82.0 3.8 20.3 

441746 36 37 78 34 85.9 4.1 20.8 

441913 38 15 76 58 89.7 4.1 10.7 

441929 37 44 78 9 97.8 7.6 25.4 

441955 37 17 

441999 37 6 

442009 38 12 

442041 37 48 

442044 37 48 

442064 38 3 

442142 37 38 

442155 38 28 

442160 37 30 

442208 38 27 

442245 36 35 

442504 36 53 

442600 37 40 

442790 36 41 

442941 37 20 

443071 36 56 

443192 38 19 

78 58 78.5 

80 8 100.6 

77 22 165.9 

79 60 53.1 

79 60 64 0 5 

79 23 93.0 

77 48 100.8 

78 0 167.6 

78 15 101.3 

78 56 116.6 

79 23 65.0 

76 29 86.9 

80 14 59.4 

77 33 75.4 

78 23 87.6 

80 18 98.6 

77 27 159.5 

6.6 

41.9 

10.4 

5.1 

8.1 

2.5 

8.9 

0.0 

11.2 

19.8 

2.8 

16.0 

11.4 

7.6 

14.7 

0.0 

5.1 

76.5 

65.8 

16.5 

5.1 

18.8 

6.4 

26.2 

0.0 

33.0 

13.5 

9.4 

12.4 

20.8 

19.0 

36.1 

31.2 

13.0 

30.5 

5.1 

0.5 

14.0 

5.1 

25.4 

21.6 

5.6 

36.1 

23.6 

4 

85.9 

50.8 

12.7 

33.8 

19.6 

95.3 

5.1 

53.3 

77.5 

47.5 

20.3 68.6 

3.6 56.1 

16.5 48.3 

3.3 116.1 

15.5 52.1 

20.6 78.7 

21.6 48.3 

13.0 47.0 

18.3 55.4 

18.3 22.6 

11.4 83.8 

25.7 77.7 

17.8 24.4 

4.6 50.0 

17.8 17.8 

14.7 203.2 

24.6 33.0 

3.6 87.4 

o.o 0.0 

11.4 78.7 

29.2 47.5 

5.8 33.0 

1.8 o.o 

6.6 20.3 

1.3 33.0 

16.5 62.7 

16.3 10.2 

3.3 49.3 

31.8 

4.6 

19.8 

99.1 

12.7 

191.8 

64.8 

26.7 

o.o 

32.3 

36.3 

13.0 

43.2 

11.9 

23.6 

40.9 

36.8 

86.1 

8.1 

2.8 

24.9 

24.1 

148.1 

4.1 

190.5 

66.0 

122.2 

27.7 

0.0 

30.2 

47.5 

58.9 

0.0 

108.2 

6.4 

28.4 

149.1 

4.3 

November 1985 

3--4 4--5 

1.5 116.3 117.6 

o.o 55.9 55.4 

o.o 13.2 32.5 

o.o 47.8 132.8 

5.1 24.6 32.3 

12.2 120.7 

0.5 26.7 

1.3 58.9 

0.0 113.5 

0.5 71.1 

287.0 

69.9 

80.0 

77.5 

79.8 

0.0 88.9 104.9 

3.6 59.7 69.1 

o.o 64.8 91.4 

0.5 119.4 128.0 

0.5 67.6 75.7 

1.3 99.3 119.6 

o.o 

1.0 

0.0 

1.8 

0.8 

69.9 85.1 

59.9 133.1 

73.7 63.5 

40.9 25.4 

95.3 108.7 

0.0 103.4 101.9 

0.0 42.2 172.5 

1.3 54.6 54.1 

o.o 35.6 208.3 

0.0 217.9 269.2 

2.0 57.7 155.2 

2.5 90.9 115.1 

0.0 0.0 0.0 

1.5 90.2 109.0 

0.8 76.7 95.0 

1.5 38.9 91.9 

0.0 1.8 0.0 

1.3 26.9 128.5 

0.0 34.3 39.4 

0.8 79.2 91.2 

0.0 26.4 159.3 

2.5 52.6 53.6 

5-6 3-5 4--6 3--6 1--6 

33.3 148.1 119.1 

55.4 

32.5 

132.8 

37.3 

149.6 261.9 

60.5 93.7 

33.0 47.0 

146.8 186.4 

42.4 54.4 

324.6 463.0 

91.9 96.5 

86.9 108.7 

113.5 160.8 

4.6 60.5 

19.8 33.0 

99.1 146.8 

17.8 37.3 

204.0 

65.3 

27.9 

0.0 

32.8 

312.4 

91.4 

85.6 

113.5 

103.4 

299.2 

70.4 

81.3 

77.5 

80.3 103.9 158.5 

36.3 125.2 104.9 125.2 

16.5 72.6 72.6 76.2 

43.2 108.0 91.4 108.0 

12.4 131.3 128.5 131.8 

24.1 91.2 76.2 91.7 

42.2 140.2 120.9 141.5 

189.7 

89.4 

142.2 

189.2 

169.2 

221.7 

36.8 106.7 85.1 106.7 171.7 

87.1 146.1 134.1 147.1 171.2 

8.1 81.8 63.5 81.8 106.7 

4.6 43.7 27.2 45.5 60.2 

25.7 120.1 109.5 120.9 153.9 

24.1 

148.1 

5.3 

190.5 

66.0 

124.2 

30.2 

o.o 

31.8 

48.3 

60.5 

0.0 

109.5 

6.4 

29.2 

149.1 

6.9 

127.5 101.9 127.5 210.6 

190.2 172.5 190.2 297.9 

58.7 55.4 59.9 86.9 

226.1 208.3 226.1 236.2 

284.0 269.2 284.0 310.9 

179.8 157.2 181.9 190.8 

118.6 117.6 121.2 156.2 

0.0 

120.4 

124.2 

97.8 

1.8 

135.1 

0.0 

110.5 

95.8 

93.5 

o.o 

129.8 

0.0 0.0 

121.9 166.1 

125.0 158.2 

99.3 

1.8 

136.4 

111.5 

30.2 

168.7 

40.6 39.4 40.6 67.3 

107.7 91.9 108.5 159.3 

175.5 159.3 175.5 206.8 

56.9 56.1 59.4 77.5 
~ 

1 

tl) 

0 

a 

0 

~ 

a 

-::r 

tl) 

til 

0 

3 

a 

z 

0 

~ 

w 

y. 

<.C """ 

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~ 

F 

< 

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= !:: 

Table 1. Official NOM rain gage network data, October and November 1-6, 1985-Continued 

latitude longitude 

arc arc October 

Station deg min deg min 1985 

443213 3e 

443267 36 

443310 37 

443375 37 

443397 37 

443466 3e 

443470 37 

443640 37 

443991 36 

444039 37 

444044 36 

444101 37 

44412e 3e 

44414e 37 

5 76 e lle.l 

40 eo 55 63.5 

57 79 57 57.7 

37 79 26 9e.3 

22 eo 52 45.7 

5 7e 11 120.4 

59 79 30 93.5 

16 e2 5 56.6 

44 eo 44 97.3 

30 79 16 e9.7 

41 76 47 130.0 

le 77 le 15e.5 

0 79 50 49.5 

e 79 32 9e.e 

23.6 

7.6 

1.0 

17.e 

2.5 

10.7 

1.5 

0.0 

5.3 

o.o 

16.0 

19.e 

7.6 

9.4 

444234 36 39 el 10 84.6 21.3 

444410 37 14 82 21 71.6 o.o 

444414 36 36 

444565 37 51 

444568 37 10 

444600 37 43 

444676 37 14 

444720 37 5 

44476e 36 46 

444e76 37 47 

444909 39 7 

445050 3e 2 

445096 3e 40 

445120 37 20 

445271 36 49 

44533e 37 27 

445416 38 21 

445453 36 40 

445595 3e 21 

4456e5 37 53 

44569e 38 25 

445700 3e 1 

445756 3e 6 

445e2e 37 23 

7e 17 e3.e 

79 35 100.1 

7e 31 4e.3 

76 23 le3.1 

eo 13 78.o 

76 21 50.3 

77 56 64.0 

79 26 78.7 

77 43 117.3 

78 0 149.1 

7e 23 102.1 

79 12 e3.e 

el 31 e2.5 

76 17 13e.7 

79 32 125.7 

eo 27 119.1 

79 43 83.3 

79 e 91.7 

79 35 111.0 

7e 27 116.3 

79 53 65.5 

eo 32 77.o 

5.8 

15.2 

14.5 

23.4 

3e.4 

5.e 

43.2 

le.o 

18.0 

21.1 

45.7 

42.9 

3.8 

12.2 

4.6 

11.9 

3.e 

4e.o 

e.6 

11.7 

o.o 

9.4 

2 

50.8 

36.1 

11.2 

49.8 

5.6 

26.2 

21.6 

16.8 

15.2 

0.0 

13.2 

11.7 

24.6 

65.0 

15.7 

20.1 

9.1 

63.5 

1.0 

9.1 

31. e 

0.0 

21.8 

0.0 

l.e 

1.0 

12.2 

22.4 

4 

96.0 51.6 

52.1 o.o 

31.0 16e. 4 

74.2 141.0 

14.0 64.e 

5e.7 46.2 

43.2 130.e 

31.5 25.1 

10.7 67.e 

0.0 0.0 

29.0 2.8 

30.7 6.9 

34.e 209.6 

32.0 102.1 

30.5 14.0 35.6 10.7 

10.2 e.g 15.7 29.5 

27.9 

38.4 

27.7 

6.6 

43.2 

6.1 

30.5 

34.3 

0.0 

23.1 

41.9 

39.9 

11.7 

5.e 

11.7 

34.5 

e.4 

82.0 

19.e 

24.9 

0.6 

12.4 

17.0 

35.3 

8.9 

7.1 

12.2 

0.5 

0.8 

27.9 

16.3 

27.7 

50.e 

38.4 

1.8 

37.e 

43.2 

34.3 

11.9 

9.4 

23.4 

135.9 

88.6 

30.0 

53.1 

50.8 

38.1 

33.5 

2.3 16.5 

21.1 16.3 

25.9 16.3 

10.2 36.1 

60.5 108.2 

32.0 100.6 

9.4 80.5 

27.2 0.0 

18.3 63.5 

16.3 

142.7 

o.o 

3.0 

125.2 

0.0 

21.8 

17.0 

18.0 

62.5 

52.1 

1.0 

19.8 

0.0 

11.7 

106.9 

15e.e 

201.7 

57.9 

36.e 

210.8 

22.1 

November 1985 

1.3 

0.0 

0.0 

0.0 

0.8 

4.6 

2.5 

12.4 

1.5 

0.0 

0.0 

o.o 

0.0 

o.o 

3-4 

lll.e 

72.1 

40.1 

137.7 

15.0 

67.8 

74.9 

31.5 

32.5 

o.o 

30.7 

31. e 

47.0 

54.4 

0.0 49.5 

13.7 24.6 

4-5 

147.6 

52.1 

199.4 

215.1 

78.7 

104.9 

174.0 

56.6 

78.5 

o.o 

3l.e 

37.6 

5-6 

52.8 

o.o 

168.4 

141.0 

65.5 

50.e 

133.3 

37.6 

69.3 

0.0 

2.8 

6.9 

244.3 209.6 

134.1 102.1 

46.2 

45.2 

10.7 

43.2 

0.0 54.9 54.1 16.3 

o.o 

0.0 

0.5 

78.5 

43.2 

19.1 

185.9 142.7 

34.3 o.o 

15.0 3.6 

o.o 21.6 134.6 125.2 

o.o 23.9 23.4 0.0 

0.0 136.7 157.7 21.8 

0.0 116.6 105.7 17.0 

4.1 

o.o 

46.2 48.0 

80.e 115.6 

22.1 

62.5 

54.4 101.6 102.9 106.4 

o.o 76.5 39.1 1.0 

4.e 35.3 53.3 24.6 

le.8 

37.3 

42.2 

46.2 

16.5 

27.9 

123.2 

o.o 

11.7 

106.9 

194.e 163.8 

309.9 203.2 

3-5 4-6 3--6 1-6 

163.3 14e.e 164.6 239.0 

72.1 52.1 72.1 115.8 

208.5 199.4 208.5 220.7 

278.6 215.1 27e.6 346.2 

79.e 79.5 eo.5 88.6 

114.0 109.5 118.6 155.4 

205.7 176.5 208.3 231.4 

56.6 69.1 69.1 85.9 

100.3 eo.o 101.9 122.4 

o.o 0.0 o.o o.o 

33.5 31.8 33.5 62.7 

3e.6 37.6 3e.6 70.1 

256.5 244.3 256.5 288.e 

156.5 134.1 156.5 230.9 

60.2 46.2 

54.1 58.9 

60.2 112.0 

67.e 78.0 

71.1 54.1 71.1 104.9 

221.2 185.9 221.2 274.8 

43.2 34.3 43.2 85.3 

22.1 15.5 22.6 

146.8 134.6 146.8 

23.9 23.4 23.9 

52.6 

228.3 

35.8 

158.5 157.7 158.5 232.2 

133.6 105.7 133.6 le5.9 

64.3 52.1 68.3 e6.4 

143.3 115.6 143.3 le7.5 

153.7 157.2 20e.o 295.7 

77.5 39.1 77.5 160.3 

55.1 58.2 59.9 75.4 

18.e 16.5 18.e 

49.0 27.9 49.0 

149.1 123.2 149.1 

205.0 199.9 210.1 

370.3 311.4 311.9 

0.0 

0.0 

0.0 

5.1 

1.5 

0.5 

2.0 

0.0 

3.6 

16e.7 

132.6 

e9.9 

27.2 

81.8 

15e.5 5e.4 190.5 159.0 191.0 

117.3 38.9 126.7 119.4 128.8 

210.e 210.e 238.0 210.e 23e.o 

36.8 

65.3 

195.6 

222.3 

501.9 

219.5 

165.4 

23e.o 

85.6 25.7 103.9 89.2 107.4 129.3 
Cl:l 

N 

N 

~ t'l) 

0 

3 

0 

-a 

::r 

r;· 

fJl 

c: 

Q.. 

;:;;· 

~ 

~ 0 

3 

Ql 

::I 

Q.. 

"'T1 

0 

0 

Q.. 

s. 

z 

0 

~ 

w 

I 

,1.11 

... 

1.&1 

00 

-?' 

~ 

< f 

~ 

Table 1. Official NOAA rain gage network data, October and November 1-6, 1985-Continued 

Latitude Longitude 

arc arc October 

Station deg min deg min 1985 

445851 39 4 

446012 37 30 

446046 37 19 

446139 36 54 

446173 37 

446475 37 

8 

35 

446491 37 52 

77 53 149.6 

80 6 63.2 

80 31 47.0 

7 6 12 99. 6 

82 38 89.7 

75 49 134.1 

78 15 103.6 

446593 37 40 79 17 88.9 

446626 36 45 83 3 79.2 

446692 36 47 

446712 38 13 

446723 37 4 

446906 37 33 

80 2 189.0 

78 7 121.9 

80 21 121.9 

77 56 101.1 

446955 37 3 80 45 66.5 

446999 37 

447164 38 

447201 37 

447285 37 

447312 37 

8 80 33 59.9 

24 77 44 159.5 

30 77 20 129.3 

19 79 58 95.8 

48 78 45 124.0 

447338 37 0 79 54 101.3 

447925 36 42 78 53 100.1 

448022 37 16 80 43 81.0 

448062 38 9 79 2 87.9 

448084 38 59 77 

448129 36 55 77 

80 

28 

21 

119.1 

86.4 

448170 36 38 16 148.8 

448192 36 44 

448323 37 50 

76 36 114 0 6 

75 60 217.2 

448396 38 54 77 45 129.3 

448448 38 39 78 43 129.3 

448547 36 40 81 24 128.3 

448600 37 38 78 56 103.9 

448737 38 54 77 13 103.9 

448800 36 59 77 0 64.3 

448829 37 45 77 3 162.8 

448837 36 36 76 26 110.0 

448888 38 41 77 

448894 37 59 76 

46 153.7 

46 122.7 

8.4 

25.9 

5.1 

2.5 

0.5 

25.4 

7.6 

6.6 

1.5 

16.8 

11.4 

11.4 

10.4 

2.3 

2.8 

45.2 

24.4 

35.3 

19.3 

21.1 

4.3 

11.2 

42.4 

3.3 

18.8 

12.7 

9.4 

16.0 

0.0 

5.1 

12.7 

10.7 

2.3 

8.4 

23.4 

22.9 

6.6 

20.6 

8.4 

22.9 

0.0 

7.1 

2.0 

2.0 

6.6 

23.6 

6.1 

40.9 

30.5 

0.0 

25.4 

11.4 

3.6 

36.6 

6.1 

23.6 

56.1 

43.7 

19.8 

13.5 

33.0 

1.8 

25.1 

26.7 

6.6 

o.o 

5.8 

12.2 

30.0 

11.7 

2.0 

8.9 

7.6 

24.9 

7.1 

8.6 

4 

5.8 52.1 21.6 

50.8 21.6 142.2 

0.0 15.2 50.8 

1.5 27.7 o.o 

0.5 11.7 33.0 

2.5 16.5 0.3 

21.8 53.8 21.6 

50.3 59.2 95.8 

8.1 13.2 7.9 

14.7 14.0 69.1 

3.8 67.8 74.4 

29.0 49.8 35.1 

5.1 125.7 29.2 

13.2 43.9 0.8 

4.1 8.1 66.5 

8.9 6.4 o.o 

9.7 42.9 0.8 

26.9 167.9 0.3 

27.4 

18.3 

10.4 

5.1 

17.8 

0.8 

o.o 

14.0 

o.o 

10.2 

3.8 

11.9 

9.7 

52.3 

3.8 

1.5 

6.4 

12.7 

5.1 

9.7 

85.3 

22.9 

41.1 

33.5 

58.9 

22.4 

48.5 

85.6 

31.5 

9.4 

42.2 

43.2 

27.2 

58.9 

36.6 

33.0 

17.5 

27.4 

51.6 

18.0 

54.4 

50.8 

21.8 

23.4 

83.1 

13.7 

13.5 

2.3 

o.o 

o.o 

19.6 

41.7 

30.2 

6.4 

7.4 

2.5 

5.1 

18.8 

17.8 

1.3 

November 1985 

11.4 

o.o 

o.o 

o.o 

3-4 

57.9 

72.4 

15.2 

29.2 

12.2 

19.0 

75.7 

109.5 

21.3 

28.7 

4-5 

73.7 

163.8 

66.0 

27.7 

44.7 

16.8 

75.4 

154.9 

21.1 

83.1 

15.2 

o.o 

3.0 

0.0 

o.o 

o.o 

2.8 71.6 142.2 

29.5 

1.8 

o.o 

0.5 

0.0 

o.o 

o.o 

1.0 

o.o 

1.3 

1.0 

1.5 

9.1 

o.o 

o.o 

o.o 

o.o 

8.6 

0.3 

0.3 

o.o 

2.0 

0.0 

1.8 

o.o 

8.6 

0.5 

78.7 

130.8 

57.2 

12.2 

15.2 

52.6 

194.8 

112.8 

41.1 

51.6 

38.6 

76.7 

23.1 

48.5 

99.6 

31.5 

19.6 

46.0 

55.1 

36.8 

111.3 

40.4 

34.5 

23.9 

40.1 

56.6 

27.7 

84.8 

154.9 

44.7 

74.7 

6.4 

43.7 

168.1 

139.7 

73.7 

63.0 

56.9 

142.0 

36.1 

62.0 

87.9 

31.5 

9.4 

61.7 

84.8 

57.4 

65.3 

43.9 

35.6 

22.6 

46.2 

69.3 

19.3 

5-6 3-5 4-6 3--6 1--6 

33.0 79.5 85.1 90.9 107.7 

142.2 214.6 163.8 214.6 263.4 

50.8 66.0 66.0 66.0 71.1 

0.0 29.2 

48.3 45.2 

0.3 19.3 

24.6 97.3 

95.8 205.2 

7.9 29.2 

69.1 97.8 

77.2 146.1 

64.5 113.8 

31.0 160.0 

0.8 

67.1 

o.o 

0.8 

0.3 

57.9 

78.7 

15.2 

53.3 

195.1 

55.4 167.1 

50.8 91.9 

23.1 73.4 

24.4 62.0 

84.6 159.8 

22.9 36.8 

13.5 62.0 

2.3 101.9 

0 0 0 31.5 

0.0 19.6 

28.2 

41.9 

30.5 

6.4 

9.4 

2.5 

6.9 

18.8 

26.4 

1.8 

65.5 

96.8 

67.1 

117.6 

47.8 

37.1 

29.0 

58.9 

74.4 

29.0 

27.7 29.2 38.9 

59.9 60.5 63.0 

16.8 19.3 

78.5 100.3 

154.9 205.2 

46.7 

114.6 

235.5 

21.1 29.2 36.8 

83.1 97.8 155.4 

145.0 148.8 190.8 

114.3 143.3 154.7 

156.7 161.8 197.6 

44.7 

75.2 

6.4 

43.7 

168.1 

140.7 

73.7 

64.3 

57.9 

143.5 

45.2 

57.9 

79.2 

15.2 

53.3 

195.1 

71.6 

85.6 

97.0 

83.8 

254.0 

168.1 243.6 

91.9 156.7 

74.7 98.8 

63.0 87.6 

161.3 236.7 

46.0 51.1 

62.0 62.0 105.9 

87.9 101.9 141.2 

31.5 31.5 47.5 

9.4 19.6 35.6 

70.4 

85.1 

57.7 

65.3 

46.0 

35.6 

24.4 

46.2 

78.0 

19.8 

74.2 80.0 

97.0 114.3 

67.3 110.0 

117.6 140.0 

49.8 54.1 

37.1 54.4 

30.7 61.7 

58.9 106.7 

83.1 96.8 

29.5 58.7 
~ 

~ II) 

0 

a 

0 

~ 

0 

-... 

:::r 

II) 

~ 

0 

3 

0 

-

z 

0 

~ 

~ ... 

1,0 

,:n = 

~ 

~ 

~ 

CICI 

~ 

w 

Table 1. Official NOAA rain gage network data, October and November 1-6, 1985-Continued 

Latitude Longitude 

arc arc October 

Station deg min deg min 1985 

448903 38 57 

448906 38 51 

448975 38 16 

449025 37 31 

449151 37 18 

449169 36 51 

449181 39 11 

449186 39 11 

449213 37 20 

449215 36 58 

449263 38 54 

449272 36 43 

449301 36 56 

77 27 103.1 

77 2 97.8 

79 19 138.4 

76 50 106.9 

76 42 115.6 

80 29 94.2 

78 9 132.1 

78 7 139.4 

77 39 127.0 

82 34 53.6 

78 28 124.5 

80 17 170.4 

81 5 77.2 

460094 39 29 79 38 115.8 

460102 37 44 80 38 46.7 

460355 37 26 81 0 51.1 

460527 39 16 79 22 137.7 

460580 37 47 81 11 39.6 

460582 37 47 81 7 39.9 

460633 39 2 79 57 0.0 

460921 37 18 81 13 40.4 

460939 37 39 80 53 49.0 

461075 38 14 82 12 111.5 

461083 39 40 79 37 85.9 

461215 38 11 80 8 94.2 

461220 39 0 80 16 124.7 

461282 38 51 

461324 39 30 

461330 39 14 

461363 38 22 

80 38 152.7 

78 18 120.7 

81 11 134.9 

80 37 116.1 

461393 39 3 79 26 175.3 

461526 38 37 80 35 96.5 

461570 38 22 81 36 92.7 

461677 39 16 80 21 116.6 

461696 38 27 81 5 114.3 

461900 39 41 79 

461959 38 29 81 

47 108.2 

16 105.7 

4.1 

1.5 

17.8 

20.6 

38.1 

16.3 

5.1 

5.3 

17.8 

3.6 

7.4 

50.0 

12.2 

0.0 

o.o 

1.3 

1.5 

0.0 

0.0 

0.0 

4.6 

0.8 

0.0 

o.o 

0.8 

0.8 

0.0 

5.6 

o.o 

o.o 

6.6 

8.1 

0.0 

o.o 

0.0 

o.o 

0.0 

2 

1.0 

0.8 

35.6 

9.1 

18.0 

18.8 

13.5 

15.5 

22.6 

10.9 

20.1 

50.8 

27.2 

0.5 

4.3 

30.5 

4.8 

1.5 

1.5 

0.0 

0.5 

2.5 

4.8 

1.8 

5.8 

4.3 

2.5 

10.4 

3.0 

0.0 

8.4 

2.5 

2.3 

4.1 

5.6 

2.0 

6.4 

7.9 

0.8 

20.3 

4.1 

7.4 

10.2 

8.1 

9.9 

0.8 

4.6 

6.1 

39.4 

11.9 

6.1 

3.6 

68.6 

10.9 

0.5 

4.6 

5.1 

2.5 

0.8 

0.0 

12.7 

6.9 

15.7 

9.4 

13.2 

5.6 

10.2 

6.6 

44.5 

13.5 

4.8 

1.5 

15.2 

12.7 

November 1985 

4 

34.5 

24.6 

40.6 

10.9 

13.5 

7.4 

39.1 

38.6 

69.9 

18.8 

33.0 

114.3 

40.1 

10.4 

0.3 

o.o 

1.5 

0.3 

108.7 

23.4 

29.2 

15.7 

4.6 

49.5 

14.5 

18.8 

0.0 

0.3 

0.0 

0.3 

0.0 

o.o 

6.1 

7.6 

0.5 

2.0 

6.6 

0.0 

0.0 

West Vi.rqinia 

23.4 80.0 10.2 

14.7 8.6 0.0 

61.7 12.2 3.8 

14.0 

30.0 

63.5 

3.8 

52.1 

32.5 

23.9 

29.0 

11.4 

82.8 

30.5 

40.9 

25.4 

24.4 

71.1 

81.3 

52.6 

43.4 

35.1 

39.6 

53.3 

115.6 

35.8 

7.4 

14.0 

2.5 

40.6 

38.1 

51.1 

93.5 

52.1 

114.0 

48.0 

79.2 

115.1 

134.6 

5.6 

33.0 

127.0 

76.5 

65.0 

4.8 

6.4 

5.6 

2.5 

94.0 

1.0 

1.5 

8.6 

7.6 

0.8 

3.0 

6.4 

4.1 

7.6 

24.4 

0.8 

2.5 

0.5 

6.4 

14.7 

23.6 

2.5 

3-4 

42.4 

25.4 

61.0 

15.0 

20.8 

17.5 

47.2 

48.5 

70.6 

23.4 

39.1 

153.7 

52.1 

4--5 

45.0 

24.9 

40.6 

12.4 

13.7 

116.1 

62.5 

67.8 

85.6 

23.4 

82.6 

128.8 

58.9 

29.5 103.4 

18.3 23.4 

130.3 73.9 

24.9 129.5 

30.5 65.8 

68.1 70.9 

8.9 17.8 

54.6 54.6 

33.3 73.2 

23.9 62.0 

41.7 80.0 

18.3 104.9 

98.6 134.9 

39.9 144.5 

54.1 88.9 

31.0 104.6 

34.5 139.4 

77.7 205.7 

125.7 86.9 

66.0 85.6 

48.3 170.4 

36.6 111.5 

54.9 104.6 

66.0 58.2 

S-6 

10.4 

0.5 

o.p 

1.8 

0.3 

108.7 

29.5 

36.8 

16.3 

6.6 

56.1 

14.5 

18.8 

3-5 

52.8 

25.7 

61.0 

16.5 

21.1 

126.2 

70.6 

77.7 

86.4 

27.9 

88.6 

168.1 

70.9 

4-6 

45.0 

25.1 

40.6 

12.7 

13.7 

116.1 

68.6 

75.4 

86.1 

25.4 

89.2 

128.8 

58.9 

3--6 

52.8 

25.9 

61.0 

16.8 

21.1 

126.2 

76.7 

85.3 

1--6 

57.9 

28.2 

114.3 

46.5 

77.2 

161.3 

95.3 

106.2 

86.9 127.3 

30.0 44.5 

95.3 122.7 

168.1 269.0 

70.9 110.2 

90.2 109.5 113.5 119.6 120.1 

8.6 26.9 23.4 26.9 31.2 

16.0 142.5 77.7 146.3 178.1 

121.9 140.5 135.9 146.8 153.2 

41.4 66.3 71.4 71.9 73.4 

9.9 75.4 73.4 78.0 79.5 

108.0 22.9 111.8 116.8 116.8 

3.6 57.2 55.6 58.2 63.2 

42.2 73.9 74.7 75.4 78.7 

46.7 62.0 70.6 70.6 75.4 

58.7 

94.2 

92.7 

111.8 

87.6 100.3 

105.7 112.5 

102.1 

119.1 

55.1 150.6 137.9 153.7 158.8 

120.4 153.9 150.9 160.3 162.8 

52.1 102.1 93.0 106.2 122.2 

86.9 110.2 112.3 

139.4 149.6 163.8 

135.4 212.3 206.5 

8.1 131.3 89.4 

33.5 99.1 86.1 

133.4 175.3 176.8 

91.2 113.0 126.2 

88.6 119.9 128.3 

117.9 120.9 

174.0 174.0 

213.1 228.1 

133.9 144.5 

99.6 101.9 

181.6 185.7 

127.8 133.4 

143.5 145.5 

7.4 70.9 60.7 73.4 79.8 
= t.J 

~ 

C1 

~ 

3 

0 

-a 

::r 

;:;· 

~ c 

Q. 

;· 

... rn 

~ 0 

3 

l» 

5. 

"T'' 

(5'" 

&. 

s. 

z 

0 

~ 

w 

Sn 

... 

1.1:) 

QQ 

~ 

~ 

; 

~ 

Table 1. Official NOAA rain gage network data, October and November 1-6, 1985-Continued 

Latitude Longitude 

arc arc October 

Station deg min deg min 1985 

462054 38 57 

462151 38 48 

462358 38 30 

462462 37 52 

462522 38 1 

462718 38 53 

462920 39 28 

463072 37 35 

81 17 126.2 

79 53 166.4 

80 49 108.0 

81 28 70.6 

82 25 136.1 

79 51 

80 8 

81 6 

152.4 

86.6 

56.4 

463215 38 40 79 

463353 37 22 81 

463361 38 

463464 38 

463544 38 

40 80 

48 79 

56 80 

463798 38 39 80 

463846 38 17 82 

464128 38 6 81 

464200 38 41 82 

464372 39 39 80 

464393 38 22 82 

464397 38 25 82 

464408 37 28 81 

464763 39 23 77 

464816 37 50 82 

464956 37 44 81 

19 105.4 

33 41.7 

46 112.5 

43 180.1 

49 141.2 

23 118.1 

6 111.5 

0 79.5 

11 157.2 

25 84.3 

33 131.3 

30 133.9 

49 48.0 

53 118.9 

24 100.3 

35 71.9 

465002 

465224 

465353 

465365 

465563 

39 43 79 51 

37 46 80 28 

37 51 82 0 

38 12 81 22 

38 3 81 49 

55.4 

55.4 

94.2 

101.6 

78.5 

465600 37 44 81 53 61.0 

465626 39 32 80 30 89.4 

465707 39 24 77 59 121.4 

465739 38 52 78 52 155.7 

465871 37 59 80 45 61.5 

465963 39 29 80 52 103.9 

466163 39 2 78 58 125.7 

466202 39 39 79 55 42.2 

466212 39 37 79 58 52.6 

o.o 

o.o 

0.3 

0.0 

0.0 

0.0 

3.6 

0.8 

13.2 

o.o 

0.0 

0.3 

o.o 

0.0 

0.0 

0.0 

0.5 

0.0 

23.9 

0.3 

0.0 

2.0 

o.o 

o.o 

o.o 

o.o 

0.0 

o.o 

o.o 

o.o 

4.3 

11.4 

8.4 

o.o 

o.o 

3.8 

0.5 

0.0 

3.8 

0.0 

3.3 

1.5 

19.8 

11.7 

5.8 

6.1 

11.9 

3.6 

5.1 

1.8 

2.5 

2.0 

5.1 

4.8 

6.6 

1.8 

2.3 

26.9 

25.9 

4.3 

0.0 

4.3 

0.8 

13.2 

8.4 

1.3 

3.8 

8.1 

7.9 

2.0 

9.9 

4.8 

2.5 

4.1 

3.3 

0.8 

6.6 

9.4 

3.3 

o.o 

0.5 

4 

26.7 

i2.7 

32.5 

41.7 

25.4 

67.1 

145.3 

67.6 

27.2 

30.5 

4.6 127.5 19.3 

29.0 93.0 11.2 

1.0 37.6 44.5 

23.9 191.8 0.0 

o.o 26.4 27.9 

7.4 109.2 37.8 

5.6 12.2 110.7 

10.4 43.2 88.1 

0.0 27.9 136.1 

0.5 25.9 37.1 

1.3 

14.0 

5.8 

34.3 

27.9 

0.8 

6.4 

0.0 

17.8 

5.1 

0.0 

o.o 

1.3 

0.8 

1.0 

38.1 

23.6 

10.7 

41.4 

14.7 

14.7 

51.1 

37.8 

o.o 

50.5 

29.5 

76.2 

31.5 

22.9 

23.9 

23.6 

109.0 

73.9 

33.5 

90.7 

14.2 

17.8 

48.3 

16.5 

0.0 

37.3 

66.0 

o.o 

34.5 

50.8 

51.3 

37.3 

4.3 

30.7 30.0 5.8 

19.6 101.6 72.9 

1.3 22.1 88.9 

5.3 40.6 86.4 

4.8 27.9 71.9 

24.4 88.6 11.4 

2.8 33.0 90.4 

November 1985 

3.8 

8.9 

14.5 

15.7 

~ 

33.3 

22.1 

35.8 

41.7 

4-5 

93.7 

158.0 

100.1 

68.8 

12.7 25.9 55.9 

1.8 132.1 146.8 

1.5 121.9 104.1 

5-6 3-5 4-6 H 1--6 

70.9 100.3 97.5 104.1 108.0 

154.2 167.4 166.9 176.3 176.3 

82.0 103.4 114.6 117.9 121.4 

42.9 68.8 84.6 84.6 86.1 

43.2 56.4 68.6 69.1 88.9 

21.1 151.4 148.6 153.2 164.8 

12.7 133.1 105.7 134.6 144.0 

10.2 

1.0 

5.1 

3.8 

38.6 82.0 54.6 83.1 92.2 93.2 

215.6 192.8 216.7 

100.1 

215.6 191.8 1.0 241.8 

16.0 

1.5 

17.0 

8.9 

26.4 54.4 33.0 

116.6 147.1 41.7 

17.8 122.9 126.7 

22.9 

2.8 

5.6 

0.5 

2.0 

21.6 

3.3 

0.0 

9.1 

1.8 

0.0 

13.0 

16.5 

16.0 

13.2 

1.3 

0.0 

2.5 

21.1 

53.6 131.3 

27.9 164.1 

26.4 63.0 

24.9 97.5 

24.6 44.2 

47.2 132.1 

49.0 29.0 

42.7 32.5 

51.8 99.3 

44.2 54.4 

0.0 o.o 

68.3 87.9 

34.5 95.5 

76.2 76.2 

31.5 66.0 

24.1 73.7 

24.6 75.2 

24.6 

147.1 

60.7 

121.2 

23.4 

61.0 

113.3 

35.8 

174.5 

111.0 

5.8 46.0 127.0 

6.6 32.8 

2.3 113.0 

99.8 

100.1 

8.4 35.8 123.4 

89.7 

153.2 

46.0 

96.8 

36.3 

96.3 

14.7 

19.8 

69.9 

19.8 

0.0 

46.5 

67.8 

0.0 

47.5 

67.3 

67.3 

50.5 

5.6 

5.8 

75.4 

110.0 

92.2 

78.5 

13.7 

98.8 

54.4 59.4 59.4 

154.4 150.9 158.2 

128.5 138.9 144.5 

141.7 132.8 143.3 

164.1 181.1 181.1 

63.5 71.9 72.4 

98.8 120.4 121.7 

58.2 47.0 61.0 

137.9 137.7 143.5 

63.2 29.5 63.8 

60.5 34.5 62.5 

100.1 120.9 121.7 

60.7 57.7 64.0 

0.0 0.0 o.o 

105.7 

100.6 

76.2 

97.0 114.8 

97.3 102.4 

76.2 76.2 

66.0 79.0 79.0 

74.9 90.2 91.4 

75.9 91.2 91.9 

62.0 

151.4 

74.2 75.2 

114.6 152.7 

63.0 

163.3 

146.6 

145.8 

183.1 

77.5 

126.5 

68.1 

145.3 

89.9 

89.7 

147.6 

70.4 

0.0 

119.1 

103.1 

89.4 

87.4 

92.7 

95.8 

83.3 

164.8 

66.5 35.8 66.5 80.0 

194.1 177.0 196.6 214.9 

112.3 132.1 133.4 138.2 

132.3 132.8 

104.6 106.4 

124.5 102.4 

126.2 131.8 

138.2 

111.3 

140.7 

119.1 

126.7 130.6 

134.6 135.4 
~ I'D 

~ a 

0 

~ 

0 

--::r 

I'D 

{II 

0 

3 

s. 

z 

0 

~ 

w 

... & 

.... 

~ 

,?1 = 

~ 

; 

~ 

CCI 

N 

V1 

Table 1. Official NOAA rain gage network data, October and November 1--6, 1985-Continued 

Station 

466248 

466442 

466591 

466849 

466859 

466867 

466900 

466960 

466982 

466991 

467018 

467029 

467207 

467287 

467455 

467552 

467730 

467785 

468051 

468172 

468308 

468384 

468433 

468614 

468662 

468777 

468807 

468844 

469011 

469049 

469086 

469281 

469323 

469333 

469368 

469436 

469522 

469605 

469610 

latitude longitude 

arc arc October 

deg min deg min 1985 

39 

40 

37 

39 

39 

39 

37 

38 

39 

38 

40 

37 

37 

38 

38 

38 

39 

39 

38 

38 

38 

38 

38 

38 

38 

39 

39 

37 

37 

38 

38 

39 

38 

38 

40 

39 

37 

37 

37 

54 

30 

58 

21 

16 

6 

21 

53 

9 

40 

9 

35 

22 

55 

0 

53 

20 

20 

20 

43 

24 

48 

41 

14 

39 

27 

9 

57 

33 

47 

33 

6 

14 

29 

17 

3 

48 

40 

42 

80 

80 

81 

81 

81 

79 

81 

79 

80 

80 

80 

81 

81 

81 

80 

81 

78 

79 

79 

79 

79 

81 

79 

80 

80 

79 

79 

81 

80 

79 

80 

78 

82 

80 

80 

80 

80 

82 

82 

45 

36 

9 

26 

34 

40 

52 

12 

2 

13 

42 

32 

5 

55 

22 

41 

46 

41 

54 

38 

60 

21 

31 

53 

41 

33 

30 

5 

32 

17 

2 

35 

27 

25 

37 

28 

18 

17 

17 

67.3 

47.0 

71.1 

124.2 

99.3 

153.9 

42.2 

148.1 

126.7 

136.9 

70.6 

54.6 

43.4 

116.3 

121.4 

169.7 

126.2 

163.3 

85.1 

110.0 

115.3 

145.8 

96.0 

115.1 

118.4 

131.1 

157.5 

83.1 

41.1 

113.0 

94.2 

125.5 

169.4 

105.7 

66.8 

126.5 

52.3 

98.0 

95.3 

o.o 

3.3 

o.o 

0.3 

0.0 

0.0 

21.6 

7.6 

0.0 

o.o 

o.o 

0.3 

0.5 

0.0 

o.o 

o.o 

o.o 

0.0 

4.1 

2.0 

2.5 

o.o 

8.6 

0.0 

o.o 

o.o 

12.7 

0.0 

0.3 

7.1 

0.0 

7.1 

o.o 

o.o 

o.o 

0.0 

6.9 

0.0 

0.0 

3.8 

5.6 

3.0 

10.4 

4.6 

2.8 

o.o 

17.8 

9.7 

4.6 

1.8 

1.0 

7.6 

5.1 

5.1 

7.1 

0.0 

1.0 

11.2 

5.1 

6.4 

5.1 

20.6 

3.6 

1.8 

0.8 

17.8 

1.8 

7.4 

10.7 

6.4 

12.2 

40.6 

1.3 

2.8 

6.1 

13.2 

10.2 

o.o 

10.7 

29.2 

0.3 

20.6 

4.3 

7.4 

27.9 

7.6 

2.8 

1.8 

14.0 

1.0 

1.3 

8.6 

8.6 

3.0 

0.0 

7.9 

16.0 

4.1 

11.7 

2.8 

9.1 

1.0 

6.9 

9.9 

7.1 

0.5 

1.8 

27.7 

3.8 

6.6 

6.6 

0.0 

3.3 

6.1 

0.5 

o.o 

o.o 

4 

38.1 

67.3 

23.4 

43.7 

24.1 

10.4 

28.4 

41.9 

18.8 

8.6 

27.9 

34.3 

41.9 

16.3 

16.3 

21.6 

o.o 

30.7 

157.5 

20.3 

38.1 

35.3 

41.7 

29.7 

35.6 

22.1 

13.7 

31.8 

10.4 

53.1 

20.6 

33.3 

33.3 

9.7 

50.8 

47.8 

13.0 

15.7 

o.o 

95.8 

18.3 

53.3 

12.2 

45.0 

132.1 

9.9 

146.1 

107.4 

173.2 

80.0 

28.4 

54.6 

36.6 

80.0 

53.3 

0.0 

116.1 

14.7 

152.4 

127.0 

66.0 

187.2 

86.1 

111.3 

74.9 

137.2 

51.3 

77.5 

188.0 

78.0 

66.5 

34.3 

120.4 

71.1 

57.2 

90.2 

33.3 

0.0 

November 1985 

2.8 

1.3 

14.5 

1.8 

4.6 

7.6 

0.0 

3.8 

14.5 

20.8 

3.6 

12.2 

3.3 

12.7 

1.0 

8.1 

o.o 

12.2 

0.5 

8.4 

5.8 

5.6 

1.3 

23.4 

11.2 

10.2 

11.4 

4.1 

1.0 

o.o 

3.8 

8.4 

12.7 

22.9 

2.5 

3.8 

2.0 

12.2 

o.o 

3-4 

48.8 

96.5 

23.6 

64.3 

28.4 

17.8 

56.4 

49.5 

21.6 

10.4 

41.9 

35.3 

43.2 

24.9 

24.9 

24.6 

o.o 

38.6 

173.5 

24.4 

49.8 

38.1 

50.8 

30.7 

42.4 

32.0 

20.8 

32.3 

12.2 

80.8 

24.4 

39.9 

39.9 

9.7 

54.1 

53.8 

13.5 

15.7 

o.o 

4-5 

133.9 

85.6 

76.7 

55.9 

69.1 

142.5 

38.4 

188.0 

126.2 

181.9 

108.0 

62.7 

96.5 

52.8 

96.3 

74.9 

0.0 

146.8 

172.2 

172.7 

165.1 

101.3 

228.9 

115.8 

146.8 

97.0 

150.9 

83.1 

87.9 

241.0 

98.6 

99.8 

67.6 

130.0 

121.9 

104.9 

103.1 

49.0 

o.o 

5-6 

98.6 

19.6 

67.8 

14.0 

49.5 

139.7 

9.9 

149.9 

121.9 

194.1 

83.6 

40.6 

57.9 

49.3 

81.0 

61.5 

0.0 

128.3 

15.2 

160.8 

132.8 

71.6 

188.5 

109.5 

122.4 

85.1 

148.6 

55.4 

78.5 

188.0 

81.8 

74.9 

47.0 

143.3 

73.7 

61.0 

92.2 

45.5 

0.0 

3-5 4--6 

144.5 136.7 

114.8 86.9 

77 .o 91.2 

76.5 57.7 

73.4 73.7 

149.9 150.1 

66.3 

195.6 

129.0 

183.6 

121.9 

63.8 

97.8 

61.5 

104.9 

78.0 

0.0 

154.7 

188.2 

176.8 

176.8 

104.1 

238.0 

116.8 

153.7 

106.9 

158.0 

83.6 

89.7 

268.7 

102.4 

106.4 

74.2 

130.0 

125.2 

111.0 

103.6 

49.0 

0.0 

38.4 

191.8 

140.7 

202.7 

111.5 

74.9 

99.8 

65.5 

97.3 

83.1 

0.0 

159.0 

172.7 

181.1 

170.9 

106.9 

230.1 

139.2 

158.0 

107.2 

162.3 

87.1 

88.9 

241.0 

102.4 

108.2 

80.3 

152.9 

124.5 

108.7 

105.2 

61.2 

0.0 

~ 

147.3 

116.1 

91.4 

78.2 

78.0 

157.5 

66.3 

199.4 

143.5 

204.5 

125.5 

75.9 

101.1 

74.2 

105.9 

86.1 

0.0 

166.9 

188.7 

185.2 

182.6 

109.7 

239.3 

140.2 

164.8 

117.1 

169.4 

87.6 

90.7 

268.7 

106.2 

114.8 

86.9 

152.9 

127.8 

114.8 

105.7 

61.2 

0.0 

1--6 

151.1 

125.0 

94.5 

88.9 

82.5 

160.3 

87.9 

224.8 

153.2 

209.0 

127.3 

77.2 

109.2 

79.2 

111.0 

93.2 

o.o 

167.9 

204.0 

192.3 

191.5 

114.8 

268.5 

143.8 

166.6 

117.9 

199.9 

89.4 

98.3 

286.5 

112.5 

134.1 

127.5 

154.2 

130.6 

120.9 

125.7 

71.4 

0.0 
= Table 2. Nonofficial rainfall data from bucket surveys, November 1-6, 1985 ~ 

a'l [Collected by T. Purkey, Soil Conservation Service, during March 1986, tabulated and checked by S. Kite, West Virginia University. Values in millimeters. Dashes indicate missing values. Asterisks mark 

estimated values] ~ t'l) 

0 Date in November 3 

0 Site UTM coordinates Total Notes 

-a 1 2 3 4 5 6 :::r 

;::;· Greenbriar River Basin, Pocahontas County, W.Va. f.ll 

2' 

Q.. Durbin 4267000N 602000E - - - 203.2 

;:;- Arborvale 4255000N 603000E 4.6 10.2 17.8 154.9 16.5 204.0 Thunder 10:35 a.m., Nov. 4. ~ 

~ Cass 4250000N 594500E 5.3 15.7 22.1 104.6 50.3 2.5 198.1 Usually read 5 p.m. 0 Clover Lick 4243000N 590000E - - >127.0 - >127.0 Ran over 127-mm gage in 7 h. 3 

Ill Dilleys Mill 4234500N 591500E 3.8 14.0 14.0 17.8 109.2 .0 158.8 Usually read at 6:30a.m.; 58 mm between :::1 6:30a.m. and 4:30p.m., Nov. 4. Q.. 

"T'' 

0 Tygart Valley River Basin, Randolph County, W.Va. 0 

Q.. Usually read 7 p.m.; read at 10 p.m., 0 Montrose 4325000N 603000E 6.3 6.3 25.4 137.9 6.3 184.2 - Nov. 3, 11 p.m., Nov. 4. z 

0 Elkins 4310500N 592000E 10.2 2.5 12.7 139.7* 21.6 186.7* 127-mm gage overflowed Nov. 5. ~ 

w Cheat River Basin, Randolph County, W.Va. I 

1.11 

~ Kerens 4319000N 608500E 38.1 50.8 63.5 88.9 241.3 Usually read 7:30 a.m. ..... 

I.C 

= South Branch Potomac River Basin, Pendleton County, W.Va. ~ 

~ Fort Seybert 4284000N 659000E 15.2 14.0 36.8 196.8 2.5 - 265.4 Usually read 7-8 p.m.; rain ended about 

<:: 12 a.m., Nov. 4. 

f Variable reading time: 116.8 mm between 

<:: 6 p.m., Nov. 3, and 2 p.m., Nov. 4; PI Franklin 4284500N 641000E ------------------ 104.1 ----------------- 175.3 45.7 .0 325.1 58 mm more by 7 p.m., Nov. 4; 46 mm 

more by 3:00a.m., Nov. 5; end of rain. 

Variable reading times; 152-mm gage 

Franklin 4281000N 639000E - - 114.5 - >267.0 overflowed 10 a.m., Nov. 4; 114 more 

by 7 a.m., Nov. 5; end of rain 10:15 

p.m., Nov. 4. 

Variable reading times; 102 mm 9:30 

Dahmer 4270000N 638000E 20.3 25.4 38.1 185.1 33.0 302.3 p.m., Nov. 3, to 3:45p.m., Nov. 4; 84 mm 

more by 10:15 p.m., Nov. 4. 

Riverton 4290000N 638000E 69.8 114.3 57.2 152.4 - 393.7 Usually read in morning. 

Circleville 4281000N 631500E 29.2 19.0 226.1 55.9 - >330.2 Usually read at sunset; read at 

sunset Nov. 4 and 8 a.m., Nov. 5. 

North Fork Shenandoah River Basin, Rockingham County, Va. 

Fulks Run 4283500N 678500E 127.0 133.4 127.0 - - 387.4 Unknown reading time. 

Fulks Run 4281000N 682000E 15.2 22.9 20.3 91.4 106.7 12.7 265.5 Usually read at 7:00 a.m. 

Linville 4265000N 689000E -------------------- 94.0 ------------------- 85.1 - 179.1 Usually read at 7:00 a.m. 

James (Jackson) River Basin, Bath County, Va. 

Mill Gap 4243000N 611500E 3.8 8.4 10.2 36.1 158.8 5.1 222.2 Usually read at 7:00a.m. 

Monterey 4252000N 611500E 8.6 19.8 32.0 100.6 57.9 .5 219.4 Usually read at 5:00p.m. 
40 Mathias 40 Dale Enterprises 

20 20 

(/) 0 0:: 

L.U 

IL.U 

~ 40 :::::i 

Elkins 40 Mustoe 

....J 

~ 

z 20 20 ....J~ 

....J 

<( 

II 1111111 0 

u.... 

z 0 <( 

0:: 

40 Valley Head 40 Hot Springs 

20 20 

0 0 

2 3 4 5 6 2 3 4 6 

DAYS DURING NOVEMBER, 1985 

Figure 9. Representative hourly rainfall data for November 2-6 from gages in West Virginia and Virginia (data from 

NOM, 1986). 

....J_J 

....J_J 

~~ Zz 

~ ~ 1.0 

::2!a::: 

cx:::>- Oo 

I- 0 C/) ~ 

. . 0.5 0 

~ 0:: 

0.0 L....L __ L___....L...__--L.._ _ _____.. __ ~---'---------'---'--~ 

2 3 6 12 24 48 96 168 

RAINFALL DURATION IN HOURS (LOG SCALE) 

Figure 10. Ratio of storm rainfall to rainfall of the 100-yr 

event for durations of 1-168 h (7 days). The 100-yr rainfall 

is estimated from Hershfield (1961) and Miller (1964). Data 

are from hourly gages in figure 9 plus Franklin and Spruce 

Knob (data from NOM, 1986). 

responsible for the storm was complex. Especially notable 

is the role of a late-season tropical storm that brought 

moisture and latent heat up the Mississippi Valley. Most 

tropical storms that affect the United States hug the eastern 

seaboard, and most occur in June-September (Neumann and 

others, 1981). Jacobson and others (1989) argued that 

tropical storms produce extreme rainfall and flood events in 

the Piedmont and Blue Ridge of the central Appalachians 

more so than in the Valley and Ridge province and 

Appalachian Plateaus, but stress that extreme rainfall can 

also arise from frontal and convective storms. While it is 

unknown whether intensity and duration of rainfall similar 

to the November 1985 storm could be generated in the same 

place by different meteorological conditions, it is clear that 

the specific characteristics of this storm were strongly 

influenced by an anomalous tropical storm track. 

Distinct outliers of some of the highest magnitude 

events in the rainfall records suggest that different meteorological mechanisms may operate at low frequencies. 

Identification of the specific meteorological conditions that 

produce these events would increase our ability to predict 

extreme rainfall and its geomorphic effects. Synoptic-scale 

meteorological conditions conducive to extreme floods have 

been identified elsewhere in the United States (Maddox and 

others, 1979; Hirschboeck, 1987) but have not been studied 

in detail in the central Appalachians. It is unclear whether a 

particular set of conditions is sufficient or necessary to 

produce extreme rainfall in this area. 

In addition to point total rainfall values, the geomorphic effectiveness of a storm is dependent on intensity and 

duration of rainfall, areal extent of rainfall, position with 

respect to drainage divides, antecedent moisture conditions, 

and geology and physiography of the area affected (Jacobson and others, 1989). Different combinations of intensity 

and duration may produce either similar or different geomorphic effects, depending on where the rain falls. In 

comparison with other flood- and landslide-triggering 

storms, the 1985 storm produced rainfall at lower intensities 

Meteorology of the Storm of Nov. 3-5, 1985, W. Va., Va. 827 
Cl) 

E5 200 1-

UJ 

~ 

:3 150 

~ 100 __ r 

_J 

~ 

z 50 

<( 

0:: 

Cl) 

0:: 

~ 200 UJ 

~ 

:3 150 

=~ 100 _J 

~ 

z 50 

<( 

0:: 

Cl) 

0 

1945 

E5 200 1-

UJ 

~ 

:3 150 

0 

1945 

1955 

1955 

1955 

1965 1975 

YEAR 

FRANKLIN 24-HOUR RAINFALL 

1965 1975 

YEAR 

FRANKLIN 48-HOUR RAINFALL 

1965 1975 

YEAR 

FRANKLIN 96-HOUR RAINFALL 

1985 1995 

1985 1995 

1985 1995 

Figure 11. Franklin and Spruce Knob gage records showing (A, D) 24-h, (8, f) 48-h, and 

(C, F) 96-h duration rainfall (data from NOAA, 1986). 

828 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W.Va., Va. 
U) 

ffi 200 1--

LJ..J 

::2: 

~ 150 

::2: 

z 

_.r 100 .....J 

<( 

u.. 

z 50 

<( 

c: 

U) 

ffi 200 1--

LJ..J 

::2: 

~ 150 

U) 

c: 

~ 200 LJ..J 

::2: 

~ 150 

::2: 

z 

.....J~ 100 .....J 

<( 

u.. 

z 50 

<( 

c: 

1955 

1955 

1955 

Figure 11. Continued. 

1965 1975 1985 1995 

YEAR 

SPRUCE KNOB 24-HOUR RAINFALL 

1965 1975 1985 1995 

YEAR 

SPRUCE KNOB 48-HOUR RAINFALL 

1965 1975 1985 1995 

YEAR 

SPRUCE KNOB 96-HOUR RAINFALL 

Meteorology of the Storm of Nov. 3--5, 1985, W. Va., Va. 829 
Franklin 24 hr Spruce Knob 24 hr 

5.0 

4.5 

Cl) 

cc 

L.U 

IL.U 4.0 

~ 

::::i 

_J 

~ 

z 

_J 

_J 

<( 5.5 u... 

z 

<( 

cc Franklin 48 hr Spruce Knob 48 hr Q.l 

C!J 

0 5.0 _J 

4.5 

4.0 

,, 

.... 

.99 .9 .7 .5 .3 .1 .01 .99 .9 .7 .5 .3 .1 .01 

EXCEEDENCE PROBABILITY 

Figure 12. Plots of loge (rainfall) against exceedence probability for annual series of 24- and 48-h rainfall at Franklin and 

Spruce Knob rain gages. Heavy curve is the log Pearson type Ill distribution fit to each record using a regional skew 

coefficient. Light curves mark the 95 percent confidence limit. 

Table 3. Estimated recurrence intervals of peak rainfall 

Plotting Log Pearson Log Pearson 

Gage position type Ill type Ill 

(Gringorten, population regional 

1963) skew skew 

Franklin 

1 day 70 71 111 

2 day 70 67 166 

Spruce Knob 

1 day 68 122 133 

2 day 

Upper Tract1 

68 263 200 

2 day 83 286 

1

Estimated from Franklin record. 

and somewhat longer durations (see discussions by Jacobson and others, chapter C, this volume, and Miller and 

Parkinson, chapter E, this volume). Other Appalachian 

storms have had similar rainfall totals, but the 1985 storm 

covered a larger area (Miller, 1990), had moderate soil 

moisture levels at the time of the rainfall, and had minimal 

interception and evapotranspiration. Thus the sequence of 

meteorological events leading to the November 1985 storm 

and the suite of geomorphic effects it produced may be 

sufficiently complex that the event cannot be readily compared with other historical events. 

REFERENCES CITED 

Case, R.A., 1986, Atlantic hurricane season of 1985: Monthly 

Weather Review, v. 114, p. 1390-1405. 

Embree, W.N., Friel, E.A., and Taylor, F.M, 1987, Water 

resource data, West Virginia water year 1985: U. S. Geological Survey Water-Data Report WV-85-1, 224 p. 

830 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W.Va., Va. 
Gringorten, 1.1., 1963, A plotting rule for extreme probability 

paper: Journal of Geophysical Research, v. 69, no. 3, p. 

813-814. 

Gryta, J.J., and Bartholomew, M.J., 1989, Factors influencing 

the distribution of debris avalanches associated with the 1969 

Hurricane Camille in Nelson County, Virginia, in Schultz, 

A.P., and Jibson, R.W., eds., Landslide processes of the 

eastern United States and Puerto Rico: Geological Society of 

America Special Paper 236, p. 15-28. 

Hershfield, D.M., 1961, Rainfall frequency atlas of the United 

States: U.S. Weather Bureau Technical Paper 40, 114 p. 

Hirschboeck, K.K., 1987, Catastrophic flooding and atmospheric 

circulation anomalies, in Mayer, L., and Nash, G., eds., 

Catastrophic flooding: London, Allen and Unwin, p. 25-56. 

Holton, J.R., 1979, An introduction to dynamic meteorology: San 

Diego, Calif. , Academic Press, 341 p. 

Jacobson, R.B., Miller, A.J., and Smith, J.A., 1989, The role of 

catastrophic geomorphic events in central Appalachian 

landscape evolution, in Gardner, T.W., and Sevon, W.D., 

eds. Appalachian geomorphology: Geomorphology, v. 2, 

p. 257-284. 

Maddox, R.A., Chappell, C.F., and Hoxit, L.R., 1979, Synopticand meso-scale aspects of flash flood events: Bulletin of the 

American Meteorological Society, v. 60, p. 115-123. 

Miller, A.J., 1990, Flood hydrology and geomorphic effectiveness in the central Appalachians: Earth Surface Processes and 

Landforms, v. 15, p. 119-134. 

Miller, J .F., 1964, Two- to ten-day precipitation for return periods 

of 2 to 100 years in the contiguous United States: U.S. 

Weather Bureau Technical Paper 49, 29 p. 

National Oceanic and Atmospheric Administration, 1986, Climatic data: Asheville, N.C. , National Climatic Data Center, 

digital media. 

Neumann, C.J., Cry, G.W., Caso, E.L., and Jarvinen, B.R., 

1981, Tropical cyclones of the North Atlantic 

Ocean,1871-1980: Asheville, N.C., National Climatic Data 

Center, 152 p. 

Robertson, F.R., 1987, Use of GOES IR data in estimating 

synoptic-scale rainfall, Algorithm development and transferability: Unpublished manuscript available from author, Mailcode ED42, Space Science Laboratory, Marshall Space 

Flight Center, AL 35812. 

Waylen, P.R., 1985, Stochastic flood analysis in a region of 

mixed generating processes: Transactions, Institute of British 

Geographers, v. 10, p. 95-108. 

Williams, G.P., and Guy, H.P., 1973, Erosional and depositional 

aspects of Hurricane Camille in Virginia, 1969: U.S. Geological Survey Professional Paper 804, 80 p. 

Meteorology of the Storm of Nov. 3-5, 1985, W.Va., Va. 831 

Chapter C 

Landslides Triggered by the Storm of 

November 3-5, 1985, Wills Mountain 

Anticline, West Virginia and Virginia 

By ROBERT B. JACOBSON, JOHN P. MCGEEHIN, 

ELIZABETH D. CRON, CAROLYN E. CARR, 

JOHN M. HARPER, and ALAN D. HOWARD 

U.S. GEOLOGICAL SURVEY BULLETIN 1981 

GEOMORPHIC STUDIES OF THE STORM AND FLOOD OF NOVEMBER 3-5, 1985, IN 

THE UPPER POTOMAC AND CHEAT RIVER BASINS IN WEST VIRGINIA AND VIRGINIA 
II Contents 

CONTENTS 

Abstract Cl 

Introduction C2 

Factors Controlling Landslide Locations C2 

Magnitude and Frequency of Landslide-Triggering Events C4 

Landslides, Basin Morphology, and Flood-Induced Geomorphic Changes C4 

Methods C5 

Terminology C6 

Acknowledgments C6 

Geology, Geomorphology, and Climate C6 

Storm of November 1985 Along the Wills Mountain Anticline C7 

Description of Landslides CS 

Terminology and Classification CS 

Slides and Slide Flows CS 

Debris Avalanches and Transitional Slide Flows Cll 

Controls on the Spatial Distribution of Landslides Cll 

Surficial Geology C12 

Bedrock Geology C12 

Physical Properties of Unstable Regolith C12 

Geologic Structure C16 

Slope Morphology and Land Cover C17 

Slides and Slide Flows C17 

Debris Avalanches C18 

Slope Aspect and Land Cover C18 

Magnitude and Frequency of Landslide Events C19 

Cumulative Rainfall Thresholds for Landslides C19 

Rainfall Intensity and Duration Thresholds for Landslides C19 

Rainfall and Spatial Density of Landslides C22 

Landslides and Flood-Induced Geomorphic Change C23 

Channel Changes and Landslides C24 

Tributary Channel-Change Index, Analytical Methods, and Results C24 

Landslide Spatial Density, Basin Morphology, and Flood Effects C25 

Discussion and Conclusions C27 

References Cited C31 

PLATE 

1. Maps showing geology, rainfall, and landslides, Wills Mountain anticline, 

West Virginia and Virginia In pocket 

FIGURES 

1. Location map showing the Wills Mountain Study area and nearby towns C2 

2. Stratigraphic column, diagrammatic cross section, and locations of the study 

areas C3 
3-9. Photographs of 

3. Slides on Reedsville Shale C9 

4. Slump on Reedsville Shale colluvium C9 

5. Slide on Greenbriar Group C9 

6. Slide flow on Reedsville Shale ClO 

7. Twin Run debris avalanche scar Cll 

8. Twin Run debris flow runout Cll 

9. Hartman debris flow runout snout Cll 

10. Histogram of percentage and landslide density by stratigraphic unit C13 

11-14. Range diagrams of residuum 

11. Clay contents by bedrock stratigraphic unit C14 

12. Plasticity of bedrock stratigraphic unit C14 

13. Porosity by bedrock stratigraphic unit ClS 

14. Infiltration rates by bedrock stratigraphic unit ClS 

15. Photograph of B horizon soil structure, Trenton Group residuum C16 

16. Aerial photograph showing slope aspect distribution of landslides C18 

17. Graph showing intensity and duration data for Appalachian 

landslides C20 

18. Graph showing storm duration and recurrence spectra for Appalachian 

storms C21 

19. Plot of rainfall and landslide density along Wills Mountain anticline C23 

20. Plot of landslide density and 48-h rainfall C23 

21. Probability model for landslide density C23 

22. Measurement parameters for basin morphology C25 

23. Scatter plots of channel-change index and explanatory variables C28 

TABLES 

1. Distribution of slope movements in study area by bedrock stratigraphic unit ClO 

2. Particle-size distributions for sampled regoliths C14 

3. Atterberg limits, plasticity indexes, activities, and dominant clay minerals of 

regolith samples C14 

4. Bulk density, void ratio, and porosity for selected regoliths ClS 

5. Effects of slope morphology and land cover on landslide location C17 

6. Association between slope movement and damage to stream channel for 79 

drainage basins C24 

7. Correlation coefficients between basin variables C26 

8. R2 values for multivariate models explaining the channel-damage index C30 

Contents Ill 

Landslides Triggered by the Storm of November 3-5, 

1985, Wills Mountain Anticline, West Virginia and 

Virginia 

By Robert B. Jacobson,1 John P. McGeehin,1 Elizabeth D. Cron,1 Carolyn E. Carr/ john M. 

Harper/ and Alan D. Howard3 

Abstract 

More than 3,000 landslides were triggered by heavy 

rainfall in the central Appalachian Mountains of West 

Virginia and Virginia, November 3-5, 1985. These landslides provided the opportunity to study spatial controls 

on landslides, magnitude and frequency of triggering 

events, and the effects of landslides on flood-induced 

geomorphic change. The study area consists of parts of 

the Wills Mountain anticline, a major NE-trending structure in the central Appalachians, and a portion of the 

adjacent Appalachian Plateau. Across the anticline and 

adjacent plateau, bedrock lithologies vary markedly and 

include pure marine limestone, marine shale, deltaic 

mudstone/sandstone sequences, and orthoquartzites. 

Because of the geologic structure, bedrock lithology varies little along strike. 

The spatial distribution of landslides triggered by the 

storm was controlled primarily by rainfall, bedrock lithology, surficial lithology, land cover, and slope morphology. 

The triggering rainfall was of moderate intensity and long 

duration. Two-day storm totals varied from 170 mm to 

more than 240 mm in the study area. Most landslides 

occurred at the northeast end of the study area, where 

48-h rainfall totals were in excess of 200 mm. Different 

rainfall thresholds are apparent for triggering landslides 

on different bedrock lithologies. The highest density of 

landslides occurred in shallow colluvium and residuum of 

the Reedsville Shale (Ordovician), followed by regolith of 

the Greenbriar and Mauch Chunk Groups (Mississippian). 

Most of the landslides in these fine-grained regoliths were 

shallow slides and slumps, many of which transformed to 

mudflows and delivered sediment directly to streams; a 

smaller number of debris avalanches were triggered high 

on quartzite ridges. 

Manuscript approved for publication February 22, 1991. 1 U.S. Geological Survey. 2 Geology Department, Carleton College, Northfield, MN 55057. 3 Department of Environmental Sciences, University of Virginia, 

Charlottesville, VA 22903. 

Instability of colluvium and residuum derived from 

the Reedsville Shale, compared with regolith from four 

other fine-grained bedrock lithologies, is attributable to 

its low strength combined with moderate infiltration rates 

that allowed soil moisture to accumulate under the moderate intensities of the rainfall. Slopes covered by coarse, 

cobbly debris flow and alluvial deposits, mostly of Pleistocene age, were very stable due to their low slope angles 

and high frictional strength. 

For a particular bedrock lithology, the spatial distribution of landslides appears controlled by interdependent 

influences of slope morphology and land cover. On the 

Reedsville Shale, most landslides occurred on north- to 

northeast-facing slopes, which might have had higher 

antecedent levels of soil moisture; these slopes have also 

been preferentially cleared because they produce better 

pasture forage for livestock. A secondary concentration of 

landslides on south- to southwest-facing slopes cannot be 

explained by conventional soil-moisture models. Landslide density was 100--200 percent higher on cleared land 

than on forested land. On pastured land, most landslides 

occurred on laterally planar slopes, but on forested land, 

most landslides occurred in slope positions that were 

laterally concave (hillslope hollows). 

Compared with other documented Appalachian 

storms that have triggered landslides, the November 1985 

storm had lower rainfall intensities over longer durations. 

Comparison with these other storms suggests that the 

anomalously high degree of slope instability in 1985 is due 

to the long duration of low-intensity rainfall on finegrained regolith derived from shale; the triggering rainfall 

can be approximated by the 48-h storm total. Landslide 

density in Reedsville Shale regolith is linearly related to 

the varying 48-h rainfall along the anticline. These data 

define a probabilistic model that estimates return intervals 

of 43 to 300 yr for landslide densities ranging from 1 to 70 

lands I ides/km2 • 

Analysis of flood-induced geomorphic changes in 79 

small drainage basins that received 210-240 mm of rainfall 

showed a clear local association between landslides and 

channel erosion or deposition adjacent to where the 

landslides delivered sediment to the stream. When chanLandslides Triggered by the Storm of Nov. 3-5, 1985, W.Va., Va. Cl 
WEST VIRGINIA 

80° 79° 

N 

• Petersburg 

39° 

Champe Rocks / 

•Elkins / 

eMathias 

/'' / .. "-./ 

VIRGINIA 

Valley Head 

• 

Upper Tract 

. ) 

Franklin/ 

~ ...... -J • Dale Enterprises 

38° 

WEST VIRGINIA 

I 

/ 

/ 

/ 

I 

I 

( MillGap 

Hot Springs 

• 0 

0 

VIRGINIA 

25 

25 

Figure 1. Wills Mountain study area and nearby towns. 

nel change was quantified using an index evaluated at 

each basin mouth, most of the channel change was 

attributable to the influence of basin morphology on flood 

discharge. Landslide density in the basins was of secondary, although measurable, importance in explaining floodinduced channel changes at the basin scale. 

INTRODUCTION 

Heavy rainfall during November 3-5, 1985, triggered 

more than 3,000 landslides and caused extreme flooding in 

small drainage basins in Pendleton County, W. Va., and 

Highland County, Va. One of the main areas receiving high 

rainfall totals straddled the Wills Mountain anticline, a 

major Appalachian structure. Rainfall varied from less than 

170 mm to more than 240 mm along the anticline (figs. 1, 

2; pl. 1), triggering shallow landslides on a variety of 

bedrock lithologies and in a variety of geomorphic settings. 

Because of the elongate outcrop pattern, the full range of 

storm rainfall was applied to all the bedrock lithologies and 

derived regoliths, thus providing a unique, well-defined 

geomorphic experiment for evaluating the influences of 

rainfall, geologic materials, land use, and other factors on 

slope stability. 

50 MILES 

50 KILOMETERS 

Our study of the storm focused on three areas of 

inquiry: ( 1) analysis of landslide locations to determine the 

dominant factors that control landslide susceptibility, (2) 

analysis of the magnitude and frequency with which landslides occur in this landscape, as reflected by the relationship between rainfall and landslide occurrence along the 

anticline, and (3) investigation of the extent to which 

flood-induced geomorphic changes are related to sediment 

added from upstream landslides. 

Factors Controlling Landslide Locations 

Empirical studies of landslide distributions in the 

Appalachian Mountains have attempted to rank the influences of various geologic, geomorphic, land cover, and 

human factors on slope stability (Pomeroy, 1980, 1982a, 

1984, 1987; Lessing and Erwin, 1977; Lessing and others, 

1976, 1983; Jacobson, 1985). Because the mechanical 

equilibrium of a slope site is determined by a complex, and 

probably nonunique, combination of these variables, empirical studies rarely produce unequivocal results, even with 

large data sets and rigorous statistical analyses. Furthermore, many studies have been handicapped because they 

used data sets consisting of landslides recognized on air 

C2 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W.Va., Va. 
A 

Period Stratigraphic Unit 

Pennsylvanian Pottsville Group 

Mauch Chunk Group 

Mississippian 

Greenbriar Group 

Pocono Group 

Hampshire Formation 

Devonian Chemung Group 

Brallier Formation 

Harrel to Needmore Shales, undivided 

Oriskany Sandstone and 

Helderburg Group, undivided 

Tonoloway, Wills Creek, 

Williamsport Formations, undivided 

McKenzie Formation, Rochester Shale, 

Silurian and Keefer Sandstone, undivided 

Clinton Group 

~ Tuscarora Sandstone 

Juniata Formation 

~ Oswego Sandstone I 

Reedsville Shale 

Ordovician 

Dolly Ridge Limestone 1 

Trenton 

Nealmont Limestone Group 

Black River Group 

New Market Limestone 

1 of Perry (1972) 

Figure 2. A, Generalized stratigraphic column for 

the study area, with simplified bedrock units used 

in plate 1. Units are from Cardwell and others 

(1968) except as noted. B, Simplified cross section 

Map Unit (pl. 1A) Approx. Thickness, ft. 

Pottsville Group 0 

-

Mauch Chunk Group 

1--- 2000 

Greenbriar Group 

Pocono Group 

-

Hampshire Formation 

1--- 4000 

1---

Chemung Group 1--- 6000 

1---

Devonian shales, 

undifferentiated Undifferentiated 1--- 8000 

Devonian 

rocks 

Oriskany Sandstone and 

Helderburg Group, undivided 1---

Tonoloway, Wills Creek, 

Williamsport Formations, undivided 

McKenzie Formation, Rochester Shale, 

Keefer Sandstone, and Clinton Group, 1--- 10000 

undivided 

Tuscarora Sandstone 

Juniata Formation and 1---

Oswego Sandstone 

1--- 12000 

Reedsville Shale 

1---

Trenton Group 

14000 

Black River Group 

St. Paul Group 

of the Wills Mountain anticline, modified from 

Kulander and Dean (1986). Section A-A' is located 

in figure 2C. C, Locations of study areas. 

Landslides Triggered by the Storm of Nov. 3-5, 1985, W.Va., Va. C3 
_J 

LU 

> LU 

_J 

<( 

LU 

U) 

s 

0 

_J 

UJ 

en 

B 

~ ('~ 

Q~ 

<%)-

1 

-y'.A A Pennsylvanian ~ 

NW c, 

0 

2000 

~ 4000 LU 

~ 

LU 

~ 

Figure 2. Continued. 

Ordovician 

Cambrian 

photos or in the field, regardless of the age of the landslide. 

Landslides that heal quickly can be expected to be underrepresented in these data sets, and those that occur where 

healing processes are slower are probably overrepresented. 

Our study of spatial controls on landslides along the 

Wills Mountain anticline avoids some of these complications first, by including only landslides triggered by the 

November 1985 storm. Hence, all landslides are equally 

mappable, except for a small possible bias against the 

smallest landslides, which might not be identifiable on 

large-scale air photos. Second, our study is limited to 

landslides triggered on natural slopes; thus we avoid the 

biases inherent in including slopes destabilized by man. 

Third, to the extent possible, our analytical methods characterize the entire landscape, not just the sites of landslides. 

In this way, we can consider why sites are stable as well as 

why sites are not. 

Magnitude and Frequency of LandslideTriggering Events 

Previous studies of storm-induced landslides in the 

Appalachians have identified rare rainfall events of high 

intensity and short duration as triggers (Stringfield and 

Smith, 1956; Hack and Goodlett, 1960; Williams and Guy, 

1973; Schneider, 1973; Bogucki, 1976; Everett, 1979; 

Pomeroy, 1980, 1984; Clark, 1987; Neary and Swift, 

1987). For the most part, these studies documented peak 

rainfall amounts that were inferred to have triggered landslides. Because they did not measure a range of rainfall 

bracketing the triggering amount, the studies could only 

2 4 MILES 

2 4 KILOMETERS 

A' 

SE 

0 _J 

LU 

> UJ 

_J 

5000 <( 

UJ 

U) 

s 

10000 0 

_J 

UJ 

OJ 

~ 

15000 UJ 

UJ 

LL. 

make the limited conclusion that the peak rainfall exceeded 

stability thresholds for some portion of the slope sites 

considered; the actual threshold was not determined. 

The natural geomorphic experiment produced by the 

1985 storm along the Wills Mountain anticline provided the 

opportunity to investigate slope instability in regolith 

derived from several bedrock lithologies over a range of 

rainfall. We were able to define the threshold cumulative 

rainfall at which the least stable site of a given bedrock 

lithology failed, and, for the bedrock lithology that experienced the most failures, we were able to document the 

variation of spatial density of landslides with cumulative 

storm rainfall. By estimating the recurrence interval for 

rainfall amounts along the anticline, we were able to 

estimate the recurrence interval for the associated degree of 

slope instability. 

Landslides, Basin Morphology, and 

Flood-Induced Geomorphic Changes 

Field observations in the study area shortly after 'the 

1985 event indicated that flood-induced erosion and deposition in stream channels were related to landslides on 

adjacent and upstream slopes. Almost all channel change 

began where a landslide delivered sediment to the channel, 

and many channels without upstream landslides showed 

negligible channel changes compared with channels of 

comparable drainage area with upstream landslides. These 

observations suggest that flood effects downstream from 

tributary drainage basins could be measurably related to 

sediment supply from landslides upstream in the basins. We 

C4 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W. Va., Va. 
c 79'30'00" 79'07'30" 

39'00'00" .--------r-------,--------, 

Germany Valley study area 

Slope-morphology study area 

Paddy Knob Mustoe Monterey SE 38'15'00" c____ ____ ____.l... _____ _..L ____ ____j 

Laneville Hapeville Petersburg 

West 

N 

I 

Wills Mountain anticline study area 

79'52'30" 79'30'00" 

Figure 2. Continued. 

have tested this hypothesis by comparing a channel-change 

index with extent of upstream slope instability, as well as 

basin morphometric parameters and rainfall amounts. 

Methods 

Landslides were documented by 1:24,000-scale aerial 

photographs flown in April 1986. The aerial photography 

covered the eastern limb of the Wills Mountain anticline to 

the rim of the Appalachian Plateau, and extended along 

strike from near Mill Gap, Va. , in the southwest to near 

Ketterman, W.Va., in the northeast (fig. 1; also Jacobson, 

chapter A, this volume, pl. 1). Landslides triggered during 

the storm of November 1985 were easily and accurately 

identified on these photos. 

Two separate maps were prepared from the aerial 

photographs. The first map, outlining the entire photocoverage area (fig. 2C), was prepared by identifying landLandslides Triggered by the Storm of Nov. 3-5, 1985, W.Va., Va. C5 
slides with a stereoscope and then transferring the photo 

data to 1:24,000 bases by zoom-transfer scope. This map 

was used to relate locations of landslides to bedrock 

lithology, surficial lithology, land cover, flood-related damage, and rainfall. A version of this map compiled at 

1:150,000 scale is shown in plate 1. The entire study area is 

referred to here as the Wills Mountain anticline study area. 

A second map (area shown in fig. 2C) for a smaller 

area of homogeneous rainfall near Circleville, W. Va., was 

prepared by accurate plotting from the same set of photographs with a PG-2 stereoplotter (Cron, 1990). This map 

was used for analysis of bedrock lithology, surficial lithology, land cover, and topographic controls on locations of 

landslides. This study area is referred to here as the 

Germany Valley study area. 

Both maps were extensively evaluated in the field 

during the spring and fall of 1986, and the spring of 1987 by 

field mapping of selected test areas. Field checking disclosed accuracy in identification of approximately 95 percent on cleared slopes and 90 percent accuracy in identification under tree cover. The smallest landslide mapped was 

approximately 15 m2 . 

A third nonmapped data base was compiled of landslide data in an area that overlaps the Germany Valley study 

area and continues to the southwest (area shown in fig. 2C). 

This data base, referred to as the slope morphology data 

base, was used to evaluate slope morphology controls on 

locations of 852 landslides in an area of homogeneous 

rainfall and bedrock lithology. 

Channel changes downstream of tributary drainage 

basins were assessed from low-altitude aerial photography 

(1:10,000 approximate scale), flown for the West Virginia 

Department of Highways in November 1985, and compared 

with pre flood aerial photos. These data constitute the data 

base for tributary flood damage. 

Geology was compiled from a variety of sources, 

including Cardwell and others (1968), Perry (1971), unpublished file maps of the Virginia Division of Mineral Resources, and unpublished mapping by R.B. Jacobson. 

Meteorological data were obtained in digital form 

from the National Climatic Data Center (National Oceanic 

and Atmospheric Administration, 1986). These data were 

used to prepare isohyetal maps of the storm using projection, gridding, and contouring programs routinely used by 

the USGS for contouring geophysical data. The data were 

also used to graph hourly rainfall intensities and for frequency analysis of rainfall data from representative gages, 

following the guidelines of the Interagency Advisory Committee on Water Data (1982). 

Terminology 

The term "landslide" is used in this paper to include 

all downslope movements of earth materials that are initiated at distinct times, that move over time intervals of 

seconds to days, and that create distinct scars and (or) 

deposits that can be identified by eye in the field or in aerial 

photographs. In general, scars and deposits had to be larger 

than 15m2 in area to be included in the data sets used in this 

study. 

The term "regolith" is used for the surficial geologic 

units that mantle bedrock, including residuum, colluvium, 

debris, and alluvium. "Residuum" is surficial material that 

has weathered in place from underlying bedrock. "Colluvium" is poorly sorted surficial material that has been 

transported and deposited downslope by nonchannelized, 

diffusive, gravitational processes that include seasonal 

creep, bioturbation, and landslides. Colluvium is usually 

very poorly sorted and nonbedded. "Debris" is poorly 

sorted to well-sorted surficial material transported and 

deposited by fluid flow but characterized by the presence of 

diamicton units with matrix-supported clasts, indicative of 

debris-flow processes. Debris is often characterized by 

interbedded well-sorted sand, gravel, and cobbles of fluvial 

origin, and poorly sorted diamicton originating from debris 

flows. "Alluvium" is moderately sorted to well-sorted 

fine-to-coarse sediment transported by fluid flow in channels and characterized by the absence of debris flow 

deposits. The term regolith is used in place of the term 

"soil" as used by engineers. "Soil" is used in the pedological sense to describe the material resulting from subaerial 

mineralogical, chemical, biological, and physical changes 

to regolith from weathering processes. 

Acknowledgments 

This manuscript benefited from thorough and 

thoughtful reviews by J.S. Schindler and S.D. Ellen. We 

are also grateful for advice offered by our colleagues R.H. 

Campbell, R.W. Jibson, and G.F. Wieczorek and for the 

continuing support of the U.S. Geological Survey National 

Center Geographic Information System Laboratory. 

GEOLOGY, GEOMORPHOLOGY, AND 

CLIMATE 

A generalized geologic map of the study area and a 

regional stratigraphic column are provided in plate 1 and 

figure 2A, respectively. Stratigraphic nomenclature is from 

Cardwell and others (1968) except as noted. For detailed 

descriptions of bedrock geology, the reader is referred to 

works by Cardwell and others (1968), Diecchio (1986), and 

Kulander and Dean (1986). The following description of 

bedrock geology and geomorphology concentrates on bedrock geologic controls on the landscape. 

At a regional scale, the geomorphic form of the study 

area is controlled by deformed, resistant sandstones of the 

Paleozoic section (pl. 1, figs. 2A, B). The Tuscarora 

C6 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W.Va., Va. 
Sandstone underlies the ridges that outline the doubly 

plunging, asymmetric Wills Mountain anticline. The southeastern limb dips 20°-40° and forms North Fork Mountain. 

The northwestern limb is nearly vertical to overturned and 

forms a hogback ridge known as the River Knobs. Streams 

draining the interior of the anticline pass through constricted 

gaps in the ridges formed by the anticlinal limbs. Sandstones of the Mississippian Pocono Group form the Fore 

Knobs, which interrupt the steep slopes ascending westward 

to the Appalachian Plateau, and buttress a narrow bench 

underlain by Greenbriar Group and mudstones and sandstones of the Mauch Chunk Group (Cardwell and others, 

1968). Pebbly sandstones of the Pottsville Group (Cardwell 

and others, 1968) of Pennsylvanian age underlie the highest 

parts of the Appalachian Plateau in this area. 

The oldest rocks in the area are pure Ordovician 

limestones of the St. Paul Group and the Black River 

Group, exposed in the core of the Wills Mountain anticline 

(Diecchio, 1986). Overlying the pure limestones are shaley 

limestones of the Trenton Group. Slopes on these limestones are gentle (0°-12°) except near incised tributaries or 

the numerous karst depressions. Drainage density in the 

limestones is very low, and many stream valleys are dry 

most of the year. Much of the area underlain by limestone 

is covered with a mantle of coarse debris shed from North 

Fork Mountain. This debris is composed of large angular 

cobbles of Tuscarora Sandstone with varying amounts of 

silty and sandy matrix. Residual soils on limestones vary in 

thickness from 0 to approximately 1 m. 

Above the Trenton Group in the stratigraphic section 

(fig. 2A) is the Reedsville Shale, a calcareous marine shale. 

This unit forms long, gently sloping spur ridges oriented 

mainly northwest-southeast, normal to the trend of the 

anticlinal ridges. Reedsville Shale slopes are embayed by 

areas of alternating concave- and convex-out contours. 

Areas of concave-out contours are focal points for studies of 

slope processes because they serve to converge hillslope 

sediment and moisture (Hack and Goodlett, 1960; Dietrich 

and others, 1987). The term "hollow" was originally 

proposed by Hack and Goodlett to describe areas of 

concave-out contours. In this paper the term is modified to 

"hillslope hollow" to avoid confusion with local Appalachian usage of "hollow" to apply to first- and second-order 

valleys. Side slopes, areas of generally straight contours, on 

the Reedsville Shale generally range from 12° to 25°, 

although some areas adjacent to laterally eroding stream 

channels are much steeper. Like limestone slopes, extensive 

areas of Reedsville Shale are covered with debris shed from 

North Fork Mountain. Where debris mantles the Reedsville 

Shale, the slopes are gentle (1°-12° along the former 

direction of transport) and hillslope hollows are poorly 

developed. 

Stratigraphically above the Reedsville Shale, the 

Oswego Sandstone, interbedded mudstone and sandstone of 

the Juniata Formation, and the Tuscarora Sandstone support 

steep slopes along North Fork Mountain and the River 

Knobs. These slopes range from approximately 22° to 

vertical and overhanging cliffs. North Fork Mountain slopes 

are corrugated in form and have developed hillslope hollows superimposed on the dominant northwest-facing slope 

aspects. The hillslope hollows are commonly filled with 

coarse colluvium and debris. 

From the valley of the North Fork River to the Fore 

Knobs (fig. 2B), slopes are cut into shale, limestone, and 

sandstone of Devonian and Mississippian age. At their 

bases, these slopes are mantled with debris and are only 

slightly embayed. Upslope, toward the Fore Knobs, the 

embayment of hillslope hollows increases in the Devonian 

Chemung Group and Hampshire Formation. Slopes on the 

bench protected by the Pocono Group are smooth and gentle 

on residuum derived from Greenbriar Group and Mauch 

Chunk Group. Slopes up to the Pottsville Group are mantled 

with pebbly sandstone debris and are gently corrugated. 

Dipslopes on the southeastern limb of the Wills 

Mountain anticline (North Fork Mountain) are slightly 

corrugated where mantled by debris in areas where firstorder streams have not incised the Tuscarora Sandstone. 

Interbedded sandstone, shale, shaley limestone, and limestone of the Silurian through Devonian section are rarely 

exposed on these dipslopes because they are covered by 

extensive and thick debris accumulations. In areas where 

the first-order streams have incised the Tuscarora Sandstone, long, steep valleys embay North Fork Mountain. 

The climate of the study area is seasonal and sensitive 

to elevation. In general, the late summer and autumn 

months are dry, whereas the winter and spring are wet. 

Mean annual temperature and precipitation vary from 

8.4 oc and 1037 mm at 930 m elevation to 10.9 oc and 824 

mm at 580 m elevation (National Oceanic and Atmospheric 

Administration, 1985). Additional climatic data are presented by Colucci and others (chapter B, this volume). 

STORM OF NOVEMBER 1985 ALONG THE 

WILLS MOUNTAIN ANTICLINE 

Total rainfall from the November 1985 storm was 

especially heavy in an area centered over the Wills Mountain anticline, near Upper Tract, W. Va., (pl. 1; also 

Jacobson, chapter A, this volume, pl. 1). Because of the 

coarseness of the official National Oceanic and Atmospheric Administration (NOAA) rain gage network, the 

rainfall depicted on these maps is a general model for the 

storm; local orographic effects that might be expected to 

modify the rainfall pattern are not represented, and it is 

unlikely that the extremes of rainfall were actually measured by the rain gage network. The general form of the 

distribution of rainfall has been corroborated by residents' 

observations; bucket survey data of unknown accuracy 

suggest that local areas of total rainfall in the study area may 

Landslides Triggered by the Storm of Nov. 3-5, 1985, W.Va., Va. C7 
have been as high as approximately 225 mm over 24 h and 

390 mm over 4 days (Colucci and others, chapter B, this 

volume, table 2). The highest officially measured 24-h 

rainfall was 191 em at Franklin, and the highest 48-h 

rainfall was 241 em at Upper Tract. 

Only one rain gage, recording hourly, operated 

within the study area during the storm (Mustoe, fig. 1). Five 

additional rain gages, recording hourly, range in distance 

from 22 to 42 km from the study area. Data from the six 

sites are given by Colucci and others (chapter B, this 

volume, fig. 9); we assume that these data are representative of conditions in the study area. These gages show that 

rainfall was continuous for a little more than 24 h, and 

intensities of 10 mm/h or greater were recorded for more 

than 12 h at some gages. The peak recorded intensity of 

38.1 mm/h at Hot Springs, Va., however, was not extreme 

for the Appalachian Mountains (Colucci and others, chapter 

B, this volume). 

Although hourly rainfall intensities were not extreme, 

the rainfall measured over 24- and 48-h durations achieved 

long recurrence intervals (Colucci and others, chapter B, 

this volume). The 48-h total at Franklin had an estimated 

recurrence interval between 67 and 166 yr, while that of 

Spruce Knob was in excess of 200 yr. The peak 48-h total 

at Upper Tract had a recurrence estimated at between 83 and 

286 yr. As discussed by Colucci and others (chapter B, this 

volume), estimates of recurrence intervals are necessarily 

rough because of the highly skewed rainfall records. 

DESCRIPTION OF LANDSLIDES 

Terminology and Classification 

Most of the landslides triggered by the storm are 

classified as debris slumps, earth slumps, debris slides, 

earth slides, debris flows, and earth flows, according to 

accepted landslide terminology (Varnes, 1978); the reader 

is referred to Varnes (1978) and Campbell and others (1985) 

for more detailed discussion of landslide classification. The 

population of landslides is dominated by slides in fine 

materials (clay to sand with gravel-size clasts) derived from 

shales, shaley limestones, and interbedded shale, mudstone, and sandstone. Most are shallow, planar slides with 

depths rarely exceeding 2 m and minor rotational movement 

at the head of the sliding mass (fig. 3). In this paper, the 

term "slides" is used in cases where most of the slide mass 

remained coherent, and "slide flows" are used in cases 

where the slide mass showed signs of flowing earth or 

debris at the toe or lateral margins. 

A smaller number of landslides occurred in thick 

(greater than 2 m) colluvial aprons at the bases of slopes and 

were presumably triggered by lateral stream erosion of the 

toeslopes (fig. 4). Rotational movement dominates in these 

landslides; in this paper they are referred to as slumps and 

slump flows. 

Eight large landslides on North Fork Mountain began 

as sliding masses of sandstone residuum and colluvium. 

The masses avalanched down steep slopes and flowed long 

distances, up to 2 km, with varying amounts of erosion and 

deposition. These complex landslides are best classified as 

complex debris slide-avalanche flows (Campbell and others, 1985). For simplicity, they are referred to here as debris 

avalanches. 

Slides and Slide Flows 

Ninety-five percent of the landslides triggered by the 

November storm were slides, slide flows, slumps, or slump 

flows; the remaining 5 percent can be classified as debris 

avalanches and slide flows transitional to avalanches. 

Among all landslides, approximately 90 percent were shallow planar slides on thin residuum and colluvium. Typically, the failure plane of these slides was parallel to the 

surface slope and occurred at depths of 0.5-2 m. Commonly, the failure plane occurred at the transition between 

pedogenic B horizon and weathered, saprolitic bedrock, or 

at the contact between thin colluvium and weathered bedrock. Very shallow planar slides, less than 50 em deep, 

were common on 50°-70° side slopes along stream margins. 

These slides usually completely stripped off a thin carpet of 

roots, organic matter, and residual soil to expose hard 

bedrock beneath. The deeper planar slides tended to occur 

in hillslope hollows where thick colluvium had accumulated. Slides in hillslope hollows often eroded down to 

weathered bedrock in the axes of the hill slope hollows, but, 

in most cases, significant volumes of colluvium remained 

intact around the margins of the slide scar. 

Rotational failures were less common, approximately 

10 percent of the total, and occurred in two specific 

situations. Many rotational failures occurred as deep-seated 

slumps in thick toeslope colluvium along streams. Presumably these landslides were triggered by lateral erosion and 

undercutting of colluvial deposits by floodwaters. Projection of failure planes suggests maximum depths as much as 

5 m. Benches of nearly flat lying, interbedded mudstone 

and limestone high above stream channels were also 

affected by rotational sliding (fig. 5). In these cases, 

rotation occurred as sliding masses of weathered bedrock 

were forced to toe out above underlying competent layers. 

Many landslides mobilized as muddy debris flows. 

Of the 583 landslides mapped in the Germany Valley study 

area, 89 percent showed some evidence of flow (Cron, 

1990). Among the 3,562 landslides mapped over the entire 

study area, 30 percent delivered some fraction of sediment 

to streams (table 1). Flows from slides on Reedsville Shale 

were very fluid, some flowing for tens of meters on 0°-8° 

slopes over intact turf (fig. 6). On forested slopes, some 

C8 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W.Va., Va. 
Figure 3. Shallow slides and slide flows in residuum derived from the Reedsville Shale. (Photograph taken june 1987. 

Note sheep for scale.) 

Figure 4. Large slump in toeslope colluvium derived from 

Reedsville Shale. Slump dammed stream at base of slope, 

causing several cubic meters of deposition upstream. 

Slump is approximately 5 m across. 

Figure 5. Typical landslide on a Greenbriar Group slope. 

Large solution-bounded blocks of limestone slid out on 

red shale interbeds. 

Landslides Triggered by the Storm of Nov. 3-5, 1985, W. Va., Va. C9 
Table 1. Distribution of slope movements in study area by bedrock stratigraphic unit 

[Units are from Cardwell and others except as noted] 

Bedrock unit Predominant Number Area, km2 Density, Percent 

lithology landslides/km2 of total 

Greenbriar Group Limestone/ shale 10 27.3 4.03 3.09 

Pocono Group Sandstone 40 31.8 1.26 1.12 

Mauch Chunk Group Sandstone/shale 54 38.7 1.40 1.52 

Hampshire Formation Sandstone/ shale 9 65.3 .14 .25 

Chemung Group Sandstone( siltstone) 10 76.4 .13 .28 

Devonian shales, 1 undifferentiated Shale 2 9.3 .22 .06 

Oriskany Sandstone Sandstone 21 48.3 .43 .59 

Helderberg Group Limestone 20 37.5 .53 .56 

Devonian rocks, undifferentiated Limestone/ shale 31 73.6 .42 .87 

Tonoloway, Wills Creek, and Williamsport Limestone/ shale 54 62.1 .87 1.52 

Formations, undivided 

McKenzie Formation and Clinton Group, Limestone/shale 47 100.8 .47 1.32 

undivided 

Tuscarora Sandstone Sandstone 7 56.3 .12 .20 

Juniata Formation and and Oswego Sandstone, Sandstone/shale 177 80.9 2.19 4.97 

undivided 

Reedsville Shale Shale 2812 135.7 20.72 78.94 

Trenton Group Limestone/shale 156 36.0 4.33 4.38 

Black River Group Limestone 11 27.8 .40 .31 

St. Paul Group Limestone 1 22.7 .04 .03 

Total 3562 930.5 100 

1 Undifferentiated Devonian shales include thin shales of the Brallier Formation, Harrell Shale, Mahantango Formation, Marcellus Formation, and 

Needmore Shale, all of Cardwell and others (1968). 

Figure 6. Typical slide flow on Reedsville Shale. Slide flow 

initiated in thin colluvium and residuum and flowed over 

turf on toeslope colluvium. Part of the flow was delivered 

to the stream channel at the base of slope. Flow track is 6 

m across. 

muddy debris flows passed over the forest floor without 

disturbing leaf litter. Splash marks 1-1.5 m high on tree 

trunks on 30°-40° slopes indicate that flows were able to 

achieve high velocities. 

Slopes underlain by residuum and colluvium of the 

Reedsville Shale had the greatest percentage of mapped 

landslides (79 percent, table 1). The remaining 21 percent 

were distributed dominantly among other fine lithologies: 

colluvium and residuum derived from interbedded sandstone and mudstone of the Juniata Formation (5.0 percent), 

clayey residuum derived from Trenton Group shaley limestone (4.0 percent), clayey residuum derived from interbedded mudstone and limestone of the Greenbriar Group (3. 1 

percent), and residuum and colluvium derived from shaley 

limestone of the Tonoloway Limestone and Wills Creek 

Formation and shale and mudstone of the Mauch Chunk 

Group (1.5 percent each). 

Slides and slide flows on the Reedsville Shale were 

approximately 90 percent shallow, planar failures in thin 

colluvium and residuum and 10 percent rotational failures in 

toeslope colluvium. Landslides in clayey residuum and thin 

colluvium of the Tonoloway, Wills Creek, and Williamsport Formations, Trenton Group shaley limestone, and the 

Mauch Chunk Group were all shallow, planar slides, most 

of which transformed into muddy debris flows. Regolith on 

these bedrock units is generally thin (less than 1 m), and 

slopes are relatively steep (20°-40°). 

In contrast to the landslides described above, landslides on slopes underlain by interbedded mudstone and 

limestone of the Greenbriar Group often involved large 

fracture- and solution-bounded blocks of intact limestone 

bedrock sliding on thin red shale interbeds (fig. 5). Many of 

the limestone blocks were transported tens of meters, and 

mudflows that mobilized from the landslides flowed hundreds of meters. 

C1 0 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W. Va., Va. 
Figure 7. Debris avalanche scar at Twin Run. From 25 to 

100 em of fractured sandstone slid along bedding planes at 

left; diamicton colluvium at right was mostly stable. 

Debris Avalanches and Transitional Slide Flows 

Landslides of thin residuum and colluvium derived 

from interbedded mudstone and sandstone of the Juniata 

Formation accounted for 5 percent of the total number of 

landslides (table 1). Almost all of these landslides occurred 

on steep forested slopes on North Fork Mountain on planar 

side slopes or subtle hills lope hollows. Most landslides 

initiated as planar slides generally less than 50 m2 in area 

and transformed into flows that delivered sediment to steep 

first-order channels. In classification, these slide flows are 

transitional to debris-avalanche flows, in that they began as 

shallow slides and changed to flows. However, evidence for 

a rapid avalanching phase was generally absent. 

The most dramatic landslides triggered by the 

November 1985 storm were eight debris avalanches that 

started at the contact between the Juniata Formation and 

Tuscarora Sandstone or on dipslopes underlain entirely by 

Tuscarora Sandstone (figs. 2, 7, 8). Two of these features 

are documented in detail by Kite and others (1987). Of the 

eight large debris avalanches triggered by the storm, five 

occurred on dipslopes on the southeast side of North Fork 

Mountain. (Dipslopes are slopes with aspects within 90° of 

the bedrock dip direction; aspect is azimuth the slope faces.) 

Of the five landslides on dipslopes, three were initiated in 

fractured Tuscarora Sandstone bedrock on slopes parallel to 

bedding planes dipping 30°-35° (fig. 8). The other two were 

initiated in thin colluvium and weathered rock at the contact 

between the Juniata and the Tuscarora. The three debris 

avalanches that started on antidipslopes also occurred in 

thin colluvium and weathered rock at the contact. At all 

eight sites, the landslides occurred adjacent to thick masses 

of colluvium that were not mobilized or were only partially 

mobilized. 

Runout tracks of debris flows below the slide and 

avalanche scars were as long as 2 km (fig. 8). The runout 

Figure 8. Track of debris flow from Twin Run debris 

avalanche. Note superelevation around curve. 

Figure 9. Snout of deposit of debris flow at Hartman's 

farm, southeast of North Fork Mountain. Snout is approximately 4 m wide, and deposit is about 1.5 m thick. 

tracks were characterized by variable scour and deposition, 

common formation of lateral levees, superelevated flow 

around bends (fig. 8), and large snoutlike deposits of debris 

and logs (fig. 9). Substantial fluvial reworking of the 

original deposits took place subsequent to debris flow 

deposition. 

CONTROLS ON THE SPATIAL DISTRIBUTION 

OF LANDSLIDES 

Examination of the distribution of landslides on plate 

lA reveals some obvious controls on landslide location, 

notably rainfall and bedrock. Landslide density generally 

increases with increasing rainfall along the anticline except 

for local gaps in the distribution and a large gap in the 

northeastern quarter of the study area. Most of the landslides occurred on regolith derived from Reedsville Shale in 

Landslides Triggered by the Storm of Nov. 3-5, 1985, W. Va., Va. C11 
the center of the Wills Mountain anticline, with smaller 

numbers of landslides originating in regolith derived from 

other fine-grained bedrock lithologies (table 1). Coarser 

grained bedrock lithologies produced many fewer landslides. Gaps in the distribution that apparently are not 

related to rainfall or bedrock lithology suggest that other 

controls are important influences at a more detailed scale of 

resolution. Comparisons of landslide locations with surficial geologic maps of the study area (pl. 1B) indicate that 

surficial geology is an important determinant of where 

landslides occurred in 1985. At more detailed scales of 

resolution, land use, slope morphology, and slope aspect 

also are apparent controls on landslide locations. 

Surficial Geology 

Gaps in the distribution of landslides occurring on 

Reedsville Shale slopes are controlled largely by preexisting debris deposits (pl. 1B). In the study area, the 

thickness of the debris varies from negligible to greater than 

5 m. The deposits are arranged on the landscape as gently 

sloping terrace treads separated by riser slopes underlain by 

bedrock. Similar deposits have been described in southwestern Virginia (Mills, 1981, 1988). Debris deposits owe 

their origin to debris-avalanche flow events similar to the 

eight events triggered in 1985. However, because areas of 

debris are so extensive on the present-day landscape, it is 

unlikely that all of the debris could have been produced 

during the Holocene. Cross-cutting relationships, qualitative evaluation of weathering, and geomorphic positions on 

the landscape suggest that debris has been deposited during 

at least four or five discrete episodes dating as far back as 

500,000 yr B.P. (Jacobson and others, 1987, 1989). Presumably, debris has accumulated episodically as a response 

to climatically induced changes in regolith production and 

(or) transport rates. 

In the Germany Valley study area, only 6 percent of 

583 landslides occurred on debris deposits; most of these 

were caused by sliding in underlying Reedsville Shale 

rather than the overlying debris deposit. Debris covers 

almost the entire outcrop area of Reedsville Shale and 

underlying shaley limestones in the northeast quarter of the 

study area. Gentle slopes (generally less than 8°), presumed 

high frictional strength imparted by the interlocking structure of the poorly sorted diamicton, and the armoring effect 

of coarse material have served to stabilize these deposits. 

Physical properties, thickness, and stratigraphy of 

colluvium vary with many other factors on the landscape, 

including source bedrock lithology, underlying bedrock 

lithology, mode of deposition, age, and slope morphology. 

Because of this variability, colluvium may be either weaker 

or stronger, and more permeable or less permeable, than 

adjacent and underlying residuum and bedrock. Hence, 

colluvium is often an important factor influencing slope 

instability by producing zones of strength or weakness and 

sites of subsurface moisture accumulation (Dietrich and 

others, 1987; Fleming and others, 1981; Royster, 1973). 

Because of the variety of bedrock lithologies in the study 

area, colluvial properties are also highly variable, and it is 

difficult to generalize about the importance of accumulations of colluvium at the resolution of this study. In the 

Germany Valley study area, only 17 percent of the 583 

landslides triggered in 1985 occurred on colluvium (that is, 

in areas where colluvium is greater than 1-2 m thick). On 

the other hand, field observations indicate that landslides in 

colluvium tended to be deeper and larger, suggesting that 

colluvial landslides may have contributed more than 17 

percent of the landslide volume. It was beyond the scope of 

this study to collect sufficiently detailed data to test that 

hypothesis. 

Bedrock Geology 

Bedrock controls on slope instability can be divided 

into those factors that influence the hydrologic properties 

and strength of regolith, structural factors that influence 

flow of ground water along bedding planes and provide 

zones of weakness for preferential sliding, and factors that 

influence slope morphology and hence influence redistribution of shallow ground water. 

Physical Properties of Unstable Regolith 

Several regoliths within the study area were chosen 

for detailed analyses to relate landslide susceptibility to 

physical properties. Residuum derived from interbedded 

sandstone and mudstone of the Mauch Chunk Group, 

interbedded mudstone and limestone of the Greenbriar 

Group, interbedded sandstone and mudstone of the Juniata 

Formation, marine shale of the Reedsville Shale, and shaley 

limestone from the Trenton Group, along with debris 

derived from Tuscarora Sandstone mixed with components 

from the Juniata Formation and Reedsville Shale, were 

sampled for general characterization. The residuum samples 

were chosen to represent a selection of clayey to sandy 

regoliths that varied markedly in the spatial density of 

landslides triggered in 1985 (fig. 10); debris was sampled to 

characterize materials that were extremely stable during the 

1985 event. 

Representative sites were chosen for sampling and for 

performing falling-head, double-ring infiltrometer tests to 

measure infiltration and drainage characteristics of the 

regolith. Each site was sampled for bulk density, particle 

size, Atterberg limits, and clay mineralogy. Because all the 

regolith types failed dominantly by shallow slides, samples 

were taken from depths of 10-50 em. Infiltration rates were 

recorded during application of 250-750 mm of water in 

100-mm falling-head cycles. Final infiltration rates under 

fully saturated conditions and zero head were used as 

C12 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W. Va., Va. 
80 

A 

70 n = 3562 

Iz 60 L.U 

20 B E5 

~ 18 n = 3562 ::2: 

s 16 (_) 

a: 

L.U 50 a... 

~ 

>-':;:2 

!:::::w 14 (/)0:: 

z<t: 

w::::> 12 Cld 

(/)- 40 L.U 

0 

:::i 30 (/) 

0 

wC/:l 

Cl a: 10 -w u:So.... 

CJ(/) 

zw 

<t:e z 

<( 20 _J 

---'---' (/) 

Cl 

z 

10 ::i 

~ 

BEDROCK STRATIGRAPHIC UNITS BEDROCK STRATIGRAPHIC UNITS 

Figure 10. A, Histogram of percentages of landslides by bedrock stratigraphic units. B, Histogram of density of landslides 

(landslides/km2

) by bedrock stratigraphic units. Characteristic regoliths on these units are discussed in text; lithologies 

are given in table 1. 

indicative of saturated infiltration and drainage rates for the 

0.5-1 m of regolith. 

Residuum derived from the Reedsville Shale is much 

richer in clay than the residuum from the Juniata Formation 

and Greenbriar Group (fig. 11, table 2). The Reedsville 

Shale residuum is also richer in clay than residuum of the 

Mauch Chunk Group and debris, although the differences in 

sample means are not statistically significant. Residuum 

from the Trenton Group has the highest clay content among 

those tested, and residuum from the Juniata Formation is 

significantly sandier than all other regoliths except for 

debris. 

Atterberg limits of the samples show that all samples 

are of medium plasticity (fig. 12, table 3). The highest 

liquid limits (water contents at which the samples begin 

to act like liquids) and plasticity indices (range of water 

contents over which the samples deform plastically) are 

from samples of Reedsville Shale residuum and Trenton 

Group residuum. Activities (plasticity index divided 

by percent clay) are about equal for all regolith types, 

although the range in the Reedsville Shale sample set is 

greater (table 4). 

Infiltration rate and porosity may also influence slope 

stability by regulating the rate and amount of rainfall that 

the regolith can soak up, store, and drain during a storm 

event. Porosities were calculated from measured bulk densities of fist-sized soil aggregates that were representative of 

peds of the A and B horizons of the soils at each site (table 

4, fig. 13). The Juniata Formation regolith has a significantly higher porosity than all other regoliths, presumably 

because of its high sand content. Conversely, the Reedsville 

Shale regolith has porosity that is significantly lower than 

all but the Trenton Group and debris. In general, ped-scale 

porosity of these residua increases with sand content and 

decreases with clay content. 

Although limiting infiltration rates are highly variable 

among these regoliths (fig. 14), most are much higher than 

the measured rainfall intensities of 38 mm/h (Colucci and 

others, chapter B, this volume). In general, low infiltration 

rates were measured on debris and Greenbriar limestone 

residuum, and the highest were measured on Trenton Group 

shaley-limestone residuum. Only the very lowest limiting 

infiltration rates measured on the Mauch Chunk and Greenbriar residua were comparable with the highest measured 

rainfall intensity; most of the saturated infiltration rates are 

much greater than rainfall intensities. Samples from the 

tests on infiltration rates had water contents ranging from 

79 to 100 percent of fully saturated conditions, indicating 

that most were fully saturated during the infiltrometer tests. 

Water contents less than 100 percent of saturation are 

attributed to areas in the soil that were bypassed by 

infiltrating water flowing in macropores. 

The data on physical properties of the fine-grained 

regoliths do not indicate a single variable that might be 

responsible for the differences in observed instability of 

regoliths that received virtually identical rainfall. However, 

the data can help to constrain which variables were most 

influential in causing the relative instability during this 

storm. 

Landslides Triggered by the Storm of Nov. 3-5, 1985, W. Va., Va. C13 
60 

50 

~f r 

f- 40 t- - z 

l.J.J 

u 

a: 

l.J.J 

CL 30 t-

~ 

>--

<I: 

_J 

u 20 t- I I 

10- -

Trenton Reedsville Juniata Mauch Chunk Greenbriar Quaternary 

Group Shale Formation Group Group Debris 

REGOLITH 

Figure 11. Range diagram of clay content (percent less 

than 2 microns) for six regoliths. Vertical line marks range 

of sample values, solid circle marks mean value. 

Table 2. Particle-size distributions for sampled regoliths 

[Std Dev, standard deviation. All values in weight percent. N, number in 

sample. Particle-size data exclude coarse fragments greater than 2 mm. 

Sand is 0.065-2 mm, silt is 0.002-D.065 mm, and clay is less than 0.002 

mm] 

Size class Minimum Maximum Mean Std Dev 

Quaternary debris, N=S 

Sand 14.8 42.3 28.8 11.0 

Silt 28.2 63.8 44.0 13.4 

Cla~ 19.0 38.4 27.2 7.6 

Mauch Chunk Group, mudstone/sandstone residuum, N=8 

Sand 5.7 53.7 21.8 16.4 

Silt 31.1 64.4 50.1 11.4 

Cla~ 15.2 43.0 28.0 9.3 

Greenbriar Group, limestone/mudstone residuum, N=7 

Sand 7.6 38.9 24.7 11.7 

Silt 38.4 67.5 52.3 9.5 

Cla~ 14.2 37.6 23.0 8.2 

Juniata Formation, mudstone/sandstone residuum, N=3 

Sand 29.9 58.2 47.6 15.4 

Silt 33.4 57.7 43.0 13.0 

Cla~ 4.0 12.4 9.4 4.7 

Reedsville Shale, shale residuum and colluvium, N = 19 

Sand 4.8 50.8 17.3 12.2 

Silt 29.8 60.1 46.6 7.0 

Cla~ 19.4 49.0 36.1 9.7 

Trenton Group, limestone residuum, N=4 

Sand 3.7 22.2 11.7 8.8 

Silt 34.6 43.6 37.9 4.1 

Clay 43.2 56.8 50.4 5.8 

Theoretically, failure at a slope site occurs when 

pore-water pressures reduce normal stress on a failure plane 

sufficiently to allow failure in response to applied shear 

stress, assuming that site geometry is not altered during the 

event. Hence, at sites of equal slope, failure susceptibility is 

controlled mainly by factors that determine inherent shear 

40 

30 -I -

X 

l.J.J 

Cl 

I ~ 

>- 20 - - fu 

i= I l- en I <I: 

_J 

CL 10 -

• 

Trenton Reedsville Juniata Mauch Chunk Greenbriar Quaternary 

Group Shale Formation Group Group Debris 

REGOLITH 

Figure 12. Range diagram of plasticity index (liquid 

limit-plastic limit) for six regoliths. Vertical line marks 

range of sample values, solid circle marks mean value. 

Table 3. Atterberg limits, plasticity indexes, activities, and 

dominant clay minerals of regolith samples 

[Std Dev, standard deviation. N, number in sample. Atterberg limits are 

expressed as water contents, weight percent. Activity is the plasticity index 

divided by percent clay] 

Parameter Minimum Maximum Mean Std Dev 

Quaternary debris, N=3, dominant clay minerals are illite and kaolinite 

Liquid limit 32.0 55.8 46.7 12.8 

Plasticity limit 23.7 40.0 34.4 9.2 

Plasticity index 8.3 15.8 12.3 3.8 

Activit~ .44 .83 .61 .12 

Mauch Chunk Group, N=9, dominant clay mineral is vermiculite 

Liquid limit 23.8 42.1 37.3 6.0 

Plasticity limit 17.9 32.1 26.5 4.4 

Plasticity index 5.9 14.5 10.8 3.1 

Activit~ .36 .51 .42 .05 

Greenbriar Group, N=4, dominant clay mineral is vermiculite 

Liquid limit 33.7 43.7 38.5 4.7 

Plasticity limit 26.9 31.3 29.4 1.8 

Plasticity index 4.1 13.9 9.1 4.0 

Activity .21 .56 .41 .18 

Juniata Formation, N=2, dominant clay mineral is vermiculite 

Liquid limit 33.4 38.0 35.7 3.2 

Plasticity limit 27.4 30.8 29.1 2.4 

Plasticity index 6.0 7.2 6.6 0.8 

Activit~ .50 .56 .54 .04 

Reedsville Shale, N=5, dominant clay mineral is illite 

Liquid limit 28.6 59.6 40.1 12.4 

Plasticity limit 19.7 33.2 26.1 5.8 

Plasticity index 4.2 26.4 14.0 10.2 

Activit~ .12 1.24 .53 .42 

Trenton Group, N=4, dominant clay mineral is illite 

Liquid limit 59.2 67.0 62.6 3.2 

Plasticity limit 32.5 34.7 33.4 0.9 

Plasticity index 25.9 32.3 29.1 2.6 

Activity .49 .81 .60 .14 

strength of the material and factors that influence buildup of 

pore-water pressure. These two groups of factors may have 

different degrees of importance, depending on the storm 

characteristics and regolith involved. 

C14 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W. Va., Va. 
Table 4. Bulk density, void ratio, and porosity for selected 

regoliths 

[Bulk density in g/cm3

; void ratio and porosity in decimal fraction. Std 

Dev, standard deviation. N, number in sample. Void ratio is the ratio of 

volume of voids to volume of solids; porosity is the ratio of the volume of 

voids to the total volume of the sample] 

Parameter Minimum Maximum Mean Std Dev 

Quaternary debris, N=8 

Bulk density 1.30 2.02 1.69 0.26 

Void ratio .31 1.04 0.61 .27 

Porosity .24 .51 .36 .10 

Mauch Chunk Group, mudstone/sandstone residuum, N=l6 

Bulk density 1.40 1. 77 1.57 .10 

Void ratio .50 .89 .70 .10 

Porosity .33 .47 .41 .04 

Greenbriar Group, limestone/mudstone residuum, N=lO 

Bulk density 1.39 1. 78 1.52 .11 

Void ratio .49 .91 .75 .12 

Porosity .33 .48 .43 .04 

Juniata Formation, mudstone/sandstone residuum, N=4 

Bulk density 1.24 1.43 1.32 .08 

Void ratio .85 1.15 1.02 .12 

Porosity .46 .53 .50 .03 

Reedsville Shale, shale residuum and colluvium, N=29 

Bulk density 1.45 1.80 1.63 .08 

Void ratio .47 .83 .63 .08 

Porosity .32 .45 .39 .03 

Trenton Group, limestone residuum, N=S 

1-

z 

UJ 

u 

cr:: 

UJ 

o._ 

~ 

>-' 

!::::: 

(/) 

a 

cr:: 

a 

o._ 

Bulk density 1.53 1.68 

Void ratio .58 .73 

Porosity .37 .42 

0.5 

0.4 I 

0.3 

1.64 

.62 

.38 

.06 

.07 

.02 

0.2 L__ __________________ __j 

Trenton Reedsville Juniata Mauch Chunk Greenbriar Quaterna ry 

Group Shale Formation Group Group Debris 

REGOLITH 

Figure 13. Range diagram of porosity for six regoliths. 

Vertical line marks range of sample values; solid circle 

marks mean value. 

Consistent with their high clay contents, the regoliths 

of the Reedsville Shale and the Trenton Group have the 

highest plasticity indexes and liquid limits among those 

tested. As illustrated by Mitchell (1976), residual friction 

angles of engineering soils generally decline with both 

uJ 

f-0:: 

<(::l 

0:: 0 

z:c 

a ex: - LJ.J f-a_ 

<(U) 

0::0:: 

~~ 

~~ (!):::::i 

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Trenton Reedsvil le Juniata Mauch Ch unk Greenbriar Quaternary 

Group Shale Formation Group Group Debris 

REGOLITH 

Figure 14. Range diagram of limiting infiltration rates for 

six regoliths. Vertical line marks range of sample values, 

solid circle marks mean value. 

increased plasticity index and liquid limit, although additional frictional strength may be added by the presence of 

interlocking clasts. Except for Quaternary debris, the clast 

content (greater than 2-mm diameter) of tested regoliths was 

uniformly low, ranging up to approximately 5 percent. 

Hence, the plasticity index data suggest that residuum from 

the Reedsville Shale and Trenton Group shaley limestones 

should have the lowest frictional strengths. Low strength 

may explain why the Reedsville Shale was much more 

susceptible to failure than regolith of the Quaternary debris, 

Greenbriar Group, Mauch Chunk Group, and Juniata Formation, but comparable low strength of the Trenton Group 

regolith suggests that hydrologic factors that influence 

buildup of pore-water pressure were also important. 

Buildup of pore-water pressure occurs where soil 

moisture accumulates because of vertical drainage rates that 

are less than rainfall intensity (where infiltration rate is not 

a limiting factor) or because of convergence of throughflow 

of shallow ground water. Accumulation and convergence 

are controlled by the complex interactions of rainfall intensity, infiltration rate, lateral and vertical permeabilities of 

regolith and bedrock, porosity and thickness of regolith, 

and topographic concavity or convexity (Wieczorek, 1987). 

Stability of a given regolith unit during a rainfall event will 

be determined by these hydrologic factors and the ranges 

and spatial distributions of the shearing resistance. 

Because stratigraphic and topographic controls on net 

inflow and outflow of water in regolith at slope sites are 

highly variable across the landscape, they could not be 

considered in detail in this study. As an approximation, it 

can be assumed that, for the thin regolith that constituted 

most of the landslides, drainage rates are roughly proportional to infiltration rates, although they certainly will vary. 

Other factors not measured in this study, such as regolith 

thickness and topographic convergence, also influence staLandslides Triggered by the Storm of Nov. 3-5, 1985, W. Va., Va. C15 
bility and probably should be considered in subsequem 

studies. For this analysis, it is assumed that the relative 

drainage characteristics of the studied regoliths were measured by the infiltration tests. 

The lowest infiltration rates measured were for the 

debris and Greenbriar Group residuum. Low rates in debris 

are probably due to its relative lack of intrapedal secondary 

permeability; development of soil structure in debris is 

presumably limited by the high clast content. Low infiltration rates measured on Greenbriar Group residuum are 

partly misleading because the only sites with slopes gentle 

enough for infiltration tests were benches underlain by 

shale. Fracture permeability in limestone layers (fig. 5) 

could produce much greater infiltration rates locally. 

The highest infiltration rates measured were on residuum of the shaley limestones of the Trenton Group. The A 

and B horizons of these soils were extremely well structured 

(fig. 15), and we assume that the high infiltration rates 

resulted from flow in intrapedal macropores; drainage may 

have been augmented by flow into dissolution features in 

the underlying limestone. Infiltration rates on the Reedsville 

Shale were moderate, although still substantially higher 

than the maximum rainfall intensity. 

We interpret the differences in slope stability between 

regoliths over Reedsville Shale and Trenton Group shaley 

limestone to reflect primarily the trade-off between shear 

strength and accumulation of soil moisture. Infiltration rates 

of Reedsville Shale regolith were sufficient to allow moisture to infiltrate and accumulate but low enough to bring 

many sites to failure conditions during this long storm. In 

contrast, because of higher drainage rates, few sites on 

Trenton Group slopes could accumulate sufficient moisture 

to achieve failure despite comparably low strength. Higher 

infiltration rates and (or) greater strength similarly made 

other regoliths more stable than Reedsville Shale residuum 

during this storm event. 

Geologic Structure 

Ground-water seepage from bedding planes exposed 

in road cuts is commonly observed in the study area. 

Although ground-water flow along bedding planes has not 

been evaluated directly for natural slopes, these observations suggest that bedding planes may provide important 

pathways for downdip flow of ground water. If ground 

water flows significantly down bedding planes, we would 

expect greater numbers of landslides on dipslopes (those 

slopes with dip directions within 90° of slope aspect) than 

on antidipslopes. However, downdip flow of ground water 

may trade off with topographic concentrations of shallow 

ground water, regolith properties, and land cover to determine slope stability. 

Steep forested slopes on the northwest side of North 

Fork Mountain, underlain by the Juniata Formation and the 

Tuscarora Sandstone, had a moderate number of small 

Figure 15. Well-developed, blocky soil structure at 15-cm 

depth (transition between lower A horizon and upper B 

horizon) in residual soil derived from Trenton Group 

shaley limestone. 

debris avalanches and slides. These slopes are inclined 

20°-40° away from the dip of bedrock bedding planes (that 

is, they are antidipslopes), which should cause them to be 

relatively dry to the extent that shallow ground-water flow 

will follow the bedding planes. Landslides on the Juniata 

Formation antidipslope occurred mainly in hillslope hollows (table SA), where convergence of shallow ground 

water may have compensated for lack of downdip drainage. 

Slopes on the southeastern side of North Fork Mountain generally dip with the direction of bedding planes and 

are underlain by the Tuscarora Sandstone and interbedded 

sandstone, shale, and limestone rocks of Silurian and 

Devonian age (pl. 1, fig. 2). The lower portions of these 

slopes are mantled extensively with debris. The upper parts 

of the slope show little development of hillside hollows, 

except where first-order streams have incised through the 

Tuscarora Sandstone into less resistant units of the Juniata 

Formation. Three of the four largest debris avalanches 

originated in areas of straight to convex -out contours on the 

upper slopes in thin (generally less than 1 m) colluvium 

over fractured sandstone bedrock. Most of the failure sites 

were adjacent to thicker deposits of colluvium that were 

stable or only partly involved with failure. The combination 

of low frictional strength on bedding planes and, perhaps, 

accumulation of shallow ground water by flow along 

bedding planes may have made these sites less stable during 

this rainfall event than areas of hillslope hollows with thick 

accumulations of colluvium. 

In the Germany Valley area, the 583 landslides 

studied by Cron (1990) showed no influence of geologic 

structure on locations. These landslides were mainly shallow slides and slide flows in shaley regolith that may have 

been less sensitive to downdip redistribution of ground 

water because most of the infiltrating moisture was stored in 

the slowly permeable regolith. 

C16 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W. Va., Va. 
Table 5. Effects of slope morphology and land cover on landslide location 

A. Percent of 852 landslides in topographic convergence classes for wooded and cleared slopes 1 

Topographic Percent on Percent on Total 

convergence class cleared slopes wooded slopes 

Nose 5.9 0.2 6.1 

Planar 60.4 4.1 64.5 

Subtle hillslope hollow 11.5 4.0 15.5 

Distinct hillslope hollow 5.3 8.6 13.9 

All hillslope hollow 16.8 12.6 29.4 

Total 83.1 16.9 100.0 

B. GIS data for cells with and without landslides, for slope aspect and land cover controls on landslide locations2 

Slope-aspect class Percent of cells in class Percent of cells with landslides 

Overall Wooded Cleared Overall Wooded Cleared 

North-facing 58 50 50 6 2 10 

South-facing 42 60 40 5 3 7 

1 Area of sample is approximately 100 km2

; it is underlain by Reedsville Shale, Oswego Sandstone, and Juniata Formation; approximately 220-240 

mm of rainfall fell November 4-5, 1985. 2 Area of sample is 75 km2

; it is underlain by Trenton Group, Reedsville Shale, Oswego Sandstone, Juniata Formation, and Tuscarora Sandstone; 

it received 220-240 mm rainfall November 3-5, 1985. Data from Cron (1990). 

Slope Morphology and Land Cover 

Slope morphology and land cover may also contribute 

to the stability of slope sites. Slope steepness, which is 

commonly assumed to be an important variable in landslide 

location, is not considered explicitly in this study because 

most of the variation in slope steepness is related directly to 

bedrock lithology. Cron (1990) found that 85 percent of the 

landslides in her data set in the Germany Valley area 

occurred on the most gentle slopes (0° -14 °) because gentle 

slopes are characteristic of the Reedsville Shale. Steeper 

slopes occur on the more competent sandstones and sandstone/mudstone slopes, but these were more stable during 

this storm event because factors other than slope steepness 

were also operating. Slope steepness could be an important 

predictor of landslide locations among slopes underlain 

entirely by one bedrock lithology if the resolution of the 

topographic data base was sufficient to resolve the range of 

slope inclinations for that lithology. Presumably, landslides 

would occur preferentially on the steeper slopes of that 

bedrock lithology if other factors did not vary. Topographic 

data available for this study were not sufficiently detailed to 

resolve the ranges of slope steepness for the different 

bedrock lithologies. 

In an area of homogeneous regolith, slopes with 

concave-out contours (hillslope hollows) will be sites of 

convergence of soil moisture (Dietrich and others, 1987). 

Over a time interval of years to millenia, hillslope hollows 

also accumulate colluvium (Reneau and others, 1986). 

Theoretically, convergence of moisture and colluvium 

should make hillslope hollows preferred sites for initiation 

of landslides (Reneau and Dietrich, 1987), and areas of 

convex-out contours (noses) should be relatively stable. As 

pointed out by Wieczorek (1987), however, topographic 

convergence can be less important on steeper slopes and 

where depth to bedrock is very shallow (0.2-0.5 m deep). 

Slides and Slide Flows 

The importance of topographic convergence in determining landslide location during the 1985 storm was investigated from a data base of landslides that occurred in a 

homogeneous area of approximately 100 km2 underlain by 

Reedsville Shale, Oswego Sandstone, and the Juniata Formation (slope morphology study area, pl. 1., fig. 2, table 

5). Land cover in the sample area is approximately equally 

divided between cleared grassland (48.9 percent) and woodland (51.1 percent). Using aerial photographs, each of 852 

landslides was classified according to land cover (wooded 

or cleared) and topographic convergence. 

Topographic convergence classes are defined according to convergence angle, approximated here as the angle 

between the medial axis of the hillslope hollow and a line 

perpendicular to contours at the inflection point where the 

contour changes from concave-out to convex -out. The 

topographic convergence classes were noses (areas of 

convex-out contours), planar side slopes (areas of nearly 

straight contours, convergence angles less than approximately 10°), subtle hillslope hollows (areas of concave-out 

contours with convergence angles approximately 10°-30°), 

and distinct hillslope hollows (areas of concave-out contours with convergence angles greater than approximately 

30°). 

Most of the 852 landslides (70.6 percent) were 

initiated on planar slopes or noses rather than in hills1ope 

hollows. Among landslides that occurred on planar slopes, 

94 percent occurred on cleared slopes. In contrast, among 

landslides that occurred in distinct hills lope hollows, 62 

percent were in forested areas. For all landslides in this 

Landslides Triggered by the Storm of Nov. 3-5, 1985, W.Va., Va. C17 
sample, 83 percent occurred on cleared slopes. Because 

landslides on cleared, planar side slopes in the sample area 

tended to be smaller and shallower than those in hillslope 

hollows, the smaller volume of landslide material may 

somewhat diminish the dominance implied by the large 

percentages of these landslides. 

These data suggest that on sites where trees contributed root strength, topographic convergence of moisture or 

thickened accumulations of colluvium determined the slope 

instability during this event. On sites where tree root 

strength was lacking, topographic convergence was less 

important in determining instability. 

Debris Avalanches 

As noted earlier, all eight of the debris avalanches 

occurred on forested slopes. Five of the eight were on 

dipslopes, where failure took place along bedding planes in 

fractured sandstone under residuum or thin colluvium, or at 

sites that may have received a component of ground-water 

flow along bedding planes. Of these five sites, the largest 

was on a topographic nose, three were on planar side 

slopes, and one was in a subtle hillslope hollow. In contrast, 

all three debris avalanches occurring on antidipslopes were 

in distinct hillslope hollows. These observations suggest 

that on dipslopes, low strength along bedding planes and 

(or) downdip flow of ground water can lower stability as 

much as or more than topographic convergence of moisture 

or presence of thick colluvium. 

Slope Aspect and Land Cover 

At a broader scale of resolution, landslide location is 

influenced by both slope aspect and land cover. Observations from field and aerial photographs indicate a clear 

tendency for landslides to occur on north- to northeastfacing slopes (fig. 16). Land use practices, however, are not 

independent of slope aspect (table 5B). The north- to 

northeast-facing slopes, being wetter, are preferentially 

cleared for pasture, while the drier, south- to southwestfacing slopes are preferentially wooded. 

The interrelations among slope aspect, land cover, 

and landslide occurrence were investigated in the Germany 

Valley study area (Cron, 1990). Cron used a computerassisted geographic information system (GIS) with 100-m 

by 100-m grid cells over 75 km2 to compare topography, 

land cover, bedrock geology, and surficial geology for both 

stable and unstable slopes. She concluded the following: 

• North-facing (northwest through east) and south-facing 

(southeast through west) slopes are about equally represented (58 and 42 percent, respectively) among the 

entire population of slope prospects. 

• Due to land-use practices, 50 percent of the area of 

north-facing slopes is cleared for pasture and hay, while 

only 40 percent of the south-facing slopes is cleared. 

Figure 16. Aerial photograph showing association of landslides with cleared, northeast-facing slopes on Reedsville 

Shale in the center of the Wills Mountain anticline. 

• For all slopes, 9 percent of cleared cells had one or more 

landslides, whereas only 3 percent of the forested cells 

had one or more landslides. 

• For north-facing slope cells, 6 percent had one or more 

landslides, and for south-facing slope cells, 5 percent 

had one or more landslides. 

• For north-facing cleared slopes 10 percent of the cells 

had one or more landslides, compared with 2 percent for 

wooded cells; for south-facing cleared slopes, 7 percent 

had one or more landslides compared with 3 percent for 

wooded cells (table 5). 

These data indicate that, over areas of homogeneous 

bedrock and surficial geology, tree cover was an important 

factor in determining slope stability. Because this storm 

occurred at a time of year when leaves had fallen from the 

trees and evapotranspiration by trees was negligible, the 

influence of tree cover was probably through additions of 

root strength rather than from reductions in soil moisture. 

C18 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W. Va., Va. 
Slope aspect alone had a more subtle influence on 

slope stability, accounting for a relative increase of stability 

on south-facing slopes of only 17 percent. Slope aspect and 

land cover data together show that cleared land on northfacing slopes is 5 times as unstable as woodland, whereas 

cleared land on south-facing slopes is only 2.3 times as 

unstable as woodland. The increased stability of southfacing cleared slopes is probably due to lower soil moisture, 

relative to north-facing cleared slopes antecedent to the 

storm. 

Hence, these data indicate that the spatial distribution 

of slope instability triggered by the November 1985 storm 

was controlled by a combination of slope aspect and land 

cover factors in addition to meteorologic, lithologic, structural, and topographic convergence factors. Meteorologic 

and geologic controls on landslide locations are apparent at 

the scale of the entire Wills Mountain anticline study area 

(approximately 800 km2

). Competing influences of topographic convergence, slope aspect, and land cover become 

apparent over smaller areas (tens of km2

), where meteorologic and geologic factors do not vary. The quantitative 

importance of these factors and their operating mechanisms 

remains to be determined. 

MAGNITUDE AND FREQUENCY OF 

LANDSLIDE EVENTS 

Cumulative Rainfall Thresholds for Landslides 

The spatial distribution of landslides along the Wills 

Mountain anticline can be used to estimate the 48-h rainfall 

totals that triggered landslides on different lithologies in 

November 1985. Instability in regolith derived from the 

Reedsville Shale and Juniata Formation required approximately 180 mm or more cumulative rainfall; in regolith 

derived from the Greenbriar Group and Mauch Chunk 

Group, instability required 220 mm or more, but these rocks 

are not present in areas that received less than about 200 

mm; and large debris avalanches on dipslopes of the 

Tuscarora Sandstone required more than 220 mm. 

These observations provide crude rainfall thresholds 

for landsliding in these units, but the thresholds may be 

misleading because, while they illustrate conditions that 

were sufficient for failure, they may not resolve the combination of conditions necessary for failure. For example, 

the failures may have been triggered by a high-intensity 

rainfall interval during the storm, or they might have been 

dependent on antecedent soil moisture conditions. 

Unfortunately, data on rainfall intensity and observations of the times that individual landslides were triggered 

are insufficient to determine confidently whether highintensity periods within the storm may have been responsible for triggering some of the landslides or for the observed 

differences in thresholds. The available data and reports of 

residents, however, suggest that high-intensity periods were 

not immediate triggers of landslides. According to the most 

reliable hourly rainfall data (Colucci and others, chapter B, 

this volume, fig. 8), the highest rainfall intensities were 

recorded in the afternoon of November 4. Residents of the 

area agree that landslides in the Reedsville Shale started 

during the night of November 4-5 and continued with slow 

movement and occasional flow events during the morning 

of November 5. A resident at the base of North Fork 

Mountain at Judy Gap placed the time of the large debris 

avalanche there at approximately 9:00p.m. on November 

4, and a resident near the Twin Run debris avalanche 

reported that the avalanche occurred sometime during the 

night of November 4-5 (Kite and Linton, 1987, p. 23, 36). 

The role of antecedent soil moisture cannot be evaluated directly without detailed soil moisture data. Rainfall 

and runoff during October 1985 suggest that antecedent soil 

moisture conditions were only slightly wetter than normal 

for what is usually the driest season of the year (Colucci and 

others, chapter B, this volume). 

Rainfall Intensity and Duration Thresholds for 

Landslides 

Compared with other documented landslide events in 

the Appalachian Mountains, the November 1985 storm was 

characterized by an extremely large number of small slides 

and slide flows triggered on shaley lithologies by moderateintensity rainfall. Events similar in failure style and magnitude have not been reported elsewhere in the Appalachian 

Mountains. Instead, most other documented events have 

been characterized by large, destructive debris slides and 

debris avalanches triggered by high-intensity rainfall on 

steep slopes (Stringfield and Smith, 1956; Hack and 

Goodlett, 1960; Schneider, 1973; Bogucki, 1976; Everett, 

1979; Pomeroy, 1980, 1982b; Neary and Swift, 1987). 

Debris slides and avalanches constituted only a small 

portion of the landslides triggered during the 1985 storm. 

This comparison illustrates how unusual the 1985 event was 

and, by implication, identifies the most probable rainfall 

duration responsible for triggering these landslides. 

For durations from 1 to 48 h, mean intensities of 

measured rainfall in the 1985 storm are comparable to or 

above the threshold curve of Caine (1980) for shallow 

landslide and debris-flow (fig. 17). This curve defines a 

minimum threshold estimated from 73 cases of landslides 

worldwide, collected from a variety of physiographic, 

geologic, and antecedent moisture conditions. Many of the 

data points Caine used to define the relation lie substantially 

above the minimum curve. As discussed by Sidle and others 

(1985, p. 90-93), the Caine curve describes the minimum 

intensity that is necessary to trigger failure under saturated 

antecedent conditions at the least stable sites. Also, as with 

our data from the 1985 storm, many of the data in Caine's 

Landslides Triggered by the Storm of Nov. 3-5, 1985, W. Va., Va. C19 
500 

a: 200 o a 

Jennings (1950) 

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0 2 3 4 6 12 2 3 7 30 

HOURS DAYS 

RAINFALL DURATION 

Figure 17. Intensity and duration of rainfall of some storms responsible for triggering 

landslides in the central Appalachian Mountains: (a) Smethport, Pa., july 1942 (Eisenlohr, 

1952); (b) Great Smoky Mountains, Tenn., September 1951 (Bogucki, 1976); (c) Asheville, N.C., 

November 1977 (Neary and Swift, 1987); (d) johnstown, Pa., july 1977 (Pomeroy, 1980); (e) 

Shickshinny Mountain, Pa., 1947 (Braun and others, 1989); (f) Bens Creek, W.Va., August 1972 

(Everett, 1979); (g) Greenbriar, Tenn., August 1938 (Moneymaker, 1939); (h) Reddish Knob, Va., 

june 1949 (Hack and Goodlett, 1960); (i) Petersburg, W.Va., june 1949 (Stringfield and Smith, 

1956); (j) Spring Creek, W.Va., August 1969 (Schneider, 1973); (k) East Brady, Pa., August 1984 

(Pomeroy, 1984); (I) Nelson County, Va., August 1969 (Camp and Miller, 1970). Solid circles are 

values measured in or near the Wills Mountain anticline study area November 3-5, 1985. 

Shaded area shows range of intensity and duration known to have occurred in study area. 

curve are not peak intensities but, rather, mean intensities 

averaged over a given duration and empirically associated 

with landslide initiation. Unmeasured peak intensities may 

have been the actual triggers. These factors in the Caine 

curve tend to underestimate triggering intensities. However, 

in a study of storm-triggered debris flows in the California 

Coast Range, Wieczorek (1987) found thresholds considerably below the Caine curve when the occurrence of individual debris flows could be confidently associated with a 

specific intensity and duration of rainfall. Hence, the Caine 

curve is also sensitive to spatial scale and is most appropriately applied to events where extensive slope instability 

indicates that more slope sites failed than just the least 

stable. 

That points from the 1985 storm lie above the Caine 

threshold curve (fig. 17) is interpreted as evidence that the 

1985 storm had the potential to trigger landslides under 

some undefined combination of geologic, physiographic, 

and antecedent conditions, and not that particular durations 

were instrumental in actually triggering landslides in the 

Wills Mountain anticline area. Several Appalachian storms 

noted for triggering large debris avalanches are also plotted 

in figure 17. In general, these plot higher and at shorter 

durations than the 1985 data. Because these data are mean 

intensities averaged over longer durations, they tend to 

underestimate the maximum storm intensities. This is especially true for older data in areas where hourly recording 

rain gages were not available, for example, the June 1949 

C20 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W. Va., Va. 
3.5 

3.0 

2.5 

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_J _J 

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e 

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2 3 6 12 24 48 96 168 

RAINFALL DURATION, IN HOURS (LOG SCALE) 

Figure 18. Duration spectra for some storms that have triggered lands I ides in the central 

Appalachian Mountains. Graph shows ratio of storm rainfall to rainfall of the 100-yr event for 

durations of 1 to 168 h (7 days). The 100-yr rainfall is estimated from Hershfield (1961) and Miller 

(1964). Curves represent the following storms: (a-h) November 3-5, 1985 (NOM, 1986); (i, j) 

Hurricane Agnes, june 1972 (Bailey and others, 1975); (k) June 1949, near Petersburg, W. Va. 

(Stringfield and Smith, 1956); (I) Hurricane Camille, August 1969 (Camp and Miller, 1970); (m, n, 

o) Johnstown, Pa., July 1977 (Hoxit and others, 1982); (p) Smethport, Pa., july 1942 (Eisenlohr, 

1952); (q) Burnsville, W.Va., August 1943 (Erskine, 1952). 

storm near Petersburg, W. Va. (Stringfield and Smith, 

1956). 

Another useful measure is duration spectra of the 

individual storms (fig. 18). Unfortunately, the data needed 

to prepare duration spectra are available for only a few 

storms, and estimates from early studies are crude. Compared with other Appalachian storms, the November 1985 

storm has a distinctive duration spectrum that shows high 

relative recurrence intervals at long durations (fig. 18). The 

1985 storm never reached the recurrence intervals of the 

other storms, but the moderate-intensity rainfall in the 12-

to 48-h range was very effective in destabilizing slopes. 

Hurricane Agnes in 1972 produced rainfall with 

greater amounts but over durations similar to the 1985 

storm. Few landslides were triggered by Agnes (Pomeroy, 

1980; Costa, 1974), probably because the heaviest rainfall 

occurred over relatively stable lithologies in gently sloping 

areas of the Blue Ridge and Piedmont in Pennsylvania, 

Maryland, and Virginia. Based on the effects of the 1985 

storm, one would expect rainfall from Agnes to produce 

disastrous slope instability if it had fallen on the steeper 

slopes and shaley lithologies of the Wills Mountain anticline study area. 

Data for the 1949 storm that occurred just north of the 

Wills Mountain anticline study area are not very reliable but 

are included as a minimum description of that important 

storm. Studies of the effects of the 1949 storm by Hack and 

Goodlett (1960) and Stringfield and Smith (1956) cite 

Landslides Triggered by the Storm of Nov. 3-5, 1985, W.Va., Va. C21 
evidence that peak intensities were not recorded by the 

official or unofficial rain gages. The Stringfield and Smith 

study is particularly germane to our study because the large 

debris avalanches that they described are similar in location, 

process, and size to those triggered in 1985; however, many 

more were triggered during the 1949 event (Clark, 1987, 

fig. 3). In contrast, no landslides on shaley lithologies were 

documented in the Petersburg area (Stringfield and Smith, 

1956), and air photos of the Wills Mountain anticline study 

area from 1952 reveal only a few fresh landslides. We 

suspect that the rainfall in 1949 was effective in triggering 

the large debris avalanches on sandstone lithologies because 

it was more intense than actual measurements showed 

(compare fig. 18, curves a-h and k). The rainfall intensity 

may have been sufficient to overwhelm infiltration rates on 

shaley lithologies. Alternatively, the triggering rainfall may 

have been confined to a very localized convective cell over 

sandstone. Large debris avalanches on sandstone and shaley 

sandstone slopes in the Little River area of Virginia were 

triggered by the same storm (Hack and Goodlett, 1960), but 

precipitation data are insufficient to adequately characterize 

intensity and duration of rainfall at that location. 

Two other storms depicted in fig. 18 are noteworthy. 

The rainfall in central Virginia from Hurricane Camille in 

1969 was the largest in magnitude among all the storms, 

and the duration spectrum peaked at 6 h. This storm was 

noted for the many · large debris avalanches it triggered 

along the Blue Ridge (Williams and Guy, 1973; Gryta and 

Bartholomew, 1989). The Smethport, Pa., storm of July 

1942 has one of the highest 1-h intensities ever recorded. 

Some small slides, debris flows, and "blowouts" were 

triggered by the storm, but they were not studied systematically (Eisenlohr, 1952), presumably because the effects 

were not that dramatic. 

Rainfall and Spatial Density of Landslides 

As more rainfall infiltrates during a storm event, pore 

pressures will rise to failure levels for sites of successively 

greater mechanical stability. Conceptually, the stability of 

each slope site is characterized by its factor of safety (FS), 

the ratio of summed resisting forces to summed driving 

forces. The frequency distribution of FS on the landscape, 

categorized by site and varying with moisture content, if it 

could be ascertained, would be a fundamental descriptor of 

aggregate landscape sensitivity to slope instability. Subjected to a storm delivering uniform rainfall, a landscape 

with many sites at low FS would have many failures 

triggered after the initial threshold was reached, and then 

fewer as the sites of lower stability are cleaned out. 

Conversely, a landscape with the FS distribution skewed 

toward many sites at high stability would have few failures 

in the initial stages of rainfall, but as storm rainfall 

mounted, more and more sites would be brought to failure. 

Depending on the shape of the frequency distribution, the 

number of sites destabilized may suddenly increase or 

decrease. Furthermore, secondary thresholds may be 

encountered as landslides or sediment-laden floodwaters 

erode and unload toe support of neighboring slope sites. A 

landslide response curve of this type is important for 

evaluating whether denudation and hazards are related to 

frequent, low-magnitude events or rare, high-magnitude 

events (Wolman and Miller, 1960; Wolman and Gerson, 

1978). 

The relation between rainfall and landslide density 

(number of landslides per unit area) reflects the FS frequency distribution and will indicate whether sudden 

thresholds are met with increasing rainfall totals. If the 

triggering intensity and duration of rainfall can be estimated, then frequency analysis of the triggering rainfall 

would yield an estimate of the recurrence intervals of 

associated slope instability. 

To construct a relation between rainfall and landslide 

density for the 1985 storm in the study area, we assumed 

that the peak of the duration spectrum for the storm (fig. 18) 

at 48 h is indicative of the triggering duration for Reedsville 

Shale regolith. The spatial density of landslides at various 

48-h precipitation totals on Reedsville Shale was estimated 

along the Wills Mountain anticline by counting landslides in 

a 4 km2 grid cell. Along the southwest two-thirds of the 

anticline, 48-h rainfall totals and landslide spatial density 

vary directly with one another (fig. 19). The relation seems 

to deteriorate near kilometers 45-50, approximately where 

the southwesternmost large debris avalanches were triggered. Comparison with plate 1B shows that almost all of 

the outcrop belt of Reedsville Shale in the northwestern part 

of the anticline is covered with a blanket of debris that was 

shed from North Fork Mountain. Presence of debris, which 

served to protect the Reedsville Shale slopes from failure, 

was ignored in the procedure used here to measure the 

landslide spatial density. When the sampling cells known to 

be covered by debris are eliminated from the data set, a 

linear relation between landslide spatial density and 48-h 

rainfall is evident (fig. 20). The linear relation suggests that 

no substantial secondary thresholds occurred during the 

storm. 

By using the best fit model of rainfall frequency from 

the Franklin, W.Va., rain gage, the recurrence intervals for 

landslides triggered by 48-h rainfall along the valley are 

estimated to range from 43 to 286 yr. These recurrence 

intervals can be converted to model the relationship 

between landslide spatial density and probability of occurrence in any year (fig. 21). Since this frequency analysis 

does not consider antecedent moisture conditions, it may 

substantially underestimate or overestimate recurrence 

intervals for landslide densities. To the extent that other 

combinations of intensity and duration could be equally or 

more effective in destabilizing these slopes, this frequency 

analysis may overestimate recurrence intervals. Evaluations 

C22 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W.Va., Va. 
en 

LJ..J 

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0 20 

DISTANCE ALONG ANTICLINE, IN KILOMETERS 

Fi.gure 19. Plot of landslide areal density (landslides/km2

) on Reedsville Shale regolith against 

d1stance along SW-NE longitudinal transect of Wills Mountain anticline (solid circles) and 48-h 

rainfall (solid line) along same transect. Arrows mark locations along transect of large debris 

avalanches. Northeast of kilometer 45, much of the outcrop area of Reedsville Shale is covered 

by debris. 

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150 170 190 210 230 250 

TOTAL RAINFALL, IN MILLIMETERS 

Figure 20. Landslide density on Reedsville Shale (with 

debris soil removed) plotted against 48-h rainfall totals 

with estimated recurrence intervals. Thin lines are 90 

percent confidence intervals. Equation of the line is landslide density=-169+1.0 (48-h rainfall). ~=0.90. 

of these complications and improvements in rainfall measurement will require additional study. 

LANDSLIDES AND FLOOD-INDUCED 

GEOMORPHIC CHANGE 

Both the geomorphology of the drainage basin and 

the sediment delivery from landslides influenced flood 

damage in the main valley of the North Fork of the South 

Branch Potomac River. Two methods of analysis were 

0:: 

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20 40 60 80 

LANDSLIDE DENSITY, 

IN LANDSLIDES PER SQUARE KILOMETER 

Figure 21. Probability model for landslide density on 

Reedsville Shale regolith, assuming that 48-h rainfall is the 

triggering rainfall and that frequency model for 48-h 

rainfall is accurate. Thin lines are approximate 90 percent 

confidence intervals estimated from rainfall frequency 

model (Colucci and others, chapter B, this volume, fig. 12) 

and landslide density regression. 

applied to determine the extent of this influence. In the first, 

the association between presence or absence of landslides 

and presence or absence of channel erosion or deposition 

was evaluated for 79 small draining basins. In the second 

method, the influence of water and sediment discharges 

from each of the tributary basins was evaluated by an index 

of flood-induced geomorphic change in the channel and 

flood plain at the tributary's junction with the North Fork 

flood plain and compared with basin geomorphology and 

landslide density. 

landslides Triggered by the Storm of Nov. 3-5, 1985, W.Va., Va. C23 
Channel Changes and Landslides 

The study area encompasses parts of the North Fork 

drainage area (see plate 1 in Jacobson, chapter A, this 

volume). The river flows through a relatively narrow, 

structurally controlled valley bordered on the west by the 

Allegheny Structural Front and on the east by the River 

Knobs, formed by the northwest limb of the Wills Mountain 

anticline. Tributary basins drain to the North Fork from the 

center of the Wills Mountain anticline, through narrow gaps 

in the River Knobs, and from the Appalachian Plateau. 

Seventy-nine perennial and intermittent tributary basins as 

identified on 1:24,000 topographic maps (except Seneca 

Creek, which was not covered by aerial photography used 

in the landslide mapping) were selected for the study. These 

basins ranged in size from 0.13 to 22.41 km2

• 

The tributary basins were grouped according to their 

dominant bedrock geology into the following classes: 

• ORVis the interior of Wills Mountain anticline where 

underlain primarily by Reedsville Shale (19 basins). 

• HV is high valley underlain by limestone of the Greenbrier Group and interbedded mudstone and sandstone of 

the Mauch Chunk Group ( 16 basins). 

• DCH is underlain by sandstone and interbedded mudstone and sandstone of the Devonian Chemung Group 

and Hampshire Formation (36 basins). 

• SD is underlain by Tuscarora Sandstone and limestone, 

sandstone, and shale in the stratigraphic interval up to 

the Helderberg Group (8 basins). 

For each of the 79 tributary basins in the data set, the 

association between channel changes and landslides was 

evaluated by noting the presence or absence of both 

landslides and fresh erosional and depositional features that 

were identifiable on air photos and attributable to the 1985 

event (table 6). Erosional features were reaches of streams 

that were newly entrenched, steep and freshly eroded 

banks, and anomalously widened reaches. Depositional 

features were cobble and gravel channel deposits, levee and 

splay deposits, and fans. For the data set, 97 percent of the 

changed stream channels are associated with landslides, and 

only 7 percent of nonchanged stream channels are associated with landslides. A chi-square test of the association 

between channel change and landslides is significant at the 

0.005 level. 

Although this evidence for association is overwhelming, it does not consider the causal link between landslides 

and channel change. For basins underlain predominantly by 

Reedsville Shale (ORV basins), field observations confirmed that, in the majority of cases, channel change began 

abruptly at the point where landslide sediment was delivered to the channel. This relation was not as clear in basins 

underlain by other lithologies, where channel damage 

generally increased in proportion to increasing drainage 

area. 

Table 6. Association between slope movement and damage to stream channel for 79 drainage basins 

Category Slope movement No slope movement Total 

Channel damage 

No channel damage 

Total 

36 

3 

39 

1 

39 

40 

Tributary Channel-Change Index, Analytical 

Methods, and Results 

37 

42 

79 

Geomorphic effects from flooding in tributary basins 

were widespread and locally intense. The semiquantitative 

channel-change index was developed to characterize the 

geomorphic effects at the mouths of the 79 tributaries where 

they meet the North Fork River, and to evaluate how the 

addition of sediment from landslides into the basins contributed to flood damage. The index was based on the 

presence of the following features: channel widening and 

scour, channel avulsion, deposition along the channel and at 

the mouth, braided-channel development, and damage to 

roads, vegetation, and structures. Aerial photographs (both 

preflood and postflood) were utilized to evaluate these 

criteria (see Miller and Parkinson, chapter E, this volume, 

figs. 22-28, for examples). Most of the observations were 

made from postflood photographs, which were taken for the 

West Virginia Department of Highways within several days 

after the flood (scale approximately 1:10,000). Pre-1985 

photographs from the U.S. Soil Conservation Service (scale 

approximately 1:20,000) were used as a reference for 

pre flood conditions. Many of the tributaries were also 

visited in the field in 1987 to substantiate the classification. 

The effects most commonly seen on the tributaries 

were channel widening combined with deposition or exposure of a lag deposit of coarse sediment near the mouth and 

along the lower reaches of the stream. Many of the 

tributaries had well-imbricated deposits of cobbles across 

the entire channel and along the margins, a condition 

indicative of bed mobilization during the flood. Several 

stream channels that carried large amounts of coarse sediment and organic debris had logjams that trapped substantial amounts of sediment upstream. In these cases, morphologic changes at the tributary junction are presumably 

smaller than would be expected if all the sediment was 

delivered from the basins. Most of the tributaries had a 

"gutted" appearance due to channel widening, cobble 

levees, and removal of fine sediment and vegetation. Fans 

that existed at the mouths of tributaries prior to the 1985 

event showed renewed sedimentation of gravel and cobbles 

and (or) erosion. 

The following classes of change were used to evaluate the tributary channel-change index: 

1. No apparent change 

2. Very slight change; small amount of channel scouring 

or sediment deposited at mouth 

C24 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W. Va., Va. 
Tributary basins 

North Fork of the 

South Branch M 

Potomac River 

APPROXIMATELY 1 KILOMETER 

Figure 22. Measurement parameters for basin morphology. Points Pare the highest points along the side divides. 

Basin length, L, is the length of the line that bisects PP, at 

point B, and connects the basin mouth M and the basin 

divide. 

3. Transition 

4. Slight change; sediment deposited at mouth and/or 

some disruption of preflood channel 

5. Transition 

6. Moderate change; some channel widening and/or substantial amount of sediment at mouth and/or erosion or 

deposition along portions of tributary channel; may 

have some deposition on alluvial fan (if present) at the 

mouth of the tributary 

7. Transition 

8. Major change; large deposit on fan at mouth (if flow 

does not enter directly into main flood channel) and 

disruption of major portion of preflood channel 

9. Transition 

10. Extreme change; large, well-developed deposit on fan 

at mouth or creation of new fan and modification of 

entire preflood channel 

Basin length, relief, and area were measured from 

USGS 1:24,000 topographic maps to characterize morphometry of the basins that might be related to hydrologic 

responses. Basin length was measured along the basin axis 

as defined in figure 22. The basin axis was determined by 

drawing a straight line between the mouth and the bisector 

of a line between the highest elevation points on the side 

divides of the adjacent basins. Basin length and relief were 

measured between the mouth and the point where this 

"basin axis" intersected the basin divide. In many basins, 

this point was also the highest or farthest from the mouth. 

Although this method will not work in very irregular and 

dogleg-shaped basins, it did work well to characterize these 

basins. 

Relief ratio, defined as the ratio of basin relief to 

basin length, was used as a parameter for relative steepness 

of the basins. Among basins of uniform geology, basins 

with high relief ratios should have faster, and presumably 

more erosive, runoff than those with low relief ratios. 

The change index is highly correlated with the morphometric parameters of basin length, relief, and area as 

well as with landslide density (table 7, fig. 23). For all 

basins, and for most subsets by dominant bedrock geology, 

correlations are highest with basin length. Landslide density 

is generally significantly correlated with the channel-change 

index, although it commonly ranks second or third behind 

basin length. In most cases, also, the morphometric parameters are highly correlated among themselves, reflecting the 

tendency for larger basins to encompass greater relief. 

Correlations with rainfall, which varied from 190 to 240 

mm over the study basins, are relatively poor. 

All correlation coefficients are higher for analyses 

limited to ORV basins. In ORV basins, the correlation 

between landslide spatial density and channel-change index 

is much higher than that for all basins, and precipitation is 

of minor importance. Correlation coefficients for DCH, 

SD, and HV basins are all extremely low ( <0.10), possibly 

because of the low numbers of samples, uncertainties in 

evaluation of the change index for the smaller DCH basins, 

or insensitivity of the change index to measured parameters. 

The same independent variables were used in stepwise multivariate regression in order to rank their importance in influencing channel-change index. Because high 

collinearity exists among basin length and basin area, only 

basin length was used in the analysis. Although basin length 

and basin relief also vary collinearly, basin relief was 

retained as an independent variable. 

The results of the multivariate regression (table 8) 

show that basin length explains most of the variance for all 

basins and is important for most subsets of basins. For DCH 

basins, none of the variables provides significant explanation, and for SD basins the sample size is too small to 

resolve adequately the importance of individual variables. 

Landslide density, relief, and rainfall are of secondary 

importance. Landslide density makes substantial contributions to model R2 values when all basins are combined and 

when only ORV basins are considered. 

Landslide Spatial Density, Basin Morphology, 

and Flood Effects 

Among the subsets of basins sorted by dominant 

bedrock geology, ORV basins had the highest landslide 

densities. The weak but significant relation between 

channel-change index and landslide spatial density for ORV 

basins suggests that landslide activity in these basins was 

Landslides Triggered by the Storm of Nov. 3-5, 1985, W.Va., Va. C25 
Table 7. Correlation coefficients between basin variables 

[The top number is the correlation coefficient (R) and the bottom is the probability that R=O. Density is 

landslide spatial density in basin; other variables and basin groups are explained in text. N, number of basins in 

sample] 

Variable Damage Density Length Area Relief ratio Rain 

All basins, N=76 

Damage 1.00000 0.42904 0.59807 0.50973 0.36831 0.00640 

.0000 .0001 .0001 .0001 .0009 .9556 

Density 1.00000 .34867 .19194 .16724 - .09960 

.0000 .0018 .0923 .1433 .3856 

Length 1.00000 .74599 .85356 - .25484 

.0000 .0001 .0001 .0243 

Area 1.00000 .49495 - .01819 

.0000 .0001 .8744 

Relief ratio 1.00000 - .30151 

.0000 .0073 

Rain 1.00000 

.0000 

DCH, N=36 

Damage 1.00000 0.29626 0.14406 0.08082 0.12716 - .07820 

.0000 .0794 .4019 .6394 .4599 .6503 

Density 1.00000 .00191 - .07397 - .03379 .03188 

.0000 .9912 .6681 .8449 .8535 

Length 1.00000 .71575 .34664 - .59515 

.0000 .0001 .0383 .0001 

Area 1.00000 .37693 - .47677 

.0000 .0234 .0033 

Relief ratio 1.00000 - .13282 

.0000 .4400 

Rain 1.00000 

.0000 

HV, N=16 

Damage 1.00000 0.01821 0.23714 -0.02366 -0.04921 -0.02948 

.0000 .9466 .3765 .9307 .8564 .9137 

Density 1.00000 - .27066 - .60215 - .30535 .26928 

.0000 .3106 .0136 .2501 .3132 

Length 1.00000 .61884 .90013 - .47865 

.0000 .0106 .0001 .0607 

Area 1.00000 .55999 - .26166 

.0000 .0241 .3276 

Relief ratio 1.00000 - .47419 

.0000 .0635 

Rain 1.00000 

.0000 

ORV, N=19 

Damage 1.00000 0.72059 0.77477 0.58383 -0.04282 0.47009 

.0000 .0007 .0002 .0110 .8660 .0490 

Density 1.00000 .59643 .22411 - .11531 .30348 

.0000 .0090 .3713 .6487 .2209 

Length 1.00000 .72060 .50006 .62499 

.0000 .0007 .0346 .0055 

Area 1.00000 .26213 .63119 

.0000 .2934 .0050 

Relief ratio 1.00000 .31692 

.0000 .2001 

Rain 1.00000 

.0000 

C26 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W.Va., Va. 
Table 7. Correlation coefficients between basin variables-Continued 

Variable Damage Density Length Area Relief ratio Rain 

SD, N=6 

Damage 1.00000 0.70141 0.46805 0.39806 0.28242 0.55391 

.0000 .1204 .3492 .4345 .5876 .2541 

Density 1.00000 .22357 .20915 .13413 .42333 

.0000 .6702 .6908 .8000 .4029 

Length 1.00000 .96408 .92117 - .46892 

.0000 

Area 

Relief ratio 

Rain 

sufficient to influence geomorphic changes in the flood 

plain and channel during the flood. Apparently, the spatial 

densities of landslides in basins dominated by other types of 

bedrock geology did not contribute enough sediment to the 

tributary channels to exceed channel erosion thresholds. 

The channel-change index correlates poorly with 

relief ratio (R2

=0.002-0.14), a result that is contrary to 

our initial expectations that steeper topography would be 

associated with faster runoff and more erosive flows. 

Instead, the channel-change index correlates better with 

basin length (R2 =0.02-0.60). The direct relation between 

channel-change index and basin length does not reflect 

simply the effect of greater basin area because in all cases 

the correlation between the index and basin area is weaker 

than that between the index and basin length (table 7). 

The process responsible for the importance of basin 

length is unknown, but a variety of possibilities exist. 

Longer ORV basins appear to have a greater percentage of 

the basin underlain by the Reedsville Shale, in which there 

is a greater spatial density of landslides; this condition 

would promote greater relative sediment supply in the 

longer ORV basins. Also, the lower reaches of the longer 

streams are generally wider, have lower channel gradients, 

and have better developed flood plains than the shorter 

ones. Hence, the longer streams provide a better environment for channel erosion and deposition, whereas sediment 

may be flushed through the shorter basins without producing the kinds of changes detected in this study. Also, the 

longer basins may have greater drainage densities than the 

shorter basins, and greater lengths of high-order channels; 

this would increase the efficiency of routing sediment and 

water to the lower reaches. The relative importance of each 

of these factors is unknown; further study and an expanded 

data base are needed to evaluate and rank the factors. 

DISCUSSION AND CONCLUSIONS 

Our analysis of landslides triggered by the November 

1985 storm indicates that landslide locations in this land-

.0019 .0091 .3482 

1.00000 .98855 - .49060 

.0000 .0002 .3231 

1.00000 - .56052 

.0000 .2473 

1.00000 

.0000 

scape are determined by a complex combination of factors: 

stability of slope sites related to rainfall, antecedent moisture of regolith, bedrock lithology, bedrock structure, 

surficial geology, slope morphology, and land cover. 

Among these variables, only rainfall, bedrock lithology, 

and bedrock structure can be considered independent. Slope 

morphology and surficial geology are strongly related to the 

bedrock; land cover and antecedent moisture of regolith are 

interdependent with slope morphology and the geologic 

factors. 

At the scale of the entire study area, the primary 

control on the spatial distribution of landslides is the 

distribution of rainfall. Second in importance is the bedrock 

lithology, which, through its control on regolith properties, 

determined the extent of slope stability for the rainfall 

intensity and duration of this particular storm. Third, but 

superimposed on bedrock lithology, the distribution of 

Quaternary debris had an important role in determining 

where landslides were located in a given bedrock unit. Land 

cover and slope morphology become important factors in 

slope stability for areas where the rainfall, bedrock, and 

surficial geology do not vary. 

Study of the physical properties of several of the 

materials that were more susceptible to failure during the 

1985 storm suggests that landslide susceptibility was due to 

particular combinations of infiltration rate and strength. The 

most unstable lithology, residuum derived from the Reedsville Shale, had intermediate infiltration rates and low 

strength, as indicated by its high plasticity index. However, 

regolith of the Trenton Group, which had higher plasticity 

and hence probably lower strength, had very few failures, 

probably because of its extremely high infiltration and 

drainage rates. Relative stability of other regoliths is attributable to higher infiltration and drainage rates, or other 

factors imparting higher strength. Other documented storm 

events that have been effective in triggering landslides in 

the Appalachian Mountains have involved more intense 

rainfall on coarser grained regolith that presumably would 

have relatively high infiltration and drainage rates. 

Landslides Triggered by the Storm of Nov. 3-5, 1985, W.Va., Va. C27 
X 

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z 

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0 

2 

0 

0 

0 4 8 12 16 20 24 

BASIN AREA, IN SQUARE KILOMETERS 

D ORV basins 6 DCH basins 

0 HV basins vAll other basins 

10 

0 

8 Dv 0 

£::,. 00 0 (llJ [Q)\7 0 

6 LL::,. \70 CIJ QD 0 0 0 0 

~ L. DO 

4 ~ ~vrn ~ 0 0 0 

~ DJSJ v DO 0 

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BASIN LENGTH, IN THOUSANDS OF METERS 

D ORV basins 6 DCH basins 

0 HV basins vAll other basins 

10 

0 

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fi ~ 

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n ~ £::,. 

4 n el ~ 

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2 0 g 1@: 

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200 220 240 

v SD basins 

D ORV basins 

RAINFALL, IN MILLIMETERS 

0 HV basins 

~ DCH basins 

<>CARS basins 

10 

0 

8 - 0 

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6 -DO 0 

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4 - 0 

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0 4 8 12 16 20 24 

BASIN AREA, IN SQUARE KILOMETERS 

0 ORV basins 

10 

0 

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D 

4 D 

DO DO 

2 0[[] 

0 

6 0 0 2 4 6 

BASIN LENGTH, IN THOUSANDS OF METERS 

0 ORV basins 

10 

0 

8 D 0 

0 0 

6 D 0 

D 

4 0 

D 0 

2 D 0 

0 

0 

200 220 240 

RAINFALL, IN MILLIMETERS 

0 ORV basins 

Figure 23. Scatter plots of the channel-change index and basin parameters, by basin types according to dominant 

lithology. Points labeled NTH are Noah Teter Hollow, where a large amount of sediment supplied from upstream was 

trapped behind a slump dam on the side of the stream. Separate plots of ORV, which were the basins experiencing the 

greatest landslide density, show influence of basin length and landslide density. 

C28 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W. Va., Va. 
10 

0 

X 8 0 w 

Cl 

~ 0 [IIl 0 

L.U 

(!) 6 0 0 0 z 

<( 

:::c 

u NTH ~ 4 D L.U 

z 

z 0 D 

<( 

:::c 

u 2 

0 

0 20 40 60 

LANDSLIDE DENSITY, 

IN LANDSLIDES PER SQUARE KILOMETER 

D ORV basins .c:,. DCH basins 

0 HV basins vAll other basins 

a: 

w 

1-

w D 60 ~ zo 

- _J 

>-:;;;;:: 

t:::L.U 

(1)0:: D 

z<( 40 Q]D w::::> 

od 

wC/l 0 Cl 0:: 0 -w 

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RELIEF RATIO 

D ORV basins .c:,. DCH basins 

0 HV basins vAll other basins 

Figure 23. Continued. 

Over areas underlain only by regolith derived from 

Reedsville Shale, the slope morphology and land cover type 

become additional factors in determining the distribution of 

slope instability. Interdependence of these factors is further 

complicated by trade-offs among them in determination of 

stability of individual sites. For example, the tendency for 

landslides under forest to occur in hills lope hollows, 

whereas those under pasture cover tend to occur on other 

parts of the landscape as well, suggests that strength 

imparted by tree roots is compensated by increased moisture 

and (or) thicker colluvium in hills lope hollows. Similarly, 

for sandy regolith derived from sandstone bedrock, both 

ground-water flow and low strength on bedding plane 

surfaces tend to make dipslopes relatively insensitive to 

topographic convergence, whereas on antidipslopes, topographic convergence in hillslope hollows assumes greater 

importance in determining slope stability. 

10 

8 0 

6 [~ 

0 

4 

[]]] D 

2 [~ 

D 

0 

0 

60 

40 

20 

D 

D ITJl D 

D D 

D 

20 40 

LANDSLIDE DENSITY, 

IN LANDSLIDES PER SQUARE KILOMETER 

D ORV basins 

D 

0 

ODD 

D 

0 

0 

0 

0 

0 

NTH 

0 

60 

oL_--~--~----~=-~~--~~~--~--~ D & ~ Ill 

0 0.1 0.2 0.3 0.4 

RELIEF RATIO 

D ORV basins 

Our observations on the controlling factors for landslide location may hold only for _the particular intensity and 

duration of the November 1985 triggering event. Storms of 

different intensity and duration will probably destabilize 

sites with different characteristics. In particular, our observation that the high-intensity 1949 storm destabilized large 

areas of North Fork Mountain underlain by Tuscarora 

Sandstone, and that similar areas were relatively stable in 

1985, suggests that rainfall intensity and duration are 

important determinants of what types of lithologies are 

destabilized. 

The highly selective destabilization of regoliths during this storm and comparisons with other storms suggest 

that, in the Appalachian Mountain landscape, different 

rainfall characteristics are effective in destabilizing slopes, 

depending primarily on the underlying bedrock lithology. 

Bedrock lithology, in tum, strongly determines regolith 

landslides Triggered by the Storm of Nov. 3-5, 1985, W.Va., Va. C29 
Table 8. R2 values for multivariate models explaining the 

channel-damage index 

[Basin groups are explained in text. N, number of basins] 

Number 

of variables 

in model 

1 

1 

1 

1 

2 

2 

2 

2 

2 

2 

3 

3 

3 

3 

4 

1 

1 

1 

1 

2 

2 

2 

2 

2 

2 

3 

3 

3 

3 

4 

1 

1 

1 

1 

2 

2 

2 

2 

2 

2 

3 

3 

3 

3 

4 

Variables in model 

AU basins, N=76 

0.32753208 Length 

.19937544 Density 

.13641939 Relief ratio 

.00017394 Rain 

.40251798 Length, relief ratio 

. 39205539 Length, density 

.35243367 Length, rain 

.28856567 Relief ratio, density 

.20033295 Density, rain 

.14741423 Relief ratio, rain 

.43152481 Length, relief ratio, density 

.41850116 Length, relief ratio, rain 

.41633221 Length, density, rain 

.30409283 Relief ratio, density, rain 

.44907037 Length, relief ratio, density, rain 

DCH basins, N=36 

0.08777079 Density 

.02075444 Length 

.01617088 Relief ratio 

.00611482 Rain 

.10836223 Length, density 

.10660956 Relief ratio, density 

.09545999 Density, rain 

.02753288 Length, relief ratio 

.02084254 Length, rain 

.01999700 Relief ratio, rain 

.11706091 Length, relief ratio, density 

.11153759 Relief ratio, density, rain 

.10836996 Length, density, rain 

.02753475 Length, relief ratio, rain 

.11720699 Length, relief ratio, density, rain 

HV basins, N=l6 

0.05623464 Length 

.00242114 Relief ratio 

.00086919 Rain 

.00033150 Density 

.41980936 Length, relief ratio 

.06539307 Length, rain 

. 06355956 Length, density 

.00601965 Relief ratio, rain 

.00243231 Relief ratio, density 

.00160626 Density, rain 

.42056862 Length, relief ratio, rain 

.41981953 Length, relief ratio, density 

.07039695 Length, density, rain 

.00617309 Relief ratio, density rain 

.42062404 Length, relief ratio, density, rain 

properties and slope morphology. High-intensity, shortduration storms would be more effective in destabilizing 

regolith with high infiltration and drainage rates, such as 

regolith derived from sandstones and coarse-grained igneous rocks. High-intensity, short-duration storms may be too 

short to allow concentration of sufficient moisture in regolith with slower infiltration rates, and rainfall intensities 

Table 8. R2 values for multivariate models explaining the 

channel-damage index-Continued 

Number 

of variables 

in model 

1 

1 

1 

1 

2 

2 

2 

2 

2 

3 

3 

3 

3 

4 

1 

1 

1 

1 

2 

2 

2 

2 

2 

2 

3 

3 

3 

3 

4 

Variables in model 

ORV basins, N=lS 

0.60027558 Length 

.51925368 Density 

.22098481 Rain 

.00183317 Relief ratio 

.84711837 Length, relief ratio 

. 70398994 Length, density 

.58887082 Density, rain 

.52089756 Relief ratio, density 

.26187869 Relief ratio, raid 

.84820140 Length, relief ratio, density 

.84733988 Length, relief ratio, rain 

. 70430002 Length, density, rain 

.59271532 Relief ratio, density, rain 

.84831393 Length, relief ratio, density, rain 

SD basins, N=6 

0.49197952 Density 

.30681818 Rain 

.21906862 Length 

.07976379 Relief ratio 

.98579687 Length, rain 

.81939800 Relief ratio, rain 

.59394197 Length, density 

.57243706 Density, rain 

.52810288 Relief ratio, density 

.36511838 Length, relief ratio 

.99482908 Length, density, rain 

.98926965 Length, relief ratio, rain 

.85371516 Relief ratio, density, rain 

.66746404 Length, relief ratio, density 

.99895547 Length, relief ratio, density, rain 

may be high enough to promote direct runoff. Lowintensity, long-duration storms, like the 1985 storm, would 

be slow enough to allow moisture to drain from most slopes 

on coarse-grained regolith but would allow moisture to 

accumulate on fine-grained regolith . 

One implication of this model is that predicted 

locations of landslide hazards should be determined from 

rock type and rainfall intensity and duration characteristics 

of particular storms, rather than just total rainfall. Another 

implication for general geomorphic models is that the 

magnitude and frequency of meteorologic events that are 

geomorphically effective on slopes will vary across the 

landscape, depending primarily on rock type. Hence, in the 

Appalachian Valley and Ridge, where bedrock lithologies 

are highly variable, different slopes can be said to be 

equilibrated to different types of storms. 

The 1985 storm produced long, slow rainfall with 

storm totals that were rare over durations from 24 to 72 h. 

Landslide density on Reedsville Shale has a linear relation 

with measured 48-h rainfall along the Wills Mountain 

anticline. Available evidence does not indicate any signifC30 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W.Va., Va. 
icant secondary thresholds or sudden increases in landslide 

density with increasing rainfall. Comparison of landslide 

density to recurrence frequency of the apparent triggering 

rainfall shows that the recurrence of slope instability experienced in 1985 varied from 43 yr for 1 lands1ide/km2 to 

nearly 300 yr for 70 landslides/km2

• However, error limits 

on these frequencies are large, and further refinement will 

require more well-documented landslide events, calibration 

with data from instrumented slopes, longer rainfall records, 

and refined frequency analysis techniques. 

Analysis of the relation between landslides and floodinduced geomorphic effects in stream channels shows a 

strong correlation between the presence of landslides and 

the presence of substantial channel changes. In shaley 

lithologies, individual landslides had the most influence on 

stream channels that were directly adjacent. Erosion and 

deposition attributable to individual landslides decreased 

downstream as opportunities occurred for sediment retention behind temporary dams and as water discharge 

increased and diluted the sediment concentrations. As a 

result, the direct effects of these landslides usually were not 

apparent at distances of 50-100m downstream. In contrast, 

local effects of single landslides triggered in sandy, bouldery regolith associated with the Tuscarora Sandstone were 

obvious and dramatic up to 2 km downstream (Kite and 

Linton, 1987; Jacobson and others, 1989). 

Channel changes at tributary-main stem junctions 

measured the indirect, cumulative influences of landslides 

and other morphometric variables on geomorphic changes 

induced by the flooding. This analysis showed that channel 

change is correlated best with basin length, a morphometric 

parameter that may be related to volume or rate of runoff 

from the basins. Landslide density in the basins is of 

secondary importance, being more significant in basins 

underlain by the geologic unit that is most susceptible to 

failure: the Reedsville Shale. Linkage of the magnitude of 

flood damage to landslide influences suggests that in the 

steep Appalachian landscape, flood hazards are augmented 

by upstream sediment supply from landslides. 

REFERENCES CITED 

Bailey, J.F., Patterson, J.L., and Paulhus, J.L.H., 1975, Hurricane Agnes rainfall and floods, June-July 1972: U.S. Geological Survey Professional Paper 924, 403 p. 

Bogucki, D.J., 1976, Debris slides in the Mt. Le Conte area, 

Great Smoky Mountains National Park, U.S.A.: Geografiska 

Annaler, v. 58A, p. 179-191. 

Braun, D.D., Gilmeister, N.M., and Inners, J.D., 1989, Postglacial to historic dip-slope block slides in the Valley and 

Ridge province of northeastern Pennsylvania, in Schultz, 

A.P., and Jibson, R.W., eds., Landslide processes of the 

Eastern United States and Puerto Rico: Geological Society of 

America Special Paper 236, p. 75-88. 

Caine, N., 1980, The rainfall intensity-duration control of shallow 

landslides and debris flows: Geografiska Annaler, v. 62A, 

p. 23-27. 

Camp, J.D., and Miller, E.M., 1970, Flood of August 1969 in 

Virginia: U.S. Geological Survey Open-File Report, 120 p. 

Campbell, R.H., Varnes, D.J., Fleming, R.W., Hampton, M.H., 

Prior, D.B., Sangrey, D.A., Nichols, D.R., and Brabb, 

E.E., 1985, Landslide classification for identification of mud 

flows and other landslides, in Campbell, R.H., ed., Feasibility of a nationwide program for the identification and 

delineation of hazards from mud flows and other landslides: 

U.S. Geological Survey Open-File Report 85-276, 

p. A1-A24. 

Cardwell, D.H., Erwin, R.B., and Woodward, H.P., 1968, 

Geologic map of West Virginia: West Virginia Geological 

and Economic Survey, scale 1:250,000, 2 sheets. 

Clark, G .M., 1987, Debris slide and debris flow historical events 

in the Appalachians south of the glacial border, in Costa, 

J.E., and Wieczorek, G.E., eds., Reviews in engineering 

geology, v. vii: Boulder, Colo., Geological Society of 

America, p. 125-138. 

Costa, J.E., 1974, Response and recovery of a Piedmont watershed from tropical storm Agnes, June 1972: Water Resources 

Research, v. 10, p. 106-112. 

---1987, A comparison of the largest rainfall-runoff floods 

in the United States with those of the People's Republic 

of China and the world: Journal of Hydrology, v. 96, 

p. 101-115. 

Cron, E.D., 1990, Analysis of landslides resulting from a severe 

storm; a geographic information system application: Fairfax, 

Va., George Mason University, unpublished Masters thesis, 

30 p. 

Diecchio, R.J., 1986, Taconian clastic sequence and general 

geology in the vicinity of the Allegheny Front in Pendleton 

County, West Virginia, in Neathery, T.L., ed., Centennial 

field guide, v. 6: Southeastern Section of the Geological 

Society of America, p. 85-90 

Dietrich, W.E., Reneau, S.L., and Wilson, C.J., 1987, Overview: "Zero-order basins" and problems of drainage density, 

sediment transport and hillslope morphology: Erosion and 

sedimentation in the Pacific rim (Proceedings of the Corvallis 

Symposium, August 1987): International Association of 

Hydrological Sciences Publication 165, p. 27-37. 

Eisenlohr, W.S., Jr., 1952, Floods of July 18, 1942 in northcentral Pennsylvania: U.S. Geological Survey Water Supply 

Paper 1134-B, 98 p. 

Erskine, H.M., 1952, Flood of August 4-5, 1943 in central West 

Virginia: U.S. Geological Survey Water Supply Paper 

1134-A, 57 p. 

Everett, A. G. , 1979, Secondary permeability as a possible factor 

in the origin of debris avalanches associated with heavy 

rainfall: Journal of Hydrology, v. 43, p. 347-354. 

Fleming, R.W., Johnson, A.M., Hough, J.E., Gokce, A.O., and 

Lion, T., 1981, Engineering geology of the Cincinnati area, 

in Roberts, T. G. , ed. , Cincinnati 1981 field trip guidebook, 

v. 3: Boulder, Colo., Geological Society of America, 

p. 543-570. 

Gryta, J .J., and Bartholomew, M.J., 1989, Factors influencing 

the distribution of debris avalanches associated with the 1969 

Hurricane Camille in Nelson County, Virginia, in Schultz, 

Landslides Triggered by the Storm of Nov. 3-5, 1985, W.Va., Va. C31 
A.P., and Jibson, R.W., eds., Landslide processes of the 

Eastern United States and Puerto Rico: Geological Society of 

America Special Paper 236, p. 15-28. 

Hack, J.T., and Goodlett, J.C., 1960, Geomorphology and forest 

ecology of a mountain region in the central Appalachians: 

U.S. Geological Survey Professional Paper 34 7, 66 p. 

Hershfield, D.M., 1961, Rainfall frequency atlas of the United 

States: U.S. Weather Bureau Technical Paper 40, 114 p. 

Hoxit, L.R., Maddox, R.A., Chappell, C.F., and Brua, S.A., 

1982, Johnstown-western Pennsylvania storm and floods of 

July 19-20, 1977: U.S. Geological Survey Professional 

Paper 1211, 68 p. 

Interagency Advisory Committee on Water Data, 1982, Guidelines for determining flood flow frequency: U.S. Geological 

Survey, Bulletin 17B of the Hydrology Subcommittee, 27 p. 

+ app. 

Jacobson, R.B., 1985, Spatial and temporal distributions of slope 

processes in the upper Buffalo Creek drainage basin, Marion 

County, West Virginia: Baltimore, Md., Johns Hopkins 

University, unpublished Ph.D. dissertation, 485 p. 

Jacobson, R.B., Cron, E.D., and McGeehin, J.P., 1989, Slope 

movements triggered by heavy rainfall, November 3-5, 

1985, in Virginia and West Virginia, U.S.A., in Schultz, 

A.P., and Jibson, R.W., eds., Landslide processes of the 

Eastern United States and Puerto Rico: Geological Society of 

America Special Paper 236, p. 1-14. 

Jacobson, R.B., McGeehin, J.P., and Cron, E.D., 1987, Hillslope processes and surficial geology, Wills Mountain anticline, West Virginia and Virginia, in Kite, J.S., ed., 

Research on the Late Cenozoic of the Potomac highlands, 

Southeastern Friends of the Pleistocene, v. 1: West Virginia 

Geologic and Economic Survey Open-File Report OF 88--02, 

p. 31-50. 

Jennings, A.H., 1950, World's greatest observed point rainfall: 

Monthly Weather Review, v. 78, p. 4-5. 

Kite, J.S., and Linton, R.C., 1987, Judy Run debris avalanchedebris flow, in Kite, J.S., ed., SEFOP 1987 Field guide for 

the first annual meeting of the Southeastern Friends of the 

Pleistocene: Southeastern Friends of the Pleistocene, v. 2: 

West Virginia Geologic and Economic Survey Open-File 

Report, OF 88--02, p. 23-24, 36. 

Kite, J.S., Linton, R.C., and Gerritsen, S., 1987, The Twin Run 

debris avalanche-debris flow, in Kite, J.S., ed., SEFOP 1987 

Field guide for the first annual meeting of the Southeastern 

Friends of the Pleistocene: Southeastern Friends of the 

Pleistocene, v. 2: West Virginia Geologic and Economic 

Survey Open-File Report, OF 88--02, p. 34-52. 

Kulander, B .R., and Dean, S .L., 1986, Structure and tectonics of 

central and southern Appalachian Valley and Ridge and 

Plateau provinces, West Virginia and Virginia: American 

Association of Petroleum Geologists Bulletin, v. 70, 

p. 1674-1684. 

Lessing, Peter, and Erwin, R.B., 1977, Landslides in West 

Virginia, in Coates, D.R., ed., Landslides, Reviews in 

engineering geology series, v. III: Boulder, Colo., Geological Society of America, p. 245-254. 

Lessing, Peter, Kulander, B.R., Wilson, B.D., Dean, S.L., and 

Woodring, S.M., 1976, West Virginia landslides and slideprone areas: West Virginia Geological and Economic Survey, 

Environmental Geology Bulletin 15, 64 p., 35 pls. 

Lessing, Peter, Messina, C.P., and Fonner, R.F., 1983, Landslide 

risk assessment: Environmental Geology, v. 5, p. 93-99. 

Miller, J.F., 1964, Two- to ten-day precipitation for return periods 

of 2 to 100 years in the contiguous United States: U.S. 

Weather Bureau Technical Paper 49, 29 p. 

Mills, H.H., 1981, Boulder deposits and the retreat of mountain 

slopes, or "gully gravure" revisited: Journal of Geology, v. 

89, p. 649--660. 

---1988, Surficial geology and geomorphology of the Mountain Lake area, Giles County, Virginia, including sedimentological studies of colluvium and boulder streams: U.S. 

Geological Survey Professional Paper 1469, 57 p. 

Mitchell, J.K., 1976, Fundamentals of soil behavior: New York, 

Wiley and Sons, 422 p. 

Moneymaker, B.C., 1939, Erosional effects of the Webb Mountain (Tennessee) cloudburst of August 5, 1938: Journal of the 

Tennessee Academy of Science, v. 14, p. 190-196. 

National Oceanic and Atmospheric Administration, 1985, Climatological data, West Virginia, v. 93, no. 11: Asheville, N.C., 

National Climatic Data Center, 19 p. 

---1986, Climatic data: Asheville, N.C., National Climatic 

Data Center, digital media. 

Neary, D.G., and Swift, L.W., Jr., 1987, Rainfall thresholds for 

triggering a debris avalanching event in the southern Appalachian Mountains, in Costa, J.E., and Wieczorek, G.E., 

eds., Reviews in engineering geology, v. vii: Boulder, Colo., 

Geological Society of America, p. 81-92. 

Perry, W.J., Jr., 1971, Structural development of the Nittany 

Anticlinorium, Pendleton County, West Virginia: New 

Haven, Conn., Yale University, unpublished Ph.D. dissertation, 227 p. and maps. 

Pomeroy, J.S., 1980, Storm-induced debris avalanching and 

related phenomena in the Johnstown area, Pennsylvania, with 

reference to other studies in the Appalachians: U.S. Geological Survey Professional Paper 1191, 23 p. 

---1982a, Mass movement in two selected areas of Washington County, Pennsylvania: U.S. Geological Survey Professional Paper 1170-B, 17 p. 

---1982b, Landslides in the greater Pittsburgh region, Pennsylvania: U.S. Geological Survey Professional Paper 1229, 

48 p. 

---1984, Storm-induced landslides at East Brady, northwestem Pennsylvania: U.S. Geological Survey Bulletin 1618, 

16 p. 

---1987, Slope stability in the Marietta area, Washington 

County, southeastern Ohio: U.S. Geological Survey Bulletin 

1695, 47 p. 

Reneau, S.L., and Dietrich, W.E., 1987, Size and location of 

colluvial landslides in a steep forested landscape: Erosion and 

sedimentation in the Pacific rim (Proceedings of the Corvallis 

Symposium, August 1987): International Association of 

Hydrological Sciences Publication 165, p. 39-48. 

Reneau, S.L., Dorn, R.I., Berger, C.R., and Rubin, Meyer, 

1986, Geomorphic and paleoclimatic implication of latest 

Pleistocene radiocarbon dates from colluvium-mantled hollows, California: Geology, v. 14, p. 655--658. 

Royster, D.L., 1973, Highway landslide problems along the 

Cumberland plateau in Tennessee: Association of Engineering Geologists Bulletin, v. 10, p. 255-287. 

C32 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W.Va., Va. 
Schneider, R.H., 1973, Debris slides and related flood damage 

resulting from Hurricane Camille, 19-20 August, and subsequent storm, 5-6 September, 1969, in the Spring Creek 

drainage basin, Greenbriar County, West Virginia: Knoxville, Tenn., University of Tennessee, unpublished Ph.D. 

dissertation, 131 p. 

Sidle, R.C., Pearce, A.J., and O'Loughlin, C.L., 1985, Hillslope 

stability and land use, Water Resources Monograph 11: 

Washington, D.C., American Geophysical Union, 140 p. 

Stringfield, V.T., and Smith, R.C., 1956, Relation of geology to 

drainage, floods, and landslides in the Petersburg area, West 

Virginia: West Virginia Geological and Economic Survey, 

Report of Investigation 13, 19 p. 

Varnes, D.J., 1978, Landslides, types and processes, in Schuster, 

R.L., and Krizek, R.J., eds., Landslides-analysis and 

control: National Academy of Sciences, Transportation 

Research Board Special Report 176, p. 11-33. 

Wieczorek, G .E., 1987, Effect of rainfall intensity and duration 

on debris flows in central Santa Cruz Mountains, California, 

in Costa, J.E., and Wieczorek, G.E., eds., Reviews in 

engineering geology, v. vii: Boulder, Colo. , Geological 

Society of America, p. 125-138. 

Williams, G. P. , and Guy, H. P. , 1973, Erosional and depositional 

aspects of Hurricane Camille in Virginia, 1969: U.S. Geological Survey Professional Paper 804, 80 p. 

Wolman, M.G., and Gerson, Ran, 1978, Relative scales of time 

and effectiveness of climate in watershed geomorphology: 

Earth Surface Processes, v. 3, p. 189-208. 

Wolman, M.G., and Miller, J.P., 1960, Magnitude and frequency 

of forces in geomorphic processes: Journal of Geology, v. 68, 

p. 54-74. 

Landslides Triggered by the Storm of Nov. 3-5, 1985, W. Va., Va. C33 

Chapter D 

Depositional Aspects of the November 1985 

Flood on Cheat River and Black Fork, West 

Virginia 

By j. STEVEN KITE and RON C. LINTON 

U.S. GEOLOGICAL SURVEY BULLETIN 1981 

GEOMORPHIC STUDIES OF THE STORM AND FLOOD OF NOVEMBER 3-5, 1985, IN 

THE UPPER POTOMAC AND CHEAT RIVER BASINS IN WEST VIRGINIA AND VIRGINIA 
II Contents 

CONTENTS 

Abstract Dl 

Introduction Dl 

Learning From Catastrophe Dl 

Scope of Research D2 

Study Area D2 

Bedrock Geology and Topography D2 

Land Use in the Cheat River Basin D4 

Acknowledgments D4 

The Flood of November 1985 D4 

Meteorology and Hydrology D4 

Damage and Fatalities D4 

Historic Floods and the Recurrence Interval of the 1985 Flood DS 

Deposits Formed During the November 1985 Flood D6 

General D6 

Methods Used to Study 1985 Flood Deposits D7 

Physical Characteristics of Slack-Water Deposits D7 

Slack-Water Deposits as Indicators of Flood Stage Dll 

Other Fine-Grained Deposits Dl3 

Deposits of Small Boulders and Cobbles DlS 

Extremely Large Boulders D16 

Paleohydraulic Reconstructions From Large Boulders D18 

Miscellaneous Deposits D19 

Sources of Flood-Plain Sediments D20 

Conclusions and Implications D21 

Summary of Flood Geomorphology D21 

Effectiveness of Large Floods in Long-Term Flood-Plain Evolution D21 

Implications for Flood-Plain Management D22 

References Cited D22 

FIGURES 

1. Map showing Cheat River, Black Fork, and selected tributaries D3 

2. Aerial photograph of destruction at Albright, W. Va. DS 

3. Map and cross section of slack-water deposit formed at the mouth of Glade Run 

during the 1985 flood DlO 

4. Diagram showing upper limit of slack-water sediments compared with the highwater mark at the mouth of Glade Run D12 

5-9. Aerial photographs showing: 

5. Cheat River flood plain near St. George, W. Va. D13 

6. Parabolic and complex dunes on Black Fork flood plain at Parsons Tree 

Nursery D14 

7. Sand deposits at the Preston County Country Club, south of 

Albright D14 

8. Cobble-boulder splay on the Black Fork flood plain near Hendricks DlS 
9. Cobble-boulder splay on Black Fork flood plain near Parsons Tree 

Nursery D16 

10. Photograph of the largest clast documented to have moved during the 1985 flood 

in Cheat Narrows D18 

11. Aerial photograph showing building that served as nucleus for tree jam, Black 

Fork flood plain near Hendricks D20 

TABLES 

1. Comparison of selected large floods in the Cheat River basin D6 

2. Comparison of discharges reported for historic floods on the Cheat River at 

Rowlesburg D7 

3. Historic floods in the Cheat River basin through 1985 D8 

4. Slope-area discharge calculations based on high-water levels versus those based on 

slack-water deposits D12 

5. Comparison of hydraulic variables predicted from empirical equations with 

calculations based on slope-area determinations of discharge and velocity D19 

Contents Ill 

Depositional Aspects of the November 1985 Flood 

on Cheat River and Black Fork, West Virginia 

By j. Steven Kite and Ron C. Linton 1 

Abstract 

Widespread, intense rainfall in November 1985 produced floods that exceeded all historic events on Cheat 

River and most of its tributaries. Official discharge estimates for Cheat River ranged from 4,800 to 5,380 m3

/s 

(170,000-190,000 fets) with a recurrence interval of >100 

yr. In addition to considerable property damage and the 

loss of five lives, the November 1985 flood left a variety of 

deposits, many of which differ from those produced by 

moderate floods. 

Clay or silt deposits were uncommon after the flood; 

most were restricted to slack-water deposits at the mouths 

of hydraulically dammed or back-flooded tributaries. 

These slack-water deposits were composed of four different sedimentary units: basal gravel and sand (unit A), 

sandy loam (unit B), silt loam (unit C), and upper fine 

sandy loam (unit D). The four units always occurred in the 

same stratigraphic order, but low-gradient tributaries 

lacked the top and bottom units. The silt loam unit was 

deposited by water from Cheat River, but the other three 

were derived from the tributaries. Simple one-unit sandy 

slack-water deposits formed near very large boulders and 

bridges. Neither type of slack-water deposit proved to be 

an accurate indicator of flood stage, so these deposits may 

be imprecise paleohydraulic indicators for central Appalachian streams. 

Sand dunes and arcuate splays of cobbles and small 

boulders developed on flood-plain sites downstream from 

isolated scours or erosional ramps attached to the river 

channel. Gravel deposits commonly were juxtaposed on 

top of sandy preflood alluvium, providing evidence of 

considerable tractive force in what is normally a lowenergy overbank environment. The flood transported 

large volumes of cobbles and boulders from the channel 

margin to sites hundreds of meters from the channel. 

Most of the mobilized sediment originated on the flood 

plain. 

Extremely large boulders (>2.75-m intermediate 

axes) were transported in two of the steeper reaches of 

Cheat River. Published empirical equations relating 

Manuscript approved for publication February 22, 1991. 1 Department of Geology and Geography, West Virginia University, 

Morgantown, WV 26506. 

stream competence to mean flow velocity, tractive force, 

and unit stream power suggest these boulders 

approached the largest size that a flood of this magnitude 

could transport. 

Trees and trash appeared to be the most voluminous 

sediments left by the November 1985 flood. These nonclastic deposits commonly were scattered widely about 

the flood plain, but they also occurred as clusters of 

dunelike forms on unforested surfaces or as thick lobate 

forms on forested bottomlands. 

Postflood mitigation has destroyed most of the 

November 1985 flood deposits, precluding detailed study 

of some effects of the flood. If the extensive mitigation 

had not occurred, some of the morphologic and stratigraphic effects of this extreme flood would have persisted 

in the Cheat River and Black Fork fluvial systems for 

centuries. 

INTRODUCTION 

Learning From Catastrophe 

The November 1985 flood left more than a legacy of 

death and property damage. It created deposits and landforms that revealed much about the geomorphology of 

extremely large floods in the Appalachian region. Many of 

these deposits and landforms differ from those formed by 

more moderate floods. Some are important to the long-term 

development of the flood plain, and others have potential to 

reveal the risk from future catastrophic flooding. 

Extreme floods are serious hazards in mountainous 

landscapes that cannot store storm runoff. Unfortunately, 

gage records in the United States usually are too short to 

determine the likelihood of floods with recurrence intervals 

exceeding 50-200 yr (Thomas, 1987). Sediments and 

landforms on or near flood plains can be used to extend 

flood records far beyond historic gage data. Two promising 

approaches to extending flood records are reconstructi(lfl of 

floodwater levels from slack-water deposits (Kochel and 

Ritter, 1987; Baker and Kochel, 1988; Kochel and Baker, 

1988) and estimation of various indices of flow strength, 

such as flow velocity, based on the size of the clasts that 

Depositional Aspects of the Nov. 1985 Flood, W. Va. 01 
were transported by the flood (Costa, 1983; Williams, 

1984; Komar, 1988). These and other geomorphologic 

methods can be powerful flood-plain management tools, if 

users thoroughly understand their accuracy and limitations. 

The November 1985 flood in the Cheat River basin provides 

a test of how well these methods reconstruct a catastrophic 

flood of known discharge. 

Scope of Research 

This paper is a general survey of a wide variety of 

deposits formed along Cheat River and its largest tributary, 

Black Fork, during the November 1985 flood. Much of this 

paper is based on initial field reconnaissance conducted in 

late 1985 and early 1986, supplemented by interpretation of 

aerial photographs taken before and after the flood. Later 

field work was directed at testing various methods of 

paleohydraulic reconstruction (Linton and Kite, 1987). In 

this pursuit, most of our detailed work has been devoted to 

fine-grained slack-water deposits and to the largest boulders 

transported during the flood. Preliminary findings concerning paleohydraulic aspects are described briefly. Other 

types of deposits were studied only at a reconnaissance 

level. 

Postflood mitigation by man included extensive 

removal or relocation of flood deposits by heavy equipment. The mitigation efforts destroyed or modified most of 

the features studied at reconnaissance level within a few 

months of the flood, including many of the larger and more 

unusual deposits and landforms. Only the study of aerial 

photographs taken right after the flood can sustain research 

on these features. We repeat the warnings of Williams and 

Guy (1973) and Williams and Costa (1988) that many 

geomorphologic aspects of major floods must be studied 

immediately after the event, before mitigation begins. 

Study Area 

Cheat River begins at the confluence of Black Fork 

and Shavers Fork at Parsons, W. Va. (fig. 1; Jacobson, 

chapter A, this volume, pl. 1). The Cheat flows 125 km (78 

mi) northward from Parsons to Point Marion, Pa., where it 

flows into the Monongahela River. Fr~m an altitude of 497 

m (1 ,630 ft) at Parsons, Cheat River descends to 238 m 

(780 ft) at Point Marion, giving an average gradient of 

0.00207. The total drainage area is 3,688 km2 (1,424 mi2 ; 

U.S. Army Corps of Engineers, 1963). 

Black Fork begins at Hendricks, W. Va., at the 

confluence of Dry Fork and Blackwater River. Only 6.5 km 

(4 mi) long, Black Fork descends 21 m (70 ft), giving a 

gradient of 0.00324. Drainage area of Black Fork is 1,295 

km2 (500 mi2

), nearly 70 percent of which is in the Dry 

Fork basin (U.S. Army Corps of Engineers, 1963). Shavers 

Fork has a drainage area of 560 km2 (216 me; U.S. Army 

Corps of Engineers, 1963). Slightly more than half of the 

Cheat River basin lies upstream from Parsons. The only 

large tributary that enters Cheat River downstream from 

Parsons is Big Sandy Creek, which drains 539 km2 (208 

mi2). 

Bedrock Geology and Topography 

The entire drainage basin lies in the rugged eastern 

Appalachian Plateau. The bedrock geology of the basin is 

dominated by clastic sedimentary rocks, ranging from 

Upper Devonian to Upper Pennsylvanian (Cardwell and 

others, 1968). Most formations include thick, resistant 

sandstone lenses. Weak rocks, such as limestone or shale, 

are relatively minor. The bedrock is deformed by gently 

plunging, open folds that produce relatively wide northeastsouthwest trending strike belts. 

Although influence of bedrock lithology and structure 

on topography is less striking in the Cheat River basin than 

in some parts of the central Appalachians, one lithostratigraphic unit, the Lower and Middle Pennsylvanian Pottsville Group, produces distinctive effects on the landscape. 

Sandstones and conglomerates of the Pottsville are the most 

resistant bedrock lithologies in the Cheat basin. The Pottsville Group caps most of the prominent ridges in the basin. 

Pottsville outcroppings support steep valley walls where the 

unit has been incised deeply, especially in the Cheat 

Canyon and Cheat Narrows. Extremely large boulders 

occur in streams wherever the Pottsville crops out in or near 

the channel. The steepest gradients on Cheat River occur in 

two of these bouldery reaches: Cheat Narrows (0.0044) and 

Cheat Canyon (0.0067). 

Upper Devonian Chemung Group and Hampshire 

Formation or Lower Mississippian Pocono (Price) Sandstone form some ridges in the basin (Cardwell and others, 

1968). However, unlike the Pottsville Group, these units 

produce neither steep canyons nor extremely large boulders. 

The Cheat River's headwaters are steep, with many 

small flashy streams, although there are a few subbasins 

with considerable runoff storage (see Jacobson, chapter A, 

this volume, pl. 1). Blackwater River has storage in the 

wetlands of Canaan Valley and adjacent uplands, but 

between Davis and Hendricks (fig. 1) this tributary flows 

through steep, scenic Blackwater Canyon. Shavers Fork 

drains the highest point in the basin (1 ,478 m, or 4,850 ft) 

in Pocahontas County, but Shavers Fork has an elongate 

drainage basin and a relatively wide flood plain; flood crests 

attenuate upstream from the Cheat at Parsons. Dry Fork is 

the flashiest of the Cheat's large tributaries because of its 

dendritic drainage pattern and steep headwater slopes. 

02 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W. Va., Va. 
• MORGANTOWN 

N 

l 

10 KILOMETERS 

PENNSYLVANIA 

PISGAH 

Figure 1. Map showing Cheat River, Black Fork, and selected tributaries. The extent 

of Cheat Narrows and Cheat Canyon is shown by bracketlike symbols. Refer to 

Jacobson, (chapter A, this volume, pl. 1) for topography. 

Depositional Aspects of the Nov. 1985 Flood, W.Va. 03 
Land Use in the Cheat River Basin 

Most of the basin is forested, although cropland and 

pastures are common along the bottomlands and terraces 

adjacent to Cheat River and its larger tributaries. Most 

agricultural land on slopes is pasture. Total farmland in 

Tucker and Preston Counties decreased from 62.4 percent 

in 1900 to less than 24.8 percent in 1987; total cropland 

decreased from 31.3 percent to 9.9 percent (U.S. Bureau of 

the Census, 1913; 1989a, b). 

Coal strip mining is important in areas underlain by 

Pennsylvanian rocks, particularly the northwestern third of 

the basin. The rest of the basin has no useful coal resource 

and no coal mines (West Virginia Geological and Economic 

Survey, no date). 

Nearly the entire basin was clear-cut for timber 

between 1850 and 1930 (Fansler, 1962; Preston County 

Historical Society, 1979). Poor logging practices led to fires 

that burned surface organic horizons in soils over much of 

the basin (Fansler, 1962; Venable, 1990). Loss of forest 

cover and organic horizons has been shown to decrease 

runoff storage and contribute to accelerated runoff (Dunne 

and Leopold, 1978). Forest cover has increased over most 

of the Cheat River basin since 1920 (Fansler, 1962; North, 

1985), although surface organic horizons have not recovered completely from the disturbance caused by logging and 

burning (Venable, 1990). Land use probably contributes to 

less rapid runoff today than it did at the tum of the century, 

but there may be somewhat less runoff storage today than 

prior to 1850. 

A few communities occur on flood plains in the Cheat 

River basin, including Hendricks, Hambleton, Parsons, and 

St. George in Tucker County and Rowlesburg and Albright 

in Preston County (pl. 1). All of these communities have 

experienced repeated historic flooding, and all were badly 

damaged by the flood of November 1985. Point Marion, in 

Fayette County, Pa., is prone to flooding from both the 

Cheat and Monongahela Rivers. 

Acknowledgments 

This work was supported by the West Virginia Water 

Research Institute, the Southeastern Section of the Geological Society of America, and Sigma Xi, the Scientific 

Research Society. This research has benefited from discussions with R. Jacobson, A. Miller, D. Parkinson, J. Harper, 

and R. Behling and from reviews of an earlier draft by J. 

Grimm and J. Schmidt. Commissioner W. Ritchie and M. 

Christianson facilitated procurement of aerial photographs 

from the West Virginia Department of Highways. 

THE FLOOD OF NOVEMBER 1985 

Meteorology and Hydrology 

The meteorologic events that produced the flood of 

November 1985 are described elsewhere (Clark and others, 

1987; Colucci and others, chapter B, this volume) and are 

not repeated here. Most of the Cheat River basin received 

between 125 and 17 5 mm of precipitation in October 1985 

(Colucci and others, chapter B, this volume, fig. 6), 

somewhat above the monthly means of 83 mm at Parsons 

and 110 mm at Rowlesburg (U.S. Army Corps of Engineers, 1963). High flows produced by October rains subsided by November 1, when flows at Parsons (14.5 m3

/s, or 

513 fets) and Rowlesburg (21 m3/s, or 743 fe/s) were only 

one-third of the daily average discharges and more than 3 m 

below flood stages at both gage stations (USGS-WRD, 

unpublished gage data; Embree and others, 1985). Rainfall 

was recorded on the first three days of November, but flow 

of the Cheat River increased only gradually until the 

afternoon of November 4. 

The primary flood-producing event occurred during 

the 48-h period ending on the morning of November 5. The 

headwaters of Dry Fork and Blackwater River were under 

the western end of a heart-shaped cell of precipitation that 

exceeded 150 mm (Jacobson, chapter A, this volume, pl. 1; 

Colucci and others, chapter B, this volume, fig. 6). Canaan 

Valley received 238 mm during the 48-h period ending on 

the morning of November 5 (GAl Consultants, 1985). On 

November 4, flood stage was reached at Parsons at 5:40 

p.m., following a 1.5-m rise in 100 min, and flood stage 

was reached at Rowlesburg between 8 and 9 p.m. during a 

1-m rise in 60 min (USGS-WRD, unpublished gage data). 

Flow at Parsons crested 3. 3 m above flood stage 

between 3 and 5 a.m. on November 5 (GAl Consultants, 

1985; Charleston Gazette, 1985; Teats and Young, 1985). 

The flood crest moved downstream at an average velocity of 

15-20 km/h, reaching Rowlesburg around 6-7 a.m., 

Albright at 9:30 a.m., and Lake Lynn about 11 a.m. that 

same day (GAl Consultants, 1985; Charleston Gazette, 

1985; Plum, 1985; Teats and Young, 1985). Peak runoff 

was 2.59 m3

/slkm2 (237 fets/mi2

) on the Cheat at Parsons 

and 2.14 m3/slkm2 (195 fe/s/mi2

) at Rowlesburg. 

Damage and Fatalities 

Receding waters in the next few days revealed the 

worst damage in the written history of the Cheat River. 

Discharge far exceeded previous historic floods except for 

tributaries in the northern end of the basin. Five people 

drowned in the Cheat River basin (R.E. O'Dell, West 

Virginia State Police, telephone communication, 1988). All 

communities adjacent to the Cheat River and most of its 

major tributaries were severely damaged, particularly those 

located inside meander bends, such as Albright (fig. 2), 

04 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W.Va., Va. 
Figure 2. Aerial photograph of destruction at Albright, W. Va., taken a few days 

after the November 1985 flood. Note numerous foundations where buildings 

were washed away. Cheat River flow is from right to left (northward) (West 

Virginia Department of Highways photograph). 

Rowlesburg, and Parsons. Half or more of the buildings in 

each community were destroyed or damaged. Property 

damage in the basin may have exceeded $100 million. 

Initial estimates of damages were more than $30 million in 

Preston County and more than $66 million in Tucker 

County (Region III Interagency Flood Hazard Mitigation 

Team, 1985). A total of 479 private homes were destroyed 

and another 162 condemned because of flood damage in 

these two counties, which are mostly within the Cheat 

drainage basin (Teats and Young, 1985). These estimates 

do not include considerable destruction from Cheat River 

tributaries in Randolph County, W.Va., or damage near the 

mouth of the Cheat in Fayette County, Pa. Runoff from the 

Cheat River basin contributed to flooding by the Mononga-

. hela River, which caused damage to 2,784 homes and 

created losses in excess of $11 million to commercial and 

industrial establishments downstream from Point Marion 

(Murphy, 1986). 

The fundamental cause of the unique severity of the 

1985 floods in the Cheat River basin is the extraordinary 

amount of rain that fell over most of the drainage basin in a 

short amount of time. Much of the rainfall was delivered 

rapidly to streams because antecedent rainfall and minimal 

plant transpiration produced partially saturated soils. The 

estimated average rainfall for the week ending November 5, 

1985, was 164 mm (6.45 in) for the Cheat River basin 

upstream from Parsons and 152 mm (6.00 in) for the basin 

upstream from Rowlesburg (R. Jacobson and J. McGeehin, 

unpublished data). Total runoff from the Cheat River basin 

was approximately 125 mm (4.93 in) at the outlet to Lake 

Lynn (GAl Consultants, 1985). 

Historic Floods and the Recurrence Interval of 

the 1985 Flood 

Discharge during the November 1985 flood was 

unprecedented for most of the Cheat River basin (tables 1 

and 2). Five of six active U.S. Geological Survey (USGS) 

gaging stations in the basin experienced record floods, 

exceeding previous maximum discharges by 72-231 percent. Only the gage on Big Sandy Creek recorded an event 

that was relatively minor in comparison with previous 

floods. These are no USGS gages on Cheat River downstream from Big Sandy Creek, but estimates of the flow into 

Lake Lynn (GAl Consultants, 1985) indicate that discharge 

decreased downstream from Rowlesburg (table 1). The 

flood attenuated because of runoff storage on the flood plain 

and because downstream tributaries were outside the area of 

maximum precipitation and had crested well before the peak 

flood on Cheat River reached their confluence. The 1985 

flood had approximately 25 percent greater discharge than 

the greatest previously recorded floods near the mouth of 

the Cheat (table 1). 

The oldest gage record in the Cheat River basin has 

been maintained at Rowlesburg since 1884 (Embree and 

others, 1985). The Rowlesburg record (table 2) includes 

historic accounts of two substantial mid-19th century floods 

that were not recorded at other stations. The flood of July 6, 

Depositional Aspects of the Nov. 1985 Flood, W. Va. 05 
Table 1. Comparison of selected large floods in the Cheat River basin 

[Unit of measure is cubic meters per second. Equivalent values in cubic feet per second are given in parentheses. Rowlesburg data are based on most recent 

rating curve (see discussion in table 2). The 1844 and 1888 floods predate USGS discharge gage stations; discharges were estimated from historical 

accounts or National Weather Service gage data. Sources: Speer and Gamble (1965), U.S. Geological Survey (1976), Embree and others (1985), Lescinsky 

(1986), Robert Eli, Department of Civil Engineering, West Virginia University (personal commun., 1988), R.S . Runner, U.S. Geological Survey, 

Charleston, W. Va. (personal commun., 1988). "?" denotes no record known] 

Stream 

Measure Blackwater Big Sandy Dry Fork Shavers Fork River Cheat River Cheat River Creek Cheat River 

Locality Hendricks Parsons Davis Parsons Rowlesburg Rockville Three stations 

Area, ha 89,400 55,400 22,300 186,000 252,000 1,800 (see notes below) 

(345 mi2

) (214 mi2

) (86.2 mi2) (718 mi2

) (972 mi2

) (200 mi2

) ca. 357,000 

(ca. 1,380 mi2

) 

Gage record 1940-present 1910-1926, 1921-present 1913-present 1923-present 1909-1918, 

1940-present 1921-present 

Date of flood 

July 6, 1884 ? ? ? ? 2,520 ? ? 

(89,000) 

July 10, 1888 ? 708 ? 1,450 2,380 850 1

4,530 

(25 ,000) (51 ,300) (84,000) (30,000) (160,000) 

October 16, 1954 1,330 453 193 1,475 1,880 447 2

4,160 

(47 ,000) (16,000) (6,800) (52, 100) (66,300) (15,800) 147 ,000) 

November 5, 1985 2,830 1,230 354 4,810 5,380 202 3

5,660 

(100,000) (43,500) (12,500) (170,000) (190,000) (7' 140) (200,000) 

1 Near Morgantown, drainage area is 357,000 ha (1 ,380 mi2

) ; gaged in 1903-1905 , 1909-1917, and 1923-1926; station inundated by Lake Lynn 

in 1926. 2 Near Pisgah, drainage area is 351 ,000 ha (1 ,354 m?); gaged in 1927-1958; upstream from Lake Lynn. 3 Estimated flow into Lake Lynn (Cheat Lake), from calculations by R. Eli, who calculated discharge at Lake Lynn spillway was 4,960 m3

/s 

(175,000 fe/s) , somewhat more than the GAl Consultants (1985) preliminary estimate of 4,250 m3/s (150,000 fe/s) . Drainage area at the spillway is 

366,000 ha (1,413 mi 2

) . 

1844, was the greatest recorded at Rowlesburg prior to 

1985. Four of the seven largest floods at Rowlesburg 

occurred between 1888 and 1907, roughly coincident with 

peak logging activity in the basin. The October 1954 flood 

on the Cheat came in the aftermath of Hurricane Hazel. 

However, if the northern end of the Cheat River basin is 

excluded, none of the earlier gaged floods exceeded 60 

percent of the 1985 flood discharge. Log Pearson type III 

analysis of the flood frequencies for the Dry Fork, Blackwater River, Shavers Fork, and two stations on Cheat River 

estimated recurrence intervals of > 100 yr (Lescinsky, 

1986; Carpenter, 1990) to >500 yr for the 1985 flood (E.A. 

Friel, unpublished data). The flood at the two gages on 

Cheat River was particularly impressive, being 2.1-2.3 

times the calculated 100-yr flood at Rowlesburg and 

2.3-3.0 times the calculated 100-yr flood at Parsons (based 

on data from U.S. Army Corps of Engineers, 1963; U.S . 

Geological Survey, 1985; R. S. Runner, personal communication, 1988). 

Historic accounts, summarized in table 3, have been 

of limited use in estimating the recurrence interval of the 

1985 flood. The bottomlands along the Cheat have been 

settled continuously since 1773 (Wiley and Frederick, 

1882), but no floods were recorded before 1834 (Maxwell, 

1884; Fansler, 1962). In fact, the earliest history written 

about Preston County (Wiley and Frederick, 1882) makes 

no specific mention of floods, despite at least nine references to bridge construction and discussion of one bridge that 

was destroyed by wind and another by an act of war. 

Fansler (1962) discussed floods in length in his history of 

Tucker County. He described the July 1888 flood as the 

worst in the history of Cheat River, but this assessment may 

reflect flood damage, not stream discharge. The 1844 flood, 

the greatest known at Rowlesburg prior to 1985, is not 

discussed by Fansler (1962) or any other published history 

of Preston or Tucker Counties. Communities on the flood 

plains remained quite small until after 1850 (Wiley and 

Frederick, 1882; Fansler, 1962), so the lack of an early 

flood record may reflect sparse settlement, rather than a 

lack of flooding. The historic accounts indicate that the 

1985 event exceeded any recorded on Cheat River, a 

conclusion consistent with recurrence-interval estimates of 

> 100 yr. 

DEPOSITS FORMED DURING THE NOVEMBER 

1985 FLOOD 

General 

The 1985 flood deposited a complex array of sediments. Clay and silt were not abundant on the flood plain 

and generally were deposited only in silt loam and sandy 

loam units in slack-water settings. Sand was deposited in 

many different facies, including slack-water environments, 

06 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W. Va., Va. 
Table 2. Comparison of discharges reported for historic 

floods on the Cheat River at Rowlesburg 

[Discharge measured downstream from Saltlick Creek, except as noted. 

Unit of measure is cubic meters per second; equivalent values in cubic feet 

per second are given in parentheses] 

U.S. Army 

Date of flood Corps of 

Engineers 

(1963)1 

Nov. 5, 19853 

July 6, 1844 3,310 

(117 ,000) 

July 10, 1888 2,970 

(105,000) 

April 18, 1852 2,605 

(92,000) 

July 22, 1896 2,270 

(80,000) 

Feb. 22, 1897 2,210 

(78,000) 

July 17, 1907 2,100 

(74,000) 

Oct. 16, 1954 2,010 

(71 ,000) 

Wells 

(1957); 

Paulson 

(1953)2 

3,540 

(125,000) 

3,340 

(118,000) 

U.S. Geological 

Survey (1971, 1976); 

Hendricks (1964); 

Embree and 

others (1985); 

Lescinsky (1986) 

5,380 

(190,000) 

2,520 

(89,000) 

2,380 

(84,000) 

1,880 

(66,300) 

1 Data for the proposed Rowlesburg Dam site, upstream from 

Saltlick Creek. Data appear to be derived from an obsolete rating curve, 

with a reduction for discharge from Saltlick Creek. (This reduction may be 

inappropriate; in the 1985 flood, lower Saltlick Creek was hydraulically 

dammed and did not contribute to peak flow on Cheat River.) 2 Data are based on obsolete rating curve. 3 Discharge for 1985 flood reflects revisions of preliminary data 

published by Lescinsky (1986). 

thin veneers in low-to-moderate energy overbank environments, and dunes in high-energy overbank environments. 

Gravel was deposited at the base of slack-water sequences, 

in high-energy overbank environments, and near all stream 

channels. Extremely large boulders were transported and 

deposited along the steepest reaches of Cheat River. 

Organic and manmade sediments appeared to be more 

voluminous than clastic sediments. Accumulations of large 

trees and branches were widespread in high-energy environments, whereas smaller organic sediments were deposited in low-energy environments, including the high-water 

limit. Manmade materials were the dominant sediments in 

and immediately downstream from towns. 

Methods Used to Study 1985 Flood Deposits 

Deposits in the study area were examined between 

November 1985 and December 1987. Most field work was 

conducted along Cheat River between Parsons and 

Albright. Field work was supplemented by examination of 

1 :3000-scale aerial photographs that were taken by the West 

Virginia Department of Highways a few days after the 

November 1985 flood. The 1:3000-scale photography covers all of the Black Fork flood plain and most of the Cheat 

River flood plain between Parsons and Albright. Length and 

width dimensions for most deposits were determined from 

the aerial photographs, but slack-water deposits were measured in the field. 

Particle-size distributions for fine gravel, sand, silt, 

and clay were determined in the Quaternary Geology 

Laboratory at West Virginia University. Standard drysieving was used for sand or fine gravel; pipette analysis 

was used for silt and clay (Bell, 1986; Linton, 1992). 

Long, short, and intermediate axes of at least ten 

boulders were measured at each site where boulder deposition was studied, although only the five largest intermediate 

axes were used in paleohydraulic equations (Costa, 1983). 

Aerial photographs of various scales were used to identify 

boulders to be examined in the field or to confirm movement of clasts that was suggested by field criteria. Aerial 

photographs were not used for particle-size determinations, 

although some of the transported boulders could be measured from the photographs with error of less than 10 

percent. 

In general, paleohydraulic and hydraulic reconstruction followed the methods of Costa (1983). Detailed discussion of methods used in the study of slack-water deposits, and of methods used to determine discharge, mean flow 

velocity, tractive force, and unit stream power, are given by 

Linton (1992). 

Physical Characteristics of Slack-Water Deposits 

Distinct slack-water deposits formed in two different 

settings during the 1985 flood, namely, near large obstructions on the flood plain and at sheltered mouths of tributaries to Cheat River. Slack-water deposits were poorly 

developed at flood-plain expansions and contractions, and 

the few slack-water deposits in these sites commonly were 

disturbed by mitigation efforts soon after the flood. Slackwater deposits less than 2 em thick were not studied in detail 

because these thin deposits have little chance of long-term 

preservation as a recognizable stratigraphic unit and are 

unlikely to be of use in paleohydraulic reconstructions of 

prehistoric floods. Bioturbation and surface runoff in the 

first 2 yr after the flood have supported this interpretation. 

Slack-water deposits near flood-plain obstructions 

such as bridges or large boulders are relatively simple lenses 

or pockets of laminated sand, up to 25 em thick and 

interbedded with thin layers of transported coal, fly ash, or 

leaf detritus. Except where sheltered from precipitation and 

surface runoff, the sand was eroded and severely gullied 

soon after the flood peak. 

Slack-water deposits were not equally developed at 

all tributary mouths. The most important prerequisite for 

development of slack-water deposits was that the tributary 

mouths be sheltered from direct flow of Cheat River 

Depositional Aspects of the Nov. 1985 Flood, W.Va. 07 
Table 3. Historic floods in the Cheat River basin through 1985 

[Except as noted, discharge values for Cheat River at Rowlesburg are from U.S. Army Corps of Engineers (1963), which is based on an older rating curve, 

briefly discussed in footnote 1 to table 2] 

Date 

1773 

1834 

July 6, 1844 

1851 or 1852 

April 18, 1852 

July 1855 

1857 

July 10, 1888 

July 21, 1896 

Feb. 22-23, 1897 

July 17, 1907 

July 24-25, 1912 

March 29, 1924 

Oct. 15-16, 1954 

Aug. 17, 1955 

March 20, 1982 

Reference Comment 

Wiley and Frederick (1882); First permanent settlement on Cheat River (Preston County). 

Fansler (1962) 

Maxwell (1884); 

Auvil ( 1977) 

Embree and others, (1985); 

U.S. Army Corps of 

Engineers (1963) 

Morton (1914); Wiley 

and Frederick 

(1882) 

U.S. Army Corps of 

Engineers (1963) 

Preston County Journal 

(1888a) 

Fansler (1962) 

Embree and others 

(1985); 

Fansler (1962); 

Preston County 

Historical Society 

(1979); 

U.S. Army Corps of 

Engineers (1963); 

Preston County 

Journal (1888a,b) 

Fansler (1962); 

U.S. Army Corps of 

Engineers (1963) 

Fansler (1962); 

U.S. Army Corps of 

Engineers (1963) 

Embree and others (1985); 

U.S. Army Corps of 

Engineers (1963); 

Preston County Journal 

(1907) 

U.S. Army Corps of 

Engineers (1963); 

Fansler (1962) 

Lescinsky (1986); 

U.S. Army Corps of 

Engineers (1963) 

Fansler (1962); 

U.S. Army Corps of 

Engineers (1963); 

Preston County Historical 

Society (1979) 

Fansler (1962) 

Embree and others 

(1985) 

Timbers to be used for covered bridge at the Northwest Turnpike were washed away 

by a flood before construction. Discharge unknown, but flood may have been 

minor. Oldest flood recorded on Cheat. Completed bridge withstood all floods until 

it burned in 1964. 

Cited as highest flood known at Rowlesburg before the November 1985 flood. See 

table 2. Not recorded at other stations. Not discussed in other historical references 

given here, including several written in 1880s. 

B&O Railroad bridge constructed at Rowlesburg. Later upgraded for heavier traffic, 

but never destroyed until1985 flood. Prior to onset of work on B&O, there was only 

one house in Rowlesburg. 

Fourth largest peak discharge recorded at Rowlesburg: 2,605 m3

/s (92,000 fe/s). Not 

discussed in other historical references cited here. 

Worst flood known at Albright before 1888. Stage 0.6 m lower than 1888. 

Destroyed a mill in Parsons built after 1844; rebuilt mill survived until after 1920. 

Only three families lived in Parsons, all on higher ground. 

Worst flood damage on Cheat and Black Fork (Fansler, 1962) prior to 1985. 

Discharge on Cheat at Parsons was greater in 1954 (Embree and others, 1985), but 

apparently damage was greater in 1888. Black Fork and Dry Fork flooded at same 

time. Large slope failures (debris flows?) on Backbone Mtn. near Hendricks. 

Erosion of new WVC&P railroad grade between Parsons and Hendricks. The 1844 

flood was higher at Rowlesburg, but a mill that survived 1844 flood was destroyed 

on Black Fork. Third greatest flood at Rowlesburg since 1844 (table 2), $150,000 

damage; B&O bridge badly damaged, but water was 1 m below floor of bridge; 

scour up to 2 m deep, sand deposition up to 1 m thick at Rowlesburg. Albright 

streets navigable only by boat. Flood of record on Big Sandy Creek (850 m3

/s). 

Discharge on Cheat downstream from Big Sandy Creek, 4,530 m3

/s, nearly that of 

1985. Many buildings and much livestock lost throughout basin. 

Fifth greatest flood on Cheat at Rowlesburg since 1844: 2,270 m3

/s (80,000 ft3/s). 

Shavers Fork flooded business district of Parsons. 

Snowmelt event; washed out railroads on Dry Fork and Black Fork. Lumber mill and 

other logging structures severely damaged on Black Fork. Most flow came from Dry 

Fork. Rebel Run in Hendricks was roaring cataract. Sixth greatest flood on Cheat at 

Rowlesburg since 1844: 2,210 m3

/s (78,000 fe/s). 

Equaled 1888 flood on Shavers Fork (second greatest on record: 708 m3/s (25,000 

fe/s)). Seventh greatest recorded flood on Cheat at Rowlesburg: 2,100 m3

/s (74,000 

fe/s). Shavers Fork flooded Parsons business district. 

Twelfth worst recorded flood on Cheat at Rowlesburg: 1,620 m3

/s (57,200 fe/s). One 

of 12 worst floods on Black Fork from 1888 to 1962 (Fansler, 1962). Highest flow 

since 1888 on Big Sandy Creek at Rockville: 603 m3

/s (21,300 ft3/s). 

Highest gaged flood on Blackwater River at Davis between 1921 and 1985. Relatively 

minor flood on Cheat at Rowlesburg: 1,170 m3

/s (41,300 fe/s). 

Hurricane Hazel. Worst gaged flood prior to 1985 at many stations. USGS discharge 

estimate greater on Cheat at Parsons than during 1888 flood, but Fansler stated 1888 

flood was worse on Black Fork. Eighth worst flood since 1844 on Cheat at 

Rowlesburg (table 2). Black Fork and Shavers Fork flooded at same time. Damage 

to streets, tannery ($100,000) and railroad ($60,000) in Hendricks. Cheat well 

below 1985 level at St. George. Basements flooded in Hendricks and Albright for 

first time since 1888. 

Hurricane Diane. Dry Fork and its tributaries hit hard. One of 12 worst floods on 

Black Fork from 1888 to 1962 (Fansler, 1962). Not listed in Corps of Engineers 

(1963) table of floods. 

Discharge of 476 m3

/s (16,800 fe/s) on Shavers Fork at Parsons slightly exceeded 

pre-1985 flood of record ( 1954). Little flow on Dry Fork and no significant flood on 

Cheat River. 

08 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W. Va., Va. 
Table 3. Historic floods in the Cheat River basin through 1985-Continued 

Date Reference Comment 

Nov. 5, 1985 Lescinsky (1986); 

Region III 

Interagency Flood 

Hazard Mitigation 

Team (1985); 

Carpenter (1990) 

Greatest recorded floor on Cheat River at Parsons and Rowlesburg, on Dry Fork at 

Hendricks, on Blackwater River at Davis, and on Shavers Fork at Parsons. 

Apparently worse than 1888 flood at Albright, but there are no published gage 

records. Floods of 1888 and 1954 may have approached the same discharge near 

mouth of the Cheat (table 2). Unlike 1888 and 1954 floods, Big Sandy Creek 

contributed little to this flood. Much destruction in all towns along Cheat. Point 

Marion flooded by Monongahela and Cheat Rivers. Damage in Cheat basin may 

have exceeded $100 million. Five deaths in basin. 

floodwaters. Wherever adjacent terraces or valley walls 

were high enough to block overbank currents of the Cheat 

River, hydraulic damming by the swollen river backflooded the lower reaches of these tributaries. Deposits with 

various morphologies and a wide range of particle sizes 

formed in the back-flooded areas. 

The slack-water deposits at tributary mouths ranged 

from thin mantles conformable to preexisting surfaces on 

low-gradient tributaries, to relatively flat-topped surfaces 

resembling Gilbert-type deltas (Elliot, 1986) at the mouths 

of steep tributaries. Deposits in the deltalike landforms lack 

sedimentary structures typically associated with Gilberttype deltas, specifically fine-grained bottomset beds and 

steeply dipping foreset beds. Tributaries incised new channels during the falling stage of the November 1985 flood or 

very soon after flood recession. Most slack-water deposits 

are exposed along the banks of these 0.4- to 1.2-m-deep 

channels. 

The sedimentology of slack-water deposits at sheltered tributary mouths is complicated (fig. 3). Each depositional package contains up to four distinct sedimentary 

units (Linton and Kite, 1987). The units always occur in the 

same stratigraphic sequence, but low-gradient tributaries 

typically lack the first and fourth units. Gravel and sand 

make up the lowest unit (unit A), which underlies a sandy 

loam (unit B) and a silt loam (unit C). The uppermost unit 

is fine sandy loam (unit D), which was severely eroded soon 

after the November 1985 flood. 

The basal gravel and sand unit A occurs at the mouths 

of tributaries with relatively steep gradients, in excess of 

0.050. In general, thickness and particle size in unit A are 

proportional to tributary gradients. The unit is up to 1.0 m 

thick at the mouth of the steepest (2::0.127) tributaries; 

cobbles are the largest clasts. Commonly, unit A is clastsupported, but a few exposures reveal matrix support. The 

upper 5-10 em is finer grained than the rest of the unit. The 

unit occurs only within, or adjacent to, the tributary 

channels and has imbrication showing down-tributary flow. 

Upstream from the slack-water sites, reconnaissance study 

of tributaries with steep gradients indicated that gravel beds 

of these streams were mobilized during the 1985 flood. Unit 

A represents tractive-load deposition in, or adjacent to, the 

preflood tributary channel near its confluence with Cheat 

River during the early rising stages of the flood. 

Light olive-brown (7 .5Y 5/4) sandy loam dominates 

unit B in the slack-water strata. Portions of this unit range 

in texture to loamy sand. The sandy loam unit attains 20 em 

in thickness and forms nearly continuous mantles over 

either unit A or over pre-1985 flood-plain surfaces. The unit 

has fine laminations and abundant organic matter. A gradational contact occurs where unit B caps unit A. The unit 

is thickest near the tributary channel and thinnest near the 

tributary valley walls. It appears to have been derived from 

the tributary, probably when high waters on the Cheat River 

began to impede tributary flow. 

Unit C is mostly silt loam, although loam is locally 

important. Organic matter, typically leaves or twigs, is 

abundant in unit C. Color varies from dark brown (lOY 3/3) 

to black (5Y 2.5/2). The unit generally shows a sharp 

contact with underlying sandy loam of unit B. Unit C was 

the uppermost sediment on many slack-water surfaces, and 

it commonly displayed desiccation cracks when examined 

after the flood. It is thickest (up to 25 em) near Cheat River 

and forms a mantle over slack-water sites that is more 

extensive than any other unit in the slack-water sediment 

package. 

Unit Cis typically massive to weakly laminated, but 

one locality showed cross-bedding that was dipping 

up-tributary. It is the only unit in the slack-water package 

that was derived largely from waters of Cheat River. Unit C 

thins abruptly at the mouth of one large tributary, Clover 

Run, where thickness decreases from more than 10 em to 

zero within a few meters. This abrupt thinning occurs about 

110 m from Cheat River and has little relationship to 

flood-plain topography. 

The uppermost slack-water unit (unit D) is olivebrown (7.5Y 4/4) fine sandy loam that occurs near the 

channels of steep tributaries. Unit D is easily eroded and 

forms a discontinuous mantle, best developed where the 

surface is sheltered from direct precipitation and surface 

runoff. Maximum thicknesses of 5 em occur near tributary 

channels. Most of this unit was eroded away before the 

Depositional Aspects of the Nov. 1985 Flood, W.Va. 09 
9 

Q 

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meters 

Maximum extent of 

slack-water deposits 

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adjacent to flood plain 

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Pre-1985 

Alluvium 

Glade Run Channel 

Inferred Contact 

Inferred Contact 

0 5 

meters 

10 

Vertical Exaggeration • 20X 

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fine sandy loam 

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silt loam 

Unit B: 

sandy loam 

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Vertical Exaggeration • 20X 

Unit D: fine sandy loam 

Unit C: silt loam 

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Unit A: gravel and sand ~~j~ 

Figure 3. Map and cross section of slack-water deposit formed at the mouth of Glade Run during the 1985 flood. 
summer of 1986. Much of the eroded sediment was either 

deposited within mud cracks in the underlying silt loam or 

washed into nearby topographic lows. Current indicators 

have not been identified, but its geometry indicates that unit 

D was derived from the tributary, probably after peak flow 

on Cheat River. 

Locally, unit D is capped with scattered pebbles, 

granules, or wood fragments. The pebbles and granules are 

always adjacent to the tributary channel, but are too few and 

too scattered to be considered a separate unit. These 

coarse-grained clasts may have been eroded from unit A 

when the slack-water deposit was incised, either during the 

waning stages of the November 1985 flood or soon after. 

Discontinuous, thin ( <2 em) sand lenses, covering 

up to 2 m2

, exist in some tributaries that experienced 

slack-water sedimentation. These sand lenses are not 

attached to the main slack-water sedimentary package and 

may occur well up the tributaries, many meters above 1985 

flood levels on Cheat River. Although some of the sand 

lenses may be related to back-flooding of the tributary 

mouth, these minor deposits cannot be considered useful for 

the purpose of paleohydraulic reconstructions. Even if they 

could be assigned to true slack-water sedimentation, they 

are too thin to have much potential for long-term preservation as a distinct unit. 

The lower three units in the slack-water sediment 

present a sequence of gradually finer deposits, from bottom 

to top, reflecting a decrease in flow velocity at the tributary 

mouth as Cheat River rose to its flood peak. Cross beds and 

deposit geometry show that the lower two units were 

derived from tributary flow, but unit C was deposited from 

turbid Cheat River water ponded in the mouth of the 

tributary. Unit D and associated gravels were deposited 

during the resumption of flow by the tributary, as the 

slack-water conditions abated. 

Cheat River slack-water sediments exhibit some 

attributes in common with sediments formed in similar 

settings during extreme floods in other basins. Moss and 

Kochel (1978) described two units in slack-water sediments 

formed at mouths of tributaries to the Susquehanna River 

during Hurricane Agnes in 1972. Their basal unit consisted 

of coarse silt, sand, and gravel derived from the tributaries, 

comparable to units A and Bin the Cheat River basin. The 

upper unit was made up of fine sand, silt, and clay 

deposited by water from the Susquehanna River, comparable to unit C along Cheat River. Moss and Kochel (1978) 

did not describe sediments comparable to the fine sandy 

loam of unit D and associated gravel. Baker (1973) and 

Baker and Bunker (1985) have suggested that slack-water 

rhythmites may be formed by multiple flow surges during 

one flood. There is little repetition of beds in slack-water 

deposits at tributary mouths along the Cheat, but surge 

phenomena may have caused the stratification in deposits 

associated with flood-plain obstructions. 

Slack-Water Deposits as Indicators of Flood 

Stage 

Slack-water deposits have been used in many different environments as indicators of flood stage (Patton and 

others, 1979; Baker and others, 1985; Baker and Kochel, 

1988; Kochel and Baker, 1988). Many of these stage 

reconstructions have successfully extended flood records, 

but the accuracy and precision of slack-water deposits as 

stage indicators remains poorly known for the temperate 

humid climate of the Eastern United States. Slack-water 

deposits created on Cheat River in 1985 provide an excellent opportunity to evaluate the utility of these methods in 

the central Appalachians. If the highest slack-water deposits 

on the 1985 flood correspond with maximum flood stage, 

then an incentive exists to use prehistoric slack-water 

deposits to study recurrence intervals of extreme floods for 

rivers in the region. 

We conclude that slack-water deposits in the study 

area are not good indicators of 1985 flood levels compared 

to high-water marks, such as rounded wood debris and other 

flotsam deposited on the ground or in large trees (Linton, 

1992). This conclusion is reached in spite of the many hours 

spent searching for deposits that would correspond well 

with high-water marks up the back-flooded tributaries. 

Particular emphasis was put on the elevation of the maximum stage. The upper limit of significant (2:2 em thick) 

slack-water deposits ranged from 2.9 to 5.6 m below 

high-water marks at sites of detailed study (fig. 4). The 

mean difference between slack-water deposits and highwater marks was 3. 8 m, a significant fraction of the 6- to 

11-m mean water depths at these localities during the 1985 

flood. Accordingly, slope-area method reconstructions of 

the flood based on the levels of slack-water deposits 

underestimated discharge by 51-67 percent (table 4). 

The conspicuous differences between high-water 

marks and the upper limit of slack-water deposits are 

difficult to explain. Individually or collectively, three factors may contribute to the lack of slack-water sediments at 

higher levels: 

1. The tributaries were contributing water to the flood, so 

perfect slack-water conditions probably did not develop. 

Nonflooding tributaries are a prerequisite for a good 

match between high-water levels and the limit of slackwater deposition (Kochel and Baker, 1988). 

2. Tributary inflow may not have mixed readily with Cheat 

River water; waters from the two different sources may 

have interacted as two distinct, partly stratified water 

masses, separated by a pycnocline. Most of the tributaries in the study area experienced less severe flooding 

than those farther upstream and reached peak flow 

earlier than the Cheat River. These factors suggest that 

the sediment load on the tributaries was less than that of 

the main stream during maximum flood flows on the 

Cheat. This contrast in sediment load would have 

Depositional Aspects of the Nov. 1985 Flood, W. Va. 011 
A A' 

Extent of slack-water deposit 

Maximum flood-water depth a: 

w 

12 > 

a: 

.... :~: cO 

wt-

:z::lSlack-water deposit 8 oO m 

/ w..J 

>w Oz 

mz 

4 c(c( 

(1)% 

a::O 

w 

1-

w 

:I 

80 40 0 

METERS FROM CHEAT RIVER 

0 10 20 meters 

VE = 2.5x 

Figure 4. Diagram showing upper limit of slack-water sediments compared with the high-water mark at the mouth of 

Glade Run. Profile follows line A-A' on figure 3. 

Table 4. Slope-area discharge calculations based on high-water levels versus those 

based on slack-water deposits 

[Locations, methods, and discharge estimates at additional localities are given by Linton (1991). Slope-area 

discharge values based on high-water indicators are greater than published discharge estimates for the Cheat 

River (table 1)] 

Locality and profile criteria Stream Manning's Mean depth Mean velocity Discharge 

(m3 gradient n /s) 

Glade Run I 

High-water marks 0.00117 0.025 

Slack-water deposits .00117 .025 

Glade Run II 

High-water marks .00117 .025 

Slack-water deposits .00117 .025 

Cheat Narrows I 

High-water marks .00441 .050 

Slack-water deposits .00441 .050 

Cheat Narrows II .00441 .050 

High-water marks 

Slack-water deposits .00441 .050 

produced a relatively clear, low-density water mass from 

the tributary, overlapping a sediment-laden high-density 

water mass from Cheat River. The abrupt thinning of 

unit C at Clover Run supports the existence of distinct 

water masses. The zone in which the unit thins does not 

coincide with any change in flood-plain topography, 

suggesting that a sediment-laden water mass was unable 

to migrate up the tributary flood plain beyond this zone. 

Relatively clear tributary inflow would have ponded 

(m) (m) 

4.78 3.89 6,027 

3.72 3.29 2,084 

5.34 4.19 6,540 

3.17 2.96 2,189 

8.79 5.67 5,392 

6.38 4.58 2,611 

9.66 6.04 6,281 

6.26 5.03 2,857 

upstream of the turbid Cheat River water, but left little 

evidence of high-water levels except for flotsam strewn 

over the Clover Run flood plain and thin, discontinuous 

sandy deposits farther upstream. 

3. Maximum water discharge may have occurred before or 

after the maximum sediment load had been transported. 

If either of these conditions occurred, then slack-water 

deposits may accurately mark high water at the time of 

deposition, but not at peak flood stage. 

012 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W. Va., Va. 
Figure 5. Aerial photograph of Cheat River flood plain near St. George, W. Va. 

Note evidence of bank retreat (bottom), incision of long narrow grooves (right 

and center), and deep scour around a standing tree (left). Deposits include sand 

dunes, sand ribbons, and flood-rafted trees. Normal flow in the river is from right 

to left (northwestward), but the grooves and tree alignment show flow was 

diverted northward across the flood plain during the flood (West Virginia 

Department of Highways photograph). 

The low estimates of discharge for the 1985 flood 

evoke questions about the accuracy and precision of paleohydraulic reconstructions based on slack-water deposits, at 

least for this type of flood in the Cheat River basin. 

Reconnaissance study of slack-water deposits left by the 

1985 flood along the South Branch Potomac River (Jacobson, chapter A, this volume, pl. 1) suggests that the 

deposits have better correlation to other high-water indicators than do similar deposits on the Cheat River (J.S. Kite 

and S.J. Tharp, unpublished data). However, we lack 

adequate data to determine whether slack-water methods 

can be applied accurately and precisely to floods on other 

rivers in the Appalachian region. 

Other Fine-Grained Deposits 

Thin veneers of sand or sandy loam were deposited at 

many sites. In general, sand and silty sand veneers ranged 

in thickness from 0.2 to 10 em. Thicker, blanketlike sand 

deposits occurred only in slack-water areas. In open, wide 

flood plains, fine-grained veneers tend to be transitional to 

dune forms, suggesting that the 1985 flood produced 

currents over most of the flood plain that were capable of 

transporting sand. The same flood-plain sites experience 

low-energy overbank deposition of sand and silt during less 

extreme floods. 

Mitigation and natural postflood modification make it 

impossible to quantify how much of the flood plain was 

covered by veneers. However, veneers could not be seen on 

most flood-plain surfaces during reconnaissance field work 

undertaken soon after the flood. It is likely that some 

undetected sites experienced minor deposition and that 

these sediments quickly washed in between the leaves of 

plants on the flood plain, but many surfaces received no 

sediments except for flotsam and a few isolated starved 

ripples. A terrace in St. George provided a good example. 

The terrace has a well-developed soil profile and was not 

inundated during the October 1954 flood (Fansler, 1962). 

Floodwaters, 1.8 m deep, flowed over the terrace in 1985. 

Considerable flotsam, including home appliances, was 

strewn over the surface, but no fresh alluvium could be 

discerned on the terrace in December 1985. Lower floodplain surfaces at St. George showed some sand veneer and 

shallow dune development, but much of the flood plain 

either was eroded or experienced little deposition or erosion. Throughout the basin, plowed fields tended to experience severe surface scour, whereas pastures were more 

typically damaged by bank retreat or incision of long 

narrow grooves (fig. 5). 

Sand dunes formed at many sites in the study area. 

The best developed dune fields occurred at the Parsons Tree 

Nursery (fig. 6) and the Preston County Country Club, 4 km 

south of Albright (fig. 7). Dunes are composed of sand and 

a minor amount of granules. The largest dunes occurred at 

Parsons and were up to 1.3 m high, 40 m wide, and 70 m 

long. Dune shape varied. Larger dunes tended to have 

Depositional Aspects of the Nov. 1985 Flood, W. Va. 013 
Figure 6. Aerial photograph showing parabolic and complex dunes on Black Fork 

flood plain at the Parsons Tree Nursery. Note buildings and automobiles for scale. 

Dunes occur just downstream from gravel splay and gravel stripes shown in figure 

9. Transported asphalt slabs occur at left (south); dune sediments have been 

bulldozed from the roads (center) (West Virginia Department of Highways 

photograph). 

Figure 7. Aerial photograph showing sand deposits at the Preston County Country 

Club, south of Albright. Normal streamflow is from right to left (northward). 

Complex and parabolic dunes near Cheat River indicate flow at a 45° angle to the 

channel. Barchan-shaped dunes and sand "shadows" in the lee of trees near the 

top of the photograph indicate that flow over the flood plain was nearly parallel 

to the channel. Much of the sand at this site was derived from sand traps on the 

golf course. Tree shadows are more obvious than trees in this vertical aerial 

photograph (West Virginia Department of Highways photograph). 

D14 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W. Va., Va. 
Figure 8. Aerial photograph showing cobble-boulder splay on the Black Fork 

flood plain near Hendricks. Flow was from left to right across meander. The 

channel bank and adjacent flood plain were severely eroded during the creation 

of an elliptical ramp at the upstream (left) end of the meander. The gravel splay 

(center) overlies eroded pre-1985 alluvium (which also occurs at right). Complex 

sand deposits occur among standing trees (bottom) (West Virginia Department of 

Highways photograph). 

parabolic forms, whereas smaller ones displayed transverse 

or barchan forms. Many dunes had irregular plan geometry 

and appeared to be composite forms modified during 

waning flows. Where dunes were not disturbed during flood 

mitigation, establishment of vegetation has been slow. 

Wind has modified unmitigated dune surfaces, leaving 

granule lags and subduing some of the dune topography. 

All of the major dune fields were associated with 

sediment from source areas less than 1 km upstream. Most 

of these source areas were zones of intense scour of 

preexisting flood-plain sands, but much of the dune sand at 

the Preston County Country Club was derived from sand 

traps on the golf course (fig. 7). 

Deposits of Small Boulders and Cobbles 

Cobbles and small boulders were transported in the 

channel along most reaches of Cheat River and Black Fork 

during the 1985 flood. These coarse-grained sediments 

were commonly deposited on top of alluvial sand or sandy 

loam in environments that receive relatively low-energy 

overbank deposition during less severe floods. Most coarsegrained sediments deposited in overbank environments 

were scoured from preexisting flood-plain deposits within a 

few hundred meters. Some scour sites were isolated holes or 

clusters of holes in the middle of the flood plain, commonly 

where flow around a large tree caused turbulence (fig. 5). 

Many of these isolated scour holes exceeded 3-m depth. 

Typical maximum widths were 15-20 m, and at least two 

exceeded 100 m in length. Virtually all deep scours were 

filled in and graded during mitigation efforts soon after the 

flood. 

Scouring of ramps along channel margins produced 

most of the cobbles and small boulders deposited on top of 

the flood-plain sands. Ramps developed at the downstream 

end of cutbanks on many meanders, where floodwaters had 

jumped the meander and flowed nearly straight down the 

valley. Most of the ramps were obliterated during flood 

mitigation, but aerial photographs and reconnaissance field 

work done soon after the flood show that individual ramps 

were up to 100m long, 50 m wide, and at least 3-4m deep 

(figs. 7, 8). Thousands of cubic meters of alluvium were 

eroded from the larger ramps, and much of this material was 

deposited in splays on the flood plain just downstream from 

the site of erosion. 

A typical ramp had an elliptical form, rising from the 

channel onto the flood plain (figs. 8, 9). At many sites, 

cobbles and small boulders were washed from the channel, 

up the ramp, and onto the flood plain. Knox (1987) has 

suggested that ramps extending from the channel onto the 

flood plain are important avenues for large clasts to be 

juxtaposed on top of fine-grained overbank alluvium. However, it is not clear whether most of the large clasts 

transported onto the flood plain were in the river channel or 

Depositional Aspects of the Nov. 1985 Flood, W.Va. D15 
Figure 9. Cobble-boulder splay (left) on the Black Fork flood plain near the 

Parsons Tree Nursery. Splay is associated with semi-elliptical ramp (lower left). 

Cobble-boulder stripes occur downstream of (right of) splay. Figure 6 shows sand 

deposits farther downstream on same meander (West Virginia Department of 

Highways photograph). 

had been buried in flood-plain deposits prior to the 1985 

flood. 

The large ramps can be traced into broad arcuate 

cobble-boulder splays on the downstream end of the ramp. 

The splays commonly have a shape similar to parabolic 

dunes, with steep downstream faces and "horns" on each 

side projecting upstream to the point of attachment to the 

channel bank. These arcuate splays are typically 100 m 

wide by 140m long. Gravel thickness in the arcuate splays 

locally exceeded 1 m. Typically, cobbles and boulders at 

the steep downstream ends of the splays were deposited 

over fine-grained pre flood deposits. Unfortunately, few of 

these splays were visited before they were destroyed during 

mitigation. 

The ramps and associated boulder-cobble splays were 

the surface expression of high-velocity currents over the 

flood plain, as in the upper Potomac River basin (Miller and 

Parkinson, chapter E, this volume). High-velocity currents 

developed over the flood plain where the river temporarily 

increased its gradient by short-cutting preflood meanders. 

We presume that these erosional forms developed at or near 

peak flow. Unlike less extreme floods, erosion was much 

more common on the inside of meander bends than on the 

outside. In several reaches, the least damage to flood-plain 

vegetation was on the outside of meanders, where flow 

must have had much less energy than at the ramps and 

splays. However, the duration of these high-velocity currents was insufficient to erode new low-flow channels on 

Cheat River. 

Sand dunes were abundant on flood-plain surfaces 

that were downstream from splays. Longitudinal cobbleboulder stripes developed downstream from the splays at 

the Parsons Tree Nursery (fig. 9) but were rare elsewhere. 

The stripes were composed of large cobbles and small 

boulders with minor amounts of high-density manmade 

trash. Stripes typically were one clast thick, 0.5-5 m wide, 

and 100 m long. The stripes probably represent portions of 

the arcuate cobble-boulder splays that were detached by 

extremely fast currents during or near peak flow. 

Flood mitigation efforts have modified most of the 

ramp-and-splay associations beyond recognition and may 

destroy evidence that sites are susceptible to repeated flood 

damage. Old newspaper accounts of the July 1888 flood 

describe a "new channel" eroded nearly 2 m deep across the 

inside of a large meander at Rowlesburg (Preston County 

Journal, 1888a). Between 0.6 and 1.0 m of sand was 

. deposited just downstream from the new (1888) channel 

(Preston County Journal, 1888b). The site of erosion in 

Rowlesburg was later filled in, but similar scour took place 

at the same site in 1985. Many buildings were destroyed at 

the site during both floods. 

Extremely Large Boulders 

Extremely large boulders transported during the 1985 

flood occur in several reaches of Cheat River. So many 

boulders in Cheat Canyon were reworked during the flood 

D16 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W. Va., Va. 
that white-water raft guides had to relearn almost all of the 

major falls along this popular waterway. Photographs and 

personal accounts by white-water raft guides indicate that 

clasts with intermediate axes up to 2. 75 m long were 

moved. Reconnaissance field work in Cheat Canyon has 

confirmed transportation of clasts with intermediate axes in 

excess of 1.5 m. 

Our study of large clasts transported during the 1985 

flood has concentrated on Cheat Narrows, near the Cheat 

Narrows slack-water deposit. Various criteria were used to 

determine which clasts were moved by the flood. Some 

clasts were large enough to be identified on preflood and 

postflood aerial photographs, but utility of the photographs 

was limited by the resolution of pre flood photography, by a 

tree canopy that obscured most of the boulders prior to the 

1985 flood, and by high water levels that obscured most of 

the channel-bottom clasts on postflood photographs. 

Because of these limitations, aerial photography was used 

only to identify boulders to be examined in the field or to 

confirm movement suggested by field criteria, such as 

the location of impact marks and oxide staining, or fragments of fresh wood or manmade materials trapped under 

boulders. 

Two types of impact marks were common on boulders in Cheat Narrows: flakes and bruises. Boulder-boulder 

or boulder-bedrock collisions were sufficient to spall 

off flakes. Flake scars as large as 35 em by 25 em were 

readily discerned from undisturbed surfaces because they 

lacked lichen growth or weathering rinds. Intact flakes were 

rarely found; most were possibly crushed during subsequent 

collisions. 

Bruises, created by surface compression during clast 

collisions, were the most common impact features on 

boulders in Cheat Narrows. Where bruised, a boulder 

surface was crushed and lacked vegetation, oxide straining, 

or a well-developed weathering rind. Bruises commonly 

occurred at the point of impact where a flake scar was 

created. A typical bruise was 5-10 em in diameter and had 

a very irregular shape. Some bruises either were elongate or 

occurred in association with chatter marks, both conditions 

suggesting scraping and shearing of large boulders during 

transportation. 

Although impact marks show that a collision between 

large clasts occurred, they are not sufficient to determine 

that a clast has moved. However, the position of impact 

marks may be used to document clast transportation. Some 

of the transported boulders showed impact marks on all 

sides, including those that would be sheltered from impact 

in their present orientation. A few of the boulders had tens 

of fresh impact marks on many different faces, indicating 

that the clast experienced many collisions and was probably 

transported many meters. 

Well-developed impact marks were observed on 

boulder or bedrock surfaces that were beneath a large 

boulder. The overlying boulder could not have been at that 

location when the impact marks were created, unless it had 

been the colliding clast. In either case, fresh impact marks 

on a surface under a boulder show that the overlying 

boulder was transported in the 1985 flood. 

A weathering varnish, presumably composed of iron 

or manganese oxides, coats many clasts exposed at the 

surface to a level 1-1.5 m above typical low flows in the 

Cheat Narrows. This varnish gives way to lichen- and 

moss-covered surfaces farther above the low-water levels. 

Boulders exhumed from preflood deposits do not show this 

varnish. The varnish can be identified on clasts that were 

transported from positions in the channel to positions on the 

flood plain above the varnish limit. In one case, the 

orientation of the varnish allowed reconstruction of the 

amount of rotation that an extremely large clast experienced 

during the 1985 flood (fig. 10). We have not used the 

distribution of varnish on boulders as the sole criterion to 

determine which clasts were transported, but we have found 

it helpful in finding boulders that show other evidence of 

recent transportation. 

The most convincing field evidence of transportation 

occurs where the full weight of a clast had trapped something demonstrably young. Boulders pinning automobile 

frames, tires, sheet metal, and other common artifacts had 

clearly moved since those artificial materials were introduced to the river. The 1985 flood was so much larger than 

any other flood in the past few decades that it was 

considered reasonable to attribute deposition of the largest 

of these boulders to the 1985 flood. A relatively young age 

also could be assigned to boulders that overlie cut lumber, 

uprooted trees, or broken branches. To confidently determine that a boulder has been transported, the wood beneath 

it had to be partly crushed by the weight of the boulder. 

Lumber fragments beneath boulders were examined carefully; many looked convincing but could be extracted with 

some effort. It is likely that some of these weakly lodged 

pieces of lumber were washed in by floodwaters but then 

expanded as they became water-saturated with prolonged 

exposure. 

The largest transported clast identified in the field at 

Cheat Narrows measured 2.4 m by 4.0 m by 10.0 m (fig. 

10). The mass of this clast is estimated to be 160,000-

200,000 kg, somewhat larger than the largest clasts transported by either floodwaters or debris flow in the upper 

Potomac River basin (Kite and others, 1987; Miller, 1987). 

Most clasts of this size in the Cheat channel were not 

transported in 1985. 

Many boulders with diameters greater than 1 m were 

moved in 1985, but many smaller boulders were not. 

Orientation relative to other clasts and position within the 

flood channel are just as important as clast size in determining susceptibility to movement. Local hydraulic effects, 

such as macroturbulence, were also important, but these are 

difficult to reconstruct after the flood (Baker, 1973). 

Depositional Aspects of the Nov. 1985 Flood, W. Va. 017 
Figure 10. Photograph of the largest clast (intermediate axis of 4.0 m) documented 

to have moved during the 1985 flood in Cheat Narrows. The clast rotated about 

70°, and its center of gravity was moved less than 5 m by flow from right to left. 

Many clasts with intermediate axes in excess of 2.0 m were transported much 

farther in Cheat Narrows. The boulders have numerous fresh impact marks on all 

surfaces; some were deposited on 1985 trash or the stumps of freshly killed trees. 

The mean of the intermediate axes of the five largest 

transported clasts was used in paleohydraulic reconstructions; that value for Cheat Narrows was 2.76 m. 

Paleohydraulic Reconstructions From Large 

Boulders 

Various empirical equations have been used to relate 

the competence of floods with hydraulic variables, including mean flow velocity, tractive force, and unit stream 

power (Costa, 1983; Williams, 1984). Unfortunately, these 

empirical equations are derived from very few data on the 

transportation of clasts with intermediate axes greater than 1 

m (Costa, 1983). The November 1985 flood in bouldery 

Cheat Narrows presents an opportunity to examine which of 

these equations best describe the relationship between 

the transportation of very large boulders and hydraulic 

variables. 

Obviously, paleohydraulic reconstructions based on 

competence require that the largest clast that a flow could 

transport be present in the channel (Baker and Ritter, 1975). 

This is a particular problem because it appears that the most 

accurate paleohydraulic curves are those indicating that 

relatively low flows can move very large clasts (Williams, 

1984). Field observations in Cheat Narrows showed that 

clasts of the maximum size should be abundant, because 

some clasts the same size or smaller than the largest 

transported clast were not moved because of sheltering by 

other clasts, close packing, or other local considerations. 

The only practical way to determine if a reach 

contains clasts that were large enough to test the competence of a stream during a given flood is to identify reaches 

with numerous clasts that were too large to be transported 

during that flood. Only two reaches of Cheat River meet 

this criterion: Cheat Narrows and Cheat Canyon. Both of 

these reaches contain very large boulders derived from 

sandstones of the Pottsville Group. 

Table 5 shows predicted values (P) of velocity, 

tractive force, and unit stream power determined by substituting Cheat Narrows boulder data into published paleohydraulic equations (Linton, 1992). For comp~rison, table 5 

also shows values of the same indices of flow strength 

determined from slope-area (Manning equation) calculations and field measurements. Slope-area calculations are 

sensitive to the selection of roughness coefficients (Manning's n). The 0.050 roughness coefficient used for these 

calculations gave good match to discharge values reported 

for Cheat River at Rowlesburg and Parsons (Lescinsky, 

1986; R.S. Runner, unpublished data). Selection of different roughness coefficients would affect the calculated values, but we believe this source of error is less than the 

25-100 percent likely error that is reported for this type of 

prediction (Williams and Costa, 1988). 

Most of the published equations for flow strength 

overestimate velocity, tractive force, and unit stream power 

D18 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W. Va., Va. 
Table 5. Comparison of hydraulic variables predicted from empirical equations with calculations based on slope-area 

determinations of discharge and. velocity 

[Field measurements made at Cheat Narrows after the 1985 flood. Calculated values are averaged from two cross sections (table 4) by Linton (1992)] 

Equation 

Mean velocity v 

v=0.20cfAss m!s 

Reference 

Costa (1983, eq. 10) 

Costa (1983, eq. 8) 

Costa (1983, eq. 8) 1 

Value pr~dicted Value calculated b P/Cx100 

from equat1ons and Y 

particle size (P) slope-area method (Q 

8.53 5.86 146 

7.36 5.86 126 

6.42 5.86 110 

v=0.18cfA87 rn!s 

v=0.27cfA rn!s 

v=0.216cf.44 rn!s 

v=0.065cf 5 rn!s 

Modified from Williams (1984) after Koster (1978)2 7.05 5.86 120 

Williams (1984) 3.41 5.86 58 

Tractive force ('r): 

T=0.056dl. Costa (1983) 836 397 210 213 N/m2 

T=0.030d1A9 N/m2 

T=0.17d N/m2 

Williams (1984) after Baker and Ritter (1975) 4,019 397 1,012 

Unit stream power w 

w=0.009dl. 686 N/rn!s 

w=0.079dl. 29 N/rn!s 

Williams (1984) 

Costa (1983) 

Williams (1984) 

469 

5,697 

2,170 

397 118 

2,567 222 

2,567 85 

1 Equation modified to fit only clasts with intermediate axes measuring 500-3,200 mm (Costa, 1983). 2 Based on equation for critical velocity (vc = 0.18cf 44), assuming that v = 1.2vc (Williams, 1984). 

(table 5). Although most of these overestimates are within 

the likely error of the method, they suggest that the boulders 

transported by the Cheat River do approach the upper limit 

of sizes that could have been transported by a flood of this 

magnitude. 

Field observations in Cheat Narrows showed important aspects of using large boulders to reconstruct flood 

flows. Extremely large clasts were deposited only in or 

adjacent to the channel in Cheat Narrows, where flow 

velocity and depth were greatest during the flood. It is likely 

that more useful empirical equations could be constructed 

by regression of clast size with maximum values of velocity, tractive force, or unit stream power, rather than with 

mean values of these variables. Mean values in most 

reaches of Cheat River were inappropriately lowered by 

inclusion of parts of the flood plain that experienced little 

flow and no boulder movement. 

Miscellaneous Deposits 

A number of curious, yet somber, deposits of manmade articles were strewn about the flood plain after the 

1985 flood. Many low-density items were scattered across 

the flood-plain surface, stranded when floodwater receded. 

Clothing, plastic items, and foam rubber tended to be 

trapped in trees or shrubs. Most of the lumber, refrigerators, 

propane tanks, trash dumpsters, and other manmade debris 

that clogged the Lake Lynn floodgates was entrained at 

Albright, 40 km away, or even farther upstream. Heavier 

manmade objects, such as automobiles and hot-water heaters, traveled shorter distances, apparently as bedload. A 

few residential buildings and mobile homes remained relatively intact after being swept from their foundations, but 

most disintegrated into smaller fragments carried in flotation, suspension, or traction. 

Large slabs of asphalt were eroded from roads and 

parking lots on the flood plain. The largest slabs were 4 m 

wide by 6 m long, but only 10-15 em thick (fig. 6). Some 

of the asphalt slabs were transported more than 100 m 

without being broken into small fragments. Their survival 

suggests transportation by flows of relatively high velocity 

but little turbulence, near the bottom of flow over the flood 

plain. 

Trees and trash appeared to make up most of the 

volume of deposits left by the 1985 flood. Uprooted trees 

and broken branches were the most obvious sediment in 

these deposits, although great volumes of trash were deposited immediately downstream from towns. It appears that 

virtually all of the trees grew on the flood plain before the 

flood. Many were quite large and presumed to be over 100 

yr old. Some of the transported tree trunks, particularly 

Platanus (sycamore), sprouted new growth barely 6 months 

after the flood. 

Many flood-plain surfaces lacked forest cover before 

the 1985 flood. Hundreds of individual trees, transported as 

flotation load, were stranded on unforested surfaces during 

waning stages. Most were stripped of much of their bark 

and smaller branches, and were deposited with root masses 

pointing upstream. Long narrow grooves incised into floodplain pastures may have been initiated by trees dragged 

across the surface (fig. 5). 

Trash and trees were deposited in dunelike forms on 

several reaches with wide flood plains (Kite, 1986). These 

dunelike forms may have formed during the waning stage, 

as larger trees lodged on the flood plain and served as a 

nucleus for deposition of other trees and trash. 

Depositional Aspects of the Nov. 1985 Flood, W.Va. 019 
Figure 11. Aerial photograph of building that served as nucleus for tree jam, Black 

Fork flood plain near Hendricks. Flow is from left to right (northward) (West 

Virginia Department of Highways photograph). 

Trees and trash were deposited more commonly in 

logjams than in dune like forms. The nuclei of most logjams 

were one or more substantial trees not toppled by the flood. 

Some buildings also served as logjam nuclei (fig. 11). 

These buildings suffered severe damage from the impact of 

large trees floating in high-velocity currents, but the trees 

provided armoring that deflected currents from the buildings and kept them from being swept away (Fonner, 1987). 

Logjams were widespread on forested bottomlands. 

Tree-and-trash accumulations were thickest along fronts 

that separated upstream surfaces (from which most trees 

were swept away) and downstream surfaces (on which most 

trees remained standing). Logjams developed lobate morphology where high-velocity currents swept forested bottomlands. Several meanders were nearly cleared of forest 

cover, particularly those that experienced high-velocity 

flows and development of ramps and cobble-boulder splays. 

Log-dammed pseudo-terraces, like those formed during the 

same flood in the Little River basin of Virginia (Kochel and 

others, 1987), were rare on Cheat River and Black Fork, 

possibly because the width of these rivers allowed toppled 

trees to float more freely than did the narrower Little River. 

Deposits of mineral sediments were not well developed along valley sidewalls or on many other low-energy, 

low-terrace, and upper flood-plain environments, but floating wood fragments and trash were widespread, and the 

most easily observed indicators of high water. The trash 

component was quite varied; clothing, bottles, and objects 

made of styrofoam, foam rubber, or lightweight plastics 

were abundant. Most of the wood consisted of well-rounded 

sticks, less than 15 em long, but slightly larger pieces of 

lumber were common. Painted surfaces and nails in many 

of these boards suggest they were derived from structures 

destroyed during the flood. 

It is difficult to assess the significance of tree-andtrash deposits to the long-term flood-plain stratigraphy of 

Cheat River and Black Fork. Obviously, much of the trash, 

such as styrofoam and lightweight plastics, would not have 

been deposited by floods before the 20th century. Trees and 

shrubs would have been the only significant source of 

low-density sediments during prehistoric floods. Even if 

landforms were made from these sediments during earlier 

floods, these landforms would have collapsed almost completely as the organic matter decayed. Large, coarse organic 

deposits may have a significant indirect effect on floodplain geomorphology before they decay; they may either 

block or deflect flow, setting up extreme turbulence and 

erosion at some sites and backwater effects and deposition 

at others. 

SOURCES OF FLOOD-PLAIN SEDIMENTS 

Slope failures during the 1985 flood are beyond the 

scope of this report, but our reconnaissance field work and 

our examination of aerial photographs show that slope 

failures were much less common here than in the upper 

Potomac River basin, where thousands of failures have been 

mapped (Jacobson and others, 1987a, b; chapter C, this 

volume). Two large landslides occurred adjacent to Cheat 

River between Macomber and Rowlesburg, and tens of 

020 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W.Va., Va. 
small failures were triggered along channel margins, presumably the result of scour at the base of slopes and of high 

pore pressures in the failed colluvial deposits. Debris-flow 

and debris-avalanche deposits have not been identified in 

our study area. 

Gully erosion and piping of coarse-grained colluvium 

appear to have been important slope phenomena during the 

flood. Surface A horizons in typical colluvial soils of the 

Cheat basin are composed of loose, organic-rich channery 

loam (Pyle and others, 1982). After the flood, these soils 

showed steep, shallow gullies, tens of meters long and less 

than a meter wide, in which organic-rich surface horizons 

had been washed away. Angular coarse-grained clasts 

exposed in the shallow gullies were totally clast-supported, 

lacking the loose loam matrix found in adjacent soils. On 

rainy days after the flood, surface runoff was observed 

infiltrating into the coarse-grained clasts and continuing 

downslope through subsurface piping. If piping occurred 

during the 1985 flood, it may have facilitated runoff on 

colluvial slopes, thereby reducing the number of localities 

where pore-water pressure reached the level necessary for 

slope failures. Moreover, the scarcity of slope failures may 

help explain why silt and clay deposits were uncommon and 

poorly developed on flood plains in the Cheat River basin. 

The distribution of flood deposits shows that most 

sediments transported by Cheat River and Black Fork 

during the flood were on the flood plain prior to 1985. In 

effect, flood-plain sediments were traded from preflood 

deposits to new deposits downstream. The close proximity 

of gravel bars and sand dunes to areas of intense floodplain scour suggests that the average distance of transport 

was much less than a kilometer. Flood-plain surfaces 

that were not near sites of scour generally received little 

sedimentation. 

The route of clast transport during the 1985 flood was 

not typical of sediment trading, where sediment is eroded 

from a cut bank on the outside of one meander and 

deposited on a point bar at the inside of the next meander 

downstream. The high-velocity turbulent flows across the 

Cheat River and Black Fork flood plains eroded clasts from 

the channel margin at the downstream end of a cut bank and 

deposited them on the flood-plain surface well away from 

the normal channel of the river. 

CONCLUSIONS AND IMPLICATIONS 

Summary of Flood Geomorphology 

Many landforms and deposits created by the 1985 

flood are unlike those formed by more frequent flows in the 

Cheat River basin. Extremes of sediments ranged from silty 

loam slack-water deposits to boulders more than 2 m in 

diameter. Well-developed slack-water deposits formed at 

back-flooded tributary mouths but were far below highwater levels indicated by flotsam. The creation of large 

ramps and arcuate gravel splays juxtaposed coarse tractiveload sediments and sand dunes on top of low-energy 

overbank deposits. This juxtaposition extended hundreds of 

meters away from the preflood channel. The boulders 

transported on steep reaches of Cheat River appear to be 

nearly the largest clasts that can be moved by a flow of this 

magnitude. Organic and artificial deposits were quite voluminous and probably warrant considerably more attention 

by fluvial geomorphologists. All of these deposits have 

long-term significance to fluvial geomorphology. 

Effectiveness of Large Floods in Long-Term 

Flood-Plain Evolution 

The 1985 floods on Cheat River and Black Fork have 

implications about how flood plains evolve in the central 

Appalachians. These implications are clearer when postflood changes in vegetation, morphology, and stratigraphy 

are considered separately. Recovery periods for these types 

of changes are quite different, so the significance of 

extreme floods depends on which type of change is under 

consideration and on the nature of the flood plain. Disregarding the artificial influences of postflood mitigation, the 

1985 flood shows that high-magnitude, low-frequency 

floods can have significant long-term influence on the 

geomorphology and stratigraphy of Appalachian flood 

plains. 

Extreme floods probably are not particularly effective 

controls of bottomland vegetation (Wolman and Gerson, 

1978; Hupp, 1988). Many trees in the age range of 50-100 

yr (or older) were destroyed by the November 1985 flood, 

but the recovery of flood-plain vegetation is relatively short 

(decades for most trees, less for most non tree species). 

Bottomland plant ecology is more affected by frequency of 

inundation than by age of flood-plain surface, so more 

frequent floods play a larger role than extreme floods 

(Hupp, 1988). 

Channels floored with cobbles and small boulders 

recover their preflood morphology rapidly. These clasts can 

be moved by moderate events on Cheat River and Black 

Fork, so the channel will soon approach a hydraulic 

geometry adjusted to these flows. Rapid morphologic 

recovery has been documented after extreme floods elsewhere in the Eastern United States (Costa, 1974; Moss and 

Kochel, 1978); new point-bar deposits on the Cheat River 

flood plain show that morphologic recovery is occurring in 

cobble and small-boulder channels in the aftermath of 1985. 

If no other extremely large floods occur before the "adjustment" landforms are vegetated, then the cobble and smallboulder channels will recover morphologically in less time 

than the > 100-yr recurrence interval of the flood. 

Morphologic recovery of the channel takes much 

longer where moderate flows cannot transport bedload 

clasts (Baker, 1977; Kochel, 1988). The easiest places to 

Depositional Aspects of the Nov. 1985 Flood, W.Va. D21 
demonstrate dominance by high-magnitude, low-frequency 

events are steep, bouldery reaches like Cheat Narrows and 

Cheat Canyon. The November 1985 flood has been the only 

event during this century capable of transporting the large 

boulders in these two reaches. These boulders are the main 

control on valley-bottom morphology and flood hydraulics 

in these reaches, so deposition during moderate and frequent flows is indirectly determined by boulder movement 

during much larger floods. 

Although most discussions of morphologic recovery 

in fluvial systems (e.g., Wolman and Gerson, 1978~ 

Kochel, 1988) focus on channel morphology, we should 

remember that moderate flows are probably less effective at 

recovery of flood-plain morphology. River channels are 

much higher energy environments than flood plains during 

moderate floods in humid landscapes. This situation 

reversed on parts of the flood plain during the 1985 flood, 

creating erosional and deposition landforms at many sites 

that are unlikely to experience other high-velocity flows 

until the next catastrophic flood. Bioturbation, local colluviation or slope wash, and the periodic draping of finegrained sediment are the main natural processes of recovery 

between extreme floods. Many of the 1985 landforms had 

relief of a meter or more, so morphologic recovery may 

have taken centuries if postflood mitigation by humans had 

not obliterated most of the new landforms. 

Events like the November 1985 flood have longlasting effects on flood-plain stratigraphy, too. Widespread 

juxtaposition of cobbles and small boulders on top of 

fine-grained overbank alluvium only occurs when deep, 

high-velocity flows develop on the flood plain. In a natural 

system the cobble and boulder deposits would persist until 

destroyed by lateral channel migration or subsequent 

extreme floods. In either case, these deposits could last a 

long time. 

The stratigraphic framework of the flood plain may 

reflect a catastrophic event long after the channel and flood 

plain return to their preflood morphology. Waning stages of 

a catastrophic flood and later moderate floods leave deposits 

that fill many of the erosional features created during the 

large flood. Much of the deposition is in direct response to 

the scour and channel widening by the catastrophic flood. 

Postflood filling is part of morphologic recovery to preflood 

hydraulic geometry, but the flood plain may never recover 

its preflood stratigraphy. Many stratigraphic units formed as 

a result of a catastrophic flood will last until either another 

extreme flood erodes them away or lateral channel migration completely reworks the flood plain. 

There is one major unresolved question concerning 

the effectiveness of floods like the 1985 event on controlling morphology and stratigraphy: Is this flood representative of floods that have occurred in the past? The 20th 

century drainage basin is not analogous to the prehistoric 

basin, so there is a natural tendency to attribute some of the 

radical flood-plain and channel changes to artificial influences acting on runoff, flood-plain cover, and resistance to 

overbank flow. Yet, as was stated previously, the unique 

severity of the 1985 flood in the Cheat River basin can be 

attributed to the extraordinary amount of rain that fell over 

most of the drainage basin in a short amount of time. We 

believe that if similar meteorologic events occurred in the 

drainage basin before the local historic record began, a 

similar flood would have resulted, producing deposits and 

landforms like those formed on Cheat River and Black Fork 

in 1985. 

Implications for Flood-Plain Management 

Our research suggests that it is feasible to extend the 

Cheat flood record with paleohydraulic reconstructions 

from slack-water deposits and large transported boulders. 

However, the ability of slack-water deposits to serve as 

precise indicators of prehistoric water levels may be poor. 

More work in other basins affected by catastrophic flooding 

is essential before we can evaluate the applicability of these 

methods to practical flood-plain management in the region. 

Extreme floods in the Appalachians present many 

flood hazards that can be avoided by flood-plain management based on geomorphology. Much of the damage in 

1985 was caused by high-velocity flows over flood-plain 

surfaces, presenting a much greater problem than simple 

inundation. Buildings experienced serious structural damage or were swept completely away. These high-velocity 

flows also created diagnostic landforms such as ramps and 

arcuate gravel splays. Sites that exhibit either of these 

features should not be developed without considering 

whether development entails unnecessary risk to lives or 

property. Although the merits of costly postflood mitigation 

are far beyond the scope of this research, it does bear notice 

that postflood disturbance may obliterate geomorphologic 

and sedimentologic evidence that may be of great use to 

sound flood-plain management. 

REFERENCES CITED 

Auvil, Myrtle, 1977, Covered bridges of West Virginia, past and 

present, third ed.: Parsons, W.Va., McClain Printing, 249 p. 

Baker, V. R., 1973, Paleohydrology and sedimentology of Lake 

Missoula flooding in eastern Washington: Geological Society 

of America Special Paper 144, 79 p. 

---1977, Stream response to floods, with examples from 

central Texas: Geological Society of America Bulletin, v. 88, 

p. 1057-1071. 

Baker, V.R., and Bunker, R.C., 1985, Cataclysmic late Pleistocene flooding from glacial Lake Missoula: Quaternary Science Reviews, v. 4, p. 1--41. 

Baker, V.R., and Kochel, R.C., 1988, Flood sedimentation in 

bedrock fluvial systems, in Baker, V.R., Kochel, R.C., and 

Patton, P.C., eds., Flood geomorphology: New York, John 

Wiley and Sons, p. 123-137. 

022 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W.Va., Va. 
Baker, V.R., Pickup, G., and Polach, H.A., 1985, Radiocarbon 

dating of flood events, Katherine Gorge, Northern Territory, 

Australia: Geology, v. 13, p. 344--347. 

Baker, V.R., and Ritter, D.F., 1975, Competence of rivers to 

transport coarse bedload material: Geological Society of 

America Bulletin, v. 86, p. 975-978. 

Bell, A.M., 1986, Morphology and stratigraphy of terraces in the 

upper Shenandoah Valley, Virginia: Morgantown, West Virginia University, M.S. thesis, 161 p. 

Cardwell, D.H., Erwin, R.B., and Woodward, H.P., 1968, 

Geologic map of West Virginia: Morgantown, W. Va., West 

Virginia Geological and Economic Survey, 2 sheets. 

Carpenter, D. H. , 1990, Floods in West Virginia, Virginia, Pennsylvania, and Maryland, November 1985: U.S. Geological 

Survey Water-Resources Investigations Report 88-4213, 

86 p. 

Charleston Gazette, 1985, Rivers' crests in flooded areas: Charleston [W. Va.] Gazette, Nov. 6, p. 3A. 

Clark, G.M., Jacobson, R.B., Kite, J.S., and Linton, R.C., 1987, 

Storm-induced catastrophic flooding and related phenomena 

in Virginia and West Virginia, November 1985, in Mayer, 

Larry, and Nash, David, eds., Catastrophic flooding: London, Allen and Unwin, p. 355-380. 

Costa, J.E., 1974, Response and recovery of a Piedmont watershed from Tropical Storm Agnes, June 1972: Water Resources Research, v. 10, p. 106-112. 

---1983, Paleohydraulic reconstruction of flash-flood peaks 

from boulder deposits in the Colorado Front Range: Geological Society of America Bulletin, v. 94, p. 986-1004. 

Dunne, T., and Leopold, L.B., 1978, Water in environmental 

planning: San Francisco, Calif., W.H. Freeman and Company, 818 p. 

Elliott, T., 1986, Deltas, in Reading, H.G., ed., Sedimentary 

environments and facies, second ed.: Oxford, Blackwell 

Scientific Publications, p. 113-154. 

Embree, W.N., Friel, E.A., and Taylor, F.M., 1985, Water 

resources data, West Virginia water year 1984: U.S. Geological Survey Water-Data Report WV-84--1, 323 p. 

Fansler, H.F., 1962, History of Tucker County, West Virginia: 

Parsons, W. V a. , McClain Printing, 702 p. 

Fonner, R.F., 1987, Homeowner's guide to geologic hazards: 

Mountain State Geology: Morgantown, W. Va., West Virginia Geological and Economic Survey, p. 1-9. 

GAl Consultants, Inc., 1985, West Penn Power Company, 

Greensburg, Pennsylvania, Cheat River basin flood of 4-5 

November 1985, Postflood inspection report Lake Lynn 

Dam, FERC Project 2459-W. Va.: Monroeville, Pa., GAl 

Consultants, Inc., 20 p. and app. 

Hendricks, E.L., 1964, Compilation of records of surface waters 

of the United States, October 1950 to September 1960, part 

A, Ohio River basin except Cumberland and Tennessee River 

basins: U.S. Geological Survey Water-Supply Paper 1725, 

560 p. 

Hupp, C.R., 1988, Plant ecological aspects of flood geomorphology and paleoflood history, in Baker, V. R. , Kochel, R. C. , 

and Patton, P.C., eds., Flood geomorphology: New York, 

John Wiley and Sons, p. 335-356. 

Jacobson, R.B., Cron, E.D., and McGeehin, J.P., 1987a, Preliminary results from a study of natural slope failures triggered by the storm of November 3-5, 1985, Germany Valley, 

West Virginia and Virginia, in Schultz, A.P., and Southworth, C. S. , eds. , Landslides of eastern North America: U.S. 

Geological Survey Circular 1008, p. 11-16. 

Jacobson, R.B., McGeehin, J.P., and Cron, E.D., 1987b, Hillslope processes and surficial geology, Wills Mountain anticline, West Virginia and Virginia, in Kite, J.S., ed., 

Research on the late Cenozoic of the Potomac Highlands, 

Southeastern Friends of the Pleistocene, vol. 1: Morgantown, 

W. Va., West Virginia Geological and Economic Survey 

Open-File Report 88-2, p. 31-55. 

Kite, J.S., 1986, Erosion and deposition in the Monongahela and 

Potomac drainage basins during the floods of November 

1985: Geological Society of America Abstracts with Programs (North-Central sectional meeting), v. 18, p. 313. 

Kite, J.S., Linton, R.C., and Gerritsen, S., 1987, The Twin Run 

debris avalanche-debris flow, in Kite, J .S., and Linton, 

R.C., eds., SEFOP 1987, Field guide to the first annual 

meeting of the Southeastern Friends of the Pleistocene: 

Morgantown, W. Va., West Virginia Geological and Economic Survey Open-File Report 88-1, p. 34-52. 

Knox, J.C., 1987, Stratigraphic evidence of large floods in the 

upper Mississippi Valley, in Mayer, Larry, and Nash, David, 

eds., Catastrophic flooding: London, Allen and Unwin, 

p. 155-180. 

Kochel, R.C., 1988, Geomorphic impact of large floods, review 

and new perspectives on magnitude and frequency, in Baker, 

V.R., Kochel, R.C., and Patton, P.C., eds., Flood geomorphology: New York, John Wiley and Sons, p. 169-187. 

Kochel, R.C., and Baker, V.R., 1988, Paleoflood analysis using 

slackwater deposits, in Baker, V.R .. Kochel, R.C., and 

Patton, P.C., eds., Flood geomorphology: New York, John 

Wiley and Sons, p. 357-376. 

Kochel, R.C., and Ritter, D.F., 1987, Implications of flume 

experiments on the interpretation of slackwater paleoflood 

sediments, in Singh, V .J., ed., Regional flood frequency 

analysis: Boston, Mass., D. Reidel, p. 365-384. 

Kochel, R.C., Ritter, D.F., and Miller, J., 1987, Role of tree 

dams in the construction of pseudo-terraces and variable 

geomorphic responses to floods in Little River valley, Virginia: Geology, v. 15, p. 718-721. 

Komar, P.O., 1988, Sediment transport by floods, in Baker, 

V.R., Kochel, R.C., and Patton, P.C., eds., Flood geomorphology: New York, John Wiley and Sons, p. 97-111. 

Koster, E.H., 1978, Transverse ribs: their characteristics, origin 

and paleohydraulic significance, in Miall, A.D., ed., Fluvial 

sedimentology: Calgary, Alberta, Canadian Society of Petroleum Geologists, p. 161-186. 

Lescinsky, J.B., 1986, Flood of November 1985 in West Virginia, 

Pennsylvania, Maryland and Virginia: U.S. Geological Survey Open-File Report 86-486, 33 p. 

Linton, R.C., 1992, Slackwater deposits along the Cheat River in 

east-central West Virginia: Morgantown, West Virginia University, M.S. thesis, 173 p. 

Linton, R.C., and Kite, J.S., 1987, Slack-water deposits along the 

Cheat River in east-central West Virginia: Geological Society 

of America Abstracts with Programs (Southeast sectional 

meeting), v. 19, p. 95. 

Maxwell, H., 1884, History of Tucker County, West Virginia: 

Kingwood, W. Va., Preston Publishing, 531 p. 

Depositional Aspects of the Nov. 1985 Flood, W.Va. 023 
Miller, A.J., 1987, Stop 1, Hapeville Canyon overlook, in Kite, 

J.S., and Linton, R.C., eds., SEFOP 1987, Field guide to the 

first annual meeting of the Southeastern Friends of the 

Pleistocene: Morgantown, W. Va., West Virginia Geological 

and Economic Survey Open-File Report 88-1, p. 57. 

Morton, 0. F. , 1914, A history of Preston County, West Virginia: 

Kingwood, W.Va., The Journal Publishing, 564 p. 

Moss, J.H., and Kochel, R.C., 1978, Unexpected geomorphic 

effects of the Hurricane Agnes storm and flood, Conestoga 

drainage basin, southeastern Pennsylvania: Journal of Geology, v. 86, p. 1-11. 

Murphy, A.J., 1986, Testimony of Hon. Austin J. Murphy, a 

Representative in Congress of the State of Pennsylvania, 

Flood damages along the Monongahela and Cheat Rivers in 

Pennsylvania and West Virginia as the result of severe 

flooding in November 1985, (99-41) hearing before the 

Subcommittee on Water Resources of the Committee on 

Public Works and Transportation, House of Representatives, 

99th Cong., 2nd sess., p. 2-8. 

North, E.L., 1985, The 55 West Virginias, a guide to the State's 

counties: Morgantown, W. Va., West Virginia University 

Press, 118 p. 

Patton, P.C., Baker, V.R., and Kochel, R.C., 1979, Slack-water 

deposits, a geomorphic technique for the interpretation of 

fluvial paleohydrology, in Rhodes, D.P., and Williams, 

G.P., eds., Adjustments of the fluvial system: Dubuque, 

Iowa, Kendall/Hunt Publishing, p. 225-253. 

Paulson, C.G., 1953, Surface water supply of the United States 

1950, part 3, Ohio River basin: U.S. Geological Survey 

Water-Supply Paper 1173, 730 p. 

Plum, K., 1985, Albright, Rowlesburg devastated by flood: The 

Morgantown Dominion Post, Nov. 6, p. 14A-15A. 

Preston County Historical Society, 1979, Preston County West 

Virginia history: Dallas, Texas, Taylor Publishing, 514 p. 

Preston County Journal, 1888a, A great flood, destruction along 

Cheat, the highest waters ever known, bridges, houses, 

lumber, and all kinds of property swept away: Kingwood, W. 

Va., Preston County Journal, no. 1143, July 12, p. 1. 

---1888b, More about the great flood of '88: Kingwood, W. 

Va., Preston County Journal, no. 1144, July 19, p. 1. 

---1907, Cloudburst-Preston County suffered many dollars 

damage: Kingwood, W. Va., Preston County Journal, July 

18, vol. 46, no. 46, p. 3. 

Pyle, R.E., Beverage, W.W., Yoakum, T., Amick, D.P., Hatfield, W.F., and McKinney, D.E., 1982, Soil survey of 

Randolph County area main part, West Virginia: U.S. 

Department of Agriculture Soil Conservation Service and 

Forest Service, 167 p., 59 maps. 

Region III Interagency Flood Hazard Mitigation Team, 1985, 

Interagency flood hazard mitigation report in response to the 

November 7, 1985, disaster declaration: Federal Emergency 

Management Agency, Report FEMA-753-DR-WV, 56 p., 9 

app. 

Speer, P.R., and Gamble, C.R., 1965, Magnitude and frequency 

of floods in the United States, part 3-A, Ohio River basin 

except Cumberland and Tennessee River basins: U.S. Geological Survey Water-Supply Paper 1675, 630 p. 

Teats, B., and Young, S., 1985, Killing waters, the great West 

Virginia flood of 1985: Terra Alta, W. Va., Cheat River 

Publishing, 112 p. 

Thomas, W.O., Jr., 1987, Techniques used by the U.S. Geological Survey in estimating the magnitude and frequency of 

floods, in Mayer, Larry, and Nash, David, eds., Catastrophic 

flooding: London, Allen and Unwin, p. 267-288. 

U.S. Army Corps of Engineers, 1963, Review of reports (House 

Document 645, of 78th Cong., 2nd sess.) Rowlesburg 

Reservoir, app. I, Hydrology: Pittsburgh, Pa., 26 p. and 

20 pls. 

U.S. Bureau of Census, 1913, Thirteenth census of the United 

States taken in 1910, vol. II, Agriculture 1909 and 1910, 

Nebraska-Wyoming: Washington, D.C., U.S. Department of 

Commerce, 1013 p. 

---1989a, 1987 Census of agriculture advance copy report, 

Preston County, W. Va.: Washington, D.C., U.S. Department of Commerce, 2 p. 

---1989b, 1987 Census of agriculture advance copy report, 

Tucker County, W. Va.: Washington, D.C., U.S. Department of Commerce, 2 p. 

U.S. Geological Survey, 1971, Surface water supply of the United 

States 1961-1965, part 3, Ohio River basin, vol. 1, Ohio 

River basin above Kanawha River: U.S. Geological Survey 

Water-Supply Paper 1907, 621 p. 

---1976, Surface water supply of the United States 

1965-1970, part 3, Ohio River basin, vol. 1, Ohio River 

basin above Kanawha River: U.S. Geological Survey WaterSupply Paper 2107, 668 p. 

---1985, National water conditions, November 1985, Streamflow during November: U.S. Geological Survey, 7 p. 

Venable, N.J., 1990, Canaan Valley: West Virginia Renewable 

Resources Unique areas series 812, West Virginia University 

Extension Service, 32 p. 

Wells, J.V.B., 1957, Compilation of records of surface waters of 

the United States through September 1950, part 3-A, Ohio 

River basin except Cumberland and Tennessee River basins: 

U.S. Geological Survey Water-Supply Paper 1305, 652 p. 

West Virginia Geological and Economic Survey, no date, Generalized geologic map of the coal fields of West Virginia: 

Morgantown, W. Va., West Virginia Geological and Economic Survey, 1 sheet. 

Wiley, S.T., and Frederick, A.W., 1882, History of Preston 

County (West Virginia): Kingwood, W. Va., The Journal 

Printing House, 529 p. 

Williams, G.P., 1984, Paleohydrologic equations for rivers, in 

Costa, J.E., and Fleisher, P.J., eds., Developments and 

applications of geomorphology: Berlin, Springer-Verlag, 

p. 343-367. 

Williams, G.P., and Costa, J.E., 1988, Geomorphic measurements after floods, in Baker, V.R., Kochel, R.C., and 

Patton, P.C., eds., Flood geomorphology: New York, John 

Wiley and Sons, p. 65-77. 

Williams, G.P., and Guy, H.P., 1973, Erosional and depositional 

aspects of Hurricane Camille in Virginia, 1969, U.S. Geological Survey Professional Paper 804, 80 p. 

Wolman, M.G., and Gerson, R., 1978, Relative scales of time 

and effectiveness of climate in geomorphology in watershed 

geomorphology: Earth Surface Processes, v. 3, p. 189-208. 

024 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W. Va., Va. 
Chapter E 

Flood Hydrology and Geomorphic Effects 

on River Channels and Flood Plains: 

The Flood of November 4-5, 1985, in the 

South Branch Potomac River Basin of West 

Virginia 

By ANDREW j. MILLER and DOUGLAS j. PARKINSON 

U.S. GEOLOGICAL SURVEY BULLETIN 1981 

GEOMORPHIC STUDIES OF THE STORM AND FLOOD OF NOVEMBER 3-5, 1985, IN 

THE UPPER POTOMAC AND CHEAT RIVER BASINS IN WEST VIRGINIA AND VIRGINIA 
II Contents 

CONTENTS 

Abstract El 

Introduction El 

Purpose and Scope E6 

Organization E6 

Bottomland Morphology E6 

Structural Control of Drainage E6 

Patterns of Valley Width E7 

Geomorphic Surfaces E7 

Channel Pattern E7 

Hydrology of the November 1985 Flood in the South Branch Potomac River Basin ElO 

Peak Discharge ElO 

Crest Stage and Longitudinal Profiles E17 

Timing of Flood Wave and Shape of the Hydrograph E18 

Recurrence Intervals E19 

Hydraulic Parameters E21 

Sediment Loads E23 

Flood Impacts E23 

Erosion and Deposition at Tributary Confluences E23 

Delta Forms E24 

Fan Deposits E25 

Erosion Features on Bottomland E26 

Longitudinal Grooves E27 

Scour Marks E28 

Bank Erosion and Channel Widening E37 

Stripping E39 

Chutes E44 

Anastomosing Channels and Jet-Shaped Erosion Forms E52 

Deposition Features E66 

Channel Bars E66 

Bottomland Deposits E69 

Classification of Impacts on the Valley Floor E73 

Spatial Distribution of Erosion Classes E75 

Discussion E85 

Summary and Conclusions E93 

References Cited E93 

PLATE 

1. Geomorphic effects of flood November 3-5, 1985, South Branch Potomac 

River In pocket 
FIGURES 

Unless otherwise indicated, all postflood aerial photographs are from a set of flight lines flown for 

the West Virginia Department of Highways within 3 days after the flood. Preflood aerial 

photographs are from a project flown in 1980 for the Army Corps of Engineers. 

1. Map showing major streams, drainage divides, and gaging stations in the 

South Branch Potomac River basin E3 

2. Location map of the Potomac River basin E4 

3,4. Photographs showing: 

3. Property damage on flood plain, North Fork South Branch Potomac 

River ES 

4. Trailer frame wrapped around tree by floodwaters ES 

5. Sketch maps illustrating river channels and valley-floor outlines: (A) North 

Fork South Branch and South Branch Potomac Rivers upstream of their 

confluence, to South Branch Potomac River downstream of Petersburg Gap; 

(B) South Branch Potomac River, from downstream of Petersburg Gap to 

Sector, downstream of the Trough ES 

6. Graph showing longitudinal profiles of North Fork South Branch, South 

Branch, and South Fork South Branch Potomac Rivers upstream of 

Moorefield ElO 

7. Sketch map showing locations of valley constrictions and bedrock canyons 

and average width of valley floor along the three forks of the South Branch 

Potomac River upstream of Moorefield Ell 

8. Photointerpretive sketch showing valley planform and associated geomorphic 

features along the North Fork South Branch Potomac River downstream of 

Riverton El2 

9. Aerial photographs illustrating reoccupation and incision of old flood-plain 

channels: (A and B) North Fork South Branch Potomac River at Judy Gap, 

before and after November 1985 flood; (C and D) South Fork South Branch 

Potomac River near Milam, before and after November 1985 flood El3 

10. Graph of peak discharge versus drainage area for the November 1985 

flood, compared with the largest rainfall-runoff floods recorded for the 

United States El5 

11. Photograph showing spillway of Soil Conservation Service flood control dam 

eroded by the 1985 flood El5 

12. Sketch map illustrating river channel and valley-floor outline along South 

Branch Potomac River from Franklin to Smoke Hole canyon El6 

13-16. Longitudinal profiles of November 1985 flood crest: 

13. Along South Branch Potomac River from Franklin gage to Smoke Hole 

downstream of Upper Tract El7 

14. Along South Branch Potomac River from downstream of Petersburg Gap 

to Sector El7 

15. Along South Branch Potomac River from unnamed gap upstream of 

Petersburg to downstream end of Petersburg Gap El7 

16. Along North Fork South Branch Potomac River from Hapeville to 

confluence with South Branch Potomac River, and extending along 

the South Branch Potomac River to the site of the Petersburg gaging 

station El8 

17. Stage hydrographs for the November 1985 flood at Brandywine and 

Franklin El9 

18. Photograph showing the valley floor along the South Branch upstream of 

Petersburg E20 

19. Plot of estimated time of flood crest versus distance upstream of the 

confluence of the South Branch and North Branch Potomac Rivers E20 

Contents Ill 
IV Contents 

20-32. Photographs showing: 

20. Scouring and widening of small tributary to the North Fork South Branch 

Potomac River between Judy Gap and Riverton E23 

21. Scoured channel and exposed colluvium of adjacent slope, along 

Dry Run about 1 km upstream of confluence with North Fork South 

Branch Potomac River E23 

22. Incised channel and birds-foot delta at confluence of small unnamed 

intermittent stream with South Fork South Branch Potomac River at 

Palo Alto E24 

23. Valleys of two unnamed tributaries to the South Branch Potomac River 

near the Virginia-West Virginia border E24 

24. Delta formed at mouth of unnamed tributary to the South Branch 

Potomac River at Blue Rock in Smoke Hole canyon E25 

25. Aerial view of delta E25 

26. Delta at the mouth of Redman Run, tributary to South Branch Potomac 

River in Smoke Hole canyon E25 

27. Erosion and deposition on fan at the mouth of Nelson Run, tributary to 

North Fork South Branch Potomac River between Circleville and Judy 

Gap E26 

28. Incision of fan and flood-plain deposits by anastomosing channel system 

at the confluence of Big Run and the North Fork South Branch Potomac 

River E26 

29. Longitudinal grooves (A) formed by the limbs of a tree dragged across 

valley floor, North Fork South Branch Potomac River about 0.6 km 

upstream of Seneca Rocks; (B) oriented along direction of flow, North 

Fork South Branch Potomac River about 10 km upstream of Hopeville; 

(C) incised along crop rows, South Branch Potomac River near 

Fisher E28 

30. Grooves formed as drag marks by trees entrained in flood flow, South 

Fork South Branch Potomac River, 2 km upstream of Milam E29 

31. Deeply incised grooves oriented subparallel to crop rows, Cheat River 

about 2 km upstream of Rowlesburg E29 

32. Grooves incised along trend of shallow erosional trough, South Branch 

Potomac River just downstream of Petersburg gaging station E30 

33. Drawing showing flow pattern of longitudinal corkscrew vortices and their 

hypothesized effects on the shape of the underlying bed E30 

34-58. Photographs showing: 

34. Scour marks on valley floor (A) along South Branch Potomac River 

between Redman Run and Austin Run and (B) along Cheat River about 2 

km upstream of Rowlesburg E31 

35. Elongate scour marks along South Fork South Branch Potomac River, 7 

km downstream of Brandywine E32 

36. Headward branching scours (A) on North Fork flood plain, about 2 km 

downstream of Circleville and (B) on South Fork flood plain, 13 km 

upstream of Moorefield E33 

37. Headward-eroding scour, North Fork 1.5 km downstream of 

Riverton E34 

38. Irregular scour pattern on forested surface upstream of a field cleared for 

row crops, Cheat River, 10 km upstream of Rowlesburg E34 

39. Scour marks created by flow separation around isolated objects on the 

flood plain (A) on South Branch Potomac River between Redman Run and 

Austin Run and (B) on Black Fork River, tributary to Cheat River, 1 km 

upstream of Parsons E35 
34-58. Photographs showing-Continued: 

40. Fallen tree flanked by a pair of elliptical scour marks, Cheat River about 

8 km downstream of Parsons E36 

41. Debris jam formed on upstream side of tree, South Branch Potomac 

River 5.4 km upstream of confluence with North Fork E36 

42. Sand deposit formed in the lee of a standing tree, South Branch 

Potomac River between Redman Run and Austin Run E36 

43. Scour marks associated with flow obstructions on (A) South Fork South 

Branch Potomac River at Brandywine and (B) South Branch Potomac 

River near Durgon, 9 km downstream of Petersburg E38 

44. Headcut in a new channel actively retreating upstream at low flow, 

South Branch Potomac River 4.4 km upstream of confluence with the 

North Fork E39 

45. Complex pattern of scour and incision, flood plain of Black Fork River 

at Hendricks (tributary to Cheat River) E40 

46. Channel widening: (A and B) along the South Branch upstream of 

Petersburg, before and after the November 1985 flood; (C) and (D) 

along the South Fork about 6 km downstream of Milam, before and 

after the November 1985 flood E41 

47. Channel widening along the North Fork at Macksville, 4. 7 km upstream 

of Seneca Rocks E43 

48. Channel of South Branch downstream of confluence with North Fork; 

steep cutbank grades into a stripped area E43 

49. Channel widening and stripping of flood plain along North Fork 8.4 km 

upstream of Hopeville (A) before and (B) after the flood E44 

50. Before-and-after views showing scour of forested channel margins and 

low flood plain along South Fork, 2 km upstream of Milam E45 

51. Before-and-after views illustrating channel widening and stripping of 

flood plain along the North Fork at Hopeville E46 

52. Before-and-after views showing channel widening downstream of a 

bridge crossing the South Fork at Fort Seybert E47 

53. Channel widening and flood-plain scour, South Fork at Brandywine gaging station E48 

54. Three examples of flood-plain stripping: (A) North Fork in canyon 

upstream of Hopeville; (B) North Fork near North Fork Gap; (C) South 

Branch, 0.8 km downstream of the Trough E49 

55. Imbricated pavement of cobbles and boulders on stripped flood plain, 

North Fork in canyon upstream of Hopeville E50 

56. Tree stump next to low-water channel, North Fork in canyon upstream 

of Hopeville E51 

57. Gradation from stripped surface to depositional lobe derived from 

stripped material, North Fork, 2.5 km downstream of Hopeville E51 

58. Mounds of rolled-up turf located around margins of an elongate scour 

mark, South Branch flood plain E52 

59. Postflood cross section of North Fork valley at Seneca Rocks Visitor 

Center E52 

60-101. Photographs showing: 

60. South Fork near Fort Seybert, (A) before and (B) after the flood; chutes 

in (B) are incised along the trends of swales visible in (A) E53 

61. Incipient chute eroded in South Fork flood plain near Oak Flat E54 

62. Chute on flood plain of North Fork at Seneca Rocks Visitor Center E54 

63. Chute on flood plain of North Fork about 0.6 km upstream of Seneca 

Rocks E55 

64. Ground view of upstream end of chute illustrated in figure 63 E55 

Contents V 
VI Contents 

60-101. Photographs showing-Continued: 

65. Chute with branching headcuts, South Branch at Smith Creek, about 3. 5 

km upstream of Franklin E56 

66. Chute in figures 63 and 64, shown looking downstream E56 

67. Two views of the right bank of the chute in figure 66, illustrating 

sequence of cobbles and gravels underlying flood plain E57 

68. The left bank of the chute illustrated in figures 66 and 67; exposure 

reveals a sequence of fine-grained alluvium with interbedded gravel 

lenses E57 

69. The left bank of the South Fork at Brandywine; exposure reveals a 

gravel lens (near the base) that resembles the lenses shown in 

figure 68 E57 

70. Narrow chutes on forested bottomland, South Fork, 1.9 km downstream 

of Brandywine gaging station, seen (A) before and (B) after the 

flood E58 

71. Before-and-after views illustrating channel widening and dissection of 

the flood plain, South Branch about 3 km upstream of Franklin E59 

72. Before-and-after views of valley floors extensively dissected by 

anastomosing erosion channels: (A and B) Adamson dairy farm, South 

Fork 6 km downstream of Fort Seybert; (C and D) North Fork near 

Zeke Run, 12 km downstream of Seneca Rocks and 10 km upstream 

of Hapeville E60 

73. Before-and-after views of valley floors dissected by jet-shaped erosion 

forms: (A and B) South Fork about 3 km downstream of Brake; ( C and 

D) North Fork about 3 km downstream of Seneca Rocks; (E and F) 

North Fork about 8 km downstream of Seneca Rocks and 14 km 

upstream of Hapeville; ( G and H) South Branch about 5 km downstream 

of Franklin E62 

7 4. Two views of sediment deposited in the streets of Petersburg, W. Va. 

(A) Mud deposits about 30 em deep; (B) ripple marks in sand E67 

7 5. Mud deposited on flood plain of Potomac River near upstream end of 

C&O Canal tunnel, 2 km downstream of Paw Paw, W. Va. E68 

76. Mud deposited on flood plain and silt line on vegetation indicating 

elevation of high water during the November 1985 flood; Monocacy 

Aqueduct, junction of Monocacy River with Potomac River E68 

77. Before-and-after views of South Branch near the Virginia-West Virginia 

boundary E68 

78. Before-and-after views of South Branch at Ruddle E70 

79. Before-and-after views of South Branch at Franklin E70 

80. Gravel bar in South Branch channel, 1 km downstream of confluence 

between South Branch and North Fork E71 

81. Before-and-after views illustrating bank erosion and bar formation along 

South Branch at the mouth of Redman Run, about 6 km upstream of the 

confluence with the North Fork E71 

82. Lateral bars attached to slightly convex banks: (A) North Fork, 2.7 km 

downstream of Circleville; (B) North Fork, 0.8 km downstream of 

Riverton E72 

83. Longitudinal bars (A) along South Branch, about 5 km upstream of 

Franklin and (B) along North Fork, about 2 km upstream of Seneca 

Rocks E73 

84. Compound bar formed from dissected flood-plain remnants and freshly 

deposited gravels, North Fork between Cabins gage site and 

Hope ville E7 4 

85. Compound bar, North Fork about 2 km upstream of Riverton E75 
60-101. Photographs showing-Continued: 

86. Gravel splays derived from bottomland erosion downstream of bridge, 

South Branch Potomac River 1 km upstream of Romney E76 

87. Gravel splays with dentate outer margins and scrolled ridges and 

troughs; (A) South Branch about 4 km upstream of confluence with 

North Fork; (B) North Fork between Seneca Rocks and Hapeville; 

(C) South Fork near Fort Seybert E77 

88. Steep slipface near downstream end of gravel splay deposits, South 

Branch 5. 5 km upstream of confluence with North Fork E78 

89. Gravel sheets flanking the main river channel: (A) North Fork, 3.6 km 

upstream of Seneca Rocks; (B) South Branch downstream of the 

Trough ESO 

90. Levee deposits bordering the channel and sand splays on the flood 

plain, Cheat River, 8 km downstream of Parsons ESt 

91. Feathered or dentate sand deposits on the valley floor: (A) South Fork, 

2 km upstream of Milam; (B) South Fork, 6 km downstream of 

Milam; (C) North Fork, 9 km downstream of Seneca Rocks; (D) South 

Fork, 8.5 km downstream of Brandywine E82 

92. Gravel levee, South Branch Potomac River 4 km upstream of 

Franklin E83 

93. Sand levees associated with flow obstruction by trees bordering the 

channel: (A) South Branch 20 km upstream of confluence with North 

Fork; (B) South Fork at Fort Seybert E83 

94. Backwater deposits upstream of a road embankment at the entrance to 

a bedrock gorge, South Branch 2 km downstream of Franklin E84 

95. Sand sheet on right bank of South Branch at the site shown in 

figure 94 E84 

96. Sand dunes near left bank of South Branch Potomac River at the site 

shown in figure 94 E84 

97. Sand deposits bordering South Branch channel 0. 8 km upstream of the 

confluence with the North Fork E84 

98. Before-and-after views of the South Fork just downstream of the 

Moorefield gage, illustrating characteristics associated with erosion 

class B E85 

99. Before-and-after views of the North Fork valley about 10 km downstream of Seneca Rocks and 12 km upstream of Hapeville, illustrating 

characteristics associated with erosion class C; (C) photointerpretive 

sketch identifying erosion and deposition features E86 

100. Before-and-after views of the confluence of the North Fork South 

Branch and South Branch Potomac Rivers, illustrating characteristics 

associated with erosion class D ESS 

101. Before-and-after views of the North Fork valley about 7 km upstream 

of Seneca Rocks, illustrating characteristics associated with erosion 

class D E89 

102. Map showing generalized spatial distribution of severe valley-floor 

erosion. E90 

103,104. Plots of percent reach length assigned to erosion classes C and D versus: 

103. Average width of valley floor E91 

104. Reach-average values of unit stream power E91 

TABLES 

1. Hydrologic data compiled for U.S. Geological Survey gage sites: November 1985 

flood, South Branch Potomac River basin E2 

Contents VII 
VIII Contents 

2. Comparison of 1985 peak discharge with estimated 100-yr and 500-yr peak 

discharge E2 

3. Channel gradients along the three forks of the South Branch Potomac River ElO 

4. Peak discharge estimates for four Soil Conservation Service flood-control 

reservoirs: November 1985 flood, South Fork South Branch Potomac River 

basin E15 

5. Hydraulic parameters calculated for U.S. Geological Survey gage sites E21 

6. Unit stream power calculated for U.S. Geological Survey gage sites E22 

7. Definition of erosion classes E75 

8. Summary data on erosion classes E79 

9. Physiographic parameters, reach-average values of unit stream power, and spatial 

extent of severe erosion for individual valley reaches along the three forks of the 

South Branch Potomac River E79 
Flood Hydrology and Geomorphic Effects on River 

Channels and Flood Plains: 

The Flood of November 4-5, 1985, in the South 

Branch Potomac River Basin of West Virginia 

By Andrew J. Miller1 and Douglas J. Parkinson2 

Abstract 

The November 1985 flood was the largest recorded 

in the South Branch Potomac River basin. Discharges 

exceeded values estimated for a recurrence interval of 500 

yr at four of six stations in the basin. Flow velocities in the 

channel were as high as 4.6 m/s and may have exceeded 6 

m/s at some locations; estimated values of unit stream 

power at U.S. Geological Survey gage locations were as 

high as 988 W/m2 and may have exceeded 2,500 W/m2 at 

some locations. Along the three forks of the South Branch 

Potomac River, discharges of 1,000-7,000 m3/s flowed 

through valley cross sections that ranged in width from 

less than 70 m to 1,700 m, and, as a result, hydraulic 

conditions were extremely variable. Valley constrictions 

and expansions were important determinants of erosion 

and deposition patterns. 

Geomorphic impacts on valley floors along the three 

forks of the South Branch Potomac River included formation of a wide array of erosion and deposition features. 

Flood-generated erosion features included longitudinal 

grooves, scour marks, widened channels, stripped flood 

plains, chutes, anastomosing erosion channels, and jetshaped erosion forms. Deposition features were generally 

adjacent to eroded areas and included channel gravel 

bars, gravel splays, gravel and sand sheets, isolated gravel 

bars and sand dunes on flood plains, wake deposits, and 

backwater deposits. 

Mapping of erosion damage classes along 384 km of 

channel and valley floor revealed that 82.8 percent of the 

valley length experienced at least incipient erosion, 30.2 

percent experienced severe erosion, and 5.7 percent 

experienced catastrophic erosion of the valley floor. 

Reach-average values of unit stream power were positively 

correlated with the percent of the valley reach that expeManuscript approved for publication February 22, 1991. 1 Department of Geography, University of Maryland Baltimore 

County, Baltimore, MD 21228. 2 Department of Geography and Environmental Engineering, The 

Johns Hopkins University, Baltimore, MD 21218. 

rienced severe erosion; percentages of 50 percent or 

more were associated with average values of 200-500 

W/m2 • These results suggest that, with further research, it 

should be possible to define threshold conditions for 

bottomland erosion. 

INTRODUCTION 

The flood of November 4-5, 1985, was the largest 

recorded in the South Branch Potomac River basin. Peak 

discharges exceeded previous records at five of six gaging 

stations and exceeded the estimated 500-yr discharge at four 

of those gage sites (tables 1, 2). Crest stage exceeded the 

1949 record flood crest by amounts ranging from 0. 79 to 

3.41 m at five gages and equaled the 1949 record at the 

sixth gage. 

The three major forks of the South Branch Potomac 

River (pl. 1, fig. 1) began to overflow their banks on the 

afternoon of November 4. The actual time of the flood crest 

was recorded at only one gage, and there are few eyewitness 

reports available for other locations. From these reports, we 

project that the upper reaches reached crest stage between 6 

p.m. and 9 p.m., the middle reaches between 10 p.m. and 

2 a.m. the next morning, and the South Branch below the 

confluence of the forks after 4 a.m. on November 5. 

Reports from some locations along the middle reaches 

indicate that the flood receded rapidly and the rivers were 

only slightly above flood stage by midmorning; thus, the 

most extreme flow conditions occurred under cover of 

darkness. The only complete stage record from the South 

Branch basin was collected on the South Fork South Branch 

Potomac River at Brandywine, W. Va., and shows that the 

South Fork exceeded bankfull stage for 27-28 h; however, 

the stage was more than 1 m above bankfull for only 14 h. 

During the daylight period of November 5, the flood crest 

continued moving down the main stem of the South Branch; 

Flood Hydrology and Geomorphic Effects, Flood of Nov. 4-5, 1985, W.Va. E1 
Table 1. Hydrologic data compiled for U.S. Geological Survey gage sites: November 1985 flood, South Branch Potomac 

River basin 

Drainage area Peak discharge Peak unit discharge Ratio of peak Average 

Station 

km2 mi2 m3

/s fels m3

/s/km2 fe/s/mi 2 discharge to previous precipitation 

record discharge upstream of gage (mm) 

South Branch Potomac River 471 182 1,246 44,000 2.65 242 2.93 191 

at Franklin, W.Va. 

North Fork South Branch 813 314 2,549 90,000 3.14 287 1.80 221 

Potomac River at 

Cabins, W.Va. 

South Branch Potomac River 1,663 642 3,681 130,000 2.21 202 2.10 220 

near Petersburg, W.Va. 

South Fork South Branch 264 102 1,147 40,500 4.34 397 .98 158 

Potomac River near 

Brandywine, W.Va. 

South Fork South Branch 733 283 3,115 110,000 4.25 389 2.82 171 

Potomac River near 

Moorefield, W.Va. 

South Branch Potomac River 3,810 1,471 6,796 240,000 1.78 163 1.68 176 

near Springfield, W.Va. 

Table 2. Comparison of 1985 peak (Qpk) discharge with estimated 100-yr (Q100) and 500-yr (Q500) peak discharge 

P=0.01 (Q100) P=0.002 (Q500) November 1985 Opk/01oo 

Station Bulletin 17B1 Regional curves2 Bulletin 17B1 Regional curves2 (Qfk) 4 

(m3/s) (m3/s) (m3

/s) (m3

/s) (m /s) 

South Branch Potomac River 595 736 883 1,199 1,246 2.09 1.69 

at Franklin, W.Va. 

North Fork South Branch 1,371 1,209 2,330 1,992 2,549 1.86 2.11 

Potomac River at Cabins, 

W.Va. 

South Branch Potomac River 2,071 2,316 3,440 3,873 3,681 1.78 1.59 

near Petersburg, W.Va. 

South Fork South Branch 818 445 1,361 735 1,147 1.40 2.58 

Potomac River near 

Brandywine, W.Va. 

South Fork South Branch 1,453 1,099 2,748 1,808 3,115 2.14 2.83 

Potomac River near 

Moorefield, W.Va. 

South Branch Potomac River 4,305 4,927 7,404 8,374 6,796 1.58 1.38 

near Springfield, W.Va. 

1 Estimates based on individual station records, supplemented by data on historic floods (Interagency Advisory Committee on Water Data, 1982). 

Results furnished by W.O. Thomas, U.S. Geological Survey. 2 Regional flood-frequency curves for West Virginia region 3 (Runner, 1980). 3 Ratio of November 1985 peak to estimated 100-yr peak as computed using Bulletin 17B (see footnote 1). 4 Ratio of November 1985 peak to estimated 100-yr peak as computed using West Virginia regional flood-frequency curves. 

crest stage was recorded at about 10:15 p.m. at Paw Paw, 

W. Va., downstream of the confluence with the North 

Branch (fig. 2). 

No direct observations of current velocity were made 

during the flood. Estimates based on slope-area measurements of peak discharge indicate cross-section average 

velocities up to 4.6 rn!s in constricted canyon reaches and 

average velocities in the range 2-2.5 rnls in broader 

reaches. The force of the flow was sufficient to cause 

widespread erosion of valley floors and transportation of 

enormous amounts of debris, with the largest boulders 

transported exceeding 2 m along the intermediate axis. 

Property damage in some areas was reminiscent of the 

effects of a tornado (figs. 3, 4). Groves of trees were 

uprooted or broken off above ground level, and many trees 

came to rest in debris jams accumulating around flow 

obstructions on the valley floor. Buildings were lifted off 

their foundations or torn apart where they stood; debris jams 

often contained fragments of houses or their contents. In 

several cases, people trapped by the rising water took refuge 

in houses and later drowned when those buildings were 

overturned or destroyed (West Virginia Advocate, 1986). 

Mobile homes and motor vehicles at some sites were 

entrained in the flow and transported tens to hundreds of 

E2 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W.Va., Va. 
10 MILES 

~ Gaging Station 0 10 20 30 KILOMETERS 

Figure 1. Major streams, drainage divides, and gaging stations in the South 

Branch Potomac River basin. Drainage divides within the basin are represented by dashed lines. 

meters along the valley floor. Railroad tracks in at least two 

areas were lifted off their beds, carried down valley, and 

twisted into spiral patterns. 

Where erosion was most intense, particularly along 

the North Fork South Branch Potomac River downstream of 

Circleville, W. Va., roads and bridges were swept away. 

News reports following the flood suggested that many farms 

in prime agricultural bottomland would never grow crops 

again, owing either to total removal of topsoil or to 

deposition of sheets of gravel on the flood plain (West 

Virginia Advocate, 1986). Only a massive relief effort, in 

some cases including the use of imported fill material, 

permitted reestablishment of agriculture at these sites. 

Channel rehabilitation efforts generally restored the river 

Flood Hydrology and Geomorphic Effects, Flood of Nov. 4-5, 1985, W. Va. E3 
~--------­

i 

i 

i 

I 

0 

0 

10 MILES 

10 20 

I 

I 

I 

,. / 

/ ,., 

30 KILOMETERS 

HINGTON 

D.C. 

Figure 2. Potomac River basin. The shaded area is the South Branch Potomac River basin. 

channels to their former courses, although the channels 

themselves were often widened substantially and denuded 

of vegetation. Debris and large boulders were generally 

cleared from the channel, and thick lobes of sediment on the 

flood plain were scraped off and piled along channel 

margins to form levees. 

Few reliable observations of flow patterns and processes were obtained during the flood, and flood-plain and 

channel rehabilitation efforts quickly erased or obscured 

much of the physical evidence. An excellent documentary 

record was preserved, however, in aerial photographs 

(average scale about 1:8,000) flown for the West Virginia 

Department of Highways within 5 days following the flood. 

Although intended for assessment of road damage, the 

photographs show the intensity and spatial distribution of a 

series of erosion and deposition features formed by the 

flood on valley floors throughout the South Branch Potomac 

River basin. Most of these bear some resemblance to 

features that have been described in the literature before; 

however, we know of no previous flood in which the visual 

evidence of valley-floor erosion was both so widespread 

and so well documented. Although this report is concerned 

E4 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W. Va., Va. 
Figure 3. Property damage on flood plain, looking upstream along valley of North Fork South Branch Potomac River 

immediately upstream of North Fork Gap. The river is located to the left of the field of view. Photograph by F .N. Scatena. 

Figure 4. Trailer frame wrapped around tree by floodwaters. Note severely damaged house in background. 

Photograph by D. Lafon, U.S. Army Corps of Engineers. 

Flood Hydrology and Geomorphic Effects, Flood of Nov. 4-5, 1985, W. Va. E5 
primarily with the South Branch basin, the aerial photographs of the Cheat River basin have superior resolution, 

and some have been used to illustrate type examples of 

particular erosion and deposition features. 

Purpose and Scope 

The primary purpose of this report is to describe the 

November 1985 flood and its geomorphic impacts on valley 

floors in the South Branch Potomac River basin. This is an 

essential prerequisite to more detailed analysis of the factors 

controlling spatial distribution and morphology of fluvial 

erosion and deposition features of the flood. 

The report concentrates on the South Branch, North 

Fork South Branch, and South Fork South Branch Potomac 

Rivers between the Virginia-West Virginia border and the 

confluence of the South Branch and the South Fork South 

Branch Potomac Rivers at Moorefield. Some additional 

information has been compiled for the South Branch downstream of Moorefield. We first visited the field area in 

December 1985 as part of a reconnaissance study for the 

Interstate Commission on the Potomac River Basin (Scatena, 1986). Subsequent to this trip, we visited the study 

area many times beginning in the spring of 1986. Much of 

the analysis is based on examination of preflood and 

postflood aerial photographs. 

Organization 

The report is organized as follows. 

• Discussion of bottomland morphology in the study 

basin and of the interaction between boundary conditions and flood hydraulics; 

• Presentation of hydrologic and hydraulic data for the 

November 1985 flood in the South Branch Potomac 

River basin; 

• Brief description of erosion and deposition features 

observed at the mouths of tributaries to the three forks 

of the South Branch Potomac River; 

• Description and classification of channel and floodplain erosion features formed in the November 1985 

flood; 

• Description and classification of channel and floodplain deposition features formed in the flood; 

• Definition of a simple four-part hierarchical system for 

classifying erosion patterns in order to map their spatial 

distribution at basin scale; 

• Description and analysis of the spatial distribution of 

erosion classes along the three forks of the South 

Branch Potomac River; 

• Discussion and conclusions. 

Previous studies that discuss aspects of the fluvial 

geomorphology of the South Branch basin include Fridley 

(1939, 1940), VerSteeg (1940), Hack and Goodlett (1960), 

Clark (1967, 1987), Sites (1973), and Hack (1973). References on bedrock geology and hillslope geomorphology are 

provided by Jacobson and others (chapter C, this volume). 

Background data on basin hydrology are reported in Baloch 

and others (1971), Hobba and others (1972), and Friel and 

others (1975). Preliminary observations on the aftermath of 

the 1985 flood are reported in Scatena (1986), Clark and 

others (1987), Kite (1987), and Kite and Linton (chapter D, 

this volume). 

BOTTOMLAND MORPHOLOGY 

The trajectory of flood flow and resulting patterns of 

erosion and deposition appear to have been guided by the 

shape and orientation of the valley boundaries as well as the 

channel boundaries. Local valley topography and spatial 

configuration of roughness elements in the path of the flow 

also played an important role in determining where the 

flood had the greatest impact on the valley floor. The 

following discussion focuses on aspects of bottomland 

morphology that apparently influenced the spatial distribution and intensity of flood impacts in November 1985 in the 

South Branch basin. 

Structural Control of Drainage 

The South Branch Potomac River basin (fig. 1, pl. 1) 

is primarily in the Valley and Ridge physiographic province; the western tributaries to the North Fork drain the 

Appalachian Plateau. Drainage forms a trellis pattern, with 

the three main forks of the South Branch following parallel 

trends approximately N30°E. Valleys are underlain mostly 

by shale and limestone, and intervening ridges are capped 

by sandstone. Although the valleys run dominantly along 

strike, local structural weaknesses (Clark, 1967) have 

allowed river channels to cut paths transverse to strike, 

forming prominent water gaps (fig. SA) where streams flow 

across ridge-forming sandstones and quartzites. The strike 

valleys are narrow but generally have some alluvial bottomland. There are also several extended valley reaches parallel 

to strike where the rivers run through bedrock canyons; but 

even in the canyons, the lithologies exposed in the channel 

and valley walls are variable. Geologic structure exerts a 

dominant but poorly understood influence on valley morphology in this region, one of the most complex areas of the 

Appalachians; some of the structural features have yet to be 

resolved (C. Scott Southworth, U.S. Geological Survey, 

written communication, 1987; Gerritsen and Dunne, 1988). 

Channel gradients along the three forks of the South 

Branch upstream of Moorefield generally range from 0.002 

to 0.009, and gradients in the bedrock canyons typically are 

steeper than reaches immediately upstream and downstream. The North Fork is steeper than either the South Fork 

or the South Branch (fig. 6, table 3), and this difference 

E6 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W. Va., Va. 
probably accounts in part for greater erosion in the North 

Fork valley during the November 1985 flood. Between 

Moorefield and the confluence with the North Branch 

Potomac River, the gradient of the South Branch becomes 

much gentler, with an average value of 0.0009. 

Patterns of Valley Width 

Average valley widths upstream of the confluences of 

the North Fork with the South Branch and of the South Fork 

with the South Branch generally range between 200 and 400 

m for drainage areas up to about 800 km2

. Although a few 

locations have valley floors up to 1 ,000 m wide, geologic 

structure effectively prevents any systematic increase in 

width of the three valleys of the South Branch as drainage 

area increases. Downstream of the major confluences the 

valleys broaden locally; the valley floor at Petersburg is 

almost 1,400 m wide at its broadest point (fig. SA), and the 

valley floor downstream of Moorefield broadens to more 

than 1, 700 m (fig. 5B). However, broad flood plains 

continue to alternate with constricted valley floors and 

bedrock canyons. Along the South Branch downstream of 

Moorefield, average valley-floor widths range from 95 to 

1 ,250 m; from Romney to the confluence with the North 

Branch, the valley floor is generally 350 to 500 m wide. 

Figure 7 illustrates the spatial distribution of average 

valley widths and of constrictions and canyon reaches along 

the three forks of the South Branch between the Virginia 

State line and Moorefield (also see pl. 1). In the canyons 

oriented along strike and in the water gaps cut through 

prominent ridges, the valley floors often are 125 m or less 

in width. Even where the river does not flow through a 

canyon or a major water gap, alternating expanding and 

contracting reaches are characteristic of these valleys and 

appear to have had an important influence on flow hydraulics during the 1985 flood. In some reaches, resistant 

bedrock spurs form local constrictions where the valley 

floor is no more than 50-70 m wide. Local constrictions 

may also be created by terraces or by fans at the mouths of 

tributaries, as can be seen along some parts of the North 

Fork valley (fig. 8). In some cases, valley-floor width 

varies by an order of magnitude within a longitudinal 

distance of 1 km. 

Geomorphic Surfaces 

Valley-floor topography and large roughness elements strongly influenced both depth and direction of flood 

flow and local patterns of erosion and deposition in the 

November 1985 event. At some locations, planform of the 

flooded area and the spatial pattern of features providing 

flow resistance changed significantly with flood stage. 

Features contributing to elevation and roughness variations 

included secondary channels, topographic steps, roads, 

bridges, fence lines, and patches of forest. Flow often 

separated around buildings or trees, affecting erosion and 

deposition nearby; in some cases, flow separated around a 

local topographic rise on the valley floor. Although preexisting overflow channels and tributaries were eroded in 

many places, new channels also formed at sites throughout 

the basin. Our discussions of flood-plain erosion and 

deposition forms include numerous illustrations and qualitative information about the role of these features. 

The bottomlands inundated in the 1985 flood generally consist of two main geomorphic surfaces. One surface 

appears to be a flood plain and is 2. 5-4 m above the 

low-water channel; this surface occupies the majority of the 

valley floor in most reaches. Local residents have stated that 

this surface was flooded in 1949 and 1985 but that only the 

swales and overflow channels incised in this surface were 

flooded in other events. At some locations this surface was 

not flooded even in 1949. Although it is generally relatively 

flat, the surface sometimes tilts either laterally or downvalley. and therefore its elevation above the channel may vary 

along a reach that is several hundred meters in length. 

Furthermore, debris fans and colluvial deposits commonly 

grade to the valley floor, creating local areas of greater 

relief. Although this surface does not conform strictly to the 

flow criterion used for defining a flood plain (Wolman and 

Leopold, 1957), it is not a well-defined terrace either. 

Subsequent use of the term "flood plain" in this report 

includes this surface. 

A lower surface is present at many sites but is much 

less extensive and appears to occupy channel-margin belts 

and point-bar locations. It is most prominently developed in 

the South Fork basin. Whereas the upper surface is generally cleared for pasture or crops, the lower surface ( 1-1.5 m 

above low water) is commonly forested. Coarse particle 

sizes, hummocky surface relief, and greater frequency of 

inundation make this surface less suitable for agriculture 

than the higher surface. The low surface may be characterized either as flood plain or as active channel shelf, a 

geomorphic surface that is inundated during semiannual 

high-flow events (Osterkamp and Hedman, 1977); correlations with specific flow durations are not available at 

present to make a distinction between these possibilities. At 

some locations during the 1985 flood, especially where the 

main thread of flow was diverted around or away from the 

forested area, the low surface was marked by debris jams 

wrapped around trees, but relatively little erosion occurred. 

Other locations experienced complete devastation as the 

forest cover and underlying materials were stripped away. 

Channel Pattern 

The North Fork, South Branch, and South Fork can 

be classified as either confined (Lewin and Brindle, 1977), 

restrained (Lane, 1957), or partially confined (Nanson, 

Flood Hydrology and Geomorphic Effects, Flood of Nov. 4-5, 1985, W. Va. E7 
m 

= 

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0 1 MILE 

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HOPEVILLE \ ... 

Figure 5. Sketch maps illustrating river channels and valley-floor outlines. (A) North Fork South Branch and South Branch Potomac Rivers upstream of their 

confluence, to South Branch Potomac River downstream of Petersburg Gap. (B) South Branch Potomac River, from downstream of Petersburg Gap to Sector, 

downstream of the Trough. 
B 

Figure 5. Continued. 

South Fork 

South Branch 

Potomac River 

Sector 

0 1 MILE 

I I I 

0 2 KILOMETERS 

Flood Hydrology and Geomorphic Effects, Flood of Nov. 4-5, 1985, W.Va. E9 
800 

I 

I -----North Fork South Branch Potomac River I 

--South Fork South Branch Potomac River / I 

700 --South Branch Potomac River / 

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a: I 

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300 

// 

--/ - 200 

70 90 110 130 150 170 190 210 

DISTANCE UPSTREAM OF CONFLUENCE WITH 

NORTH BRANCH POTOMAC RIVER, IN KILOMETERS 

Figure 6. Longitudinal profiles of North Fork South 

Branch, South Branch, and South Fork South Branch 

Potomac Rivers upstream of Moorefield. 

1986) meandering rivers whose ability to migrate laterally is 

limited by the presence of resistant valley walls. Valley 

confinements in the South Branch drainage encompass a 

range of types: channels entrenched in bedrock and lacking 

significant bottomland development; channels with isolated 

flood-plain segments alternating from one side of the valley 

to the other; channels that abut a valley wall or terrace scarp 

at least once in every meander crossing; channels that 

occupy relatively broad bottomlands but whose migration is 

constrained by valley walls at critical locations (figs. 5, 8). 

Channels commonly have bedrock floors veneered with 

coarse sediment, and measured thickness of alluvial fill 

beneath flood plains in the Petersburg and Moorefield areas 

is generally less than 6 m (Jacobson and others, 1989). 

The channels and the valleys they occupy have 

relatively low sinuosity, generally ranging from 1.05 to 

1. 25. Some of the broader valley reaches have multiple 

anabranching or anastomosing channels, and tributary channels commonly run parallel to the main river along the 

valley wall for some distance. The anastomosing channel 

patterns typically approach a major confluence or a major 

constriction in the valley walls (fig. 5). Most of these are 

sites where a relatively broad valley experienced comparatively minor geomorphic changes during the November 

1985 flood. However, at other sites, unstable multiplechannel patterns were created by the 1985 flood. The 

phenomenon of erosional anastomosis or braiding by an 

extreme flood is also described by Carson (1984, p. 14) 

from the Canterbury Plains of New Zealand: "Many presently meandering rivers on the Plains have, at previous 

times this century, been exposed to high return-period 

floods that have rutted large parts of the floodplain, as well 

as producing rapid bend migration and concomitant dissection of wide point bars. The result has been a braided 

appearance that only slowly reverts to the single-thread 

Table 3. Channel gradients along the three forks of the 

South Branch Potomac River 

Extent 

North Fork South Branch Potomac River 

from Laurel Fork to confluence with 

South Branch near Cabins 

South Branch Potomac River from Virginia 

State line to confluence with North Fork 

near Cabins 

South Branch Potomac River from 

confluence with North Fork near Cabins to 

confluence with South Fork at Moorefield 

South Fork South Branch Potomac River 

from Virginia State line to confluence 

with South Branch at Moorefield 

South Branch Potomac River from 

confluence with South Fork at Moorefield 

to confluence with North Branch Potomac 

River 

G d. t Distance ra 1en (km) 

0.0065 70.9 

.0047 83.3 

.0021 28.8 

.0036 104.9 

.0009 92.8 

mode as ruts heal with sediment accretion and vegetation 

regrowth." 

The creation of new channels by the 1985 flood 

suggests that some of the secondary channels on flood 

plains in the South Branch basin before 1985 were themselves the remnants of overflow channels eroded in previous 

extreme floods rather than stable channels in an aggrading 

reach. At several locations, comparison of preflood and 

postflood aerial photographs reveals that these channels, 

partially filled in but persisting as depressions on the flood 

plain, were reoccupied and redissected in the 1985 flood 

(fig. 9). 

HYDROLOGY OF THE NOVEMBER 1985 

FLOOD IN THE SOUTH BRANCH POTOMAC 

RIVER BASIN 

Peak Discharge 

Discharge values at peak flood were estimated by the 

U.S. Geological Survey using indirect methods following 

the flood (Lescinsky, 1987). Estimated values of peak 

discharge at the six gage sites in the South Branch basin are 

listed in table 1; gage locations are shown in plate 1 and 

figure 1. Of the six gages, one (North Fork South Branch 

Potomac River at Cabins) was discontinued prior to November 1985, one (South Branch Potomac River at Petersburg) 

was destroyed by erosion of the river bank during the flood, 

three were disabled by rising floodwaters and failed to 

record peak or falling stages, and one (South Fork South 

Branch Potomac River at Brandywine) recorded a complete 

stage hydrograph but required a revised rating. At five of 

the six stations, the November 1985 flood exceeded the 

previous flood of record by ratios of 1.68 to 2.93; peak 

discharge at the sixth station (Brandywine) was almost 

identical to the value recorded for the record flood of June 

E10 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W.Va., Va. 
Average Width of Valley Floor 

• <200m 

• 200- 350m 

• 350- SOOm 

0 500 -1000m 

D > 1000m 

-++- Constriction C Bedrock Canyon 

0 10 20 30 KILOMETERS 

Figure 7. Sketch map showing locations of valley constrictions and bedrock canyons and average 

width of valley floor along the three forks of the South Branch Potomac River upstream of 

Moorefield. Constrictions are defined as valley cross sections that are no more than one-third as 

wide as the valley along the reach immediately downstream. 

Flood Hydrology and Geomorphic Effects, Flood of Nov. 4-5, 1985, W.Va. Ell 
1 MILE 

2 KILOMETERS 

,1 North Fork South Branch Potomac River 

D Flood plain 

~ Terrace 

@ Alluvial fan/debris fan deposits 

fa] Colluvial slope 

D Bedrock 

- Flow direction 

Figure 8. Photointerpretive sketch showing valley planform and associated geomorphic features along the North Fork 

South Branch Potomac River downstream of Riverton; morphology based on preflood aerial photography. 

1949. Unit discharge values ranged from 1.78 to 4.34 

m3

1s/km2 (163-397 felslmi2). These are among the largest 

values ever recorded for comparable drainage areas in this 

part of the United States, but they fall well within the 

envelope curve defined in figure 10. 

Unit discharge values were highest on the South Fork 

at Brandywine and Moorefield, despite the fact that much of 

the east side of the South Fork basin is regulated by a series 

of Soil Conservation Service flood-control dams. Most of 

these dams overflowed, and a few experienced severe 

spillway erosion (fig. 11). Estimates of peak discharge were 

computed by the Soil Conservation Service for four of the 

tributaries that have flood-control dams; these are listed in 

table 4. Inflow to the reservoir above each dam was derived 

using unit hydrograph routing techniques for the upstream 

drainage area, and outflow from each dam was based on 

crest stage measurements and design ratings for the dam 

spillway. Unit discharge values calculated from the inflow 

data range from 4.4 to 7.2 m3 lslkm2 (398 to 660 fe lslm?); 

outflow unit discharges range from 2.1 to 4.7 m31s/km2 

(191 to 427 fe/slmi2). 

Peak unit discharge on the North Fork at Cabins was 

lower than at Brandywine or Moorefield but higher than at 

the other stations (table 1). The unit discharge with the next 

to highest value was measured along the South Branch near 

Franklin. Although the official peak discharge for the 

Franklin gage is 1 , 250 m 3 Is ( 44,000 fe Is), the actual 

slope-area measurement was made in a short canyon several 

kilometers downstream of the gage, and the discharge 

estimate was adjusted downward to account for the smaller 

drainage area at Franklin. The peak discharge value at the 

measurement site was 1,520 m3

1s (53,500 fels). If the 

drainage area of the South Branch produced this unit 

discharge uniformly, it would have delivered 2,300 m3

1s 

(81,300 fels) peak discharge at the North Fork confluence. 

Furthermore, if the flood crests on the North Fork and the 

South Branch arrived at the confluence simultaneously, the 

peak discharge at the Petersburg gage would have been 

about 4,800 m3

1s (170,000 ft31s). However, the discharge 

measured just upstream of the Petersburg gage was only 

3,700 m3/s (130,000 fe/s). The discrepancy may be attributable to ( 1) uncertainty in estimating peak discharge at one 

or more of the gage sites, (2) flood waves on the North Fork 

and South Branch above their confluence that were out of 

phase, (3) attenuation of the flood wave moving down the 

South Branch as it traversed the reach between Franklin and 

the confluence with the North Fork, or (4) a combination of 

two or more of these possibilities. Given the rapid rise and 

fall of water level in the flood, a peak discharge value at the 

Petersburg gage smaller than the arithmetic sum of the 

tributary peaks would be generated if the two tributary 

peaks were out of phase by as much as a couple of hours. In 

addition, attenuation of the flood wave on the South Branch 

could have occurred as the combined result of valley 

widening in the reach upstream of Upper Tract and ponding 

at the entrance to the Smoke Hole canyon just below Upper 

Tract (figs. 12, 13). Backwater above the entrance to the 

canyon caused the stage on the South Branch at Upper Tract 

E12 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W.Va., Va. 
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Figure 9. Aerial photographs illustrating reoccupation and incision of old flood-plain channels: (A and B) North Fork South Branch Potomac River at Judy Gap, 

May 1980 and November 1985; flow is from bottom to top. Field of view is 780 m wide. (C and 0) South Fork South Branch Potomac River near Milam, May 

1980 and November 1985; flow is from bottom to top. Field of view is 780 m wide. 
E14 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W. Va., Va. 
to rise high enough that water flowed over the divide from 

the South Branch valley into the North Mill Creek drainage; 

an assumption that flow was critical over the divide yields 

a maximum overflow discharge value of about 140 m3

/s. 

Ponding at the entrance to Smoke Hole presumably slowed 

the arrival of peak discharge at the confluence with the 

North Fork and reduced the magnitude of the hydrograph 

peak while spreading it over a longer time interval. 

A similar case may be made in comparing peak 

discharges at the Petersburg, Moorefield, and Springfield 

gages. Peak discharge at the Springfield gage was estimated 

at 6,800 m3

/s (240,000 ft3/s), equal to the sum of the peaks 

at Petersburg and Moorefield; yet those two sites account 

for only 63 percent of the drainage area at Springfield. Witnesses report that the South Branch and the South Fork 

reached crest stage within half an hour of each other at 

Moorefield, indicating that peak discharge at the confluence 

may have exceeded the peak at Springfield. Even assuming 

that the area downstream of Moorefield received less 

precipitation and experienced lower unit discharges than the 

areas monitored by the upstream gages, the available 

100000 

Cl 

z 

Cl 

~ 10000 U) 

a: 

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0.... 

U) 

a: 1000 UJ 

fUJ 

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o November 1985 f lood 

+ Largest rainfall-runoff floods, U.S. 

(Costa, 1987) 

10 100 1000 1 0000 1 00000 

DRAINAGE AREA, IN SQUARE KILOMETERS 

Figure 10. Peak discharge versus drainage area for the 

November 1985 flood, compared with the largest rainfallrunoff floods recorded for the United States (after Miller 

(1990); printed by permission of John Wiley and Sons). 

Data from Costa (1987) and Lescinsky (1987). 

evidence suggests attenuation of the flood wave between 

Moorefield and the Springfield gage site. Ponding above 

valley constrictions may have been partially responsible; the 

Trough, a bedrock canyon downstream of Moorefield (fig. 

SA), is particularly narrow, and the high-water marks 

surveyed after the flood clearly indicate that floodwaters 

entering this canyon were ponded at its upstream end (see 

the following section). 

The correspondence between peak discharge and 

spatial patterns of precipitation is uncertain at best. The 

isohyets in plate 1 show that the highest precipitation values 

within the study area are centered over the South Branch 

Figure 11. Soil Conservation Service flood control dam on 

Little Fork with eroded spillway following November 1985 

flood. Valley of South Fork South Branch Potomac River, 

11 km upstream of Brandywine. Field of view is 500 m 

wide. 

Table 4. Peak discharge estimates for four Soil Conservation Service flood-control reservoirs: November 1985 flood, 

South Fork South Branch Potomac River basin 

Drainage area Peak inflow Inflow unit discharge Peak outflow Outflow unit discharge 

Watershed 

km2 mi2 m3/s fe/s m3/s/km2 fe/s/mi 2 m3/s fe/s m3

/s/km2 fe/s/mi 2 

10 6.94 2.68 50.1 1,770 7.2 660 30.6 1,080 4.4 403 

14 14.37 5.55 102.5 3,620 7.1 652 67.1 2,370 4.7 427 

17 44.73 17.27 194.8 6,880 4.4 398 93.2 3,290 2.1 191 

19 39.24 15.15 206.1 7,280 5.3 481 145.0 5,120 3.7 338 

Flood Hydrology and Geomorphic Effects, Flood of Nov. 4-5, 1985, W.Va. E15 
J 

Upper 

Tract 

1 MILE 

2 KILOMETERS 

r 

To North ~ Mill Creek 

Figure 12. Sketch map illustrating river channel and valley-floor outline along South Branch Potomac 

River from Franklin to Smoke Hole canyon. Some of the flow from the South Branch crossed over the 

divide near Upper Tract and was diverted into the valley of North Mill Creek for approximately 5 h on the 

night of November 4-5, 1985. 

E16 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W. Va., Va. 
540 

520 

500 Cl) 

a: 

UJ 480 IUJ 

~ 

~ 460 

z' 

0 440 

~ <( 

> 420 UJ 

_J 

UJ EXPLANATION I I 400 --- Interpolated peak flood stage 

380 -- Normal stage 

• High-water mark 

360 

150 155 160 165 170 175 180 185 

DISTANCE UPSTREAM OF NORTH BRANCH CONFLUENCE, 

IN KILOMETERS 

Figure 13. Longitudinal profiles of November 1985 flood 

crest and low-water stage along South Branch Potomac 

River from Franklin gage to Smoke Hole downstream of 

Upper Tract. 

280~-.---.--~----.--,--.---.--./.r---. 

Cl) 260 a: 

UJ 

1-

UJ 

~ 

z 

;- 240 

~ 

::X: 

> 

.u 

...J 

.u 220 

The " 

Trough ,4/ 

: ... --• 

" 

" / " 

.... 

" 

/ 

/ / / 

~--·-~: ......... --...... ...... : N, ... ..-': 

I / I :/ 

I EXPLANATION 

--- Interpolated peak flood stage 

-- Normal stage 

+ High-water mark 

75 80 85 90 95 1 00 1 05 11 0 115 

DISTANCE UPSTREAM OF NORTH BRANCH CONFLUENCE, 

IN KILOMETERS 

Figure 14. Longitudinal profiles of November 1985 flood 

crest and low-water stage along South Branch Potomac 

River from downstream of Petersburg Gap to Sector 

(downstream end of the Trough). 

between Franklin and Upper Tract. Precipitation values are 

lower over the South Fork drainage, where the highest unit 

discharge estimates were made. Cumulative volumes of 

precipitation upstream of the gages in the South Branch 

basin have been calculated, yielding average rainfall depths 

of 158-220 mm (table 1); no correlation between average 

depth and peak unit discharge is apparent. Colucci and 

others (chapter B, this volume) emphasize that, although 

the network of rain gages in this area is sparse, unofficial 

results of a bucket survey conducted by the Soil Conserva310 

300 

Cl) 

a: 

~ 290 UJ 

~ 

z 

;- 280 

0 

~ <( 

ifj 270 _J 

UJ 

260 

250 

100 

.... ..... 

105 

I 

i 

Petersburg 1 

:

1 

Gap :

1 

+q 

~ 

/cf I 

/ I 

I I /) 

: : ,....6 I 

I I : p/ 

: 'roo-o/ : ., ~;·: 

Unnamed 

: Gap: 

:~: 

.-I I 

/ I 

.... ..- I 

.... I 

I EXPLANATION 

I 

I 

: --- Interpolated peak flood stage 

110 

: -- Normal stage : 

+ High-water mark : 

o Crest stage predicted by stepbackwater model 

115 120 125 

DISTANCE UPSTREAM OF NORTH BRANCH CONFLUENCE, 

IN KILOMETERS 

Figure 15. Longitudinal profiles of November 1985 flood 

crest and low-water stage along South Branch Potomac 

River from unnamed gap upstream of Petersburg to downstream end of Petersburg Gap. Step-backwater estimates 

of peak stage provided by Army Corps of Engineers. 

tion Service tend to confirm the general patterns shown in 

the contour map based on official data. However, it is 

possible that one or more small cells generating intense 

precipitation over the mountains on the east side of the basin 

went undetected by either the rain gage network or the 

bucket surveys. 

Crest Stage and Longitudinal Profiles 

Floodwaters at crest stage were deep enough that 

virtually the entire valley floor was inundated along all three 

forks of the South Branch from the Virginia State line to 

Moorefield and along the South Branch from Moorefield to 

the confluence with the North Branch Potomac River. 

Elevations of high-water marks at selected sites were 

surveyed after the flood by U.S. Geological Survey field 

crews. Additional water surface elevations for the areas 

near Petersburg and Moorefield were generated by stepbackwater modeling performed in the preliminary phase of 

an Army Corps of Engineers flood-control study; the model 

output data are generally in agreement with measured 

high-water marks. These data, together with cross sections 

surveyed by the U.S. Geological Survey for slope-area 

discharge estimates, were used to construct generalized 

longitudinal profiles of peak flood stage (figs. 13-16). 

Comparisons of peak flood stages with topographic 

contours reveal that water depths above low-flow stages 

along the South Branch and its main forks ranged from less 

than 4 m to 12.7 m. Variations in flow depth over the valley 

floor were controlled largely by valley contractions and 

expansions. The deepest flows along the South Branch 

Potomac River occurred in the Trough (fig. 14). 

Flood Hydrology and Geomorphic Effects, Flood of Nov. 4-5, 1985, W. Va. E17 
360.---~--~--------.---~1 ~~------~----~~---

(/) 

a: 

UJ 

1-

UJ 

:2:: 

z 

340 

;- 320 

0 

i= 

:;; 

UJ 

_J 

UJ 300 

I 

I 

I I 

~ 

urnam~d 

:Gap: 

I l 

I I 

120 

I 

I 

I 

I 

J; 

/I 

I 

I 

._. .. : 

N'orth / 

Fork / 

Gap // 

: : ,. I I / 

I I / :.:/ 

~ : 

I 

I 

I 

I I____. 

Hapeville 

/ I I 

Canyon I 

I 

I 

I 

/ 

' 

/ 

,. .. / 

/ ' / I 

Confluence, 

North Fork and 

South Branch 

125 

EXPLANATION 

--- Interpolated peak 

flood stage : 

- Normal stage : 

+ High-water mark 

130 

DISTANCE UPSTREAM OF NORTH BRANCH CONFLUENCE, 

IN KILOMETERS 

Figure 16. Longitudinal profiles of November 1985 flood 

crest and low-water stage along North Fork South Branch 

Potomac River from Hapeville to confluence with South 

Branch Potomac River, and extending along the South 

Branch Potomac River to the site of the Petersburg gaging 

station. 

Along the South Branch near Moorefield, average 

water depth at peak stage was about 7 m; but as the valley 

narrowed approaching the Trough, backwater above the 

entrance caused a rapid increase in depth. Although the data 

are too sparse to construct a detailed water-surface profile 

along the Trough, deep flows appear to have persisted along 

much of its length (fig. 14). 

The South Branch valley near Petersburg is quite 

broad but is bounded by two bedrock constrictions: an 

unnamed gap at its upstream end and Petersburg Gap at its 

downstream end (fig. 5A). Flow depths above low water 

decreased slightly downstream along the upper two-thirds 

of the reach, from about 6.5-7.5 mjust below the unnamed 

gap to 5-6 m at the widest part of the valley, which is a 

short distance upstream of Petersburg (fig. 15). From there 

to Petersburg Gap, flow depth increased sharply to about 

8. 6 m above low water owing to backwater effects of the 

constriction. Maximum water depths at peak stage decrease 

almost immediately below the entrance to Petersburg Gap. 

Along the South Branch valley between Franklin and 

the Smoke Hole (fig. 12), data on crest stages are too sparse 

to define a detailed profile, but the general trend (fig. 13) is 

consistent with the results described above. The valley in 

the vicinity of Upper Tract is relatively wide (average width 

530 m), with a river gradient between 0.002 and 0.003. The 

sharp gradient break in the low-water profile 2 km downstream of Upper Tract marks the entrance to Smoke Hole. 

The abrupt constriction of the valley at this site caused 

ponding at peak stage, with water reaching depths of 8-9 m 

at the canyon entrance, as compared with estimated depths 

between 5 and 6 m above low water in the canyon and 4-5 

m above low water farther upstream at Ruddle. The 

measured elevation of the high-water mark at the Upper 

Tract bridge actually was slightly greater than the elevation 

of the next high-water mark upstream; although one or the 

other of these marks may be in error, there is little doubt 

that the general slope of the water surface at peak stage 

flattened out in the immediate vicinity of the bridge. Ponded 

water reached a maximum depth of 1. 2 m over the drainage 

divide between the South Branch and North Mill Creek 

valleys, and one eyewitness stated that water flowed over 

the divide for approximately 5 h, from 8 p.m. to 1 a.m. on 

the night of November 4-5. The overflow eroded ditches 

along the road and caused damage to some buildings, but no 

significant geomorphic impacts were observed. 

The examples cited above illustrate a pattern of 

variation in water depth at crest stage that was repeated at 

other sites throughout the basin; additional examples are 

illustrated for the South Branch between the Franklin gage 

and an unnamed gap 4 km downstream of the gage (figs. 

12, 13) and for the North Fork between Hapeville Canyon 

and the confluence with the South Branch (figs. 5A, 16). In 

all cases a tight constriction in the valley caused backwater 

effects and ponding upstream, with declining stage in and 

downstream of the constriction itself. This clearly affected 

the spatial distribution of energy expenditure along the 

valley. 

Timing of Flood Wave and Shape of the 

Hydrograph 

Peak flow along the middle reaches of the three forks 

of the South Branch occurred during the night of November 

4-5. Because instrument records and precise, reliable eyewitness reports are scarce, information about the timing of 

the flood wave and the shape of the hydrograph is spotty 

at best. The following discussion incorporates available 

information from instrument records and recollections of 

residents. 

The only available complete-stage hydrograph of the 

flood in the South Branch basin is from the South Fork at 

Brandywine (fig. 17). Crest stage was 3.63 m above 

bankfull, and the rising limb of the hydrograph was particularly steep in the last few hours before the flood crest. 

Records indicate that stage rose 1. 88 m in the last 1. 5 hours 

before the hydrograph peak and fell by about the same 

amount during the 6 h following the peak. Bankfull stage 

was exceeded for 27 h, but floodwaters were more than 1m 

above bankfull for only 14 of those 27 h. 

At the Franklin gage on the South Branch the stage 

recorders were disabled before the flood crest arrived, but 

the rising limb apparently was as steep as or steeper than 

that at the Brandywine gage (fig. 17). The last recorded 

stage was 4.87 m at 7 p.m. on November 4; peak stage of 

6.88 m, according to an unconfirmed report by a resident, 

E18 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W.Va., Va. 
C/) 

a: 

UJ 

fUJ 

~ 

~ 4 

----e-- Franklin 

Brandywine 

12 noon 12noon 12 noon 6 a.m. 

NOVEMBER 3 NOVEMBER 4 NOVEMBER 5 

Figure 17. Stage hydrographs for the November 1985 flood at Brandywine, W. Va. 

(complete stage record), and at Franklin, W.Va. (incomplete stage record; time of peak is 

indicated by dashed line and is estimated from eyewitness accounts). 

occurred between 8 and 9 p.m. Assuming that the flood 

peaked at 8:30 p.m., a rise of 2 m occurred in the last 1.5 

h before the peak. The peak could not have occurred much 

later, as the crest stage at Upper Tract (about 24 km 

downstream) apparently occurred between 10 and 11 p.m. 

Most observers from other locations in the North Fork 

and South Branch valleys recall that the water rose very 

rapidly. It is likely that there were also local surges due to 

the extremely turbulent nature of the flow. Abrupt changes 

in velocity and stage probably accompanied failure of small 

debris jams at many sites, and changes in flow pattern 

associated with scouring of new channels across the valley 

floor would have had similar effects. 

The sequence of events at Petersburg is a case in 

point. Residents stated that a sudden surge caused a rapid 

increase in water level some time after the river overflowed 

its banks. Furthermore, the surge that inundated most of the 

valley floor was described as spreading from the South 

Petersburg flood plain rather than from the channel of the 

South Branch itself. This account is consistent with the 

geomorphic evidence. Flow emerging from the gap 

upstream eroded the channel banks, causing the channel to 

widen by a factor of 2 or 3 and destroying the Petersburg 

gage and several houses. After the river overflowed its 

banks, a major component of flow headed southeast, away 

from the channel, and scoured a broad, shallow trough 

leading toward the south side of the valley (fig. 18). Flow 

that followed this trajectory combined with overbank flow 

concentrated along several other swales on the valley floor 

and reached the channel of Johnson Run, which lies along 

the southern margin of the South Branch flood plain. 

Presumably, the scouring of the valley floor upstream 

diverted a large amount of water toward Johnson Run 

shortly after the South Branch reached flood stage, thus 

causing the surge mentioned above. Similar events must 

have occurred throughout the basin as flow patterns 

changed with rising and falling stage and with erosional and 

depositional modification of the valley bottom. 

An approximate chronology of the progress of the 

flood crest is based on the recollections of witnesses (fig. 

19). Bearing in mind that the crest occurred late at night, it 

is not surprising that some of these reports yield inconsistent 

and sometimes contradictory results. Nevertheless a plot of 

the reported time of the crest against distance upstream of 

Moorefield can be used to estimate average flood-peak 

celerity, with calculated values ranging from 3 m/s to as 

much as 6 m/s. 

Recurrence Intervals 

Discharge values corresponding to probabilities of 

0.01 (recurrence interval 100 yr) and 0.002 (recurrence 

interval 500 yr) have been calculated at all six gage sites for 

comparison with 1985 flood peaks (table 2). Discharges 

Flood Hydrology and Geomorphic Effects, Flood of Nov. 4-5, 1985, W.Va. E19 
Figure 18. Valley floor upstream of Petersburg at the 

site where flood flow emerged from an unnamed gap 

(at left). This is the site where the Petersburg gage on 

the South Branch was destroyed, along with several 

houses. Note the erosional trough just left of center 

that carried flow across the flood plain toward Johnson 

were calculated using the method outlined by the Interagency Advisory Committee on Water Data (1982) and using 

regional flood-frequency curves for the Potomac Highlands 

region of West Virginia (Runner, 1980). Skew coefficients 

for the first set of estimates were weighted averages based 

on both systematic station records and regionalized skew 

coefficients. The systematic station records (including the 

November 1985 flood) were adjusted to account for historical data. After examination of historical records, we 

Figure 19. Plot of estimated time of flood crest versus .,... 

distance upstream of the confluence of the South 

Branch and North Branch Potomac Rivers. Data on 

timing of flood crest from all three forks of the South 

Branch Potomac River are based on eyewitness 

accounts; some observations may be in error by 1-2 h. 

The slopes of the two trend lines drawn through the 

data points represent maximum and minimum interpretations of flood-wave celerity, assuming constant 

celerity upstream of Moorefield. 

Run, on the south side of the valley. Other flow paths 

visible in the photograph also indicate diversion of a 

significant component of the flood flow away from the 

South Branch channel and convergence toward the 

south side of the valley. Field of view is 3,000 m wide. 

200,---.--- --.---,---,---,---.---,----.--~ 

I 

u 

z 

<( 

cr: 

180 

C:OU) 

:r:cr: 

f-LU 

~ ~ 160 z 2: 

2:g 

a::;:: 

EEz :::2: -_ 140 

<(~ 

~tiS 

~ ~ 120 ::Jz 

L.UO 

uu 

z 

<( 

1-

U) 

Cl 

100 

0 North Fork 

0 So uth Fork 

EB South Branch 

80 --L---L---L---~-- --~--~--~--~--~ 

8 p.m. 10 p. m. 12 midnight 2 a.m. 4 a. m. 6 a.m. 

NOVEMBER 4 NOVEMBER 5 

REPORTED TIME OF FLOOD CREST 

E20 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W. Va., Va. 
Table 5. Hydraulic parameters calculated for U.S. Geological Survey gage sites 

Mean velocity1 Maximum velocitl Maximum Froude number5 

Station Complete Complete 

Channel section Channel section Mean width3 Mean depth4 Complete 

(m/s) (m/s) (m/s) (m/s) (m) (m) Channel section 

South Branch Potomac River 

at Franklin, W.Va. 4.6 3.7 5.3 4.0 72 5.7 0.61 0.54 

North Fork South Branch 

Potomac River at Cabins, 

W.Va. 3.9 3.2 4.2 3.4 165 4.9 .47 .48 

South Branch Potomac River 

near Petersburg, W.Va. 4.2 4.2 4.6 4.6 118 7.2 .53 .53 

South Fork South Branch 

Potomac River near 

Moorefield, W.Va. 3.2 2.2 3.4 2.4 552 2.4 .50 .50 

South Branch Potomac River 

near Springfield, W.Va. 4.2 3.8 4.4 4.0 201 8.5 .63 .45 

1 Three cross sections surveyed at each site; mean velocity is the mean of three cross sections. 2 Maximum velocity refers to the largest value among the three cross sections surveyed. Maximum velocities within any single cross section are not 

known. 3 Mean top width of the inundated area for three cross sections at each site. 4 Mean depth for each cross section calculated as the ratio of cross-sectional area to top width; results for individual cross sections were averaged 

at each site. 

5 Maximum Froude number is the largest value among the three cross sections at each site. 

assumed that the November 1985 flood was the largest since 

1877 at all stations except Brandywine; for Brandywine, we 

assumed that the June 1949 flood was the largest since 

1877. The 1877 flood was exceeded by the 1985 flood and 

by the June 1949 flood at those stations where historical 

records are available, but we lack data to extend the 

historical record any further back. Datable materials associated with prehistoric high-magnitude floods have not been 

found in this basin, and therefore we have not had an 

opportunity to apply techniques of paleoflood hydrology to 

revise these estimates. 

The November 1985 flood exceeded the 100-yr flood 

estimated at all six stations by both methods. The November 1985 flood also exceeded the 500-yr flood peak estimated at four of the six stations by either method. Further 

downstream on the main stem of the Potomac River, the 

recurrence interval of the 1985 flood decreased with 

increasing drainage area; at Point of Rocks, Md., and 

Washington, D.C., the recurrence interval was only 25 yr 

(Lescinsky, 1987). From the available data, it is apparent 

that this was a rare event, but it was most unusual in 

drainage basins with areas ranging between 300 and 5,000 

km2 (Miller, 1990). 

Hydraulic Parameters 

Because of the tremendous destruction caused by this 

flood, data on flow hydraulics are of considerable interest. 

Velocity, water-surface slope, energy slope, Froude number, and unit stream power (defined by equations (1) and (2) 

below) can be derived at the sites where indirect discharge 

estimates were made. These parameters may be useful in 

comparing this flood with other extreme floods (tables 5, 

6). Hydraulic data are available for five of the six gage sites 

where indirect discharge estimates were made; the South 

Fork at Brandywine is not represented because a complex 

flow cross section and the presence of a bridge and tributary 

inflow make calculation of hydraulic parameters difficult 

and unreliable. 

Velocities were calculated separately for the complete 

cross section and for the channel at each gage site. Average 

velocity over three cross sections at each of the five gage 

sites ranged from 2.2 to 4.2 m/s, and average channel 

velocity ranged from 3.2 to 4.6 m/s. The highest estimate of 

average channel velocity for any single cross section was 

5.3 m/s at Franklin. Average cross-section values ofFroude 

number (Chow, 1959) ranged from 0.39 to 0.54, and the 

cross section with the highest average velocity had a 

channel Froude number of only 0.63. Although the average 

values of depth and velocity indicate that flow was not 

supercritical (i.e., Froude number > 1.0) across the entire 

cross section at any of the indirect discharge measurement 

sites, local areas of critical or supercritical flow may have 

existed along irregular boundaries or around obstructions in 

the path of the flood. 

Power supplied to the column of fluid per unit of bed 

area is a useful parameter for evaluating the ability of rivers 

to erode and transport sediment (Bagnold, 1966). This 

quantity, often referred to by subsequent authors as unit 

stream power, has been cited in discussions of highmagnitude floods in terms of competence and capacity to 

Flood Hydrology and Geomorphic Effects, Flood of Nov. 4-5, 1985, W. Va. E21 
Table 6. Unit stream power calculated for U.S. Geological Survey gage sites 

Unit stream power (W/m2

) 

Station Energy gradient Complete section Channel Flood plain 

Minimum Maximum Minimum Maximum Minimum Maximum 

South Branch Potomac River 0.0048 956 1,035 1,286 1,971 448 588 

at Franklin, W.Va. 

North Fork South Branch .0034 441 607 676 1,165 57 204 

Potomac River at Cabins, 

W.Va. 

South Branch Potomac River .0017 464 586 

near Petersburg, W.Va. 

South Fork South Branch .0023 114 133 276 347 83 119 

Potomac River near 

Moorefield, W.Va. 

South Branch Potomac River .0013 400 419 524 627 151 162 

near Springfield, W.Va. 

"Minimum" and "maximum" indicate range of values calculated for the three cross sections used in slope-area discharge computations at each gage 

site. Dash indicates that cross sections were not subdivided in original slope-area computations; unit stream power was calculated for complete cross 

sections only. 

transport sediment (Costa, 1983; Baker and Costa, 1987). 

Unit stream power is calculated either as the product of 

boundary shear stress (7) and velocity (v), 

W = 7V (1) 

or as the product of discharge (Q), unit weight of water ( 'Y), 

and energy slope (s), divided by flow width (w): 

(2) 

The largest values of unit stream power and boundary shear 

stress are developed in bedrock canyons, where the boundaries are resistant to erosion and the flow cross section 

cannot adjust its width to accommodate extreme discharges. 

Conversely, wide reaches of alluvial valley bottom are 

expected to have the lowest values of unit stream power. 

Average values of unit stream power, based on three 

cross sections each at U.S. Geological Survey gage sites in 

the South Branch basin, ranged from 125 to 988 W/m2 (the 

range of values for each site is listed in table 6). Separate 

computations for channel and overbank flow at individual 

cross sections yielded values for channel unit stream power 

as high as 1,971 W/m2 (South Branch near Franklin) and 

1,165 W/m2 (North Fork above Cabins); values for overbank flow ranged between 83 W/m2 (South Fork above 

Moorefield) and 588 W/m2 (South Branch near Franklin). 

Some of the more prominent erosion features observed in 

the South Branch basin were generated by flows moving out 

of the channel and across the valley floor just downstream 

of a constricted reach. These features are probably associated with high values of unit stream power developed in the 

upstream constriction. Scour forms commonly produced in 

other settings are probably associated with lower values of 

unit stream power, comparable to those calculated for 

overbank flow. Improved assessment of the relation 

between unit stream power and flood- plain erosion will 

require detailed information about how flow patterns are 

affected by planform and topographic characteristics of 

valley boundaries. 

Along the North Fork valley, in and below Hapeville 

Canyon, were several large boulders with maximum diameters of 2.5-2.8 m, resting on smaller imbricated boulders. 

In some cases, other objects underneath the smaller boulders, such as cut boards, indicated that the boulders were 

transported by the flood. The average intermediate axis of 

the five largest boulders believed to have moved was 1, 700 

mm. Using an empirical equation of Costa (1983), 

(3) 

the average velocity at this site was 6. 7 m/s. Costa (1983) 

also presented an empirical formula for calculating the 

minimum value of unit stream power needed to transport 

boulders of a given size: 

w = 0.009d/686 (4) 

Using the same particle size as before, we obtain a unit 

stream power value of 2,500 W/m2 for the mouth of 

Hapeville Canyon. This exceeds the values cited previously 

but is of the same order of magnitude as the maximum 

values obtained at Franklin and Cabins (table 6). As Komar 

(1988) presents evidence suggesting that many of the 

empirical formulas of flow competence tend to overestimate 

the threshold shear stress for transport of coarse particles, 

both the velocity and the unit stream power value calculated 

here should be regarded as maximum estimates. An independent estimate of unit stream power at the mouth of 

Hapeville Canyon, based on channel gradient, width at the 

exit constriction, and a discharge slightly less than the peak 

at Cabins, yields a value of about 1,650 W/m2

. 

E22 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W. Va., Va. 
The values of unit stream power derived here are 

unremarkable by comparison with the values tabulated by 

Baker and Costa (1987) in their discussion of the most 

extreme floods recorded; of the 35 events they cited, only 4 

have values of unit stream power less than 1 ,000, and the 

maximum value is 18,582 W/m2

. On the other hand, only 8 

of 35 entries had drainage areas greater than 100 km2 , and 

2 of those were floods from dam breaks. Extreme values of 

unit stream power apparently occur less often at sites with 

large drainage areas than at sites with small drainage areas. 

What is unusual about the hydraulics of the November 1985 

flood in the South Branch basin is the occurrence of 

relatively high values of unit power in environments where 

well-developed, erodible alluvial bottomlands were 

exposed to the flow. 

Sediment Loads 

The only sediment data available for comparison with 

previous floods were collected far downstream on the main 

stem Potomac River. At Point of Rocks, Md., 203 km 

downstream of the confluence of the South Branch with the 

North Branch, 3.09 megagrams (3.4 million tons) of 

suspended sediment were carried past the gage over a period 

of 3 days (James and others, 1987). The November 1985 

flood carried the largest load of any flood since 1961, when 

daily suspended sediment records were initiated, even 

though it was not the greatest flood measured during that 

period. Tropical Storm Agnes in June 1972 had a peak 

discharge of 9,830 m3

/s (347 ,000 fe/s), 12.3 percent larger 

than the peak discharge during the 1985 flood (8,750 m3

/s). 

Suspended load passing the Point of Rocks gage during 

Agnes, however, was 1.24 million tonnes, or only 40.1 

percent of the load measured for the 1985 flood. The load 

measured at Point of Rocks probably represents only a small 

fraction of the total sediment eroded from slopes and valley 

floors in the South Branch basin and elsewhere in the 

Potomac River basin. Much of the coarse fraction of 

sediment entrained by floodwaters in the South Branch 

basin remained in the basin, forming extensive deposits in 

all of the main valleys. Although much of the silt and clay 

component of the sediment load probably traveled further, 

flood-plain deposits composed largely of fine-grained sediment were observed along the South Branch downstream of 

its confluence with the South Fork and along the main stem 

Potomac downstream of the confluence of the South Branch 

with the North Branch. 

FLOOD IMPACTS 

Erosion and Deposition at Tributary Confluences 

Aerial photographs of the three main forks of the 

South Branch allow identification of tributaries whose 

Figure 20. Scouring and widening of small tributary to the 

North Fork South Branch Potomac River between Judy 

Gap and Riverton. 

Figure 21. Scoured channel and exposed colluvium of 

adjacent slope, along Dry Run about 1 km upstream of 

confluence with North Fork South Branch Potomac River 

(7.5 km upstream of Circleville). Flow is from right to left. 

lower reaches were disturbed by the flood and that may 

have delivered large amounts of sediment. Slope failures 

along the walls of the main valleys were rare in this event, 

and tributaries were the primary conduits for entrainment 

and delivery of sediment derived from landslides that 

occurred in selected areas of the basin. The sediment 

derived from landslides was augmented by scouring of 

headwater channels and adjacent bottomlands (Jacobson 

and others, chapter C, this volume). 

Many small tributary channels were scoured and 

widened during the flood, leaving a characteristic U-shaped 

cross section floored by cobbles and boulders. Small 

streams like the ones shown in figures 20 and 21 have no 

true bottomland, and channel widening occurred at the 

expense of adjacent colluvium or fan deposits. In many 

cases the angular clasts visible in the channel were derived 

from scouring and undercutting of adjacent slopes (fig. 21). 

Flood Hydrology and Geomorphic Effects, Flood of Nov. 4-5, 1985, W. Va. E23 
Figure 22. Incised channel and birds-foot delta at confluence of small unnamed intermittent stream with South 

Fork South Branch Potomac River at Palo Alto, 4 km 

downstream of the Virginia-West Virginia border. Flow 

along South Fork is toward lower right. Field of view is 430 

mwide. 

Tributaries subject to differing amounts of disturbance delivered varying amounts of sediment to the main 

valley. In some cases a tributary incised its bed but the zone 

affected by channel erosion was quite narrow, and much of 

the sediment mobilized by the stream was deposited at its 

mouth (fig. 22). Other, higher order tributaries exhibited 

more extensive scouring and reworking and appear to have 

delivered more sediment to the main channel (fig. 23). 

Delta Forms 

High flood stage and local ponding on or adjacent to 

the main stem river caused deposition and storage of 

sediment emanating from tributaries, forming small deltas 

at several locations in the South Branch basin. Although 

morphology may resemble the characteristic planform of a 

birds-foot delta (fig. 22), the term is used here primarily to 

distinguish coarse sediments deposited as a result of ponding from fan deposits left behind by diverging flow on a 

sloping surface. Despite the influence of backwater on 

deposition at tributary mouths, these deposits contain little 

silt and clay, suggesting that even under ponded conditions, 

local eddy velocities were sufficient to keep fines in 

suspension. 

Figure 24 shows a series of bars, about 1-1.5 m 

thick, deposited on the valley floor at the mouth of an 

unnamed tributary of the South Branch Potomac River in 

Smoke Hole canyon. The presence of undisturbed trees 

suggests that this site probably was occupied by a slowly 

recirculating eddy separate from the main thread of flow at 

high stage; the opposite bank of the South Branch was 

exposed to the main flow and was completely stripped of 

vegetation. Aerial photography of the site shows the sediment emerging from the tributary to form several discrete 

lobes (fig. 25). Field examination revealed that although the 

~Figure 23. Valleys of two 

unnamed tributaries to 

the South Branch Potomac River near the 

Virginia-West Virginia 

border. Reworking of 

bottomland deposits by 

stripping and deposition of coarse sediment 

occurred along most of 

the meander belt in both 

valleys; valley walls were 

undercut at several 

locations. Both tributaries delivered sediment 

directly to South Branch. 

Flow along South Branch 

is from right to left. Field 

of view is 660 m wide. 
Figure 24. Delta formed at mouth of unnamed tributary to 

the South Branch Potomac River at Blue Rock in Smoke 

Hole canyon. Poorly sorted deposits bury trees to depths 

of approximately 1 m. 

morphology suggests a series of braid bars with steep 

slipfaces, there is no imbrication or internal stratification. 

Furthermore, the surface layer of angular gravel mantles a 

deposit with a large component of poorly sorted sand-sized 

fragments. We interpret this deposit as a mass of sediment 

carried by the tributary and rapidly emplaced on the flood 

plain under slack-water conditions. Flow in the eddy or 

emanating from the tributary winnowed sands from the 

surface layer; with declining flood stage, the deposit was 

incised and partially reworked by flow draining toward the 

main channel. 

At the mouth of Redman Run, which also drains into 

the South Branch in Smoke Hole canyon (fig. 26), a poorly 

sorted gravel deposit as much as 1 m thick buried the bases 

Figure 25. Aerial view of delta shown in figure 24 (see top 

center). Flow along South Branch is from right to left. Note 

that the point bar along the left bank (bottom center) was 

stripped of vegetation, whereas vegetation along the right 

bank was left intact. Field of view is 250 m wide. 

of trees adjacent to the channel. This deposit has a relatively 

flat surface about 2 m above the low-water channel and 

gradually thins in the upstream direction. High-water marks 

indicate that peak stage was no more than 0.5 m above the 

surface of the deposit at its downstream end. Postflood 

reworking created a lower gravel bar emanating from the 

mouth of Redman Run into the channel of the South 

Branch. 

Fan Deposits 

Many of the larger tributaries of the three forks of the 

South Branch have built fans extending across the valley 

from the slope break at the mountain front. Major valley 

constrictions are formed by these fans. Extensive deposition 

Figure 26. Delta at the mouth of 

Redman Run, tributary to South 

Branch Potomac River in Smoke 

Hole canyon. Sediment up to 1 

m thick buries bases of trees 

growing on the pre-1985 surface. The approximate elevation 

of this surface is indicated by 

the tree on the edge of the 

deposit, just right of the center 

of the photograph. Much of the 

underlying material probably 

was delivered by a debris avalanche that occurred in june 

1949. Flow along South Branch 

is from right to left. 
Figure 27. Erosion and deposition on fan at the mouth of 

Nelson Run, tributary to North Fork South Branch Potomac River between Circleville and Judy Gap. Flow along 

North Fork is from right to left. Field of view is 750 m wide. 

and incision occurred on some fan surfaces during the 

flood, especially where tributaries were subjected to intensive scour and widening. A prominent example is Nelson 

Run, a tributary of the North Fork between Circleville and 

Judy Gap (fig. 27). Some of the flow emanating from 

Nelson Run evidently moved down the steepest part of the 

fan (to the right along the base of the mountain slope in the 

figure) and then crossed the flood plain along the base of the 

fan . On this fan, as on others in the South Branch basin, 

some sediment clearly reached the main channel, but a 

substantial amount of the sediment coming out of the 

tributary appears to have been deposited on the fan or on the 

flood plain at the base of the fan. 

Fanlike accumulations also occurred at the mouths of 

larger tributaries. Many of these form anastomosing patterns at the confluence and may be analogous to the 

anastomosing systems described by Smith (1983). At the 

junction of Big Run with the North Fork (fig. 28), an 

actively anastomosing channel system incised the valley 

floor. The possibility that major sediment contributions 

Figure 28. Incision of fan and flood-plain deposits by 

anastomosing channel system at the confluence of Big 

Run and the North Fork South Branch Potomac River, 

about 11 km downstream of the Virginia-West Virginia 

border. Flow along North Fork is from left to right. Field of 

view is 890 m wide. 

from tributary valleys influenced the extent and pattern of 

erosion and deposition along the main river at downstream 

locations is considered in more detail by Jacobson and 

others (chapter C, this volume). 

Erosion Features on Bottomland 

Widespread erosion on the bottomlands of the three 

forks of the South Branch took a variety of forms, many of 

which resemble erosion features reported in the geomorphic 

literature (Collins and Schalk, 1937; Jahns, 1947; Wolman 

and Eiler, 1958; Hack and Goodlett, 1960; Stewart and 

LaMarche, 1967; Baker, 1977, 1978, 1984, 1988; Sullivan, 

1983; Ritter and Blakely, 1986; Nanson, 1986; Kresan, 

1988; Ritter, 1988) or small-scale features reported in the 

sedimentology literature (Dzulynski and Sanders, 1962; 

Karcz, 1967, 1968; Allen, 1971, 1982, 1985; Paola and 

others, 1986). In the present discussion, we recognize 

E26 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W.Va., Va. 
erosion features ranging from localized disruptions of the 

surface (longitudinal grooves and scour marks) to dissection 

and stripping of much or all of the valley floor. In almost all 

cases the bottomland surface is occupied by vegetation, 

with pasture and cropland predominating over forest vegetation on the higher surface and woody vegetation more 

common on the lower surface. As a result of the resistance 

offered by dense networks of roots, the strength of the turf 

layer or of the root system appeared critical in determining 

the extent of erosion at many sites during the flood. Once a 

surface layer was breached, the underlying deposits in some 

areas were subject to rapid scour and incision. 

Subsurface stratigraphy is highly variable: at some 

locations a cobble pavement is found within 10-15 em of 

the surface, whereas other sites are underlain by as much as 

2m of cohesive alluvial soil composed largely of silty sand. 

Even the finer cohesive deposits may have cobble lenses or 

boulders occurring above basal channel gravels and cobbles. Stratigraphic heterogeneity in some cast(s is related to 

the spatial distribution of preflood overflow channels or 

buried scour-and-fill sequences. At several locations a 

partially indurated paleosol was exposed in the channel bed 

and banks by vertical incision during the flood. A similar 

paleosol, revealed during excavations on the South Branch 

flood plain near Petersburg, was estimated, on the basis of 

radiocarbon dates, to be 7,000 yr old (Jacobson and others, 

1989). 

The heterogeneous character of the valley floor 

resulted in a patchy distribution of erosion and deposition 

features. However, although bottomlands in the South 

Branch basin are less homogeneous than the substrates used 

in flume experiments reported in the sedimentology literature, the sedimentological studies provide information that 

is relevant to our understanding of the morphology and 

genesis of erosion features. In the ensuing discussion, we 

seek to draw analogies between features observed in the 

aftermath of this flood and erosion processes described in 

the sedimentology literature. 

Dzulynski and Sanders (1962) characterize erosion 

features on firm mud bottoms as either (1) scour marks, 

which are created by turbulent flow patterns impinging on 

an erodible bed, or (2) tool marks, which result from impact 

on an erodible bed by an object or particle entrained in the 

flow. Our observations indicate that both types of features 

formed on valley floors in the study area during the 

November 1985 flood. Allen (1971) suggests that most 

scour features formed in cohesive substrates are associated 

with flow separation; that flow separation may be produced 

by upward or downward steps on the bed, by obstructions in 

the path of the flow, by flow expansions, or by other types 

of irregularities or defects in the bed; and that maximum 

turbulent stress occurs where the separated flow becomes 

reattached to the bed. Observations of flood-generated 

features in the South Branch basin indicate that flow 

separation around obstructions, local heterogeneity in the 

resistance of the valley floor to erosion, and topographic 

irregularities influencing the pattern of surface drainage are 

all important in determining the pattern of erosion. Trees 

and structures such as fences, roads, buildings, and bridges 

often form the locus for initiation of separated flow, which 

may lead to creation of erosion and deposition form~. 

Longitudinal Grooves 

Elongate linear grooves were eroded by the flood at 

many sites within the study area. These typically are 

parallel or subparallel to the local direction of flood flow 

and extend down the valley floor tens to hundreds of 

meters. They generally appear in groups of parallel grooves 

and may be regularly spaced at intervals of 0.5-3 m. Size 

varies, from depths and widths measured in centimeters to 

depths and widths exceeding 1 m (fig. 29). Gravel and 

cobbles are commonly found embedded in or deposited on 

the floors of grooves; trenching of the surface beneath and 

adjacent to the groove reveals that the coarse material was 

emplaced during the flood . Although they are often found in 

close proximity to sites of severe erosion, longitudinal 

grooves also are found in areas where the valley floor is 

otherwise almost completely intact. We therefore associate 

these features with inception and early stages of bottomland 

erosion. 

In some cases the grooves clearly are tool marks or 

drag marks made by objects, usually uprooted trees, 

entrained in the flow (figs. 29A, 30; also see Kite and 

Linton, chapter D, this volume, fig. 5). Diagnostic evidence includes grooves that are parallel to uprooted trees 

lying on the valley floor, pits (possible gouge marks) along 

the trend of a set of grooves, and grooves that cross one 

another. In other cases the grooves are incised along trends 

that run parallel to crop rows or other preexisting weaknesses in the surface that may be preferred sites for incision 

(fig. 29C). Figure 31 shows an example where some 

grooves run along crop rows but . others cut across these 

rows at oblique angles. 

Longitudinal grooves often occur in straight, parallel 

sets oriented along the direction of flow and unrelated to 

crop patterns or other artifacts (figs. 29B, 32). Similar 

elongate linear features, both erosional and depositional, 

have been described in a broad range of environments (see 

Allen, 1982, pp. 24-52). Longitudinal grooves sculpted in 

cohesive river beds under the influence of bedload transport 

typically contain sand and gravel, which presumably were 

used as cutting tools in groove formation. An experimental 

study by Shepherd and Schumm (1974) of channel incision 

on a cohesive bed yielded longitudinal grooves and potholes 

in the early stages of erosion; the grooves eventually 

coalesced and ultimately a single narrow, deep inner channel formed. Similar features, formed on a much larger scale 

Flood Hydrology and Geomorphic Effects, Flood of Nov. 4-5, 1985, W. Va. E27 
A 

c 

by Pleistocene glacial meltwater floods, have been 

described by Baker ( 1978) and by Kehew and Lord ( 1986). 

Longitudinally oriented erosion and deposition forms 

may generally be attributed to secondary flows consisting of 

paired longitudinal vortex tubes with opposite directions of 

rotation (Allen, 1982). An array of helical vortices of this 

type can develop in straight stream channels (Einstein and 

Li, 1958). Allen (1985) suggests that in the absence of 

bedload, furrows will develop on a soft mud bed by fluid 

stripping where the vortices descend toward the bed and 

then diverge, but that corrasion in the presence of bedload 

could produce furrows along zones of converging and rising 

flow instead (fig. 33). Our observations of cobbles and 

gravels on the floors of some grooves (fig. 29) suggest that 

corrasion by coarse clasts embedded in the vortex was one 

of the mechanisms involved in groove formation during the 

1985 flood. 

Scour Marks 

Scour marks are erosion features that range in shape 

from small circular or elliptical pits, to elongate parabolic or 

B 

Figure 29. Longitudinal grooves (A) formed by the limbs of 

a tree dragged across valley floor, North Fork South 

Branch Potomac River about 0.6 km upstream of Seneca 

Rocks; (B) oriented along direction of flow, unrelated to 

crop patterns. Ruler is 15 em long. North Fork South 

Branch Potomac River near Zeke Run, about 10 km 

upstream of Hapeville; (C) incised along crop rows, South 

Branch Potomac River near Fisher, several kilometers 

upstream of Moorefield. Photograph by R. Gray, U.S. Soil 

Conservation Service. 

spindle-shaped marks, to irregular shapes formed by lateral 

erosion and uneven headcut retreat (figs. 34-38). Some 

examples observed in the field were smaller than 1 m in 

diameter and shallower than 0.3 m, but the largest examples 

were tens to hundreds of meters long and tens of meters 

wide. The largest of the observed scour features are referred 

to below as flood channels or chutes. 

Many of the observed scour marks had spoon-shaped 

long profiles that were steepest at the head of the scour. In 

this respect they are reminiscent of the idealized form of 

flute marks described by Allen (1971, 1982); however, 

some examples had stepped profiles and complex internal 

structure resembling discontinuous gully systems. Scour 

marks, like longitudinal grooves, were found in association 

with severe disruption of the valley floor but also occurred 

as isolated forms on otherwise undisturbed bottomland. 

Most scours observed in the study area appear to be 

associated with some form of flow separation and vortex 

action. Similar features formed on the Connecticut River 

flood plain in the flood of March 1936 were described by 

Collins and Schalk (1937) as "swirl pits"; macroturbulent 

vortex action or "kolking" (Matthes, 194 7) was identified as 

the probable cause of other circular or elliptical scours 

described by Ritter and Blakely (1986) and Baker (1978). 

One of the more common types of scour marks 

observed in the aftermath of the November 1985 flood was 

created by flow separation around individual obstacles 

projecting above the flood-plain surface. Most of the 

obstacles were trees (fig. 39A), but the same effect was 

E28 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W. Va., Va. 
('" .. "'I 

Figure 30. Grooves formed as drag marks by trees entrained in flood flow. South Fork South Branch 

Potomac River, 2 km upstream of Milam; flow along South Fork is from left to right. Field of view is 

460 m wide. 

Figure 31. Deeply incised grooves oriented subparallel to crop rows, Cheat River about 2 km upstream 

of Rowlesburg. Flow is from right to left. Diagonal white lines on left side of photograph are power 

transmission lines suspended across the river. Field of view is 140 m wide. 

Flood Hydrology and Geomorphic Effects, Flood of Nov. 4-5, 1985, W.Va. E29 
Figure 32. Grooves incised along trend of shallow erosional trough, South Branch Potomac River just 

downstream of Petersburg gaging station (station was destroyed in the flood) . Flow along South 

Branch is from left to top center. Field of view is 790 m wide. 

Figure 33. Drawing showing flow pattern of longitudinal corkscrew vortices and their hypothesized 

effects on the shape of the underlying bed (from Allen, 1985, p. 211; used by permission). (A) General 

character of motion, (B) shape of deformable granular surface adjusted to the motion, (C) shape of a 

mud bed adjusted to the motion in the absence of bedload, and (D) shape of a mud bed adjusted to 

the motion in the presence of bedload particles. 

E30 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W.Va., Va. 
A 

B 

Figure 34. (A) Small elliptical scour on valley floor along South Branch Potomac River between 

Redman Run and Austin Run, 5 km upstream of confluence with North Fork. Flow was from upper 

right to lower left. (B) Elliptical (see right edge) and elongate or spindle-shaped (see center) scour 

marks on the Cheat River flood plain, about 2 km upstream of Rowlesburg. Flow was from right 

to left. Note longitudinal grooves incised along crop rows; also note sand dunes at top and 

bottom of photograph. White lines running from top center to lower right are power transmission 

lines. Field of view is 100 m wide. 

Flood Hydrology and Geomorphic Effects, Flood of Nov. 4-5, 1985, W.Va. E31 
Figure 35. Elongate scour marks along South Fork 

South Branch Potomac River, 7 km downstream of 

Brandywine. Note that the heads of the scour marks 

are located just downstream of a fence line, which may 

have been a site for initiation of separated flow. Flow 

sometimes observed around buildings (fig. 39B). The pattern of flood flow around a tree is analogous to the 

generalized pattern of flow around a rounded, blunt body 

protruding vertically into the flow, which has been 

described in great detail. The typical horseshoe-shaped 

scour was given the name "current crescent" by Peabody 

(1947); structures formed by scour and deposition associated with flow around an obstacle were described by 

Dzulynski and Walton (1965) as obstacle marks. Additional 

discussions of these features have been presented by Karcz 

(1968), Baker (1978), Allen (1982), Sullivan (1983), Ritter 

and Blakely (1986), Paola and others (1986), and Baker and 

Kochel ( 1988). Similar phenomena associated with scour at 

bridge piers have been discussed in the engineering literature (Laursen, 1960; Moore and Masch, 1963; Shen, 1971). 

A horseshoe vortex typically forms by separation of 

the boundary layer on the upstream side, which rolls up and 

is stretched or wrapped around the obstacle (Shen, 1971, 

fig. 23-4; also see Baker, 1978, p. 102; Allen, 1982, fig. 

5-2; and Paola and others, 1986, fig. 2). The limbs of the 

in channel enters at lower right and follows meander 

clockwise to upper right, but overbank flow during the 

flood cut across the valley floor from bottom center. 

Field of view is 760 m wide. 

vortex reattach at some distance downstream, leaving a 

zone of separated flow in the wake of the obstacle. As Allen 

(1982, fig. 5-10) and Paola and others (1986) indicate, and 

as our observations confirm, erosion commonly occurs in 

the region of vortex flow on the upstream side. If the 

obstacle is a tree, scour around the base may partially 

undermine it and allow the flow to uproot or topple it 

(fig. 40). 

Debris accumulations around trees (figs. 39A, 41) 

increase the cross-sectional area of the obstacle offered to 

the flow and therefore increase the size of the area of 

separated flow. In some cases this may protect the tree from 

the immediate effects of basal scour, but in other cases the 

debris may be responsible for increasing the shear exerted 

on the tree by floodwaters, thus leading to toppling of the 

tree. Similar effects were observed along the valley of Plum 

Creek in Colorado in the aftermath of a catastrophic flood 

occurring in 1965 (W.R. Osterkamp, U.S. Geological 

Survey, personal communication, 1988; flood described by 

Osterkamp and Costa, 1987). 

E32 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W. Va., Va. 
A 

B 

Figure 36. (A) Headward branching scour on North Fork flood plain, about 2 km 

downstream of Circleville. The two headcuts diverge at the location of a fence line, which 

may have been a site of initiation of flow separation before the scour retreated headward. 

Field of view is 390 m wide. (B) Several scour features in this photograph appear to have 

retreated headward from linear flow obstructions. Flow was from upper right to lower left; 

the river channel is out of view at the bottom of the picture. South Fork flood plain, 13 km 

upstream of confluence with South Branch at Moorefield. The road is elevated 2-3 m 

above the flood plain and served to block floodwaters until it was overtopped and 

breached; the resulting scour, at right center, then retreated headward and formed two 

prominent headcuts. Another, broader headcut is visible at lower left and appears to have 

started at a fenceline oriented perpendicular to the flow, which was from right to left on 

this portion of the flood plain. Splay deposits also are clearly visible. Field of view is 620 m 

wide. 

Flood Hydrology and Geomorphic Effects, Flood of Nov. 4-5, 1985, W. Va. E33 
Figure 37. Headward-eroding scour formed where overbank flow drained back into the river channel (center of 

picture). Flow is from left to right. North Fork at Bennett Gap, 1.5 km downstream of Riverton. Field of view is 

380m wide. 
A 

Figure 39. Scour marks created by flow separation around 

isolated objects on the flood plain. (A) Tree with accumulated debris and elliptical scour, South Branch Potomac 

River between Redman Run and Austin Run, 5.7 km 

upstream of confluence with North Fork; flow was from 

left to right. (8) Scour mark formed around upstream side 

of house on the flood plain of the Black Fork River, 

tributary to Cheat River, 1 km upstream of Parsons. Field 

of view is 95 m wide. Flow direction is from left to right. 

..,.. Figure 38. Irregular scour pattern on forested surface 

upstream of a field cleared for row crops. Virtually 

every tree in the forested area has been knocked down 

and many have been uprooted, leaving small circular or 

elliptical pits. Several pits have been enlarged to form 

elongate scour marks. At top center, a turbulent thread 

of flow emerging from the forested area onto the open 

field has left an irregular scour mark, whose outline 

bears a strong resemblance to the shape of a turbulent 

jet emerging from an orifice (illustrated in Allen, 1985, 

fig. 11.10, p. 206). Flow is from left to right. Cheat River, 

10 km upstream of Rowlesburg. Field of view is 110 m 

wide. 

B 

Flood Hydrology and Geomorphic Effects, Flood of Nov. 4-5, 1985, W.Va. E35 
..,.. Figure 40. Fallen tree flanked by a pair of elliptical scour 

marks, Cheat River about 8 km downstream of Parsons. 

The scours appear to make up the limbs of a horseshoe, 

but they do not quite meet on the upstream side of the 

tree, and the scour on the left side leads into an 

elongate erosional trough that extends downstream. 

Note cutbank on left side of photograph where channel 

widening occurred in the flood. Flow along Cheat is 

toward the top. Field of view is 100 m wide. 

Figure 42. Sand deposit formed in the lee of a standing 

tree, South Branch Potomac River between Redman Run 

and Austin Run. 

Figure 41. Debris jam formed on upstream side of tree during the flood. South Branch 

Potomac River between Redman Run and Austin Run, about 5.4 km upstream of 

confluence with the North Fork. 

E36 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W.Va., Va. 
Patterns of erosion and deposition in the separation 

zone and immediately downstream of the reattachment 

point also may vary considerably (Allen, 1982, fig. 5-10, 

p. 185). In some cases there is an elliptical scoured zone 

that gradually shallows downstream (fig. 39A). In other 

cases a remnant of undisturbed bottomland is found along 

the centerline of flow downstream of the obstacle, flanked 

by scour zones; sometimes there is a mound of sediment 

deposited over undisturbed bottomland within the region of 

flow separation (fig. 42). The transition from conditions 

favoring deposition to conditions favoring erosion in the lee 

of the obstacle apparently occurs with increasing strength of 

the wake-vortex system at very high flow velocities (Shen, 

1971; Baker, 1978). 

Although scour marks formed in the November 1985 

flood were commonly found in association with isolated 

flow obstructions such as trees or buildings, linear features 

crossing the flood plain perpendicular to the main flow also 

acted as initiation sites for flow separation and scour. 

Multiple parallel scour marks were found extending downstream from roads, fence lines, rows of trees, and topographic steps on the valley floor (figs. 35, 43). Scour marks 

also were located preferentially in local topographic lows, 

where floodwaters were deeper and shear stresses were 

greater than at adjacent high points. Some of these scours 

may have reoccupied the sites of old abandoned scour 

marks formed in past floods. 

Elongate scour marks observed in the study area 

resemble parabolic or spindle-shaped transverse erosional 

marks described by Allen (1971) (figs. 34B, 35, 43). 

Allen's ( 1971) experiments demonstrated that an original 

circular or elliptical pit could become an elongate scour 

mark by progressive erosion in the downstream direction. 

The upstream end of the pit is the site of initiation of 

separated flow; the rate of bed erosion by fluid-stressing 

(i.e., shear stress exerted by the overlying fluid) is greatest 

near the point of reattachment (Allen, 1971, p. 227). As 

erosion progresses, the separated zone becomes longer and 

the locus of maximum bed erosion shifts downstream 

(Allen, 1982, fig. 7-27). Thus, some of the elongate scour 

marks observed in the South Branch basin, like the features 

developed in Allen's (1971) experiments, may have formed 

by downstream extension of smaller, initially elliptical or 

irregularly rounded scour pits. 

Some elongate scour marks appear also to have 

grown upstream by headcut retreat along existing swales 

and depressions; branching patterns resembling a simple 

drainage network were observed at several locations (fig. 

36). The headcuts at such locations were amphitheater 

shaped with well-developed plunge pools. Fluvial erosion 

by water converging toward and draining over the lip of the 

scour is considered the most likely cause here, given the 

rapid recession of floodwaters and the fact that the underlying alluvium often contained strata that were either quite 

cohesive or too coarse to be eroded and transported downstream by sapping. Headcut retreat is strongly indicated 

where the head of a scour mark is located upstream of a 

linear feature identified as the probable locus of flow 

separation responsible for initiating the scour (fig. 36). 

Similar headcuts have been observed forming knickpoints 

in cohesive alluvium underlying new channels cut by the 

November 1985 flood (fig. 44). 

Irregular, patchy patterns of scour were generated by 

highly turbulent flow on bottomlands with hummocky 

topography and numerous local obstructions of varying 

shapes and sizes (figs. 38, 43, 45). These examples attest to 

the extraordinary complexity of the flow fields that develop 

at some sites. 

Bank Erosion and Channel Widening 

Bank erosion was common along all three forks of the 

South Branch Potomac River during the November 1985 

flood. Many fresh cutbanks were formed, exposing alluvium, colluvium, and debris-fan deposits in cross section. 

In some cases, where a large component of the flood flow 

left the channel, the preflood channel remained virtually 

unmodified despite major impacts on the adjacent bottomland. However, where channel flow impinged against one 

bank or the other, the resulting erosion was often dramatic, 

doubling or tripling the width of the channel at the expense 

of the flood plain (figs. 46A-D). 

The positions of preflood banks are sometimes 

marked in the aerial photographs by a line of trees or 

organic debris in the water (figs. 46A, B). Often a cutbank 

is flanked by an area along the channel margin where 

alluvium has been partially stripped away. Downstream, the 

stripped areas commonly grade into sandy to gravelly splay 

deposits (figs. 47, 48). In some instances an example of 

radical channel widening is associated with multiple chutes 

or erosion channels on the valley floor or with formation of 

bars and remnant islands in the channel belt (figs. 47, 49). 

Where the channel was flanked by forested bottomland rather than by flood plains cleared for agriculture, 

channel widening sometimes was accompanied by irregular 

scouring and abrasion of the adjacent surface. The resistance to flow offered by the trees and the anchoring effect of 

their roots may have prevented more extensive bank erosion 

at such sites, even though many of the trees were knocked 

down by the force of the flow (fig. 50). However, presence 

or absence of forest was not a clear determinant of the 

extent of channel widening or of other forms of erosion. 

Gallery forests or lines of trees bordering the channel were 

present along most of the length of each of the three forks 

of the South Branch prior to the flood, and the trees were 

completely removed at many sites. Dense stands of trees 

failed to prevent channel widening or stripping of the 

Flood Hydrology and Geomorphic Effects, Flood of Nov. 4-5, 1985, W. Va. E37 
A 

B 

Figure 43. Scour marks associated with flow obstructions: (A) South Fork South Branch 

Potomac River at Brandywine; flow is from left to right. Note elongate scours initiated 

where flood flow crossed over the road just right of the center of the photograph and also 

where the road approaches the river channel at lower right. Field of view is 640 m wide. (B) 

South Branch Potomac River near Durgon, 9 km downstream of Petersburg; flow is from 

left to right. Complex pattern of channel widening and flood-plain erosion, with elliptical 

and elongate scours formed downstream of fence lines, rows of trees, and topographic 

steps. Note area marked by both scour marks and longitudinal grooves in cultivated field 

at the center of the photograph. Several larger channels incised along the flood-plain 

margins also are visible. Field of view is 1,400 m wide. 

E38 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W.Va., Va. 
Figure 44. Headcut in a new channel actively retreating 

upstream at low flow in the summer of 1987. Vertical drop 

in bed level over the ledge is about 1.5 m. South Branch 

Potomac River downstream of Austin Run, 4.4 km 

upstream of confluence with the North Fork. 

bottomland surface at those sites where stresses imposed by 

flood flows were most intense (fig. 51). 

Channel widening occurred at several sites where 

bridges influenced flow hydraulics, and it may have been 

caused by a combination of accelerated flow through the 

contracted opening beneath the bridge and turbulent eddies 

spawned by flow separating over and around the edges of 

the bridge (fig. 52). Similar occurrences have been reported 

previously; Ritter and Blakely (1986) describe an instance 

of extreme scour that they attribute to macroturbulent vortex 

action spawned by a bridge during a flood that was not 

considered competent to cause comparable erosion under 

natural conditions. Where Route 33 crosses the South Fork 

at Brandywine, channel widening and scour of the valley 

floor occurred downstream of the bridge, and a prominent 

arcuate scour formed along the right bank upstream of the 

bridge (fig. 53). The latter could have formed under a 

turbulent vortex generated by shear between flow moving 

through the bridge and flow piled up behind the bridge and 

road embankment along the right bank; alternatively, it 

might have formed by headcut migration under the influence of flow draining off the flood plain and back into the 

channel of the South Fork. 

Stripping 

General scouring and removal of vegetation and 

fine-grained alluvium from the valley floor that is not 

restricted to a well-defined scour mark or erosion channel is 

here referred to as "stripping." Stripping usually involved 

removal of a veneer of silty to sandy overbank deposits to 

reveal an underlying pavement of cobbles and boulders 

(figs. 54A-C, 55). At some locations, tree trunks were 

snapped or sheared off above the base, leaving behind 

stumps whose roots were exposed following removal of the 

surrounding soil (fig. 56). 

The depth of stripping generally ranged up to 1.5 m, 

depending primarily on the depth of the contact between 

any fine-grained sediment and the coarse pavement underneath. Stripping occurred most often on point bars, channel 

islands, and bottomland segments in or immediately downstream of canyon reaches. 

The coarse pavement presumably represents a channel lag deposit such as is normally found at the base of the 

alluvial sequence underneath a flood plain. Imbrication of 

cobbles and boulders exposed on the postflood surface, with 

some clasts resting against remnant clumps of vegetation 

(fig. 55), indicates that considerable reworking of this layer 

often occurred at sites where it was exposed by stripping of 

the surface layer. At some sites in the study area, cobbles 

and boulders were deposited on top of soil without stripping, leaving a continuous carpet of imbricated clasts that 

looks virtually identical to the layer exposed at other sites 

by stripping. Positive evidence for stripping is provided by 

erosional remnants of fine-grained cohesive material adjacent to the stripped surface (figs. 54A, B). 

Few sites are characterized exclusively by erosion or 

by deposition, however. More commonly there is a transition from one to the other. At sites such as those illustrated 

in figure 57 and in figure 9 of Kite and Linton (chapter D, 

this volume), the stripped surface appears to ramp upward 

from the area along the channel margin, where the depth of 

scour is greatest, to its downstream terminus. Fresh lobes of 

coarse material, derived from stripping or from bedload 

already in transit, form splay deposits that obscure the 

transition from an erosional surface to a surface affected 

only by deposition. Bedload transport of gravel along ramp 

surfaces has been described as a common mechanism for 

moving coarse materials onto upper point-bar and low 

flood-plain surfaces (Ritter, 1975; Knox, 1987). 

The process involved in stripping appears to be a 

combination of (1) surficial abrasion and gouging by 

sediment particles, trees, and other objects entrained in the 

flow and (2) fluid-stressing, which tends to cause failure of 

cohesive beds along planes of shearing or tearing (Allen, 

1971, p. 201). The reports cited by Allen (1971) include an 

experimental study of cohesive mud bottoms by Dunn 

(1959), who derived an expression for critical bed shear as 

a function of vane shear strength. In the present instance the 

critical shear stress is that required to tear the vegetation mat 

or turf layer from the underlying material. This process is 

facilitated if the turf has already been broken; the turf layer 

may then be undermined or rolled up by the flow (fig. 58). 

As turf is removed, other turf edges are exposed, and 

eventually a large portion of the flood-plain surface 

becomes unraveled. Grass-covered surfaces are more vulnerable to this type of erosion than forested surfaces, where 

turf removal is minimized by the flow resistance of standing 

Flood Hydrology and Geomorphic Effects, Flood of Nov. 4-5, 1985, W. Va. E39 
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Figure 45. Complex pattern of scour and incision, flood plain of Black Fork River at Hendricks (tributary to Cheat River). Lobe of coarse sediment 

at left is derived from a stripped area just upstream (see Kite and Linton, chapter D, this volume, fig. 8). Enlarged view of debris jam around house 

at lower right is shown in Kite and Linton (chapter D, this volume, fig. 11). Flow is from left to right. Field of view is 600 m wide. 
A 

B 

Figure 46. Before-and-after views illustrating channel widening. (A and B) Location along the 

South Branch where flow emerges from the unnamed gap upstream of Petersburg; flow is from 

left to right. The Petersburg gage and several houses on the right bank were destroyed as the 

channel more than doubled its width. Location is 2.1 km downstream of the confluence with the 

North Fork. Field of view is 1,000 m wide. (C and 0) Site along the South Fork about 6 km 

downstream of Milam. Flow is from left to right. Note that the large scored area in upper right 

center was part of a topographic surface that was lower than the adjacent flood plain; along the 

South Fork this surface was often more heavily scored than the rest of the valley floor. Field of 

view is 770 m wide. 

Flood Hydrology and Geomorphic Effects, Flood of Nov. 4-5, 1985, W.Va. E41 
c 

D 

Figure 46. Continued. 

E42 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W.Va., Va. 
Figure 47. Oblique aerial photograph showing channel widening along the North Fork at Macksville, 4.7 km upstream of Seneca Rocks. Note the surviving trees standing on stripped flood-plain 

remnants in the widened channel. A scour channel with amphitheater-shaped headcut extends 

headward between two buildings at right center. Photograph by E. Propst, Clarksburg Publishing 

Company. 

Figure 48. Channel of South Branch downstream of confluence with North Fork; exact location 

unknown. Steep cutbank at right grades into a stripped area at top right, where flow left the 

channel and crossed the flood plain. Photograph by W. E. Duliere, West Virginia Advocate. 
A 

Figure 49. North Fork near Tool Run, 8.4 km upstream of 

Hopeville (A) before and (8) after the flood. Flow is from 

bottom center to top left. Channel widening has left a 

broad stripped remnant in the channel at the apex of the 

bend. The preflood view in (A) suggests that this remnant 

trees and by the tensile and shear strength of root systems. 

As was mentioned previously, however, the power of the 

1985 flood was sufficient at many sites to overcome 

resistance by grass or standing trees. Many of the stripped 

areas were densely vegetated before the flood, and some 

thick groves of trees were removed without a trace (fig. 51). 

Trees located along the margins of the main flow were 

much more likely to survive the flood than were trees in its 

direct path. 

Chutes 

Concentrated flow on the flood plain often produced 

a well-defined channel rather than stripping the entire 

surface. These channels, many of which were comparable 

in cross-section dimensions to the preflood river channel 

(fig. 59), are referred to here as chutes. They were 

commonly several hundred meters in length; the largest 

B 

may have been an old bar that had become attached to the 

flood plain. Note also the shift in the channel toward the 

right bank and the large body of sediment deposited along 

the left bank just downstream of the bend. Field of view is 

670 m wide. 

example identified on postflood aerial photographs was 

about 800 m long and 50 m wide. Splay deposits often 

extended onto the flood plain adjacent to the margin of the 

chute, and lineations on their surfaces indicate flow divergence outward and away from the longitudinal trend of the 

chute (fig. 60). Some chutes were reoccupied swales or 

back channels that were incised and widened during the 

flood; others formed at sites lacking evidence of a preexisting channel. 

Incipient chute forms were seen at several locations in 

the South Branch drainage. In plan view they resembled 

scalpel points protruding into the bottomland and tapering 

to a point at the downstream end, with adjacent splay 

deposits (fig. 61). The term "incipient" is used here because 

these forms are interpreted as occurring in settings where 

the erosive power of overbank flow was insufficient to cut 

a longer channel across the valley floor. Fully developed 

chutes may have cut across a point bar or meander loop, 

E44 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W.Va., Va. 
A 

B 

Figure 50. (A) Before and (B) after views showing scour of forested channel margins and low flood 

plain along South Fork, 2 km upstream of Milam. Flow is from bottom center. Several shallow 

channels were cut across the forested area at right center, and a large portion of the valley floor 

was stripped. The upper flood-plain surface was affected primarily by formation of scattered 

longitudinal grooves and scour marks. Field of view is 1,100 m wide. 

Flood Hydrology and Geomorphic Effects, Flood of Nov. 4-5, 1985, W.Va. E45 
A 

B 

Figure 51. (A) Before and (B) after views of the North Fork at Hapeville. Flow is from upper right 

to upper left. The bedrock constriction at the exit of Hapeville canyon is about 60 m wide, and 

flow emerging from this constriction stripped away a large grove of trees and the underlying 

flood plain . Eleven lives were lost at the site of the house and trailer park seen at left center of 

(A). This surface is about 6-7 m above the low-water channel, and local residents noted that it 

had not been reached by floodwaters in the previous record flood of june 1949. Field of view is 

770 m wide. 

E46 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W.Va., Va. 
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Figure 52. (A) Before and (8) after views showing channel widening downstream of a bridge crossing the South Fork at Fort Seybert, 14 km downstream 

of Brandywine. Flow is from bottom to top. Channel widening affected the 

lower topographic surface; note that the scarp separating the lower surface 

from the upper flood plain in (A) coincides with the position of the channel 

B 

margin after the flood in (8). A large splay was deposited on the flood plain 

adjacent to the eroded area. Several prominent scour marks are visible in (8) 

on the upper flood plain in the center of the photograph. Their origin may 

be related to turbulent eddies spawned by flow over the road. Field of view 

is 400 m wide. 
Figure 53. Channel widening and flood-plain scour, South 

Fork at Brandywine gaging station. Flow is toward the top. 

Field of view is 300 m wide. 

intersecting the river channel at one or both ends (fig. 60), 

but there were also well-developed examples with upstream 

or downstream termini that did not intersect the channel 

(fig. 62). 

Most chutes formed at locations where a major 

component of flow followed a straight or slightly curved 

trajectory parallel with the valley walls, crossing the flood 

plain rather than negotiating a bend in the channel. Such 

chutes may have been initiated by erosion of the river bank 

at the upstream end of a flood-plain segment, followed by 

scour and incision of the flood plain progressing in the 

downstream direction. A chute believed to have formed in 

this way is illustrated in figures 63 and 64: here the 

upstream end of the chute marks the point where the main 

body of flow left the channel, and the attitude of the fallen 

trees (fig. 64) indicates progressive downstream scour 

rather than headcut retreat. In other cases there was initial 

abrasion of the flood-plain surface to form a shallow trough, 

followed by incision of a deeper channel within the area of 

the trough and upstream growth of this channel by headcut 

retreat. In the right center part of figures 99B and C, the 

area where flood flow crossed onto the flood plain is 

occupied by a shallow trough with scattered scour marks 

and longitudinal grooves; this is separated from the 

upstream end of the main chute by a vertical headcut that 

branches into discrete lobes. Initial formation of a shallow 

scoured zone followed by incision of an inner channel was 

observed in flume studies by Shepherd and Schumm 

( 197 4), and a similar sequence of events was proposed by 

Kehew and Lord (1986) for the evolution of channels 

formed by glacial meltwater floods. 

At several sites where one or more chutes formed 

below the confluence of a tributary with one of the main 

rivers, flow from both sources contributed to the pattern of 

erosion (figs. 62, 65). In such cases the main body of the 

chute branches upstream into discrete headcuts, at least one 

of which captured flow from and retreated headward along 

swales crossing the surface of a fan built by the tributary. 

Lobate headcuts were not restricted to the upstream ends of 

chutes; some also had multiple lobes radiating from the 

channel walls (figs. 62, 99B, C). The lobate scours probably were initiated where shallow swales carrying concentrated flow across the flood plain were truncated by incision 

of deeper chute channels. Flow cascading over the wall of 

a chute would have caused headcut retreat along the trend of 

the swale until flood stage declined below some threshold 

level capable of sustaining the erosion process. 

Chutes inspected in the field generally had steep 

banks. Those that did not intersect the river channel at the 

downstream end gradually shallowed downstream until they 

merged with the surrounding undisturbed valley floor; 

sometimes the transition was obscured by splays deposited 

at the downstream end of the chute. Chute floors usually 

were flat (fig. 66), but some had uneven or stepped bed 

topography with inner and outer channels (fig. 59). 

Most chutes were floored by imbricated cobbles and 

boulders (fig. 66). Although many of the cobbles and 

boulders appeared to have moved during the flood, the fact 

that cobble splays observed following the flood generally 

were contiguous to areas of channel or flood-plain scour 

(from which they presumably were excavated) suggests that 

most probably did not move further than a few hundred 

meters. Much of the floor material may have been composed of slightly reworked lag deposits: older sediments 

exposed in some chute walls were composed of rounded 

cobbles, gravel, and small boulders in a sandy matrix (fig. 

67) and were similar in texture to the fresh deposits on the 

adjacent valley floor. Along one 126-m section of chute 

(figs. 66 and 67), 63 percent of the bank length contained 

imbricated gravel, cobbles, and boulders; gravel lenses at 

this site were up to 14 m long and 1 m thick (Scatena, 

1986). That such coarse material should be found at such 

shallow depth beneath the flood-plain surface suggests that 

large floods may have played an important role in shaping 

E48 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W.Va., Va. 
A 

B 

Figure 54. Three examples of flood-plain stripping: (A) North Fork in Hopeville 

canyon, 0.9 km upstream of Hopeville (photograph by F.N. Scatena). The view is 

looking upstream. The channel is about 40 m wide. The point bar in the foreground 

was a pasture before the flood. As much as a meter of alluvium was stripped away; 

erosion scarps are visible on the remnants of the original surface. Figures 55 and 56 

show the area upstream and around the bend from this location. (B) North Fork near 

North Fork Gap. The remnant of flood-plain alluvium is virtually all that remains of the 

original surface at this location. (Q South Branch, 0.8 km downstream of the Trough. 

Flow is from right to left. Photograph by W.E. Duliere, West Virginia Advocate. 

Flood Hydrology and Geomorphic Effects, Flood of Nov. 4-5, 1985, W. Va. E49 
c 

Figure 54. Continued. 
Figure 56. North Fork in Hopeville canyon at same location as figure 55. View is facing upstream. Stump is 

standing next to the low-water channel. 

Figure 57. Gradation from stripped surface to depositional lobe derived from stripped 

material; North Fork at jordan Run, 2.5 km downstream of Hopeville. Flow is from left to 

right. The feature protruding from the valley wall at bottom center is a probable 

debris-flow lobe emplaced in june 1949. Note scour caused by flow diverted around this 

lobe. Long dimension of field of view is 670 m. 

~ Figure 55. Imbricated pavement of cobbles and boulders on stripped flood plain. North Fork in Hopeville 

canyon, 1.7 km upstream of Hopeville. Flood flow was 

from right to left. Note the fallen trees in the middle 

background and the cutbank marking the edge of the 

stripped area in the background at the right. This was a 

pasture before the flood. 

Flood Hydrology and Geomorphic Effects, Flood of Nov. 4-5, 1985, W.Va. E51 
Figure 58. Mounds of rolled-up turf located around margins of an elongate scour mark. This photograph was 

taken about 18 months after the flood, and the margins of 

the scoured area were covered by grass. South Branch 

flood plain between Redman Run and Austin Run, 5.1 km 

upstream of confluence with North Fork. 

the present form of the flood plain. However, cobbles and 

boulders are not equally important components of the 

subsurface at all locations. In some chute walls and river 

bank exposures a vertical section of fine-grained alluvium 

with interbedded gravel lenses was observed (figs. 68, 69). 

Similar alluvial sequences were observed by Costa (1974) 

and by Ritter (1975) and were interpreted as evidence for 

large rare floods in an environment otherwise characterized 

by long-term accumulation of sandy or silty lateral and 

vertical accretion deposits. 

Chutes on forested bottomlands were generally narrower and not so well defined as those formed on land 

cleared for agriculture (fig. 70). Their characteristics may 

have been controlled in part by the flow resistance and 

resistance to scour offered by tree trunks and tree roots. 

475 

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Cl: 

Furthermore, many of the forested bottomlands along the 

three forks of the South Branch are at lower elevations than 

adjacent areas cleared for agriculture, and they may in fact 

have been allowed to remain in forest precisely because 

they lack more than a veneer of fine alluvial sediment to 

cover a pavement of cobbles and boulders. Flows powerful 

enough to overcome the resistance offered by trees in this 

setting may strip the surface rather than form well-defined 

channels (fig. 50). 

Anastomosing Channels and Jet-Shaped Erosion Forms 

Dissection of bottomlands by anastomosing flood 

channels was observed at several locations in the South 

Branch basin in November 1985. In some places, two or 

more distinct chutes parallel each other across the valley 

floor (fig. 9). Elsewhere, an anastomosing pattern occurs 

within a relatively narrow belt along the preflood river 

channel; such patterns are associated with incomplete channel widening that creates remnant islands in the expanded 

channel (fig. 71). The most dramatic examples involve 

dissection and reworking of much of the width of the valley 

floor (figs. 72A-D). The catastrophic erosion at such sites, 

and the limited number and spatial extent of the areas 

affected, indicate that this pattern signals the crossing of a 

significant geomorphic threshold in the balance between 

flood hydraulics and resistance to erosion. We do not yet 

have sufficient information to quantify this threshold reliably, but previous computations of unit stream power 

suggest energy expenditures in excess of several hundred 

W/m2 may lead to catastrophic erosion of the valley floor. 

Patterns of erosional anastomosis observed here bear 

some morphologic resemblance to channel systems eroded 

by glacial meltwater floods (Bretz, 1923, 1928, 1959; 

Baker, 1978; Kehew and Lord, 1986), but spatial scale of 

the erosion forms and magnitude of the formative event are 

clearly much smaller. Transient braided patterns described 

by Carson ( 1984) also were formed by erosion during major 

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HORIZONTAL DISTANCE, IN METERS 

Figure 59. Postflood cross section of North Fork valley at Seneca Rocks Visitor Center. Chute formed in the flood is 

comparable in width to the preflood river channel. Figure 62 is an aerial photograph of this chute (after McKoy, 1987). 

E52 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W. Va., Va. 
A 

B 

Figure 60. South Fork near Fort Seybert (A) before and (B) after the flood. Location is 12 km 

downstream of Brandywine. Prominent chutes formed during the flood were incised along the 

trends of swales visible in preflood photograph. Flow is from right to left. Field of view is 1,200 m 

wide. 

Flood Hydrology and Geomorphic Effects, Flood of Nov. 4-5, 1985, W. Va. E53 
Figure 61. Incipient chute eroded in South Fork flood plain near Oak Flat, 9.3 km downstream of Brandywine. 

Flow is from right to left. Width of field of view is 460 m. 
Figure 63. Chute on flood plain of North Fork about 

0.6 km upstream of Seneca Rocks. Flow forced around 

a bedrock outcrop scoured the upstream end of the 

chute; incision proceeded from upstream to down-

..,... Figure 62. Chute on flood plain of North Fork at Seneca 

Rocks Visitor Center, 0.6 km downstream of Seneca 

Rocks. Flow is from left to right. Seneca Creek joins the 

North Fork just to the left of the area shown in this 

picture; the headcut oriented toward the upper left 

corner of the photograph evidently was exploited by 

flow coming from Seneca Creek. The cross section 

shown in figure 59 extends across the flood plain at this 

site from a point about halfway between the two 

parking loops at top left center to a point on the right 

bank of the North Fork just upstream of the bend in the 

channel. Field of view is 650 m wide. 

stream, where a coarse splay deposit flares out over 

the adjacent valley floor. Flow is from left to right. 

Field of view is 930 m wide. 

Figure 64. Ground view of upstream end of chute illustrated in figure 63. Tilted and uprooted trees indicate 

current direction and indicate that erosion of the channel 

proceeded from upstream to downstream rather than by 

upstream migration of headcuts. 

Flood Hydrology and Geomorphic Effects, Flood of Nov. 4-5, 1985, W. Va. E55 
Figure 65. Chute with branching headcuts, South Branch at Smith Creek, about 3.5 km upstream of 

Franklin. Flow along the South Branch is from right to left. Prominent headcuts in the foreground were 

created by flow emerging from Smith Creek. Photograph by E. Propst, Clarksburg Publishing 

Company. 

Figure 66. Chute in figures 63 and 64, shown looking downstream. This chute was about 40 m wide, 

1.5 m deep, and 500 m long. 

E56 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W. Va., Va. 
A 

Figure 67. Two views of the right bank of the chute seen in 

figure 66. (A) A flat bed of imbricated cobbles and a bank 

about 1.5 m high; the trees in the background are standing on a lower surface, and the North Fork is on the other 

Figure 68. The left bank of the chute illustrated in figures 

66 and 67 exposes a sequence of fine-grained alluvium 

with interbedded gravel lenses resembling those 

described by Ritter (1975). The gravel lens exposed in 

cross section presumably was deposited by a past flood in 

much the same way as the gravel lens on the surface was 

deposited by the November 1985 flood. 

B 

side of the trees. (B) A closer view of the bank section, 

indicating that the flood plain is underlain by a sequence 

of cobbles and gravel that generally resembles the material exposed on the floor of the chute. 

Figure 69. The left bank of the South Fork at Brandywine 

exposes a gravel lens (near the base) that resembles the 

lenses shown in figure 68. Such deposits may be common 

in the flood plains of the three forks of the South Branch. 

The bank is about 2-2.5 m high. 

Flood Hydrology and Geomorphic Effects, Flood of Nov. 4-5, 1985, W. Va. E57 
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Figure 70. South Fork, 1.9 km downstream of Brandywine gaging station, seen (A) before and (B) after the flood. Flow is from bottom left to top center. Chutes 

running across this forested bottomland (actually the lower of the two surfaces described previously) are generally narrower than, and not as well defined as, 

chutes running across cleared fields. The examples shown here were enlarged by the flood, but their existence predates the flood. Field of view is 630 m wide. 
A 

Figure 71. South Branch flood plain, about 3 km 

upstream of Franklin. Flow is from bottom to top. 

Channel widening and dissection of the flood plain 

left several large remnant islands separated by a set of 

floods. Although these gradually heal with deposition of 

sediment and growth of vegetation, any remaining topographic depression may be a preferred path for overbank 

flow in subsequent floods and could be excavated again if 

an event of comparable magnitude were to occur. 

At sites of erosional anastomosis in the study area, 

many residual islands are found in groups separated by 

closely spaced channels, are diamond-or rhomboid-shaped, 

and resemble braid bars in gravel-bed streams that have 

been truncated in the falling stages of a flood (figs. 72B, D). 

Island forms described in the literature (Chorley, 1959; 

Baker, 1978; Komar, 1983; Kehew and Lord, 1986; 

Osterkamp and Costa, 1987) sometimes bear strong resemblance to the lemniscate loop, a minimum-drag shape 

describing airfoils and other streamlined forms. Most of the 

residual islands at sites of erosional anastomosis in the 

South Branch basin were more irregular than those showing 

lemniscate forms. Kehew and Lord (1986, p. 167) suggest 

that groups of erosion residuals that are dominantly elongated, quadrilateral, or irregular in shape, rather than 

approaching the equilibrium streamline form, result from 

B 

anastomosing channels. The new channels shown in 

(B) appear to occupy the trends of swales and abandoned channels visible before the flood (A). Field of 

view is 690 m wide. 

short-duration flow and represent "an initial or early stage 

of erosional development which would occur where a large 

discharge of water has suddenly flowed over an area of 

underfit or nonintegrated drainage." Evidently, the short 

duration and rapid stage changes of the November 1985 

flood did not allow the resulting erosion and deposition 

forms to reach an equilibrium shape. 

Another form of catastrophic erosion observed at 

several locations in the study area resembled a plane jet 

formed by an expanding stream of fluid emerging from an 

orifice or constriction (figs. 73A-H). This type of erosion 

typically occurred in expanding reaches downstream of 

valley constrictions. At sites where the river channel below 

the constriction flowed along the left or right valley wall 

rather than down the center of the valley floor, the highvelocity core of flow emerging from the constriction left the 

channel and followed a trajectory directed down valley. The 

resulting erosion channel typically was several times as 

wide as the preflood river channel and expanded slightly 

with increasing distance downstream, with coarse splays 

and debris flaring outward in all directions. As the flow 

Flood Hydrology and Geomorphic Effects, Flood of Nov. 4-5, 1985, W.Va. E59 
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Figure 72. Examples of valley floors extensively dissected by anastomosing 

erosion channels. (A) Before and (8) after views of the Adamson dairy farm on 

the South Fork flood plain at Fame, 6 km downstream of Fort Seybert. Flow is 

from bottom to top. The South Fork emerges from a bedrock constriction 

about 3 km upstream of the dairy, but the channel follows a straight path from 

the constriction until it reaches the location shown here. Field of view is 870 m 

B 

wide. (C) Before and (D) after views of the North Fork South Branch Potomac 

River valley near Zeke Run, 12 km downstream of Seneca Rocks and 10 km 

upstream of Hapeville. Flow is from bottom to top. The undisturbed area to 

the right of the channel is a terrace several meters higher than the main valley 

floor to the left of the channel, which was dissected during the flood. Field of 

view is 670 m wide. 
Flood Hydrology and Geomorphic Effects, Flood of Nov. 4-5, 1985, W.Va. E61 
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Figure 73. Examples of jet-shaped erosion forms. (A) Before and (B) after views 

of the South Fork South Branch Potomac River valley at a site about 3 km 

downstream of Brake. Flow is from bottom to top. The preflood photograph 

shows a complex valley form with multiple abandoned or inactive overflow 

channels and several forested bars or channel islands. Field of view is 690 m 

wide. (C) Before and (D) after views of the North Fork South Branch Potomac 

River val lev at a site 1 km downstn~r~m of SP.nP.Cil Rocks. Flow is from hottom to 

B 

top. Field of view is 640 m wide. (E) Before and (F) after views of the North 

Fork South Branch Potomac River valley about 8 km downstream of Seneca 

Rocks and 14 km upstream of Hopeville. Flow is from bottom to top. Field of 

view is 670 m wide. (G) Before and (H) after views of the South Branch 

Potomac River valley about 5 km downstream of Franklin. Flow is from top to 

bottom. Field of view is 700 m wide. 
Flood Hydrology and Geomorphic Effects, Flood of Nov. 4-5, 1985, W.Va. E63 
E64 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W. Va., Va. 
""0 

ill 

::::l 

c 

c 

0 

u 

Flood Hydrology and Geomorphic Effects, Flood of Nov. 4-5, 1985, W. Va. E65 
continued to spread out, velocity and power per unit width 

of the flow decreased. Deposition occurred where the 

spreading flow was no longer competent to erode the 

underlying surface or to transport the material entrained. At 

its downstream end the erosion channel ended abruptly by 

splitting into multiple secondary channels diverging away 

from the center, dissecting splay deposits, and leaving 

residual bars and islands surrounding the eroded area. 

Downstream of the jet-shaped area of erosion, flow generally converged and drained back into the preflood channel. 

The flow patterns and morphology are similar to those 

illustrated for erosional anastomosis (fig. 72), the primary 

difference being the dominant central erosion channel. 

Maximum length of the area of valley affected either by 

erosional anastomosis or jet-shaped erosion forms was 

about 1,000 m; maximum width of the central erosion 

channel was about 220 m, and maximum width of the area 

affected (including secondary erosion channels and splays) 

was about 350 m. 

Deposition Features 

A wide variety of deposition forms were found along 

the valleys of the three forks of the South Branch Potomac 

River following the flood. Although local patterns of 

deposition were extremely heterogeneous, several important trends were noted. The following summary is based on 

our field reconnaissance and on observations by Scatena 

(1986) and by M.L. McKoy and R. Fonner (West Virginia 

Geological Survey, written communication, 1986). 

Valley-floor deposits upstream of Petersburg and 

Moorefield were dominated by coarse sediment. The largest 

boulders believed to have moved had long axes of more 

than 2.4 m, and boulders with long axes of 1 m were 

frequently observed. Many deposits were composed largely 

of cobbles and small boulders, with pebbles and granules 

between the larger grains. Sand deposits were found most 

often along the margins of flow, or where velocity declined 

as a result of backwater upstream of a barrier or valley 

constriction, diverging flow on a broad valley floor, or flow 

separation in the lee of an obstacle. Although silt- and 

clay-sized sediment was contributed by mass movement and 

fluvial processes in tributary valleys, and by erosion of 

alluvium in the larger valleys, mud deposits were rare. 

Conditions apparently were too turbulent to allow settling of 

silt and clay, even in eddies where velocities were lower 

than in the surrounding flow. 

Deposition along these valleys was patchy and discontinuous, occurring predominantly as cobble, gravel, and 

sand splays, sheets, and ribbons in proximity to erosion 

sites. Sediment thicknesses were variable; the thickest 

observed accumulation was a bar that protruded as much as 

4 m above low-water stage in the South Branch channel 

downstream of the North Fork confluence. Splay deposits 

up to 1. 5 m thick occurred on flood plains at several 

locations. Isolated gravel and cobble bars on bottomlands 

and along channel margins were 0.5-1 m thick, and sand 

dunes with amplitudes up to 1 m were observed in backwater areas or along the margins of the flooded area. These 

thicknesses, however, represent extreme values rather than 

the norm. Sand and gravel sheets and ribbons, which were 

really the most extensive deposits, generally were less than 

10 em thick. Many areas that were unaffected by erosion 

also experienced negligible deposition. 

Downstream of the confluences of the North Fork and 

the South Fork with the South Branch, particle size of 

flood-plain deposits decreased. Mud deposits were more 

common on the Petersburg flood plain than further 

upstream, and deposition of silt and clay occurred mostly 

along the reach downstream of Moorefield. Residents of 

both towns had to clean substantial accumulations of mud 

from homes and businesses (fig. 74). Gravel and cobble 

splays were less common in the lower South Branch basin 

than they were further upstream. Although overbank deposition of mud was more widespread, deposition rarely 

exceeded 10 em and probably averaged less than 1 em. 

Thicker deposits were found in backwater areas or in local 

depressions; for example, mud accumulations of 15-25 em 

were found along the South Branch valley between Moorefield and the Trough, and silt accumulations of 30-50 em 

covered part of the valley floor immediately upstream of the 

constriction at Blues Beach (14 km north of Romney). 

Along the main stem Potomac River, downstream 

from the South and North Branches, little erosion occurred 

on flood plains, and the impact of the flood was primarily 

depositional. No gravel deposits were observed on the 

valley floor. A 250-m transect across the left flood plain at 

a site near Hancock, Md., showed an average of 3.6 em of 

silt deposited by the 1985 flood (fig. 75). Far downstream, 

at the mouth of the Monocacy River, mud coatings were left 

behind on the trees, and 2-5 em of mud were deposited in 

the picnic area near the Monocacy aqueduct (fig. 76). 

In the air photographs, it was possible to distinguish 

sand bodies from coarser deposits on the basis of image tone 

and texture, but sediment finer than sand was not recognizable. The discussion below focuses on deposition patterns 

in the valleys upstream of Moorefield, where deposition of 

fine-grained sediment was relatively uncommon. 

Channel Bars 

Although much of the coarse sediment transported in 

the flood was carried by in-channel flow, more of the 

well-defined gravel deposits detectable in the postflood 

aerial photographs were on flood plains. Perhaps high river 

stages obscured the visibility of channel deposits at the time 

the photographs were taken. It is also possible that competence and transport capacity of deeper flow in the main 

channels were sufficient to carry most of the sediment 

E66 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W. Va., Va. 
A 

B 

Figure 74. Two views of sediment deposited in the streets of Petersburg, W. Va. (A) 

Mud deposits about 30 em deep. (B) Ripple marks in sand. Note also organic debris 

piled up in front of the store entrance. Photographs by Paul Porter. 

Flood Hydrology and Geomorphic Effects, Flood of Nov. 4-5, 1985, W. Va. E67 
A 

Figure 75. Mud deposited on flood plain of Potomac River 

near upstream end of C&O Canal tunnel, 2 km downstream of Paw Paw, W. Va. Average depth of mud was 

about 5 em. 

Figure 77. (A) Before and (B) after views of South Branch 

Potomac River near the Virginia-West Virginia boundary. 

Flow in South Branch is from bottom to top. Although 

some of the coarse material visible in the channel may 

have been delivered from heavily reworked tributary valB 

Figure 76. Mud deposited on flood plain and "bathtub 

ring" formed by silt marks on vegetation (note light gray 

color in bottom half of photograph), indicating elevation 

of high water during the November 1985 flood . Photograph taken from Monocacy Aqueduct, junction of Monocacy River with Potomac River. 

leys seen at the right in (B), much of the exposed sediment 

appears to be a lag deposit derived from stripping of the 

flood plain; note that the channel in (B) is 3--4 times as 

wide as in (A). Field of view is 590 m wide. 

E68 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W. Va., Va. 
supplied, whereas the combination of sediment supplied 

from the channel and excavated from the flood plain more 

often exceeded the transport capacity of shallower flow over 

hydraulically rough valley floors. 

Some of the sediment deposited in channel bars may 

have been derived from tributary contributions, but most of 

the gravel bars visible in the channel were at locations 

where substantial channel widening and bottomland erosion 

occurred. At these sites, gravel bars were difficult to 

distinguish from stripped flood-plain remnants (figs. 49, 

77-79). 

Church and Jones (1982) point out that gravel bars 

typically occur in a limited range of settings, the principal 

categories being (1) areas of channel widening, (2) channel 

junctions where backwater from the main river ponds a 

tributary, and (3) apices of channel bends, where resistance 

to flow increases and slack water may occur along the 

convex bank. Bars in these settings are associated with 

diverging flow, succeeded immediately downstream by 

converging flow and increased shear stress. For the most 

part this statement is sufficient to characterize sites of bar 

formation in the channels of the three forks of the South 

Branch Potomac River in the 1985 flood. Most bars 

observed in the postflood river channel are oriented along 

the direction of flow with a streamlined form that tapers to 

a point. Depending on position and shape, gravel bars may 

be classified following the nomenclature adapted by Church 

and Jones (1982) after Smith (1974) and Krigstrom (1962). 

However, as Ashmore (1982) points out, most bar forms 

reflect the influence of postdeposition modification 

(fig. 80). 

Lateral bars are attached to one bank, usually with a 

narrow trough between bar and bank extending along most 

of the length of the bar. The most prominent examples are 

found at locations where the bottomland on the opposite 

side of the channel has been severely eroded; in figures 49, 

78, and 81, the concave, or outer, bank has been eroded and 

the bar is attached to the convex, or inner, bank just past the 

apex of a bend in the channel. In other cases, lateral bars are 

found along relatively straight channel reaches where no 

significant channel widening has occurred (fig. 82). Both 

examples shown here are attached to a bank with a slightly 

convex planform. 

Other bar forms less common in the South Branch 

basin than lateral bars include longitudinal bars, which 

occur at sites of channel widening upstream of a zone of 

converging flow. Typical planform of longitudinal bars 

observed in the study area is tapered to a point at the 

downstream end with straight lateral margins and a diffuse, 

somewhat blunt, upstream border (fig. 83). Complex or 

compound bar types (figs. 84, 85) may incorporate both 

newly deposited sediment and eroded remnants of the 

adjacent bottomland. A fan-shaped gravel sheet in the 

channel marks the terminus of a jet emerging from a 

bedrock constriction (fig. 73H). 

Bottomland Deposits 

As noted above, the dominant particle sizes deposited 

on bottomlands upstream of the major confluences were 

sand and gravel. For the most part, gravel was deposited 

contiguous to or in proximity to source areas, whereas sand 

was carried in suspension farther from the source before 

being deposited. As a result, longitudinal sorting of deposits 

is common downstream of an area of stripping or channel 

widening. 

Bottomland deposits that can be distinguished on 

postflood aerial photographs generally fit into one of four 

categories: (1) lobate gravel splays, gravel sheets, and sand 

splays; (2) isolated gravel bars; (3) wake deposits, formed 

in regions of separated flow downstream of flow obstructions; and ( 4) backwater deposits formed in regions of 

reduced velocity upstream of a major flow constriction or a 

local barrier. Although dunes and ripples are not generally 

distinguishable in aerial photographs of the South Branch 

basin, several spectacular examples of bedforms can be 

seen in the larger scale aerial photographs of the Cheat 

River basin (Kite and Linton, chapter D, this volume, 

fig. 7). 

Splay deposits are associated with severe channel or 

flood-plain erosion (figs. 52, 57, 60, 61, 63, 73F, 86). 

Gravel splays are contiguous with the edge of the eroded 

area. In some instances the broadly curved lobate form has 

a dentate outer margin formed by a series of smaller lobes 

within the larger sediment body. The surface of the deposit 

forms a series of scrolled ridges and troughs that curve 

outward, with a convex profile terminating almost perpendicular to the main flow (figs. 87A-C). Surficial topography 

varies from one splay to another and may reflect reworking 

and incision by water draining over the margins of the 

deposit at falling stage. The upstream edge of the splay may 

be a poorly defined transitional boundary from a region of 

stripping (fig. 87B; also see Kite and Linton, chapter D, this 

volume, fig. 8), but the downstream terminus of the lobe is 

abrupt and generally is marked by a steep slipface (fig. 88). 

Preservation of the slipface may indicate that downstream 

migration of the lobe was by progressive avalanching, with 

the steep front remaining at the angle of repose after the 

stage fell or after the flow was no longer competent to 

transport cobbles over the surface. 

Locally, the valley floor is covered by a gravel and 

cobble veneer (fig. 89) that lacks the distinctive features of 

the lobate splay deposits. As these are sometimes found 

flanking the river channel, they may in some cases be 

characterized as levee deposits. Gravel sheets most often 

are downstream of and contiguous with broad areas of 

channel widening and stripping. 

Sand deposits often exhibit the lobate shape of a 

gravel splay but occur farther from the source area. Some 

sand lobes are separated from a gravel splay or from the 

Flood Hydrology and Geomorphic Effects, Flood of Nov. 4-5, 1985, W. Va. E69 
A B 

Figure 78. (A) Before and (B) after views of South Branch Potomac River at Ruddle. Flow is from lower right. Note erosion 

of valley floor along left bank of river and formation of large bar along right bank and smaller bar along left bank 

downstream. Field of view is 650 m wide. 

A B 

Figure 79. (A) Before and (B) after views of South Branch Potomac River at Franklin. Flow is from bottom to top. Channel 

islands visible in (B) look like gravel bars in a braided river but probably are stripped and dissected remnants of the valley 

floor. Field of view is 270 m wide. 

E70 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W. Va., Va. 
A 

Figure 80. Gravel bar in South Branch channel, 1 km 

downstream of confluence between South Branch and 

North Fork. Highest point on bar is about 4 m above low 

water. Flow is from right to left. Steep side profile of this 

bar appears to result from scour following peak flood 

discharge; this process probably continued during subsequent high flows. 

Figure 81. (A) Before and (B) after views of South Branch 

Potomac River at the mouth of Redman Run, about 6 km 

upstream of the confluence with the North Fork. Flow is 

from the lower right. Note that the bottomland along the 

left bank was completely eroded by the November 1985 

flood and that the bar along the right bank was formed in 

B 

sediment source by an area lacking significant deposition 

(fig. 90). In many cases the sand deposit has a feathered or 

dentate outline (figs. 90, 91A-D). This shape resembles 

the furrowed margins at the edges of some gravel splays and 

reflects either a pattern of outward-draining flow, which 

became less competent and deposited sand as it spread out, 

or a swash mark left behind as the water reversed direction 

and drained back toward the channel following the flood 

crest. 

Isolated gravel bars on the valley floor are similar to 

but smaller than the gravel splays described above. These 

bars generally are downstream of a scour mark and are 

composed primarily of material excavated from the scour. 

Longitudinal sorting, with finer sediment accumulating 

toward the downstream end (McKoy, 1987), may reflect 

selective transport of the excavated material or may result 

from trapping of sediment from the surrounding flow in the 

zone of lower velocity at the lee of the bar. 

Wake deposits, either gravel or sand, occur in the lee 

of flow obstructions throughout the study area. Examples of 

deposits in the lee of isolated trees or localized clumps of 

the same event. The section of bottomland removed in 

1985 was not present in 1945; it was emplaced by a debris 

avalanche emerging from the mouth of Redman Run 

during the flood of June 1949 and remained in place for 36 

yr until the 1985 flood removed it. Field of view is 390 m 

wide. 

Flood Hydrology and Geomorphic Effects, Flood of Nov. 4-5, 1985, W.Va. E71 
A B 

Figure 82. Lateral bars attached to slightly convex banks. (A) North Fork, 2.7 km downstream of Circleville. Field of 

view is 310m wide. (B) North Fork, 0.8 km downstream of Riverton. Field of view is 270m wide. Flow is from bottom 

to top in both (A) and (B). 

vegetation are shown in figures 42 and 92. Another type of 

deposition pattern occurs where a line of trees bordering the 

channel acts as a baffle, slowing the flow as it leaves the 

channel and causing deposition of a series of subparallel 

sand or gravel bodies. These deposits may be aligned with 

gaps between the trees, or they may be at sites of flow 

separation behind trees or vegetation clumps (fig. 93). This 

type of feature is found wherever there is intact vegetation 

along the margins of the path taken by the main body of the 

flood and, because of its location, may also be described as 

a levee deposit. A similar series of small lobate forms is 

seen at the right edge of figure 36B, where deposition 

occurred at a downward step from a road to the flood plain. 

As there are no visible gaps in the road other than the large 

scour mark at the left, the lobate pattern probably was 

created by longitudinally oriented vortices generated at the 

downward step. 

Ponding of floodwater by a local barrier or by a valley 

constriction may cause a reduction in velocity that allows 

sand to drop out of suspension. We refer to the sediment 

bodies formed by this process as backwater deposits, as 

opposed to slack-water deposits, which are ponded deposits 

that may be preserved as paleohydrologic indicators of 

flood stage (Stedinger and Baker, 1987) in tributary valleys 

or bedrock alcoves. Sediment bodies that are identifiable 

from aerial photographs as backwater deposits are rare in 

the study area, although backwater effects occurred 

upstream of valley constrictions at several locations. Two 

examples of backwater deposits are shown here. The first 

occurred upstream of a valley constriction where the 

entrance to a short bedrock gorge was the site of an elevated 

road embankment that ponded water on the flood plain 

(figs. 94, 95). Sand deposits along the right bank were 

mostly less than 10 em thick. The dunes in figure 96 were 

formed on the flood plain to the left of the channel; they 

indicate that the reduced velocity of flood flow caused sand 

to be transported as bedload rather than as suspended load. 

Silt and clay remained in suspension. 

The second example (fig. 97) is a site where a thick 

grove of trees accumulated a large amount of floating 

organic debris that formed a barrier to flow crossing the 

flood plain. A broad, nearly continuous blanket of sand was 

deposited just upstream of this barrier; note that the barrier 

E72 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W. Va., Va. 
A B 

Figure 83. Longitudinal bars (not attached to channel banks) with blunt, somewhat diffuse upstream borders. (A) South 

Branch, about 5 km upstream of Franklin. Field of view is 220 m wide. (B) North Fork, about 2 km upstream of Seneca 

Rocks. Field of view is 190 m wide. Flow is from bottom to top in both (A) and (B). 

was breached at one point and that a headward-retreating 

gully formed where flow accelerated through the opening. 

Patterns of sand deposition on the valley floor did not 

always conform to one of the types described above; in 

some broad or expanding valley reaches, stringers and 

irregularly shaped patches of sand were deposited in or on 

the margins of multiple shallow depressions that served as 

overflow channels. 

CLASSIFICATION OF IMPACTS ON THE 

VALLEY FLOOR 

The intensity of valley-floor erosion caused by the 

1985 flood varied considerably throughout the South 

Branch basin. Because the erosion and deposition forms 

created in the flood were influenced by interactions between 

highly turbulent flow and local boundary conditions, explanation of the detailed pattern of erosion would require 

intensive site-specific investigations. Broad spatial trends 

exist as well, however, and these can be described in a 

simple classification scheme. To map the distribution of 

erosion damage at a scale of 1:250,000, we devised a 

simple hierarchy of four erosion categories. Individual 

valley reaches were classified from preflood and postflood 

aerial photographs, but the assignment of each reach to a 

category was subjective because the boundaries between 

classes are necessarily gradational. The criteria used for the 

erosion mapping are described in table 7. 

The flood occupied the entire valley floor at most 

sites, and its path was guided both by the valley walls and 

by the river channel. Consequently, erosion features were 

most prominent at or below valley crossings, or at sites 

where the channel and the valley thalweg were oriented 

transverse to one another. For the incipient to moderate 

erosion class, scour features were concentrated where flow 

first crossed from the river channel onto the alluvium of the 

adjacent flood plain or at sites of flow obstructions such as 

roads and buildings (fig. 98). Erosion was less significant 

where the channel and valley were parallel and was confined mostly to areas along the channel margin, with 

isolated scour marks or sets of longitudinal grooves scattered across an otherwise intact valley floor. 

Flood Hydrology and Geomorphic Effects, Flood of Nov. 4-5, 1985, W.Va. E73 
Figure 84. Compound bar formed from dissected 

flood-plain remnants and freshly deposited gravels. 

North Fork, about 1 km upstream of the Cabins gage 

site and 5 km downstream of Hapeville. Flow is from 

right to left. Note the area of diverging flow through 

Erosion features associated with severe erosion (class 

C) characteristically extended farther downstream from a 

valley crossing than those associated with incipient to 

moderate erosion. Some examples exhibit relatively simple 

patterns of chute formation with marginal splays (fig. 60), 

leaving the majority of the inundated valley floor unaffected. Other examples reveal a more intricate pattern of 

dissection (fig. 99). Prominent erosion features at the site 

illustrated are (1) a broad stripped area surrounding irregularly shaped remnants of the eroded surface, which grades 

into a splay deposit that overlaps the intact portion of the 

valley floor; and (2) a chute, nearly as wide as the preflood 

channel of the North Fork and about 450 m long, with 

marginal amphitheater-shaped headcuts branching off along 

both sides. In addition, there are multiple scour marks, 

longitudinal grooves, and sediment deposits of various 

sizes, shapes, and textures scattered along this section of the 

valley. The large island in the middle of the reach, 

previously attached to the flood plain along the left bank, 

was created by a chute cutoff. 

drainage channels separating dissected flood-plain 

remnants and converging flow around the streamlined downstream end of the bar. Field of view is 630 

mwide. 

Classification is based on presence or absence of 

characteristic features within a valley reach; thus a site 

where two different topographic surfaces were affected by 

the flood in different ways is assigned to a single category. 

In figure 50, cultivated fields on a low terrace experienced 

local formation of scour holes and longitudinal grooves. A 

lower, forested surface was modified by formation of 

multiple narrow, shallow chutes, with a central area of more 

intense stripping and removal of vegetation just upstream of 

the apex of the bend in the channel. Additional chutes were 

incised in the valley floor along the right bank entering and 

leaving the meander. Erosion in this reach was mapped as 

class C. 

Examples of catastrophic erosion most often were 

associated with expanding flow emerging from a valley 

constriction (figs. 51, 72, 73, 100, 101). The most severe 

impacts typically were confined to the area upstream of the 

widest point in the valley expansion. The pattern of flow 

emanating outward from a central scoured zone must have 

been accompanied by powerful macroturbulent eddies with 

E74 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W.Va., Va. 
Table 7. Definition of erosion classes 

Class Definition 

A Minimal 

erosion 

B Incipient to 

moderate 

erosion 

Characteristic features 

Little or no modification of channel or valley floor; minor erosion of cut banks but 

without significant channel widening. 

Uprooted trees; longitudinal grooves and 

scour marks on flood plains; pitted or 

abraded areas along channel margins, 

with debris accumulations and chaotic 

surface texture; incipient chutes; localized stripping of point bars; channel widening by up to 100 percent. Gravel 

deposits common. 

C Severe erosion One or more fully developed flood-plain 

chutes; stripping of alluvium from a significant portion of the valley floor; 

extreme channel widening by combined 

stripping and lateral bank retreat; may 

include any or all features from previous 

class. Extensive gravel splays contiguous 

with erosion features. 

D Catastrophic Extensive dissection of valley floor by a 

erosion set of anastomosing channels or by a 

jet-shaped erosion feature; or destruction 

of most of the width of an alluvial bottomland by combined stripping and 

channel widening. (Latter criterion not 

applicable in canyon settings where preflood alluvial bottomland is only 1-2 

channel widths across.) 

a significant head loss between the center and the margins 

of the scoured zone. 

SPATIAL DISTRIBUTION OF EROSION CLASSES 

The mapping procedure involved stereo viewing of 

postflood aerial photographs and annotation of 7th-min 

topographic quadrangles to indicate location, morphology, 

and scale of all identifiable erosion and deposition features. 

The valleys were divided into longitudinal segments and 

classified after comparing preflood and postflood aerial 

photographs with the features identified on the maps. 

Segment boundaries and classes were compiled on a 

1:250,000-scale base map. Valley-floor margins were identified by stereo viewing and were traced onto 7lf2-min 

quadrangles. Average width along each valley segment was 

calculated by measuring area between the valley-floor 

margins and dividing by longitudinal distance along the 

valley thalweg. 

Two maps depicting the distribution of erosion 

classes are reproduced in this report. The first (pl. 1) shows 

locations of individual valley segments and is coded to 

indicate the class to which each segment is assigned. Plate 

1 also shows locations of bedrock canyons and valley 

constrictions along the three forks of the South Branch 

Figure 85. Compound bar form with blunt, rectangular 

upstream section and streamlined downstream section. 

North Fork, about 2 km upstream of Riverton. Flow is from 

right to left. Field of view is 250 m wide. 

Potomac River. A simpler map at smaller scale is provided 

in figure 102. On this map, each of the three forks of the 

South Branch is divided into several long reaches whose 

boundaries coincide with the reach boundaries in figure 7; 

only those reaches upstream of the South Branch-South 

Fork confluence at Moorefield are shown on this map. The 

combined percentage of each reach assigned to the severe 

and catastrophic erosion classes is indicated and provides an 

index of erosion severity. 

Valley constrictions were defined in plate 1 as sites 

where the valley floor was constrained to a width less than 

one-third the width along the reach downstream; thus, the 

area immediately downstream of a location marked on the 

plate by a pair of arrows would be an area of flow expansion 

or divergence during a flood of the stage reached in 

November 1985. Significant flow contractions and expansions occurred at other sites that did not meet the criterion 

of the 1:3 ratio; however, the width of the valley floor is so 

variable along the three forks of the South Branch that 

a larger ratio, such as 1:2, would not be effective in 

discriminating changes that significantly influenced flood 

hydraulics. 

Of 17 sites in plate 1 that were assigned to class D 

(catastrophic erosion), 14 are downstream of valley constrictions or at the mouths of bedrock canyons. In one case 

(fig. 72B) the constriction is about 3 km upstream of the site 

where the most severe erosion occurred. The channel 

follows a straight path emerging from the constriction, and 

dissection of the flood plain by a series of anastomosing 

channels occurred only where the channel changed direction 

and the main thread of flow continued straight along the 

flood plain. In a second case (fig. 72D), erosion occurred at 

a valley expansion that did not meet the 1:3 ratio criterion 

used in mapping. In a third case (fig. 73D) the width of the 

Flood Hydrology and Geomorphic Effects, Flood of Nov. 4-5, 1985, W.Va. E75 
Figure 86. Gravel splays derived from bottomland erosion downstream of bridge, South Branch Potomac River, 

1 km upstream of Romney. Flow is from left to right. Photograph by W.E. Duliere, West Virginia Advocate. 

valley floor upstream of the site of most severe erosion does 

not indicate a constriction, but a low terrace occupies much 

of the valley. Although there was shallow flow over this 

surface, most of the flow was confined within the lower 

area bordered by the terrace scarp. The pattern of erosion 

suggests that a jet formed where flow emerged from the 

confined portion of the valley section. This example demonstrates that the definition of a flow constriction varies 

with flood stage and depth of water on different topographic 

surfaces. Simple quantitative indices for mapping constrictions at a scale of 1:250,000 are thus inadequate for detailed 

explanation of the controls on flow patterns and are used 

here only to illustrate general trends. 

In compiling figures 7 and 102, we initially located 

reach boundaries where major shifts in erosion pattern or in 

the trend of valley width were observed, but the boundaries 

were modified to make reach lengths less variable. Summary data on erosion classes for these reaches are listed in 

table 8. Along 384.4 km of mapped channel reachesupstream of the confluence with the North Branch Potomac 

River, 318.2 km, or 82.8 percent, were mapped as experiencing at least incipient erosion. Classes representing 

severe or catastrophic erosion accounted for 116.2 km, or 

30.2 percent of the total, and class D alone (catastrophic 

erosion) accounted for 21.8 km or 5. 7 percent of the total. 

Examination of the erosion maps reveals several 

trends: 

• Erosion was much more severe along the North Fork 

than along the other two forks of the South Branch or 

along the · South Branch downstream of Moorefield, 

with 41.1 percent and 18.1 percent of the valley mapped 

as class C and class D, respectively. Corresponding 

values for the South Branch above the South Fork 

confluence are 20.6 percent and 4.1 percent and for the 

South Fork are 26.4 percent and 4.2 percent. Along the 

South Branch downstream of Moorefield, 14.8 percent 

of the valley was mapped as class C; class D erosion 

was not observed. 

• Along each of the three forks of the South Branch, the 

reach farthest upstream experienced minimal erosion by 

comparison with other reaches. 

• Erosion generally increased in severity in the downstream direction along the North Fork valley, except for 

a drop from 84.2 to 55.8 percent classified as severe or 

catastrophic in the lower two reaches above the confluence with the South Branch. 

E76 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W. Va., Va. 
A 

c 

B 

Figure 87. Gravel splays with dentate outer margins. 

Scrolled ridges and troughs curve outward and appear to 

be sculpted by flow that drained away from the channel. 

(A) South Branch Potomac River, about 4 km upstream of 

confluence with North Fork. Flow is from bottom to top. 

Field of view is 360 m wide. (8) North Fork South Branch 

Potomac River, 10 km downstream of Seneca Rocks and 12 

km upstream of Hapeville. Flow is from bottom left. The 

area immediately to the right of the channel has been 

stripped; lateral transition from an area of net erosion to 

an area of net deposition is poorly defined. Field of view is 

380 m wide. (C) South Fork South Branch Potomac River 

near Fort Seybert. Flow is from bottom to top. The channel 

shown here is a chute incised into the valley floor during 

the flood (see fig. 60). The fallen trees on the surface of 

the splay deposit at left center provide flow vectors. Field 

of view is 260 m wide. 

Flood Hydrology and Geomorphic Effects, Flood of Nov. 4-5, 1985, W. Va. E77 
Figure 88. Steep slipface about 1.5 m high at downstream 

end of gravel splay deposit. Although the area upstream of 

the deposit was stripped, the downstream end buries an 

intact surface, as indicated by the turf in left foreground. 

Flood flow was from right to left. South Branch Potomac 

River, 5.5 km upstream of the confluence with the North 

Fork. A similar deposit is described by Ritter (1988, figs. 

9, 10). 

• A similar downstream trend toward increasing severity 

of erosion occurred along the South Fork valley, but a 

marked decrease in erosion severity was observed along 

the last two reaches upstream of Moorefield. 

• Along the South Branch, the highest percentage of the 

valley classified as severe or catastrophic occurred 

upstream of Franklin. Erosion severity then declined in 

the downstream direction, reaching a minimum in the 

upper part of the Smoke Hole canyon near Upper Tract. 

Percent of valley reach classified as severe or catastrophic rose again in the lower part of the canyon and 

on the South Branch below the North Fork confluence. 

• Along the South Branch approaching Moorefield and 

downstream of the confluence with the South Fork at 

Moorefield, the percent of valley length assigned to 

severe or catastrophic erosion classes was low. Severe 

erosion between Moorefield and the confluence of the 

North and South Branch Potomac River was limited to 

areas at or just below major valley constrictions and 

bedrock canyons. 

Factors that are potentially important in explaining 

broad spatial patterns of flood-generated erosion include 

channel gradient, valley width, discharge, and erosion 

resistance of the valley floor. Channel gradient and valley 

width were estimated using topographic maps and aerial 

photographs (table 8), but peak discharge measurements for 

the November 1985 flood were made at only a few points in 

the basin, and values for other locations were calculated by 

interpolation. Erosion resistance has not been quantified, 

and its role is poorly understood. 

Despite these uncertainties, we suggest explanations 

for some of the spatial trends outlined above: 

• The difference between the North Fork and the other 

forks of the South Branch with respect to the spatial 

extent of severe erosion is in part a function of differences in gradient. The North Fork, with a gradient of 

0.0065, is significantly steeper than the South Branch 

above its confluence with the North Fork (0.0047) or 

the South Fork above Moorefield (0.0036). The gradient of the South Branch between the North Fork 

confluence and Moorefield is gentler (0. 0021) than any 

of the three forks, and the South Branch downstream of 

Moorefield has the gentlest gradient of all (0.0009). 

• Discharge peaks are comparatively small along the 

steepest valley reaches, which drain headwater basins 

with small contributing areas. Longitudinal trends in the 

extent of severe erosion along a single valley cannot be 

explained by gradient alone because discharge tends to 

increase with increasing drainage area as gradient 

decreases. If the rate of downstream increase of discharge is greater than the rate of downstream decrease 

in gradient, and if lithologic controls prevent any 

systematic downstream increase in valley width, then 

unit stream power should increase in the downstream 

direction. 

Along the North Fork, we observe no systematic 

increase in valley width (fig. 7, table 9), and the 

gradient remains steep as discharge increases. If we 

assume constant unit discharge for all parts of the North 

Fork basin (using the value from the Cabins site), we 

can estimate peak discharges at the midpoint of each 

reach that can be combined with other data to estimate 

reach-average values of unit stream power. Average 

channel gradient for each reach is used to approximate 

average energy gradient during the flood. The values in 

table 9 show the expected downstream increase in 

average unit stream power, paralleling the downstream 

trend toward increasing erosion. The anomalous decline 

in extent of severe erosion in reach 5 is a result of 

erosion resistance; the canyon upstream of Hapeville 

has little erodible bottomland. If the canyon portion is 

excluded from the reach, severe and catastrophic erosion classes account for 79.6 percent of reach 5 rather 

than 55.8 percent (table 9). 

• Average valley widths have a greater range and show 

less consistent trends along the South Fork than along 

the North Fork (table 9, fig. 7). Gradient decreases 

along the first few reaches and then alternately increases 

and decreases in subsequent reaches. Average gradient, 

however, is less variable than average width. Using a 

value of unit discharge based on measurements at the 

two gages in the basin, we estimated peak discharge as 

a function of cumulative drainage area for each reach. 

Reach-average values of unit stream power were calculated and compared with the percent reach length 

E78 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W. Va., Va. 
Table 8. Summary data on erosion classes 

Area 

Cumulative length (km) Percentage of total length 

Class A Class B Class C Class D Total Class A Class B Class C Class D 

North Fork 4.7 24.0 28.9 12.7 70.3 6.7 34.1 41.1 18.1 

South Branch above North 18.7 45.6 16.0 3.8 84.1 22.2 54.2 19.0 4.5 

Fork confluence 

South Branch between North .0 21.4 7.6 .8 29.8 .0 71.8 25.5 2.7 

Fork confluence and 

South Fork confluence 

South Fork 24.2 49.4 28.0 4.5 106.1 22.8 46.6 26.4 4.2 

South Branch below South 18.6 61.6 13.9 .0 94.1 20.4 65.4 14.8 .0 

Fork confluence 

All rivers combined 66.2 202.0 94.4 21.8 384.4 17.2 52.5 24.6 5.7 

Table 9. Physiographic parameters, reach-average values of unit stream power, and spatial extent of severe erosion for 

individual valley reaches along the three forks of the South Branch Potomac River 

North Fork South Branch Potomac River 

Reach Mean width of Estimated Reach-average Reach1 length Channel slope valley floor discharge2 %(C+D)4 

(km) (m) (m3

/s} unit stream power3

(W/m2

) 

1 13.8 0.0092 355 595 151 18.6 

2 12.0 .0077 243 986 306 65.4 

3 12.3 .0058 264 1,535 330 70.5 

4 16.2 .0051 288 2,050 356 84.2 

5 16.0 .0051 251 2,363 471 55.8 

South Branch Potomac River upstream of confluence with South Fork 

Reach Mean width of Estimated Reach-ave rage Reach 1 length Channel slope valley floor discharge2 %(C+D)4 

(km) (m) (m3

/s} unit stream power3 (W/m2

) 

1 12.6 0.0094 261 510 180 0.0 

2 13.8 .0060 231 930 237 63.2 

3 17.1 .0039 334 1,435 164 25.7 

4 7.9 .0029 530 1,716 92 11.8 

5 13.7 .0047 85 1,558 844 5.0 

6 19.0 .0029 125 1,671 380 26.8 

7 18.2 .0025 726 4,097 138 44.5 

8 11.6 .0015 1,539 4,568 44 .0 

South Fork South Branch Potomac River 

Reach Mean width of Estimated Reach-average Reach 1 length Channel slope valley floor discharge2 %(C+D)4 

(km) (m) (m3

/s} unit stream power3

(W/m2

) 

1 13.8 0.0073 121 377 223 15.3 

2 16.6 .0042 192 836 179 20.6 

3 20.0 .0029 461 1,439 89 22.0 

4 16.9 .0044 238 1,999 362 50.5 

5 10.4 .0030 368 2,408 192 57.3 

6 10.0 .0033 352 2,720 250 60.0 

7 9.8 .0027 482 3,041 167 20.7 

8 8.6 .0028 925 3,194 95 .0 

1 Reach numbers increase in the downstream direction for each river; all reaches identified are upstream of Moorefield. 2 Discharge estimates based on application of unit discharge values from gage sites; each value estimated for midpoint of reach. 3 Reach-average unit stream power calculated as product of estimated discharge, channel slope, and unit weight of water divided by mean width of 

valley floor. 

4 %(C+ D) represents cumulative percentage of reach assigned to erosion classes C and D. 

Flood Hydrology and Geomorphic Effects, Flood of Nov. 4-5, 1985, W. Va. E79 
A 

B 

Figure 89. Gravel sheets flanking the main river channel. (A) North Fork South Branch 

Potomac River, 3.6 km upstream of Seneca Rocks. Flow is from right to left. 

Photograph by F.N. Scatena. (B) South Branch Potomac River downstream of the 

Trough. Flow is from left to right. Photograph by W.E. Duliere, West Virginia 

Advocate. 

E80 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W. Va., Va. 
Figure 90. Levee deposits bordering the channel and sand splays on the flood plain; Cheat River, 8 km 

downstream of Parsons. Flow is from lower left. Field of view is 380 m wide. 

assigned to the severe and catastrophic erosion classes. 

The relationship between these variables shows no clear 

trend (table 9). Some of the discrepancy probably is due 

to variations in erosion resistance; for example, reach 4, 

like reach 5 along the North Fork valley, includes 

several kilometers of bedrock canyon with little erodible 

bottomland. Further explanation of the erosion pattern 

clearly would require closer attention to local conditions 

within each of the long reaches described here. 

• The pattern of erosion along the South Branch valley is 

the most difficult to explain using the information 

available. To synthesize values of unit stream power for 

comparison with erosion statistics, we estimated peak 

discharge using unit discharge based on the Franklin 

indirect discharge measurement for reaches 1 and 2 and 

using weighted average unit discharge for the measurements from Franklin and Petersburg for reaches 3-6. 

For reaches 7 and 8, additional increments of discharge 

were based on a weighted average using the Petersburg 

and Springfield measurements. When the reach-average 

values of unit stream power calculated using these 

discharge estimates are compared with corresponding 

values of percent reach length assigned to the severe and 

catastrophic erosion classes, no significant correlation is 

found. Evidently, local variations in boundary conditions affecting flood hydraulics and erosion resistance 

need to be taken into account. Closer examination 

suggests a partial explanation for the observed erosion 

patterns. 

Between reach 2 and reach 4, average valley width 

more than doubles, and between reach 1 and reach 4, 

average channel gradient declines from 0.0094 to 0.0029. 

These changes, together with the backwater effects caused 

by the constriction at the entrance to the Smoke Hole reach 

just below Upper Tract, appear to explain the sharp decline 

in severe erosion from reach 2 to reach 4. On the other 

hand, the causes for increases in severe erosion from reach 

1 to reach 2 are unclear. Although the difference between 

reach-average values of unit stream power for these two 

reaches (182 W/m2 for reach 1 and 239 W/m2 for reach 2) 

appears insufficient to explain the difference in the amount 

of flood erosion, the average stream-power values are 

predicated on the assumption that peak discharge per unit of 

drainage area was the same in both reaches. If tributaries 

instead had contributed higher unit discharge to reach 2, the 

reach-average value of unit stream power along this reach 

would be larger. 

Flood Hydrology and Geomorphic Effects, Flood of Nov. 4-5, 1985, W. Va. E81 
A B 

C D 

E82 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W. Va., Va. 
..,... Figure 91. Feathered or dentate sand deposits on the 

valley floor; flow in each case is from bottom to top. (A) 

South Fork South Branch Potomac River, 2 km 

upstream of Milam. Note sand deposits at left center. 

Field of view is 500 m wide. (B) South Fork South 

Branch Potomac River, 6 km downstream of Milam. 

Note dentate sand deposits to the right of the channel, 

at the center of the photograph. Field of view is 360 m 

wide. (C) North Fork South Branch Potomac River, 9 km 

downstream of Seneca Rocks. Note the sand deposits 

to the left of the road. Field of view is 400 m wide. (D) 

South Fork South Branch Potomac River, 8.5 km downstream of Brandywine. Field of view is 460 m wide. 

A 

Figure 93. Sand levees formed as wake deposits associated with flow obstruction by trees bordering the channel. 

Flow is from bottom to top in each case. (A) South Branch 

Potomac River, about 20 km upstream of the confluence 

with the North Fork: Field of view is 420 m wide. (B) South 

Figure 92. Gravel levee formed as a wake deposit around 

a small group of trees . Looking upstream on South Branch 

Potomac River, 4 km upstream of Franklin. Photograph by 

F.N. Scatena. 

B 

Fork South Branch Potomac River at Fort Seybert. Note the 

discrete lobes of sand emerging from between the trees 

and oriented almost perpendicular to the channel. Field of 

view is 150 m wide. 

Flood Hydrology and Geomorphic Effects, Flood of Nov. 4-5, 1985, W.Va. E83 
Figure 94. Backwater deposits upstream of a road 

embankment at the entrance to a bedrock gorge; South 

Branch Potomac River, about 2 km downstream of Franklin. Flow is from bottom to top. Field of view is 290 m 

wide. 

Figure 95. Sand sheet on right bank of South Branch 

Potomac River at the site shown in figure 94. View is 

toward the right valley wall. 

Figure 96. Sand dunes near left bank of South Branch 

Potomac River at the site shown in figure 94. 

Figure 97. Sand deposits on right and left banks of South 

Branch Potomac River, 0.8 km upstream of the confluence with the North Fork. Flow is from bottom to top. 

Backwater deposits formed on the valley floor to the 

right of the channel, where flow was blocked by trees 

and by a debris jam lodged against the trees at the 

downstream end of the open field. Note headcut on 

gully formed at breach in tree line just right of center. 

Wake deposits formed on the left side of the channel 

where trees retarded overbank flow. Field of view is 370 

mwide. 

E84 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W.Va., Va. 
A B 

Figure 98. (A) Before and (B) after views of the South Fork South Branch Potomac River at a site just downstream of the 

Moorefield stream gage and about 8 km upstream of the confluence with the South Branch Potomac River. Flow is from 

bottom to top. This site is an example of erosion class B. Field of view is 950 m wide. 

High unit stream power coincides with modest erosion in the upper part of the Smoke Hole canyon (reach 5) 

because the reach is narrow and lacks bottomland for 

development of the geomorphic features typical of the 

severe and catastrophic erosion classes. As the canyon 

broadens approaching the North Fork confluence, increased 

bottomland development is subject to erosion, and the 

extent of severe erosion increases. Below the confluence, 

the combined flood discharges of the North Fork and South 

Branch flowed through two narrow gaps, causing extensive 

erosion on the broad valley floors downstream of each gap. 

The average value of unit stream power calculated for this 

reach (138 W/m2

) is deceptive, given the spatial variability 

of hydraulic conditions between the gaps and the broader 

portions of the valley. Thus we need to supplement reachaverage values of unit stream power with more detailed 

information on local maximum values. 

DISCUSSION 

The preceding paragraphs suggest that, for both the 

South Fork and the South Branch, longitudinal trends in the 

severity of erosion along a single valley are heavily influenced by local conditions and are not readily explained by 

a single parameter such as reach-average unit stream power. 

Pooling of data from all of the valley reaches described in 

table 9 reveals some general trends, however. For example, 

the extent of severe erosion reaches a peak for valley 

reaches in an intermediate range of valley widths (fig. 103). 

All valley reaches with more than 50 percent of their length 

mapped in the severe and catastrophic erosion classes had 

mean widths between 230 and 370 m; the sole outlier 

approaching 50 percent was the South Branch below its 

confluence with the North Fork. As noted above, this is a 

broad reach punctuated by two narrow gaps. 

The trend illustrated in figure 103 may be explained 

as follows. For fixed values of peak discharge and gradient, 

a wider valley generally will have lower velocities and 

lower values of unit stream power; thus the widest valley 

reaches are unlikely to experience severe erosion. A narrower valley will be subjected to higher velocities and 

higher unit power. However, the narrowest valley reaches 

are bedrock canyons with limited bottomland. Because of 

Flood Hydrology and Geomorphic Effects, Flood of Nov. 4-5, 1985, W. Va. E85 
A 

B 

Figure 99. (A) Before and (B) after views of the North Fork valley about 10 km downstream of Seneca 

Rocks and 12 km upstream of Hopeville. (C) Photointerpretive sketch identifying erosion and deposition 

features. Flow is from left to right. This site is an example of erosion class C; features include a chute 

about 450 m long (right center), an area of flood-plain stripping (adjacent to the channel at left center), 

an island formed by cutting of a new channel (bottom center), and numerous scour marks, longitudinal 

grooves, and areas of uprooted vegetation. Field of view is 1,200 m wide. 
c 

Figure 99. Continued. 

D Open Water 

Flood plain 

Forest Cover 

Gravel and cobble 

Sand 

Scour Mark 

their greater resistance to erosion, these also experience 

relatively little change even in an extreme flood. 

Although the relation between reach-average unit 

stream power and percent of reach length assigned to the 

severe and catastrophic erosion classes appears weak for 

individual valleys, a scatterplot based on the pooled data 

does reveal a trend (fig. 104). The data appear to define an 

envelope curve for this flood, and along this curve the 

extent of severe erosion increases sharply with increasing 

unit power. Reaches with more than 50 percent of their 

length mapped in the severe and catastrophic erosion classes 

are associated with reach-average unit stream power values 

in the range of 200-500 W 1m2 . If valley reaches with 

average widths of 200 m or less are assumed to be partly 

constrained by bedrock and thus more resistant to erosion, 

we can isolate the points representing those reaches and 

examine the other points on the plot. Although the majority 

of these points still lie below the envelope curve, the 

general trend is in much closer agreement with the shape of 

the envelope. 

The explanation of spatial patterns of fluvial erosion 

presented here is a preliminary analysis of a complex 

process. Studies in progress are intended to provide a 

comprehensive approach to defining the physiographic, 

hydraulic, and hydrologic constraints on severe erosion of 

the valley floor. Miller (1990) concluded that meteorologic 

and hydrologic conditions associated with the November 

1985 event were no more severe than conditions during 

several other events occurring in other areas of the central 

Appalachians during the preceding 50 yr. Unusual impacts 

associated with this flood are attributable to the juxtaposi-

~ Cutbank or scarp 

- --__ -= _Abraded surface 

=-:::: Longitudinal grooves 

c;::> Chute 

(:__- Shallow erosional trough 

100 200 

Meters 

tion of an extreme meteorologic event with a particular 

pattern of valley physiography. Details of the interaction of 

the flood flow with the boundary conditions in any given 

valley reach remain to be explored, and threshold hydraulic 

conditions associated with different levels of erosion intensity remain to be defined. 

Although we primarily describe how the November 

1985 flood affected the valleys of the South Branch Potomac River, our observations have a bearing on broader 

questions of Appalachian geomorphology and hazards. 

In some environments, river channels and flood 

plains appear to be equilibrium landforms sculpted by 

frequently recurring events of moderate intensity rather than 

by rare, extreme events. This paradigm, stated by Wolman 

and Miller (1960), is supported by published observations 

of the modest, relatively short-lived effects of large floods 

occurring in areas of temperate climate and moderate relief 

(Wolman and Eiler, 1958; Costa, 1974; Gupta and Fox, 

1974; Moss and Kochel, 1978). The November 1985 flood 

and others reported in the literature (Hack and Goodlett, 

1960; Stewart and LaMarche, 1967; Williams and Guy, 

1973; Baker, 1977; Shroba and others, 1979; Gupta, 1983; 

N anson, 1986) appear to be counterexamples, leading 

observers to suggest that in some steep, narrow valleys the 

infrequent extreme events may be dominant in forming the 

landscape. Examples from sand-bedded streams in arid and 

semiarid piedmont or plains environments indicate that a 

large enough flood may cause spectacular channel widening 

in these settings as well, and that subsequent recovery or 

continued channel widening is dependent on the sequence 

of flood flows occurring over periods of several decades 

Flood Hydrology and Geomorphic Effects, Flood of Nov. 4-5, 1985, W. Va. E87 
A 

B 

Figure 1 00. (A) Before and (B) after views of the 

confluence of the North Fork South Branch and 

South Branch Potomac Rivers. The North Fork 

enters from the upper left, and the South Branch 

enters from bottom center. This is an example of 

erosion class D; note the extent of flood-plain 

dissection accomplished by the North Fork 

upstream of the confluence. Note also the presence of patchy sand deposits over much of the 

valley floor. Field of view is 1,900 m wide. 

E88 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W. Va., Va. 
"TT 

0 

0 

c.. 

:I: 

-< 

c.. 

0 

0 

(JQ 

~ 

Slol 

::l 

c.. 

C"l 

~ 

0 

3 

0 

~ ::r 

;:;· 

m 

~ 

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0 

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z 

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A B 

Figure 101. (A) Before and (B) after views of the North Fork valley, about 7 km upstream of Seneca Rocks. Flow is from bottom to top. This is an example of 

erosion class D. Field of view is 1,200 m wide. 
Percent of reach 

length assigned to 

severe and catastrophic 

erosion classes 

Do -25.o 

1125.1- 50 .0 

• 50.1- 75.0 

• 75.1-100.0 

~ Gaging Station 

0 

I 

0 

10 20 Miles 

I 

10 20 30 Kilometers 

Figure 102. Map showing generalized spatial distribution of severe valley-floor erosion. 

E90 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W. Va., Va. 
100 I I I I I I I 

C/) 90 1- -

UJ aU? D f-U? 80 1- - o::i 

wu 

Zz 

~0 70 1- D - C/) - C/)C/) 

<(D B a: 60 1- EtJ IL..U - f-u c..!JZI 

UJ a... 50 D 1- - _Jo 

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uf- D 

<(U? 40 1- - L..U<( 

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au 30 1- - f-Cl 

zZ D D L..U<( 

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UJL..U 

a...> D UJ 10 1- D C/) -

D 

0 I I I I -El _L I I 

0 200 400 600 800 1000 1200 1400 1600 

AVERAGE WIDTH OF VALLEY FLOOR, IN METERS 

Figure 103. Plot of percent reach length assigned to erosion classes C and D versus average width of 

valley floor. The highest percentages are associated w ith a narrow range of valley widths (shaded area). 

100 

C/) 90 UJ 0 C/) 

f- C/) 

Cl<( 80 

UJ__J 

zu 

c..!JZ 

-0 70 C/) - C/)C/) 

<(0 

Icc 60 f-LU 

c..!JU 

z:C 

UJa... _Jo 50 

>-a: l..Uf- _JC/) 

_J<( 40 

<(f-

><( 

~u 30 f-Cl 

zZ 

L..U<( 

u UJ 20 a: a: L..U L..U 

a...> L..U 

C/) 10 

0 

0 

D Average width > 200 m 

+ Average width < 200m 

100 

D 

oo• 

• 

200 

D 

300 

D 

D 

• 

400 500 600 700 

REACH-AVERAGE UNIT STREAM POWER, IN WATTS PER SQUARE METER 

800 

Figure 104. Plot of percent reach length assigned to erosion classes C and D versus reach-average values 

of unit stream power. 

Flood Hydrology and Geomorphic Effects, Flood of Nov. 4-5, 1985, W. Va. E91 
(Schumm and Lichty, 1963; Burkham, 1972; Osterkamp 

and Costa, 1987; Kresan, 1988). Wolman and Gerson 

(1978), recognizing that the paradigm described by Wolman and Miller ( 1960) did not account for these observations, described the relative effectiveness of large floods in 

terms of the comparison between recurrence interval and 

recovery time. 

Rehabilitation efforts following this and other 

extreme floods tend to limit observations of natural recovery processes. Therefore, to test hypotheses about the 

relative importance of extreme floods in valley-floor evolution, it may be necessary to develop models for interpreting the geologic record of past floods. Conceptual models 

of flood-plain morphology and stratigraphy might incorporate features analogous to those created in the November 

1985 flood. For example, extreme heterogeneity of sediment textures is to be expected, such as cobbles and 

boulders in or adjacent to erosion channels that are filled 

with finer sediment deposited during subsequent floods of 

lower magnitude. Nanson (1986) described geomorphic and 

stratigraphic patterns in valleys where channel and flood 

plain evidently do not reach equilibrium form over an 

extended period of time; his conceptual model posits a 

cyclical pattern of vertical aggradation punctuated by catastrophic erosion and reworking of older sediments. The age 

of the deposits buried beneath the flood-plain surface may 

vary greatly within a single valley cross section, depending 

on the history of erosion and subsequent aggradation. Hack 

and Goodlett (1960) suggested that a similar type of 

disequilibrium form may be common in the Appalachians. 

Observations of this flood have implications for the 

evaluation of potential hazards. The costs associated with 

"ordinary" floods often involve property loss due to inundation by water and deposition of sediment, as well as 

disruption of utility service and contamination of water 

supplies. These costs are concentrated in urban areas, as 

private property is concentrated in these areas. Thus, 

planning for flood control and mitigation of flood losses 

traditionally is focused on protection of population centers. 

Mapping programs for prediction of areas subject to inundation in flood events with recurrence intervals of 100 yr 

have been undertaken by the U.S. Geological Survey and 

the Federal Emergency Management Agency. 

Examination of the costs of the November 1985 flood 

(see Jacobson, chapter A, this volume) suggests that policymakers need a better understanding of the potential 

hazards and costs of rare floods. Costs from the flood are 

associated with extensive damage to infrastructure, including road networks, bridges, dams, and buildings. These 

costs were distributed over a broad area. Long-term loss of 

agricultural production was another result of the flood; 

without substantial infusion of Federal funds, many farms 

on valley floors in the South Branch basin might have been 

unproductive for centuries. Even after massive rehabilitation, some of these farms will never return to previous 

levels of productivity. Although it is unlikely that society 

can be fully protected from events of this type, public 

agencies, individuals, and businesses may benefit from an 

improved ability to predict what locations are potentially at 

risk from catastrophic erosion or sedimentation during an 

extreme flood. This information can be used in siting of 

roads, bridges, homes, and businesses. In some instances a 

difference in location of only a few hundred meters may be 

sufficient to avoid the most severe impacts of another flood 

like the November 1985 event; note, for example, that the 

houses destroyed at the site illustrated in figures 46A and B 

were in the direct path of flow emerging from a bedrock 

constriction. The turkey sheds in figure 9B were also in a 

vulnerable position with respect to the pattern of flood flow 

emerging from a constriction. 

The utility of selecting a single recurrence interval 

that would be uniform for all flood-hazard zoning also may 

be questioned in the aftermath of the 1985 flood. The most 

severe impacts and the greatest risks to life and property are 

not necessarily limited to the area inundated by events with 

100-yr recurrence intervals; nor are all sites within the 

confines of such an area actually exposed to the same kinds 

of hazards. In high-gradient, high-energy river basins the 

prevailing hydraulic conditions during any one event may 

vary greatly, both longitudinally along the valley and 

laterally across the valley. Instead of identifying the areas 

affected by a particular design storm, it may be more 

sensible to provide the public with information on hazards 

associated with flows of specified recurrence interval at any 

given site, or to provide estimates of the recurrence intervals associated with particular kinds of hazards. 

Erosion and deposition associated with manmade 

structures and land-use patterns show that flood-flow 

hydraulics are substantially influenced by the cumulative 

effects of human activity on the valley floor. For example, 

bridges and road embankments clearly affect flow patterns 

and are in tum affected by them. Other human impacts 

extend beyond local effects of engineering structures. 

Clearing of forested valley floors reduces roughness and 

also reduces resistance to erosion. Changes in channel 

pattern and gradient following local channel diversion, 

clearing, and straightening have undoubtedly affected 

hydraulic characteristics of flood waves in many valleys. 

Artificial filling of overflow channels and construction of 

buildings on the fill may retard or divert flow during a large 

flood and could lead to extensive damage on the valley 

floor. 

Although recent studies have improved understanding 

of impacts of drainage modifications on channel evolution 

(Schumm and others, 1984; Simon and Hupp, 1986), the 

effects of channel work or valley-floor modification on 

patterns of overbank flow and the potential for valley-floor 

erosion have yet to be thoroughly investigated. In regions 

where extreme floods have the potential for causing this 

type of damage, agencies charged with public safety and 

E92 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W. Va., Va. 
hazard mitigation have reason to be interested in achieving 

a better understanding of such effects. 

SUMMARY AND CONCLUSIONS 

It is clear from examination of the hydrologic data 

and the geomorphic evidence that the November 1985 flood 

was a rare event. Indeed, although channel widening and 

valley-floor erosion have been reported in the aftermath of 

other floods, we have not found documentation of such 

intense valley-floor modification occurring over such a 

large area. Similar events certainly have occurred in the past 

and will occur in the future. In the case of the November 

1985 flood, availability of large-scale aerial photographs 

covering most of the affected area allowed documentation 

of the various flood impacts and their spatial extents. As 

such opportunities are rare, a primary goal of this paper is 

to provide information that may serve as a useful point of 

reference for investigators studying similar events occurring 

in other times and places. 

The November 1985 flood was the largest recorded in 

the South Branch Potomac River basin, with discharges 

exceeding values estimated for a recurrence interval of 500 

yr at four of six gage sites. Flow velocities in the channel 

were as high as 4.6 m/s and locally may have exceeded 6 

m/s; estimated values of unit stream power at U.S. Geological Survey gage locations were as high as 988 W/m2 and 

may have exceeded 2,500 W/m2 at some locations. Hydraulic conditions during the flood were heavily influenced by 

valley physiography, which in turn was influenced by the 

bedrock structure of this part of the Valley and Ridge. 

Because of the presence of numerous valley constrictions 

and expansions, very large discharges were forced through 

relatively small valley cross sections. Evidence collected 

after the flood demonstrates that bedrock canyons were 

responsible for ponding of floodwaters upstream and that 

flow emerging from canyons and valley constrictions 

caused severe erosion at many sites. 

Geomorphic impacts of the flood included an array of 

erosion features, including longitudinal grooves, scour 

marks, extensive channel widening, stripping of alluvium 

from the valley floor, bottomland dissection by anastomosing erosion channels, and jet-shaped erosion forms. Widespread deposition of coarse sediment was heavily concentrated at locations laterally contiguous with eroded areas. 

Newly formed channel bars were observed at several 

locations but were relatively uncommon. Splay deposits, 

gravel and sand sheets, isolated gravel bars and sand dunes, 

wake deposits, and backwater deposits were left behind by 

the flood at many locations along the flood plain. Particle 

size of flood-plain deposits along the three forks of the 

South Branch Potomac River ranged from sand to boulders, 

with some transported particles exceeding 1 m in diameter; 

particle sizes decreased downstream along the main 

stem Potomac River, consisting primarily of fine-grained 

sediment. 

Mapping of erosion damage by classes along 384 km 

of channel and valley floor between the Virginia-West 

Virginia border and the confluence of the North and South 

Branches of the Potomac River revealed that 82.8 percent of 

the valley length experienced at least incipient erosion, 30.2 

percent experienced severe erosion, and 5. 7 percent experienced catastrophic erosion of the valley floor. Valley 

reaches with at least 50 percent of their length classified as 

experiencing severe erosion generally fell in a narrow range 

of average valley-floor widths (between 230 and 370 m). 

Reach-average values of unit stream power were calculated 

from estimates of peak discharge, valley width, and channel 

gradient; severe erosion percentages of 50 percent or more 

were associated with reach-average values of unit stream 

power of 200-500 W/m2

. The results suggest that it should 

be possible to define threshold conditions for severe bottomland erosion. Further research is required to provide 

more detailed information on relations between hydrologic 

inputs, valley physiography, flood hydraulics, and geomorphic impacts on valley floors in extreme floods. 

REFERENCES CITED 

Allen, J .R.L., 1971, Transverse erosional marks of mud and rock, 

Their physical basis and geological significance: Sedimentology, v. 5, p. 167-385. 

---1982, Sedimentary structures, Their character and physical 

basis: Developments in sedimentology, v. 30A-30B: New 

York, Elsevier. 

---1985, Principles of physical sedimentology: London, Allen 

& Unwin, 272 p. 

Ashmore, P.E., 1982, Laboratory modelling of gravel braided 

stream morphology: Earth Surface Processes and Landforms, 

v. 7, p. 201-225. 

Bagnold, R.A., 1966, An approach to the sediment transport 

problem from general physics: U.S. Geological Survey Professional Paper 422-1, 37 p. 

Baker, V.R., 1977, Stream channel response to floods with 

examples from central Texas: Geological Society of America 

Bulletin, v. 88, p. 1057-1071. 

---1978, Paleohydraulics and hydrodynamics of Scabland 

floods, in Baker, V.R., and Nummedal, D., eds., The 

channeled scabland: Washington, D.C., National Aeronautics and Space Administration, p. 59-115. (Reprinted in 

Baker, V .R., ed., 1981, Catastrophic flooding, The origin of 

the channeled scabland: Benchmark Papers in Geology, v. 

55: Stroudsburg, Pa., Dowden, Hutchinson and Ross, 361 p.) 

---1984, Flood sedimentation in bedrock fluvial systems, in 

Koster, E.H., and Steel, R.J., eds., Sedimentology of 

gravels and conglomerates: Canadian Society of Petroleum 

Geologists Memoir 10, p. 87-98. 

---1988, Flood erosion, in Baker, V.R., Kochel, R.C., and 

Patton, P.D., eds., Flood geomorphology: New York, John 

Wiley and Sons, p. 81-95. 

Baker, V.R., and Costa, J.E., 1987, Flood power, in Mayer, L., 

and Nash, D., eds., Catastrophic flooding: London, Allen 

and Unwin, p. 1-21. 

Flood Hydrology and Geomorphic Effects, Flood of Nov. 4-5, 1985, W.Va. E93 
Baker, V.R., and Kochel, R.C., 1988, Flood sedimentation in 

bedrock fluvial systems, in Baker, V.R., Kochel, R.C., and 

Patton, P.C., eds., Flood geomorphology: New York, John 

Wiley and Sons, p. 123-137. 

Baloch, M.S., Henry, E.N., and Dickerson, W.H., 1971, Streamflow characteristics of the Potomac River: Charleston, W. 

Va., West Virginia Department of Natural Resources, Division of Water Resources and West Virginia University, 

276 p. 

Bretz, J.H., 1923, The channeled scablands of the Columbia 

Plateau: Journal of Geology, v. 31, p. 617-649. 

---1928, The channeled scabland of eastern Washington: 

Geographical Review, v. 18, p. 446-477. 

---1959, Washington's channeled scabland: Washington 

Division of Mines and Geology Bulletin 45, p. 7-57. 

Burkham, D.E., 1972, Channel changes of the Gila River, Safford 

Valley, Arizona, 1846-1970: U.S. Geological Survey Professional Paper 655-G, 24 p. 

Carson, M.A., 1984, Observations on the meandering-braided 

river transition, the Canterbury Plains, New Zealand: New 

Zealand Geographer, v. 40, p. 12-17, 89-99. 

Chorley, R.J., 1959, The shape of drumlins: Journal of Glaciology, v. 3, p. 339-344. 

Chow, V.T., 1959, Open-channel hydraulics: New York, 

McGraw-Hill, 680 p. 

Church, M., and Jones, D., 1982, Channel bars in gravel-bed 

rivers, in Hey, R.D., Bathurst, J.C., and Thome, C.R., eds., 

Gravel-bed rivers: New York, John Wiley and Sons, 

p. 291-324. 

Clark, G.M., 1967, Structural geomorphology of a portion of the 

Wills Mountain Anticlinorium, Mineral and Grant Counties, 

W. Va.: University Park, Pennsylvania State University, 

Ph.D. thesis, 165 p. 

---1987, Some major topographic and drainage relationships 

in the North Fork Mountain-Smoke Hole area, Grant and 

Pendleton Counties, W.Va., in Kite, J.S., ed., Research on 

the Late Cenozoic of the Potomac Highlands, Southeastern 

Friends of the Pleistocene, v. 1: Morgantown, W.Va., West 

Virginia Geological and Economic Survey Open-File Report 

OF-88-2, p. 67-77. 

Clark, G.M., Jacobson, R.B., Kite, J.S., and Linton, R.C., 1987, 

Storm-induced catastrophic flooding in Virginia and West 

Virginia, November 1985, in Mayer, L., and Nash, D., eds., 

Catastrophic flooding: London, Allen & Unwin, p. 355-379. 

Collins, R.F .. and Schalk, M., 1937, Torrential flood erosion in 

the Connecticut Valley, March 1936: American Journal of 

Science, v. 34, p. 293-307. 

Costa, J.E., 1974, Response and recovery of a Piedmont watershed from tropical storm Agnes, June 1972: Water Resources 

Research,v.10,p.106-112. 

---1983, Paleohydraulic reconstruction of flash-flood peaks 

from boulder deposits in the Colorado Front Range: Geological Society of America Bulletin, v. 94, p. 986-1004. 

---1987, A comparison of the largest rainfall-runoff floods in 

the United States with those of the People's Republic of 

China and the world: Journal of Hydrology, v. 96, 

p. 101-115. 

Dunn, L. S., 1959, Tractive resistance of cohesive channels: 

Proceedings of the American Society of Civil Engineers, 

Journal of the Soil Mechanics and Foundations Division, 

v. 85, p. 1-24. 

Dzulynski, S., and Sanders, J.E., 1962, Current marks on firm 

mud bottoms: Transactions of the Connecticut Academy of 

Arts and Sciences, v. 42, p. 57-96. 

Dzulynski, S., and Walton, E.K., 1965, Sedimentary features of 

flysch and graywackes: New York, Elsevier. 

Einstein, H.A., and Li, H., 1958, Secondary currents in straight 

channels: Transactions of the American Geophysical Union, 

v. 39, p. 1085-1088. 

Fridley, H.M., 1939, Solution and stream piracy: Journal of 

Geology, v. 47, p. 177-188. 

---1940, Watergaps by solution and piracy, A reply: American Journal of Science, v. 238, p. 226-233. 

Friel, E.A., Hobba, W.A., and Chisholm, J.L., 1975, Records of 

wells, springs, and streams in the Potomac River Basin, West 

Virginia: Morgantown, W. Va., West Virginia Geological 

and Economic Survey Basic Data Report 3. 

Gerritsen, S., and Dunne, W.M., 1988, Reexamination of the 

Smoke Holes, W. V a. , and the role of faulting in cover 

deformation within the central Appalachians [abs.]: Geological Society of America Abstracts with Programs, v. 20, p. 

266. 

Gupta, A., 1983, High-magnitude floods and stream channel 

response, in Collinson, J.D., and Lewin, J., eds., Modem 

and ancient fluvial systems: International Association of 

Sedimentologists Special Publication 6, p. 219-227. 

Gupta, A., and Fox, H., 1974, Effects of high-magnitude floods 

on channel form, A case study in the Maryland Piedmont: 

Water Resources Research, v. 10, p. 499-509. 

Hack, J.T., 1973, Drainage adjustment in the Appalachians, in 

Morisawa, M. E., ed., Fluvial geomorphology: Binghamton, 

N.Y. , Publications in Geomorphology, p. 51-69. 

Hack, J.T., and Goodlett, J.C., 1960, Geomorphology and forest 

ecology of a mountain region in the central Appalachians: 

U.S. Geological Survey Professional Paper 34 7, 66 p. 

Hobba, W.A., Jr., Friel, E.A., and Chisholm, J.L., 1972, Water 

resources of the Potomac River Basin, West Virginia: Morgantown, W. Va., West Virginia Geological and Economic 

Survey, River Basin Bulletin 3. 

Interagency Advisory Committee on Water Data, 1982, Guidelines for determining flood flow frequency: U.S. Geological 

Survey Office of Water Data Coordination, Bulletin 17B. 

Jacobson, R.B., Linton, R.C., and Rubin, Meyer, 1989, Alluvial 

stratigraphy of the Potomac River valley bottom near Petersburg and Moorefield, W. Va.: U.S. Geological Survey 

Open-File Report 89-485, 27 p. 

Jahns, R. H. , 194 7, Geologic features in the Connecticut Valley, 

Massachusetts, as related to recent floods: U.S. Geological 

Survey Water-Supply Paper 996, 158 p. 

James, R.W., Jr., Simmons, R.H., and Strain, B.F., 1987, Water 

resources data, Maryland and Delaware, Water year 1986: 

U.S. Geological Survey Water-Data Report MD-DE-86-1, 

316 p. 

Karcz, I. , 1967, Harrow marks, current -aligned sedimentary 

structures: Journal of Geology, v. 75, p. 113-121. 

E94 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W.Va., Va. 
---1968, Fluviatile obstacle marks from the wadis of the 

Negev (southern Israel): Journal of Sedimentary Petrology, 

v. 38, p. 1000-1012. 

Kehew, A.E., and Lord, M.L., 1986, Origin and large-scale 

erosional features of glacial-lake spillways in the northern 

Great Plains: Geological Society of America Bulletin 97, 

p. 162-177. 

Kite, J.S., ed., 1987, Research on the Late Cenozoic of the 

Potomac Highlands, Southeastern Friends of the Pleistocene, 

v. 1: Morgantown, W. Va., West Virginia Geological and 

Economic Survey Open-File Report OF-88-2. 

Knox, J .C., 1987, Stratigraphic evidence of large floods in the 

upper Mississippi Valley, in Mayer, L., and Nash, D., eds., 

Catastrophic flooding, London, Allen & Unwin, p. 155-180. 

Komar, P.D., 1983, The shapes of streamlined islands on Earth 

and Mars, Experiments and analysis of the least-drag form: 

Geology, v. 11, p. 651-654. 

---1988, Sediment transport by floods, in Baker, V.R., 

Kochel, R.C., and Patton, P.C., eds., Flood geomorphology: 

New York, John Wiley and Sons, p. 97-111. 

Kresan, P.L., 1988, The Tucson, Arizona, Flood of October 

1983- Implications for land management along alluvial river 

channels, in Baker, V.R., Kochel, R.C., and Patton, P.C., 

Flood geomorphology: New York, John Wiley and Sons, 

p. 465-489. 

Krigstrom, A., 1962, Geomorphological studies of sandur plains 

and their braided rivers in Iceland: Geografiska Annaler, v. 

44, p. 328-346. 

Lane, E.W., 1957, A study of the shape of channels formed by 

natural streams flowing in erodible material: Omaha, Nebr., 

U.S. Army Engineer Division, Mississippi River Corps of 

Engineers, Sediment Series 9. 

Laursen, E.M., 1960, Scour at bridge crossings: Journal of the 

Hydraulics Division, Proceedings of the American Society of 

Civil Engineers, v. 86, p. 39-54. 

Lescinsky, J .B., 1987, Flood of November 1985 in West Virginia, 

Pennsylvania, Maryland, and Virginia: U.S. Geological Survey Open-File Report 86-486. 

Lewin, J., and Brindle, B.J., 1977, Confined meanders, in 

Gregory, K.J., ed., River channel changes: New York, 

Wiley-Interscience, p. 221-233. 

Matthes, G.H., 1947, Macroturbulence in natural stream flow: 

Transactions of the American Geophysical Union, v. 28, 

p. 255- 262. 

McKoy, M.L., 1987, Flood flow hydrology at Seneca Rocks, in 

Kite, J. S., ed., Research on the Late Cenozoic of the 

Potomac Highlands, Southeastern Friends of the Pleistocene, 

v. 1: Morgantown, W. Va., West Virginia Geological and 

Economic Survey Open-File Report OF-88-2, p. 78-85. 

Miller, A.J., 1990, Flood hydrology and geomorphic effectiveness in the central Appalachians: Earth Surface Processes and 

Landforms, v. 15, p. 119-134. 

Moore, D.O., and Masch, F.D., 1963, Influence of secondary 

flow on local scour at obstructions in a channel: U.S. 

Department of Agriculture Miscellaneous Publication 970, 

p. 314-320. 

Moss, J.H., and Kochel, R.C., 1978, Unexpected geomorphic 

effects of the Hurricane Agnes storm and flood, Conestoga 

drainage basin, southeastern Pennsylvania: Journal of Geology, v. 86, p. 1-11. 

Nanson, G.C., 1986, Episodes of vertical accretion and catastrophic stripping, A model of disequilibrium flood plain 

development: Geological Society of America Bulletin, v. 97, 

p. 1467-1475. 

Osterkamp, W .R., and Costa, J .E., 1987, Changes accompanying 

an extraordinary flood on a sand bed stream, in Mayer, L., 

and Nash, D., eds., Catastrophic flooding: London, Allen & 

Unwin, p. 201-224. 

Osterkamp, W.R., and Hedman, E.R., 1977, Variation of width 

and discharge for natural high-gradient stream channels: 

Water Resources Research, v. 13, p. 256-258. 

Paola, C., Gust, G., and Southard, J.B., 1986, Skin friction 

behind isolated hemispheres and the formation of obstacle 

marks: Sedimentology, v. 33, p. 279-293. 

Peabody, F.E., 1947, Current crescents in the Triassic Moenkopi 

formation: J oumal of Sedimentary Petrology, v. 17, 

p. 73-76. 

Ritter, D.F., 1975, Stratigraphic implications of coarse-grained 

gravel deposited as overbank sediment, southern Illinois: 

Journal of Geology, v. 83, p. 645-650. 

---1988, Floodplain erosion and deposition during the 

December 1982 floods in southeast Missouri, in Baker, V .R., 

Kochel, R.C., and Patton, P.C. eds., Flood geomorphology: 

New York, John Wiley and Sons, p. 243-259. 

Ritter, D.F., and Blakely, D.S., 1986, Localized catastrophic 

disruption of the Gasconade River flood plain during the 

December 1982 flood, southeast Missouri: Geology, v. 14, 

p. 472-476. 

Runner, G. S. , 1980, Runoff studies on small drainage areas 

(Technique for estimating magnitude and frequency of floods 

in West Virginia): U.S. Geological Survey Open-File Report 

80-1218. 

Scatena, F. N., 1986, Flood plain reconnaissance study, November 1985 flood, Potomac River Basin: Interstate Commission 

on the Potomac River Basin Technical Report 86-5, 32 p. 

Schumm, S.A., Harvey, M.D., and Watson, C.C., 1984, Incised 

channels: Morphology, dynamics and control: Littleton, 

Colo., Water Resources Publications, 200 p. 

Schumm, S.A., and Lichty, R.W., 1963, Channel widening and 

flood-plain construction along Cimarron River in southwestem Kansas: U.S. Geological Survey Professional Paper 

352-D, p. 71-88. 

Shen, H.W., 1971, Scour near piers, in Shen, H.W., ed., River 

mechanics: Ft. Collins, Colo., Colorado State University, 

p. 23.1-23.25. 

Shepherd, R.G., and Schumm, S.A., 1974, Experimental study of 

river incision: Geological Society of America Bulletin, v. 85, 

p. 257-268. 

Shroba, R.R., Schmidt, P.W., Crosby, E.J., and Hansen, W.R., 

1979, Storm and flood of July 31-August 1, 1976, in the Big 

Thompson River and Cache la Poudre River basins, Larimer 

and Weld Counties, Colorado, Part B, Geologic and geomorphic effects in the Big Thompson Canyon area, Larimer 

County: U. S. Geological Survey Professional Paper 1115, 

p. 87-152. 

Simon, A., and Hupp, C.R., 1986, Channel evolution in modified 

Tennessee channels, in Proceedings of the Fourth Federal 

Interagency Sedimentation Conference, v. 2: Subcommittee 

on Sedimentation of the Interagency Advisory Committee on 

Water Data, p. 5-71-5-82. 

Flood Hydrology and Geomorphic Effects, Flood of Nov. 4-5, 1985, W.Va. E95 
Sites, R.S., 1973, Geology of the Smoke Hole region of West 

Virginia: Southeastern Geology, v. 15, p. 153-167. 

Smith, D.G., 1983, Anastomosed fluvial deposits: modem examples from western Canada, in Collinson, J.D., and Lewin, J., 

eds., Modem and ancient fluvial systems, International 

Association of Sedimentologists Special Publication 6, 

Blackwell Scientific Publications, p. 155-168. 

Smith, N.D., 1974, Sedimentology and bar formation in the upper 

Kicking Horse River, A braided outwash stream: Journal of 

Geology, v. 82, p. 205-223. 

Stedinger, J.R., and Baker, V.R., 1987, Surface water hydrology, 

Historical and paleoflood information: Reviews of Geophysics, v. 25, p. 119-124. 

Stewart, J.H., and LaMarche, V.C., 1967, Erosion and deposition 

produced by the flood of December 1964 on Coffee Creek, 

Trinity County, California: U.S. Geological Survey Professional Paper 422-K, 22 p. 

Sullivan, J .E., 1983, Geomorphic effectiveness of a highmagnitude rare flood in central Texas: University of Texas at 

Austin, unpublished Master's thesis, 214 p. 

VerSteeg, K., 1940, The formation of watergaps by solution and 

piracy: American Journal of Science, v. 238, p. 32--41. 

West Virginia Advocate, 1986, The West Virginia killer flood of 

1985: Flood Commemorative Issue, 96 p. 

Williams, G.P., and Guy, H.P., 1973, Erosional and depositional 

aspects of Hurricane Camille in Virginia, 1969: U.S. Geological Survey Professional Paper 804, 80 p. 

Wolman, M.G., and Eiler, J.P., 1958, Reconnaissance study of 

erosion and deposition produced by the flood of August 1955 

in Connecticut: American Geophysical Union Transactions, 

v. 39, p. 1-14. 

Wolman, M.G., and Gerson, R., 1978, Relative scales of time 

and effectiveness of climate in watershed geomorphology: 

Earth Surface Processes, v. 3, p. 189-208. 

Wolman, M.G., and Leopold, L.B., 1957, River flood plains, 

Some observations on their formation: U.S. Geological 

Survey Professional Paper 282-C, p. 87-107. 

Wolman, M.G., and Miller, J.P., 1960, Magnitude and frequency 

of forces in geomorphic processes: Journal of Geology, v. 68, 

p. 54-74. 

E96 Geomorphic Studies, Storm and Flood of Nov. 3-5, 1985, W.Va., Va. ·~ U. 3. G. P. 0. 199J-J42-J89: 80004