United States

Department of

Agriculture

Forest Service

Rocky Mountain

Research Station

Fort Collins,

Colorado 80526

General Technical

Report RMRS-GTR-6

An Assessment Methodology

for Determining Historical

Changes in Mountain Streams

Mark G. Smelser

John C. Schmidt

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Abstract

Smelser, Mark G. and John C. Schmidt. 1998. An assessment methodology for determining

historical changes in mountain streams. General Technical Report RMRS-GTR-6. Fort Collins,

CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. 29 p.

Successful management of water in mountain streams by the USDA Forest Service requires that the

link between resource development and channel change be documented and quantified. The

characteristics of that linkage are unclear in mountain streams, and the adjustability of these streams

to land-use and hydrologic change has been argued in court. One way to quantify the adjustability of

a stream is to examine its geomorphic history. An excellent source of historic geomorphic data are

the records associated with stream gaging stations maintained by the U.S. Geological Survey. This

report describes what records are available, how to organize the data on computer spreadsheets, and

discusses 6 techniques that quantify the spatial and temporal magnitude of historic channel

adjustments. The discharge measurements include physical measurements of the channel. In

particular, USGS discharge measurements include physical measurements of the channel. By

analyzing these measurements collectively, it is possible to quantify monthly, annual, and decadal

scales of adjustment. Once the history of channel adjustment is determined, it can be compared to

histories of climate change, flow regulation, and land use. These comparisons may link the

geomorphic adjustments to particular patterns, events, or activities. Resource managers can use this

knowledge to better assess the ramifications of resource development, land use, and restoration

efforts on mountain stream systems.

Keywords: gaging stations, mountain streams, historic stream channel adjustments

The Authors

Mark G. Smelser received a Master of Science degree in watershed science from Utah State University

as an advisee of Dr. John Schmidt, who is an associate professor in the Department of Geography

and Earth Resources.

Publisher

Rocky Mountain Research Station

Fort Collins, Colorado

April 1998

You may order additional copies of this publication by sending your

mailing information in label form through one of the following media.

Please send the publication title and number.

Telephone (970) 498-1719

E-mail rschneider/rmrs@fs.fed.us

FAX (970) 498-1660

Mailing Address Publications Distribution

Rocky Mountain Research Station

3825 E. Mulberry Street

Fort Collins, CO 80524-8597
Contents

Introduction ..................................................................................................... 1

Mountain Stream Characteristics .............................................................. 1

Method Applicability ................................................................................... 2

Previous Studies ............................................................................................ 2

Redwood Creek ......................................................................................... 2

Others ......................................................................................................... 3

Types and Availability of Historical Data ....................................................... 4

USGS Gaging Station Data Base .................................................................. 4

Location Criteria ......................................................................................... 4

Records and Accessibility .......................................................................... 5

Data Compilation – Historic Records ............................................................. 6

Gage Station Selection .............................................................................. 6

Gage Record Requests ............................................................................. 6

Discharge Measurement Data Entry ......................................................... 8

Data Analysis – Historic Records .................................................................. 9

Rating Curve .............................................................................................. 11

Streambed Elevation.................................................................................. 12

Hydraulic Geometry ................................................................................... 18

Change in Width......................................................................................... 19

Cross Sections ........................................................................................... 20

Determination of Discharges ..................................................................... 22

Detailed Site Characterizations...................................................................... 24

Detailed Geomorphic Mapping – Phase I ................................................. 24

Detailed Geomorphic Mapping – Phase II ................................................ 25

Channel Morphology and Bankfull Discharge ............................................... 25

Management Implications .............................................................................. 28

Literature Cited ............................................................................................... 28

An Assessment Methodology for Determining

Historical Change in Mountain Streams

Mark G. Smelser and John C. Schmidt

USDA Forest Service Gen. Tech. Rep. RMRS–GTR–6. 1998 1

Introduction

Water in mountain streams is one of the primary resources managed by the USDA Forest Service. One of the

purposes for establishing the National Forest System was

to “secure favorable conditions of water flows” (Organic

Act of 1897) for downstream areas. Grazing along riparian

corridors, stream regulation, and quantification of

in-stream flows are some of the management issues related to securing favorable water flows. Sound policy

decisions associated with these issues require that the

connection between land use or stream regulation and

stream channel change be understood and documented;

this connection is unclear in steep, coarse-bedded mountain streams. Stream and watershed protection strategies

are partly based on the assumption that land use has the

potential to change the physical characteristics of streams,

and that climate changes or hydrologic manipulations

have the potential to alter runoff and sediment transport

regimes. However, the adjustability of mountain streams

to land-use, hydrologic, or sediment-transport changes

has been argued in court (Gordon 1995).

While much data describes the past condition of stream

channels, little research has documented the geomorphic

changes along streams that drain forested mountain regions. General Land Office surveys of the late 1800s rarely

extended into mountainous areas, ground-level photographs are often scarce and difficult to find, and aerial

photography did not begin until the late 1930s.

This report focuses on analysis of historic records associated with stream gaging stations maintained by the U.S.

Geological Survey (USGS). Stream gaging stations continuously measure the water surface elevation in a stream

(figure 1) and are used to monitor and inventory the

nation’s surface water supply. Although these data typically only describe the condition of mountain streams

over the past 50 years, they provide direct evidence of

whether or not mountain streams in a particular region

have adjusted to past changes in land use, hydrology, or

climate.

Mountain Stream Characteristics

The majority of mountain streams discussed in this

report are fourth-order (determined from analysis of blue

lines on 7.5 minute USGS quadrangle maps),

coarse-bedded streams with channel gradients between

0.005 and 0.05, and D84 values as large as 256 mm (84% of

all bed material particles are less than this size). These

streams typically have: 1) straight and braided channel

patterns, 2) moderate width-to-depth ratios, 3) low sinuosities, 4) nearly vertical, non-cohesive banks composed

of gravel and cobbles, and 5) usually flow through steep

forested slopes, with occasional open parks and meandering reaches. Individual reaches resemble B3, B4, C3, C4,

F3, F4, G3, and G4 types as defined by Rosgen (1994) and

are classified as step-pool, plane-bed, or pool-riffle reaches

as defined by Montgomery and Buffington (1993). Mountain streams are subject to highly variable discharges

(Schmidt and Egenzinger 1994) and are susceptible to

large sediment loads from slope failures and debris flows.

In these streams, channel roughness is high, and the

channel configurations are a complex mosaic of coarse

sediment and in-channel obstructions such as large

woody-debris.

Mountain streams typically are confined within narrow valleys, are unable to meander freely, and do not

A-Frame Cable Car

Outside

Staff Gage

A-Frame

Gage House

Intake Pipe

Water Surface

Reference

Mark

Gage Datum

Gage Datum Related to Topographic Elevation

Through the Reference Mark and Level Surveys

Cableway 

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Figure 1. Schematic sketch of a

typical U. S. Geological Survey

stream gaging station. The cable

car is used to make discharge

measurements in deep stream

flows. An automatic data logger

inside the gage house records

water-level height every 15

minutes. Reference Mark(s) are

permanently mounted brass

benchmarks used to control the

elevation of the gage datum, which

is the zero elevation point for the

gage.

GAGE HEIGHT, IN FEET

ELEVATION ABOVE

SEA LEVEL, IN FEET
2 USDA Forest Service Gen. Tech. Rep. RMRS–GTR–6. 1998

develop extensive floodplains. Straight and braided planforms prevail, and floodplains are small and discontinuous owing to local channel controls like bedrock outcrops,

large woody debris, and other coarse debris generated by

mass-wasting (Keller and Tally 1979, Andrews 1984, Lisle

1986, Grant et al. 1990, Nakamura and Swanson 1993,

Andrews and Nankerveris 1995, Grant and Swanson 1995).

Flood discharges that exceed bankfull in large alluvial

streams flow onto floodplains where flood energy is dissipated. However, in narrow mountain valleys, flood

energy remains concentrated down the axis of the valley

and has the potential to modify the stream channel. Consequently, infrequent large floods with recurrence intervals between 50 and 200 years form macro-bedforms such

as boulder steps in mountain streams (Grant et al. 1990,

Wohl 1992, Abrahams et al. 1995, Grant and Swanson

1995). Hillslope processes like landslides, rockfalls, and

debris flows are important geomorphic agents affecting

mountain streams because they supply coarse sediment

and woody debris to the stream, which blocks or reroutes

flowing water (Grant et al. 1990, Grant and Swanson 1995,

Nakamura and Swanson 1993).

Mountain streams transport a high percentage of their

sediment load as bedload, and sediment transport often is

used as an indicator of geomorphic change (Wolman and

Miller 1960, Gordon 1995). Sediment transport in mountain streams is very difficult to quantify, and research

shows that bedload transport in coarse-bedded streams is

a multi-faceted process that is imperfectly understood

(Parker et al. 1982, Parker and Klingeman 1982, Andrews

1983, 1984, 1994, Germanoski and Schumm 1995, Lisle

1995, Bunte 1996). Consequently, methodologies that

quantify geomorphic change directly, rather than indirectly by estimating changes in reach-scale sediment mass

balance, are valuable in assessing historical changes of

streams.

Method Applicability

This report explains how to analyze and interpret USGS

stream gaging station records. In addition, techniques for

characterizing the contemporary conditions of gaged

reaches, within the context of historical analyses, are

presented. This methodology is useful because:

• USGS stream gaging data may be the only historic

information available for mountain streams;

• the data are quality controlled, accessible, and

inexpensive to obtain; and

• compared to conventional space-for-time or

paired-basin studies, these data are less expensive, quicker to analyze, and may be more site

specific.

The methodology has been prepared to better understand and more efficiently manage mountain streams.

These streams are key elements of the forest ecosystem

and are becoming more viable as water sources.

Previous Studies

One way to evaluate the adjustability of mountain

streams is to determine whether these streams adjusted to

past land-use, hydrologic, and climate changes. If this

determination is possible, then future changes can be

predicted with greater assurance. The documentation of

historic channel change is of longstanding interest to

geomorphologists. The existence of terraces, which are

abandoned floodplains, along rivers throughout the world

demonstrates that channels and their valleys have changed

form. Bryan (1928) recognized that the deeply eroded

alluvial valleys of the American Southwest had formed in

the late 1800s. Determination of the timing and magnitude

of change is essential to understand why these changes

occurred. More recently, detailed analyses of channel

change have been used to evaluate the effects of large

dams (Williams and Wolman 1984), the effect of land-use

practices (Trimble and Lund 1982, Wolman 1967), and

flow augmentation (Dominick 1997) on stream channels.

Stream channel histories are valuable because they:

1) are a source of baseline data that can guide development, mitigation, or restoration plans; 2) provide a context

to evaluate erosion and sedimentation problems related to

land use and streamflow regulation; 3) reveal how natural

events and human activities affect channel change; and

4) help define recovery rates and patterns. In addition, an

understanding of geomorphic processes from a quantified history of the stream channel is a solid foundation for

models and decisions that lead to better land and water

resource management.

Redwood Creek

Recent studies of Redwood Creek, California, illustrate

the important role that a well-documented history of

geomorphic change can play in affecting policy decisions

for mountain forests. Redwood Creek empties into the

Pacific Ocean in northern California. In 1968, the lower

third of the Redwood Creek watershed, and the associated

estuary, were protected within Redwood National Park,

which was established to preserve groves of coastal redwood, Sequoia sempervirens (National Park Service 1985).

The redwood groves occur on the floodplain and terraces
USDA Forest Service Gen. Tech. Rep. RMRS–GTR–6. 1998 3

adjacent to Redwood Creek. The Tall Trees Grove contains the first, third, and sixth tallest known trees in the

world (Nolan et al. 1995). Soon after the park was established, citizens became concerned that timber harvesting

outside of the park, in the upper two-thirds of the watershed, threatened the longevity of the Tall Trees Grove.

Redwood Creek appeared to be widening and shallowing

in response to increased runoff and sediment load from

the timbered, rapidly eroding upper portion of the watershed.

In 1973, the National Park Service (NPS) and the USGS

agreed to conduct detailed studies to quantify the impacts

of timber harvesting and natural geomorphic processes

on park resources and associated ecosystems. A key part

of this research was measurement of past stream channel

changes. A variety of methods were used to decipher the

geomorphic history of the watershed including: 1) interpretation of time-sequential aerial photographs, 2) old

land survey reviews, 3) analysis of USGS stream gaging

records, 4) analysis of climate records, 5) stratigraphic

analyses, 6) dendrochronology, 7) radiocarbon dating,

and 8) interviews with long-time area residents. Contemporary conditions were characterized by detailed geomorphic maps and a multi-year monitoring program

designed to measure erosion, transport, and sediment

deposition. Results showed that the Redwood Creek

watershed is one of the most rapidly eroding landscapes

in the United States, and that the channel itself is highly

subject to change (Janda and Nolan 1979).

Although the hypotheses about channel change originally centered on the effects of timber harvest, the detailed

study revealed that climatic factors, in this case an unusually large storm, had caused much of the change along the

stream. In December 1964, a large storm persisted for 12

days. The storm generated substantial flooding and caused

dramatic geomorphic change in the Redwood Creek watershed (Harden 1995). Channel behavior in the 1970s and

1980s could still be related to this event (Nolan and Marron

1995). Through comparative analysis, it was determined

that the storm caused more landslides and had a higher

runoff than similar magnitude storms in 1953 and 1955.

This suggested that the watershed had changed during

the late 1950s. Additional historic analysis found that

between 1947 and 1964, 67% of the watershed upstream

from the park had been harvested for timber, most by

clearcutting (Best 1995). Thus, the channel change due to

timber harvesting had caused an increase in the vulnerability of the watershed to erosion.

Detailed studies of the Redwood Creek watershed revealed that large storms generate substantial runoff that

links hillslope and channel processes together resulting in

accelerated erosion. Timber harvesting appears to have

increased the scale and number of such linkages. In the

Redwood Creek watershed, the large 1964 storm generated landslides into the upper basin tributaries and main

channel. Coincident storm-related discharges flushed the

sediment out of the tributaries and into Redwood Creek,

which subsequently aggraded. The aggradation caused

higher water levels and the channel widened. Channel

widening and higher water levels effectively eroded

streambanks that supported trees and also eroded side

slopes causing additional landslides. Nolan and Marron

(1995) documented almost 15 ft of channel aggradation, a

doubling of stream width, and a number of toppled,

old-growth redwoods. Aggradation also filled inter-gravel

spaces with fine sediment, effectively eliminating gravels

as spawning sites. The aggradation and concomitant

water level increase caused the water table to rise

threatening to drown the roots of mature redwoods

(Nolan and Marron 1995). Furthermore, deposition of

sediment on the floodplain has the potential to bury

streamside trees to such an extent as to be fatal (Janda et al.

1975).

These detailed studies of the geomorphic history and

processes of the Redwood Creek watershed led to an

improved understanding of the hydro-geomorphic system. That understanding was the basis for a congressional

decision to expand the park in 1978 by an additional

48,000 acres of the upper watershed. Congress also designated a 30,000-acre buffer zone immediately upstream

from the park within which future timber harvest plans

are subject to review by the NPS.

Others

Studies that quantify the geomorphic history of stream

channels have become more common as resources have

become more limited and environmental awareness has

grown. McCaffery et al. (1988) examined 45 yrs of data

and quantified the geomorphic history of Cottonwood

Creek, California. Their purpose was to develop baseline

data on channel form and migration so that the impact of

2 proposed dams could be assessed. McCaffery et al. were

particularly interested in collecting data that would help

evaluate the effects of reduced bed load and attenuated

peak discharges on channel alignment. Simon (1994) studied approximately 35 yrs of historic data to quantify the

effects of channelization on streams in west Tennessee. He

developed a conceptual model of channel evolution caused

by channelization and formulated equations that estimate

aggradation, degradation, and channel widening. Krug

and Goddard (1986) analyzed 10 yrs of historic data to

assess the effects of urbanization on Pheasant Branch,

Middleton, Wisconsin. They quantified erosion and sedimentation of an urbanized stream and calibrated a

rainfall-runoff model for use by city planners and engineers.
4 USDA Forest Service Gen. Tech. Rep. RMRS–GTR–6. 1998

Schumm and Lichtey (1963) pieced together 86 yrs of

history for the Cimarron River, Kansas. They were able to

determine that catastrophic floods completely obliterated

the floodplain between 1914 and 1942, and that the floodplain was rebuilt within 12 yrs. In a similar study, Burkham

(1972) examined 124 yrs of data on the Gila River, Arizona.

He reported that catastrophic floods stripped away approximately 4 mi2

 of floodplain between 1905 to 1917.

However, in this case, many decades were required to

rebuild the floodplain. Erman (1992) examined 25 yrs of

USGS gaging station data for the Little Truckee River,

California, and documented changes in the hydraulic

geometry. However, because of many different land-use

activities in the watershed and the occurrence of a few

large floods, a single cause for the channel changes was

not determined. Jacobson (1995) analyzed 70 yrs of

discharge measurements at 23 gages on gravel streams in

the Ozark Plateau, Missouri, in an effort to correlate

channel change with land use. He demonstrated the magnitude of past channel adjustments and presented reasonable causal mechanisms. James (1991, 1995) analyzed

USGS discharge measurements to quantify the evolution

of California streams overwhelmed by hydraulic mining

sediment. Because the timing of the sediment influx was

known, James was able to precisely quantify rates of

channel incision, channel recovery, and sediment storage

times.

Types and Availability of

Historical Data

As discussed, it is often necessary to determine whether

certain types of streams have adjusted to past hydrologic

or land-use changes. Geomorphic change can be directly

measured, or it can be estimated by comparing the conditions of different streams within an explicit experimental

design (e.g., traditional paired watershed studies). While

there is no substitute for the development of a long-term,

reproducible data base, such as described by Harrelson et

al. (1994), there are data sets available that can be used to

quantify geomorphic change. Some of the best data sets

are photographs and government-sponsored surveys and

investigations.

Repeat photography is an invaluable tool in reconstructing landscape change. Rogers et al. (1984) compiled

and annotated an extensive bibliography of studies where

investigators found the sites of previous photographs,

occupied the original camera position, and made new

photographs of the same scene. In this way, landscape

change has been determined in many areas including

some mountain landscapes. Aerial photography was first

systematically used in the 1930s. These early photographs,

which cover most of the Western United States, are available from the National Archives. More recent photos are

available from the Eros Data Center, Sioux Falls, South

Dakota, and the U.S. Department of Agriculture photo

archives, Salt Lake City, Utah. Unfortunately, small stream

channels in forested areas are often not visible on these

photos, and it is usually impossible to detect channel

change from one photo series to another.

Even older data about some regions is obtainable from

General Land Office survey notes. Bryan (1928) used these

data to reconstruct the timing of gully incision on the Rio

Puerco River, New Mexico. Unfortunately, little of these

data are available for mountain streams. Other reproducible historical data are in various administrative and

technical studies by land management and conservation

agencies. For instance, turn-of-the-century water development investigations may include measurements of channel cross-sections and longitudinal profiles. These studies

might have been conducted by the Bureau of Reclamation,

Bureau of Indian Affairs, or General Land Office. The

remainder of this report focuses on the analysis of records

associated with USGS stream gaging stations.

USGS Gaging Station Data Base

The first USGS stream gaging station was established

on the Rio Grande River in 1895 (Leopold 1994). Today

there are over 7,500 gaging stations in operation around

the United States and over 3,000 discontinued stations

(Leopold 1994, Leopold et al. 1964). The USGS operates

stream gages as part of the gaging station network that

monitors the nation’s water supply and also for the collection of baseline data required for the design or operation

of specific water projects (Rantz et al. 1982). Gaging stations continuously measure water-surface elevation in a

channel. Approximately once a month, discharge measurements are made at the gage station to quantify the

rating relation between the water-surface level and the

rate of water flow in the stream. Each year the data

collected at every station are summarized and published.

Location Criteria

Although the analysis of gaging data is a powerful

technique for evaluating historical channel change, there

are unavoidable limitations. Gaging stations are not randomly distributed and are typically located along the

periphery of mountains. Thus, data that describes channel

change in the interior parts of some mountain ranges may
USDA Forest Service Gen. Tech. Rep. RMRS–GTR–6. 1998 5

be limited. The specific location of each gage is based on

where it most accurately will measure the water surface

elevation for long time periods. Consequently, the stations are established at sites that provide the best combination of accessibility, measurement accuracy, and

long-term channel stability. Rantz et al. (1982) lists the

following criteria as ideal for a gaging station site.

• The stream is straight for about 300 ft up and

downstream from the gage site.

• Stream flow is confined to one channel at all

stages, and no flow bypasses the site as subsurface flow.

• The streambed is not subject to scour and fill and

is free of aquatic growth.

• Banks are permanent, high enough to contain

most floods, and free of brush.

• Unchanging natural controls are present for both

low and high flows.

• A pool is present upstream from the control to

ensure a recording at extremely low flow and to

avoid high velocities at the intakes during periods

of high flow.

• The gage site is far enough upstream from the

confluence with another stream to avoid any influence that the another stream may have on the

stage at the gage site.

• A satisfactory reach for measuring discharge at

all stages is available within reasonable proximity of the gage site.

• The site is readily accessible for ease in installation and operation of the gaging station.

Although gaging stations are located along reaches

that are relatively stable, Rantz et al. (1982) acknowledged

that “all streams in a given region may have unstable beds

and banks” and sometimes “a poor site must be accepted.”

Thus, when quantifying geomorphic change at a gage site,

it is important to recognize that these sites may be more

stable than other parts of the same stream, but they are not

static or immune to change.

Records and Accessibility

For each USGS gage station, information is recorded in

7 different files. All of the files except the recorder tapes

are used to some degree in the historical analysis.

1. Miscellaneous Working Files

These are files containing correspondence and calculations regarding gage establishment and discontinuance,

corrections to the rating relation, and miscellaneous information. This file may include a Station Description Sheet

and rarely includes photographs. While a gage is in active

operation, these data are stored at State District headquarters.

After a gage is discontinued, these files may be archived.

2. Discharge Measurements

These are the actual discharge measurements made by

the hydrographers in the field. These measurements are

made approximately once a month and are recorded on a

8 x 5 inch, multi-page form (Form 9-275). These records

make up most of the subsequent historical analyses and

contain measurements of channel width, depth, flow velocity, and a measured cross-section. While a gage is in

active operation, this data set is typically maintained in its

entirety and stored at State District headquarters. After a

gage is discontinued, these files may be archived. The data

from these Discharge Measurements are summarized on

Form 9-207, which is also available from the State District

headquarters.

3. Level Notes

These are surveyed elevation measurements of the

gage datum and gage Reference Marks. These measurements are performed periodically to confirm that the gage

and datum have not changed due to ground subsidence,

flood damage, or frost heaving. These measurements are

also recorded on a 8 x 5 inch form (Form 9-276). Typically,

these data are maintained with the Discharge Measurements.

4. Recorder Tapes

These are 4-inch wide rolls of paper tape that were

punched by the mechanical water-level recorder in the

gage house. These data are not used in historical analyses.

5. Station Analysis Reports

These are annual, unpublished reports that describe all

of the activities at the gage for a given year. These reports

typically include the Station Description Sheet, annual

hydrograph, rating relation, and occasionally photographs.

These data are stored at the State District headquarters

and are periodically archived even while the gage is in

operation.

6. USGS Water-Data Reports

These are the annual reports published by the USGS

that summarize the water data collected by the USGS on

an individual state basis. Before 1975, this information

was published in a series of USGS water-supply papers

entitled Surface Water Supply of the United States. Both the

Water-Data Reports and Water-Supply Papers are in many
6 USDA Forest Service Gen. Tech. Rep. RMRS–GTR–6. 1998

libraries. Recent copies of the Water-Data Reports are

available for purchase from State District offices. The

summary information is also available on CD-ROM and

the Internet.

7. Statistical Analyses of Discharge Data

The USGS statistically analyzes the discharge data for

each gage station. These data are used to compute flow

duration curves, flood frequency, and low-flow frequency

statistics. This collection is known as the Daily Values

Statistical Program (DVSTAT) data base.

Because of differences in use, size, and volume, the files

and records listed above are not stored together while a

gage is in operation. Additionally, because of space limitations, some of these files are periodically archived. As a

result, parts of the record for a particular gage are located

at the State District headquarters, while others are at the

USGS archives. Archived data can only be accessed by

USGS personnel.

Data Compilation –

Historic Records

Gage Station Selection

Although Forest Service hydrologists may be aware of

the existence of most active gage stations, additional data

concerning channel change exist at gaging station sites

that have been discontinued. For example, there are only

40 active stream gages in the Uinta Mountains of eastern

Utah, but there are 90 other sites where gaging took place

in the past (figure 2). The introductory text of the annual

water data reports typically includes a list of the discontinued gage stations, and these data are also available on

the Internet. The exact location of these sites can be determined from the annual water data reports that were

published while the gage was active.

Since the goal of most forest hydrologists is to understand the characteristics of regional channel change and

the specific history of a few sites, investigations typically

are undertaken at a number of sites. Long-term stations

whose point of measurement has not moved and whose

bed and banks are adjustable, are the most desirable study

sites. Short-term sites may be useful if they were installed

before some land management activity that is of concern.

Discontinued sites may provide valuable data if the site

and its reference marks can be found. Even though the

record of intervening years may be unknown, channel

change at the multi-decade scale can be evaluated. Once

the gage(s) are selected for detailed analysis, all published

information describing the gage’s history should be recorded. This information is necessary to make efficient

requests for information from the USGS.

Gage Record Requests

The first request to the USGS is for 2 types of information about each gage station. The first is the Station Description Sheet that succinctly describes how to find the

gage, the Reference Marks that define the gage datum, and

the history of gage datum changes. It is essential to know

whether or not the gage station has moved or if any

datum changes have occurred. Gage stations are occasionally relocated due to wash-outs, channel pattern

changes, accessibility, and better measurement potential.

It is important to realize that, over the period of record,

data reported for a specific gage station may have been

collected at a number of different locations along the

stream. Similarly, gage datums are changed to accommodate streambed changes or modifications to the gage

house.

The second type of information concerns how many

rating relations have been developed for the particular

gage. The existence of multiple rating curves for one gage

suggests that the streambed elevation has changed over

time. For active gages, the Station Description Sheet and

rating relation information are accessible at district headquarters. This information for discontinued gages may be

similarly accessible, but may also have been archived. The

retrieval of archived records requires that USGS personnel research accession numbers of archived data and

make formal requisitions to the archives. Upon receipt of

the written requisition, the archivist locates the records

and ships them to the USGS District Office. This process

requires a minimum of 2 weeks. It is important to remember that all of the records for one gage are not archived

together, and that the USGS does not have personnel

available to review the retrieved records for completeness.

Once a gage station is selected for detailed analysis, it

is necessary to request the Discharge Measurements (DMs)

and Level Notes (figures 3 and 4) for that station. As

before, these records will be readily available for active

gages but may have been archived if the station was

discontinued. These records are entered into computer

spreadsheets and analyzed in detail. The USGS will not

release the original records to the public; work must be

done at the USGS, which requires a laptop computer, or

the records must be photocopied. If the records are photo-
USDA Forest Service Gen. Tech. Rep. RMRS–GTR–6. 1998

7

Figure 2. Map of northeastern Utah and the Uinta Mountains showing active and discontinued U. S. Geological Survey stream gaging stations.
8 USDA Forest Service Gen. Tech. Rep. RMRS–GTR–6. 1998

Figure 3. Example of a U. S. Geological Survey Discharge Measurement. This measurement was made at Ashley Creek on

September 9, 1941. The first page contains a data summary, notes concerning channel conditions, and measurement location.

The second page contains the measured cross-section and discharge calculations. A maximum depth of 1.8 ft was recorded 36 ft

from the initial point.

copied, care must be taken because they are fragile and

irreplaceable.

Although photocopying the records is an expense, it is

desirable because the records are then owned, and they

can be immediately referenced if errors in data entry are

suspected. Ease of cross-section analysis is a second benefit to owning the records. During the data entry phase of

compilation, it is impossible to know which DMs will be

used in the cross-section analysis. Additionally, since so

few DMs are used for this purpose, it is inefficient and

unnecessary to enter the cross-section measurement from

each DM into the computer. If the records are not owned,

a second request to the USGS for the records is required to

analyze specific cross-sections.

Discharge Measurement Data Entry

The basic data used in quantitative analysis of channel

change are the DMs. Analysis of this large data set is best

conducted using computer spreadsheet software and statistical graphing software. The spreadsheet used for data

entry should include the following column or field headings.

1. Record number

2. Date (actual date)

3. Julian day (days since 1/1/1900)

4. Month
USDA Forest Service Gen. Tech. Rep. RMRS–GTR–6. 1998 9

5. Width

6. Area

7. Gage height

8. Mean velocity

9. Discharge

10. Maximum depth

11. Measurement location

12. Notes

All of the data for these fields, except maximum depth,

is on the first page of each DM (figure 3). As mentioned,

this information is also available on Form 9-207. MaxiFigure 4. Example of U. S. Geological Survey Level Notes.

These notes describe a datum change on Ashley Creek. The

gage datum was lowered 1. 291 ft on July 16, 1965.

mum depth, the deepest part of the channel recorded

during the measurement, is only found on the second

page of the DM (figure 3). Maximum depth is not listed on

Form 9-207. Measurement location is where the DM was

made relative to the gage. This location is typically estimated, and terms like “1/4 mile above,” “50 ft below

cableway,” and “at gage” are recorded in the DM. The DM

location is an important parameter used to sort the spreadsheet data. Thus, numbers not phrases should be used in

this spreadsheet field. Since the gage is the reference

location, its location is recorded as zero in the spreadsheet.

Measurement locations upstream from the gage are entered as positive numbers in the spreadsheet, and measurement locations downstream from the gage are entered

as negative numbers.

The Notes field in the spreadsheet is for any noteworthy information recorded on the DM. For example, winter

measurements often note that ice affects the gage and

stream channel. DMs made under ice commonly occur as

significant outliers in plots of hydraulic geometry and

should not be used in historical analyses. Therefore, it is

important to be able to sort out these measurements from

the basic data set for selected analyses. It is recommended

that a set of simple abbreviations be developed that impart

the message of the notes and allow for systematic sorting

of this field. As the analysis proceeds, it is necessary to sort

the data by additional spreadsheet columns related to

time and data calculations. Table 1 is an example of a

computer spreadsheet with all data fields.

Data Analysis – Historic Records

The following set of analytical techniques quantifies

stream channel change through time. A basic understanding of fluvial geomorphology is necessary. This set of

analyses is not exhaustive; it is anticipated that specific

needs and personal creativity will lead to other avenues of

analysis. The techniques are presented in a sequential

manner beginning with the analysis of the rating relation.

Later sections examine changes in width, depth, and

hydraulic geometry. Lastly, geomorphic change is linked

to discharge. In the ensuing discussion, the mean annual

flood (arithmetic average of all annual peak floods for the

period of record) is used as a reference discharge because

it has a recurrence interval of 2.3 years, and floods with

recurrence intervals between 1.5 and 3 yrs are responsible

for the formation and maintenance of large alluvial streams

(Leopold 1994). Recurrence intervals are determined from

flood frequency curves (figure 5) that rank the magnitudes

of the annual peak discharges for each year of record.
10 USDA Forest Service Gen. Tech. Rep. RMRS–GTR–6. 1998 Table 1. Example of a computer spreadsheet with all data fields used to organize the data from the U. S. Geological Survey Discharge Measurements. Measure- Rectified Water Mean Minimum Julian Mean Gage Maximum Mean ment Correction gage surface streambed streambed day Width Area velocity height Discharge depth depth location factor height elevation elevation elevation Record since Water w A v GH Q MXDPTH MNDPTH from gage COFAC RGH WSE MSBE MINSBE number Date 1/1/1900 Month year (ft) (ft2) (ft/sec) (ft) (ft3/sec) (ft) (ft) (ft) (ft) (ft) (ft) (ft) (ft) Notes 19 11/14/17 6528 11 18 29 23.3 3.01 3.56 70.2 1.3 0.8 50 -1.959 1.60 6232.60 6231.8 6231.3 20 02/15/18 6621 2 18 19 20.4 1.70 3.44 34.7 1.5 1.1 1000 -1.959 1.48 6232.48 6231.4 6231.0 21 04/21/18 6686 4 18 31 22.0 1.63 3.46 35.9 1.1 0.7 100 -1.959 1.50 6232.50 6231.8 6231.4 23 08/4/18 6791 8 18 36 40.0 2.44 3.66 97.6 1.9 1.1 50 -1.959 1.70 6232.70 6231.6 6230.8 24 11/5/18 6884 11 19 32 31.6 2.04 3.55 64.5 1.4 1.0 100 -1.959 1.59 6232.59 6231.6 6231.2 25 01/22/19 6962 1 19 28 23.4 1.36 3.34 31.9 1.3 0.8 50 -1.959 1.38 6232.38 6231.5 6231.1 26 05/12/19 7072 5 19 43 55.3 3.62 3.97 200.0 2.0 1.3 100 -1.959 2.01 6233.01 6231.7 6231.0 27 09/25/19 7208 9 19 28 26.8 1.99 3.49 53.3 1.4 1.0 100 -1.959 1.53 6232.53 6231.6 6231.1 28 03/17/20 7382 3 20 29 20.5 1.40 3.38 28.4 1.1 0.7 -1.959 1.42 6232.42 6231.7 6231.3 29 05/27/20 7453 5 20 72 166.0 5.69 6.08 945.0 3.2 2.3 -100 -1.959 4.12 6235.12 6232.8 6231.9 30 05/28/20 7454 5 20 77 151.0 5.67 6.10 856.0 3.8 2.0 -1.959 4.14 6235.14 6233.2 6231.3 31 10/29/20 7608 10 21 40 36.1 1.51 4.38 54.6 1.3 0.9 10 -1.959 2.42 6233.42 6232.5 6232.1 32 03/27/21 7757 3 21 49 35.4 0.97 4.20 34.2 1.1 0.7 4 -1.959 2.24 6233.24 6232.5 6232.1 33 07/1/21 7853 7 21 55 70.5 3.60 5.25 254.0 2.1 1.3 -75 -1.959 3.29 6234.29 6233.0 6232.2 34 07/27/21 7879 7 21 45 52.4 2.36 4.86 124.0 1.8 1.2 0 -1.959 2.90 6233.90 6232.7 6232.1 35 10/7/21 7951 10 22 41 37.4 2.43 4.74 91.0 1.7 0.9 -100 -1.959 2.78 6233.78 6232.9 6232.1 36 01/23/22 8059 1 22 26 25.4 1.62 4.43 41.2 2.0 1.0 400 -1.959 2.47 6233.47 6232.5 6231.5 37 06/4/22 8191 6 22 80 155.4 6.62 7.55 1030.0 3.6 1.9 100 -1.959 5.59 6236.59 6234.6 6233.0 38 06/17/22 8204 6 22 126 147.0 4.82 7.96 700.0 2.3 1.2 -100 -1.959 6.00 6237.00 6235.8 6234.7 39 09/5/22 8284 9 22 44 44.9 2.38 6.35 107.0 2.0 1.0 -1.959 4.39 6235.39 6234.4 6233.4 40 03/25/23 8485 3 23 24 26.0 1.33 5.85 34.5 2.0 1.1 150 -1.959 3.89 6234.89 6233.8 6232.9 41 06/10/23 8562 6 23 71 131.0 4.53 7.48 594.0 2.9 1.8 50 -1.959 5.52 6236.52 6234.7 6233.6 42 06/24/23 8576 6 23 52 76.1 3.76 6.88 286.0 2.4 1.5 20 -1.959 4.92 6235.92 6234.5 6233.5 43 07/6/23 8588 7 23 51 58.9 3.02 6.62 208.0 2.1 1.4 20 -1.959 4.66 6235.66 6234.3 6233.6 44 07/18/23 8600 7 23 48 58.5 2.80 6.44 164.0 1.9 1.2 20 -1.959 4.48 6235.48 6234.3 6233.6 45 05/12/24 8899 5 24 59 106.0 3.99 7.33 423.0 2.5 1.8 30 -1.959 5.37 6236.37 6234.6 6233.9 46 09/20/24 9030 9 24 5.94 41.5 -1.959 3.98 6234.98 6235.0 47 01/26/25 9158 1 25 23 23.3 1.34 5.81 31.1 1.3 1.0 3000 -1.959 3.85 6234.85 6233.8 6233.6 48 04/25/25 9247 4 25 43 39.1 1.54 6.03 60.4 1.3 0.9 31 -1.959 4.07 6235.07 6234.2 6233.8 49 05/25/25 9277 5 25 48 66.0 3.14 6.63 207.0 1.9 1.4 -1.959 4.67 6235.67 6234.3 6233.8 50 08/14/25 9358 8 25 45 42.6 1.81 6.13 77.0 1.2 0.9 -1.959 4.17 6235.17 6234.2 6234.0 51 12/6/25 9472 12 26 44 38.0 1.47 6.04 55.8 1.2 0.9 25 -1.959 4.08 6235.08 6234.2 6233.9 52 05/2/26 9619 5 26 55 82.8 3.48 7.00 288.0 2.2 1.5 25 -1.959 5.04 6236.04 6234.5 6233.8 54 06/27/26 9675 6 26 46 49.2 2.08 6.28 103.0 1.4 1.1 20 -1.959 4.32 6235.32 6234.2 6233.9 56 08/30/26 9739 8 26 44 39.4 1.51 6.06 69.6 1.2 1.0 20 -1.959 4.10 6235.10 6234.1 6233.9 57 10/23/26 9793 10 27 42 30.4 1.26 5.93 39.2 1.0 0.7 10 -1.959 3.97 6234.97 6234.2 6234.0 59 02/8/27 9901 2 27 14 11.8 2.39 5.83 28.2 1.4 0.8 1000 -1.959 3.87 6234.87 6234.0 6233.5 60 5/29/27 10011 5 27 52 82.0 3.45 6.99 283.0 2.4 1.6 -1.959 5.03 6236.03 6234.5 6233.6
USDA Forest Service Gen. Tech. Rep. RMRS–GTR–6. 1998 11

will rectify historic gage heights to the contemporary gage

datum. The correction factor (COFAC) is calculated by:

COFAC = ECGD – EHGD (1)

where ECGD is the topographic elevation of the contemporary gage datum and EHGD is the topographic elevation of a historic gage datum. When numerous datum

changes have occurred, the calculations can be confusing

and it is useful to construct a graph of the datum changes

through time (figure 7). The sketch in figure 7 shows

specific corrections for particular time periods. These

time-specific corrections are applied to the recorded gage

heights by adding 2 new fields to the spreadsheet. One is

the correction factor (COFAC) and the second is the rectified gage height (RGH) where:

RGH = Gage Height + COFAC (2)

It is advisable to create another column in the spreadsheet that equates the RGH to a topographic elevation.

This column is referred to as water surface elevation

(WSE) and:

WSE = Topographic Elevation of the

Contemporary Gage Datum + RGH (3).

The topographic elevation of the gage datum is determined through the Reference Marks and USGS 7.5 minute

topographic maps. Once all the discharge measurements

are rectified, a new plot of the rating relation is generated

(figure 8). For Ashley Creek, the plot still shows substantial variability but not as much as the unrectified plot of

0

500

1000

1500

2000

2500

3000

3500

4000

1 10 100

RECURRENCE INTERVAL, IN YEARS

Mean Annual Flood = 1200 ft 3/s

2.3

Figure 5. Flood Recurrence Interval Curve for Ashley Creek.

This is a Log Pearson Type III curve using all 83 years of

flood data. The mean annual flood of 1200 ft3/sec plots at a

recurrence interval of 2.3 years.

-2

0

2

4

6

8

1 10 100 1000 10

DISCHARGE, IN CUBIC FEET PER SECOND

Figure 6. Rating Relation for Ashley Creek. This plot was

generated using all gage heights as recorded on the original

Discharge Measurements. There are numerous lineations that

occur over a large range of about 8 ft. This plot indicates that

either the gage datum, streambed, or both have changed

substantially through time.

Rating Curve

The first step in recognizing geomorphic change is to

analyze the rating relation. The rating relation, also known

as the stage-discharge relation, is a graph that depicts the

relation between measured stream discharges and water

surface elevations measured at the same time by the

stream gage. The premise of this analysis is that if the gage

datum and streambed elevation remain constant through

time, then a given discharge should always correspond to

the same gage height. However, if a given discharge is

correlated with different gage heights over time, then

either the gage datum or the streambed elevation has

changed. Figure 6 is a plot of the rating relation for Ashley

Creek, Utah, using all of the gage heights as recorded on

the DMs (i.e., no corrections have been made for gage

datum changes). Ashley Creek is an unregulated stream

that has been continuously gaged since 1917. As evidenced by the wide scatter of data, figure 6 suggests

substantial adjustability over the period of record, which

could be the result of aggradation, degradation, or gage

datum changes. To remove anomalous trends caused by

datum changes, it is necessary to rectify the recorded gage

heights to a common datum; the most logical choice is to

adjust all historic data to the present-day gage datum.

Rectification of gage heights requires all information

on datum changes through the period of record. This

information is in the Station Description Sheet, the Level

Notes, and the Station Analysis Reports. With this information, it is possible to calculate the correction factors that DISCHARGE, IN CUBIC FEET PER SECOND

RECURRENCE INTERVAL, IN YEARS

DISCHARGE IN CUBIC FEET PER SECOND

GAGE HEIGHT IN FEET ABOVE AN ARBITRARY DATUM
12 USDA Forest Service Gen. Tech. Rep. RMRS–GTR–6. 1998

figure 6. Because the gage heights have all been rectified,

the adjustments are due to changes in the streambed

elevation.

Streambed Elevation

The rectified rating relation (figure 8) shows that the

streambed at the gage has adjusted through time. HowDatum

1917-1942

Datum

1942-1960

Datum

1986-1996

Datum

1960-1965

Datum

1965-1968 Datum

1968-1986

3.041 

2.381

-1.959

1.09 1.0

1

2

3

1

4

5

0

1

2

Representative Staff Gage

*Correction Factor (COFAC)

Shown in Italics 

 

Figure 7. The history of gage datum

changes at the Ashley Creek gaging

station. This graph shows the history of

datum changes relative to the 1996

gage datum. The correction factor

(COFAC) is the value that will rectify

an old water surface elevation to the

contemporary gage datum using: Gage

Height + COFAC = Rectified Gage

Height (RGH). For example, a water

surface elevation of 1.959 ft in 1920

would equal, 1.959 ft + (-1.959 ft) = 0.0

ft on the contemporary gage. From the

Level Notes and Station Analysis

Reports:

1=10/1/42-Gage datum raised 5 ft

2=8/5/60-Gage datum lowered 0.66 ft

3=7/16/65-Gage datum lowered 1.291 ft

4=7/30/68-Gage datum lowered 0.09 ft

5=8/86-Gage datum lowered 1.00 ft

-2

0

2

4

6

8

1 10 100 1000 10000

DISCHARGE, IN CUBIC FEET PER SECOND

Figure 8. Corrected Rating Relation using rectified gage

heights. There are still numerous lineations, but they occur

over a significantly small range of 4 ft. Because this plot is

generated from data that has been rectified to the contemporary gage datum, the variability is solely a consequence of

changes in streambed elevation.

ever, temporal trends and spatial magnitudes are not

discernible from the rating relation. Such trends and magnitudes can be illustrated and measured by plotting the

mean streambed elevation through time. For each DM, a

mean depth can be calculated using the continuity equation:

Q = Av (4)

where Q is discharge, A is cross-sectional area, and v is

velocity. A mean depth (MNDPTH) value is calculated in

the spreadsheet with:

MNDPTH = Q/wv (5)

where w is the channel top width. It is important to

realize that mean depth is a calculated value and not a

field measurement. The subtraction of MNDPTH from the

water surface elevation (WSE) gives the mean streambed

elevation (MSBE):

MSBE = WSE - MNDPTH (6)

This relation is illustrated in figure 9. A similar calculation is that which returns the minimum streambed elevation. The minimum streambed elevation (MINSBE) is also

known as the thalweg elevation and is calculated by

substituting maximum (MXDPTH) for MNDPTH in equation (6).

MINSBE = WSE - MXDPTH (7)

Note that MXDPTH is an actual measurement to the

streambed.

Because MSBE and MINSBE values are determined

using the water surface elevation at the gage, it is assumed

that all discharge measurements have occurred along a

DISCHARGE IN CUBIC FEET PER SECOND

GAGE HEIGHT IN FEET ABOVE AN ARBITRARY DATUM
USDA Forest Service Gen. Tech. Rep. RMRS–GTR–6. 1998 13

Width

Mean

Depth Maximum

Depth

Staff Gage

Water Surface

0

WSE

MSBE

Gage Height

MINSBE

cross section adjacent to the gage. Actually, discharge

measurements are often made at some distance from the

gage. For example, DMs of Ashley Creek have been made

up and downstream as much as 3000 ft from the gage.

Assuming that all DMs were made at the gage implies

that: 1) calculated mean depths per discharge are constant

throughout the reach, 2) maximum depths measured at

different locations can be analyzed together, and 3) the

adjustability of the streambed is uniform throughout the

reach. The assumption is unavoidable because the gage is

the single point of elevation control that links the historic

record to present day conditions.

The assumption that all DMs were made at the gage is

central to MSBE and MINSBE analyses and must be substantiated. The location, measured discharge, and mean

depth of a number of DMs for Ashley Creek are in table 2.

From this table, it can be seen that mean depth, up and

downstream, is essentially the same per discharge within

a variability of 0.4 ft. Thus, at Ashley Creek, calculated

mean depths are constant up and downstream, within a

range of variability that is the same as the median particle

size.

The variability associated with maximum depth measurements is a function of both streambed irregularities

and different measurement locations. This variability is

quantified by examining the standard deviation of the

mean thalweg elevation for consecutive discharge measurements taken during periods of low flow. The record

number, date, location, and thalweg elevations for consecutive discharge measurements are in table 3. The means

and standard deviations of the thalweg elevations are also

in table 3. The discharge measurements used in this analysis were selected because they represent relatively stable

channel conditions during periods of base flow. By analyzing the bed elevations under low flow conditions, it is

assumed that the channel does not change (no scour or fill

of the channel) between measurements. Consequently,

the differences between such consecutive bed elevation

measurements are interpreted to represent the inherent

measurement variability caused by streambed irregularities and different measurement locations.

For example, on September 26, 1951, a hydrographer

measured discharge at the gage and the thalweg elevation

was 6232.4 (table 3). One month later, discharge was again

measured at the gage and the thalweg elevation was

unchanged. Table 3 shows that the standard deviations of

the mean thalweg elevations range from 0.0 to 0.4 ft and

the average standard deviation is 0.1 ft. Thus, the inherent

variability in the depth measurements caused by bed

irregularities and the use of different measuring locations

is small. Therefore, maximum depths measured at different locations within the reach can be analyzed together

and the average variability between such measurements

is ± 0.1 ft. The assumption that streambed adjustability is

similar along the reach is verified by the MSBE analysis.

In an MSBE analysis, all MSBE data points are plotted

in a time series (figure 10). The existence of a temporal

trend in figure 10, which is derived from data measured

up and downstream, indicates that the streambed

adjustability is approximately uniform throughout the

reach. A similar plot, using only data measured within 50

ft of the gage, shows the data to be consistent with the

assumption (figure 11). Since this plot reveals the same

temporal pattern of aggradation, stability, and degradation, the assumption of similar channel adjustability above

and below the gage is justified.

While the smoothed trend of the MSBE provides temporal trends and spatial magnitudes, it is not the complete

story. Since DMs are recorded almost monthly, it is possible to look at the data set in more detail and examine

changes in the streambed at a monthly scale. However,

this cannot be done using the MSBE data because they are

calculated with top width measurements that are very

different at high and low water stages. Figure 12 shows the

relationship between the low and high water MSBEs

along with the actual streambed elevation. Consequently,

Figure 9. A channel crosssection showing the elements of equation (6) MSBE

= WSE - MNDPTH and

equation (7) MINSBE =

WSE - MXDPTH. The mean

depth is calculated from the

continuity equation and the

mean streambed elevation

(MSBE) is calculated by

subtracting the mean depth

from the water surface

elevation. In contrast, the

minimum streambed

elevation (MINSBE) is

calculated using a measured

depth to the streambed.

GAGE HEIGHT

ELEVATION ABOVE SEA LEVEL

Maximum
14 USDA Forest Service Gen. Tech. Rep. RMRS–GTR–6. 1998

Difference

Gage Mean Location in mean

Record height Discharge depth from gage depth

number Date (ft) (ft3/sec) (ft) (ft) (ft)

20 02/15/22 3.44 34.7 1.1 1000

21 04/21/18 3.46 35.9 0.7 100 0.4

48 04/25/25 6.03 60.4 0.9 30.5

56 08/30/26 6.06 69.6 0.9 20 0.0

106 08/7/38 6.18 97.3 1.3 500

109 11/10/38 6.16 88.1 1.0 10 0.3

119 09/16/39 6.28 108 1.5 400

120 10/14/39 6.26 94.8 1.4 500 0.1

134 01/10/41 5.89 32.5 1.0 100

135 02/19/41 5.84 30 1.2 300

136 04/18/41 5.84 24.6 1.1 250 0.1

142 08/17/41 6.09 96.2 1.0 500

145 11/16/41 6.09 86.6 1.0 15 0.0

155 10/2/42 1.34 58.3 1.5 600

156 10/16/42 1.33 52.4 1.1 600 0.4

177 09/27/44 1.42 55.2 1.1 500

178 10/13/44 1.44 56.2 1.1 600 0.0

182 01/26/45 1.09 20.9 0.9 350

183 03/12/45 1.07 19.6 0.9 400 0.0

238 12/2/48 0.64 21.5 0.7 25

239 12/13/48 0.62 18.3 0.7 -300 0.0

240 01/12/49 0.6 16.5 0.7 -300

243 03/1/49 0.55 16.3 0.6 25 0.1

255 11/4/49 0.88 41.2 1.0 -500

256 11/25/49 0.88 41.2 0.7 50 0.3

272 10/2/50 0.89 58.7 0.9 -100

273 10/25/50 0.86 53.4 1.2 -250 0.3

340 03/21/55 0.58 17.7 0.6 40

339 03/21/55 0.58 18.6 0.9 -1000 0.3

400 12/17/57 0.2 28.9 0.5 20

401 01/22/58 0.18 28.9 0.8 -200 0.3

430 08/13/59 0.37 64.2 1.2 -200

439 04/11/60 0.39 65.6 0.8 20 0.4

435 01/18/60 -0.11 14.7 0.5 150

436 02/16/60 -0.13 12.8 0.8 -1000 0.3

497 11/20/63 0.85 18 1.0 300

498 12/18/63 0.82 16.5 1.0 -500 0.0

531 01/17/66 0.68 16.4 0.5 100

533 03/30/66 0.67 14.7 0.4 -300 0.0

546 02/6/67 0.47 11.8 0.7 -600

547 03/6/67 0.42 12 0.7 -1000

548 4/14/67 0.49 16.6 0.8 -300 0.1

560 01/24/68 0.54 14.4 0.9 -600

562 04/1/68 0.54 13.8 0.9 0 0.0

573 01/15/69 0.95 13.2 0.7 -500

574 01/24/69 0.96 15.4 0.7 0 0.1

575 02/10/69 0.93 13.1 1.0 -500

576 03/17/69 0.9 10.9 0.9 -300 0.1

584 10/13/69 1.15 32.3 1.0 -600

585 11/5/69 1.14 29.3 1.0 -500 0.0

663 03/17/76 0.17 7.02 0.5 -1000

664 04/1/76 0.14 5.92 0.5 -500 0.0

672 11/22/76 0.34 11.4 0.8 -600

673 12/9/76 0.33 11.7 0.6 -500 0.2

686 12/5/77 0.7 10.6 1.1 -500

689 4/13/78 0.69 10.5 0.7 -1000 0.4

698 10/23/78 0.6 13.6 1.1 -500

702 04/18/79 0.66 19.3 0.7 0 0.4

727 12/31/80 0.61 13.1 0.8 -500

730 04/13/81 0.62 19.5 0.8 20 0.0

Difference

Gage Mean Location in mean

Record height Discharge depth from gage depth

number Date (ft) (ft3/sec) (ft) (ft) (ft)

Table 2. Analysis of the variability associated when assuming the calculated mean depth, for a given discharge, to be equal at

different locations above and below the gage.
USDA Forest Service Gen. Tech. Rep. RMRS–GTR–6. 1998 15

Mean

Measurement Thalweg thalweg Standard

Record location elevation elevation deviation

number Date (ft frm gage) (ft) (ft) (ft)

56 08/30/26 20 6232.9

57 10/23/26 10 6233.0 6232.9 0.1

62 08/12/27 0 6232.6

63 10/14/27 0 6232.8 6232.7 0.1

80 08/27/32 0 6232.7

81 10/6/32 50 6232.8 6232.8 0.1

83 08/9/33 -500 6232.3

84 10/2/33 -100 6232.6 6232.4 0.2

94 08/28/37 500 6231.5

96 10/28/37 500 6231.5 6231.5 0.0

107 09/12/38 30 6232.7

108 10/13/38 15 6232.6 6232.6 0.1

118 08/16/39 500 6232.0

119 09/16/39 400 6231.8 6231.9 0.1

119 09/16/39 400 6231.8

120 10/14/39 500 6231.9 6231.9 0.1

130 08/22/40 500 6232.1

131 09/21/40 500 6231.9 6232.0 0.1

131 09/21/40 500 6231.9

132 10/24/40 500 6232.0 6231.9 0.1

143 09/19/41 40 6232.4

144 10/20/41 40 6232.6 6232.5 0.1

154 08/13/42 800 6232.5

155 10/2/42 600 6232.1 6232.3 0.3

155 10/2/42 600 6232.1

156 10/16/42 600 6232.6 6232.4 0.4

165 09/7/43 500 6232.3

166 10/8/43 500 6232.7 6232.5 0.3

176 08/15/44 500 6232.4

177 09/27/44 500 6232.4 6232.4 0.0

177 09/27/44 500 6232.4

178 10/13/44 600 6232.5 6232.4 0.1

178 10/13/44 600 6232.5

179 10/15/44 600 6232.5 6232.5 0.0

190 08/23/45 500 6232.5

191 09/26/45 500 6232.4 6232.4 0.1

200 09/12/46 500 6232.6

201 09/13/46 500 6232.5 6232.6 0.1

201 09/13/46 500 6232.5

202 10/8/46 500 6232.4 6232.4 0.1

217 08/26/47 50 6232.3

218 09/9/47 30.5 6232.3 6232.3 0.0

218 09/9/47 30.5 6232.3

219 09/29/47 20 6232.3 6232.3 0.0

219 09/29/47 20 6232.3

220 10/7/47 75 6232.2 6232.3 0.1

234 08/10/48 50 6232.4

235 09/24/48 -100 6232.6 6232.5 0.1

235 09/24/48 -100 6232.6

236 10/29/48 -100 6232.6 6232.6 0.0

253 08/11/49 -350 6232.1

254 09/7/49 -300 6232.1 6232.1 0.0

270 08/24/50 25 6232.4

271 09/9/50 50 6232.5 6232.4 0.1

271 09/9/50 50 6232.5

272 10/2/50 -100 6232.2 6232.4 0.2

284 08/1/51 0 6232.5

285 09/12/51 -50 6232.5 6232.5 0.0

285 09/12/51 -50 6232.5

286 09/26/51 0 6232.4 6232.4 0.1

286 09/26/51 0 6232.4

287 10/25/51 0 6232.4 6232.4 0.0

299 08/19/52 50 6232.5

300 09/18/52 40 6232.4 6232.4 0.1

300 09/18/52 40 6232.4

301 10/17/52 30 6232.1 6232.3 0.2

316 08/26/53 20 6232.5

317 09/29/53 30 6232.4 6232.4 0.1

331 08/19/54 40 6232.4

332 09/22/54 40 6232.4 6232.4 0.0

332 09/22/54 40 6232.4

333 10/26/54 0 6232.2 6232.3 0.1

352 08/12/55 40 6232.4

353 09/2/55 40 6232.5 6232.4 0.1

353 09/2/55 40 6232.5

354 09/19/55 0 6232.2 6232.4 0.2

354 09/19/55 0 6232.2

355 10/19/55 20 6232.1 6232.1 0.1

372 08/10/56 0 6232.5

373 09/12/56 0 6232.3 6232.4 0.1

373 09/12/56 0 6232.3

374 10/18/56 0 6232.5 6232.4 0.1

374 10/18/56 0 6232.5

375 10/18/56 0 6232.3 6232.4 0.1

395 08/2/57 0 6231.9

396 08/22/57 0 6232.2 6232.1 0.2

396 08/22/57 0 6232.2

397 09/24/57 0 6232.1 6232.1 0.1

397 09/24/57 0 6232.1

398 10/24/57 40 6232.1 6232.1 0.0

412 08/5/58 75 6232.3

413 09/3/58 0 6232.3 6232.3 0.0

413 09/3/58 0 6232.3

414 10/1/58 0 6232.2 6232.3 0.1

431 09/22/59 50 6232.2

432 10/13/59 0 6232.1 6232.1 0.1

447 08/11/60 0 6232.1

448 09/14/60 0 6232.2 6232.1 0.1

448 09/14/60 0 6232.2

449 10/4/60 10 6232.3 6232.3 0.1

449 10/4/60 10 6232.3

450 10/21/60 10 6232.2 6232.3 0.1

466 8/17/61 0 6232.3

467 9/11/61 0 6232.4 6232.4 0.1

Mean

Measurement Thalweg thalweg Standard

Record location elevation elevation deviation

number Date (ft frm gage) (ft) (ft) (ft)

Table 3. Analysis of variability in consecutive measurements of the Ashley Creek streambed elevation.
16 USDA Forest Service Gen. Tech. Rep. RMRS–GTR–6. 1998

Table 3.(Continued)

Mean

Measurement Thalweg thalweg Standard

Record location elevation elevation deviation

number Date (ft frm gage) (ft) (ft) (ft)

467 09/11/61 0 6232.4

468 10/16/61 0 6232.4 6232.4 0.0

479 08/15/62 0 6232.3

480 09/10/62 0 6232.5 6232.4 0.1

480 09/10/62 0 6232.5

481 10/11/62 10 6232.2 6232.4 0.2

495 09/19/63 50 6232.1

496 10/16/63 100 6232.3 6232.2 0.1

510 08/10/64 50 6231.1

511 09/17/64 75 6231.2 6231.1 0.1

511 09/17/64 5 6231.2

512 10/14/64 100 6231.1 6231.1 0.1

526 08/9/65 50 6231.0

527 09/19/65 50 6231.1 6231.1 0.1

527 09/19/65 50 6231.1

528 10/12/65 50 6231.1 6231.1 0.0

541 08/18/66 -200 6230.4

542 09/8/66 -200 6230.3 6230.4 0.1

554 08/9/67 -150 6229.9

555 09/6/67 -200 6229.8 6229.9 0.1

555 09/6/67 -200 6229.8

556 10/9/67 -200 6230.3 6230.1 0.4

569 09/20/68 0 6229.4

570 10/28/68 -500 6229.7 6229.6 0.2

582 08/12/69 -500 6229.1

583 09/10/69 -20 6229.3 6229.2 0.1

583 09/10/69 -20 6229.3

584 10/13/69 -600 6229.5 6229.4 0.1

595 08/6/70 -300 6228.9

596 09/8/70 -300 6229.5 6229.2 0.4

596 09/8/70 -300 6229.5

597 10/7/70 -500 6229.1 6229.3 0.3

607 08/6/71 10 6229.2

608 09/13/71 0 6229.4 6229.3 0.1

608 09/13/71 0 6229.4

609 10/5/71 -10 6229.4 6229.4 0.0

619 08/15/72 -10 6229.6

620 09/12/72 -10 6229.7 6229.6 0.1

620 09/12/72 -10 6229.7

621 10/10/72 -10 6229.6 6229.6 0.1

632 08/8/73 -10 6229.0

633 09/14/73 0 6229.2 6229.1 0.1

633 09/14/73 0 6229.2

634 10/8/73 0 6229.4 6229.3 0.1

643 08/8/74 0 6229.1

644 09/5/74 0 6228.9 6229.0 0.1

644 09/5/74 0 6228.9

645 10/8/74 10 6229.3 6229.1 0.3

656 08/12/75 0 6228.8

657 09/22/75 0 6228.6 6228.7 0.1

657 09/22/75 0 6228.6

658 10/8/75 0 6228.7 6228.6 0.1

669 08/13/76 -1000 6229.5

670 09/10/76 -1000 6229.2 6229.4 0.2

697 09/22/78 -500 6228.5

698 10/23/78 -500 6228.5 6228.5 0.0

710 09/10/79 0 6229.1

711 10/24/79 0 6229.0 6229.1 0.1

723 08/13/80 0 6228.9

724 09/22/80 10 6229.0 6228.9 0.1

724 09/22/80 10 6229.0

725 10/8/80 10 6229.2 6229.1 0.1

746 08/26/82 5 6229.3

747 09/30/82 0 6229.2 6229.3 0.1

747 09/30/82 0 6229.2

748 10/29/82 -1000 6229.1 6229.1 0.1

759 08/29/83 -325 6228.8

760 10/13/83 -325 6228.7 6228.8 0.1

769 08/23/84 0 6229.0

770 10/12/84 0 6228.9 6228.9 0.1

778 08/6/85 -100 6228.9

779 10/22/85 15 6228.3 6228.6 0.4

779 10/22/85 15 6228.3

780 10/24/85 -750 6228.3 6228.3 0.0

790 08/26/86 10 6228.7

791 10/10/86 10 6228.6 6228.6 0.1

800 08/28/87 -150 6228.7

801 10/9/87 -150 6229.2 6228.9 0.4

809 08/31/88 -150 6228.7

810 10/7/88 -200 6228.7 6228.7 0.0

810 10/7/88 -200 6228.7

811 10/27/88 -10 6228.9 6228.8 0.1

818 08/10/89 -30 6228.9

819 08/31/89 -15 6228.9 6228.9 0.0

819 08/31/89 -15 6228.9

820 10/4/89 -10 6229.0 6228.9 0.1

820 10/4/89 -10 6229.0

821 10/26/89 -20 6228.9 6228.9 0.1

828 08/29/90 5 6228.8

829 09/27/90 5 6228.7 6228.8 0.1

829 09/27/90 5 6228.7

830 10/15/90 0 6228.9 6228.8 0.1

839 09/11/91 5 6229.0

840 10/3/91 -50 6229.0 6229.0 0.0

849 08/3/92 -5 6229.2

850 09/1/92 5 6229.1 6229.1 0.1

850 09/1/92 5 6229.1

851 10/7/92 -80 6229.2 6229.1 0.1

858 08/19/93 0 6228.4

859 09/17/93 -400 6228.7 6228.6 0.2

859 09/17/93 -400 6228.7

860 10/7/93 100 6228.7 6228.7 0.0

Range of standard deviatrions (ft): 0.0 to 0.4

Mean of standard deviations (ft): 0.1

Median of standard deviations (ft): 0.1

Mode of standard deviations (ft): 0.1

Mean

Measurement Thalweg thalweg Standard

Record location elevation elevation deviation

number Date (ft frm gage) (ft) (ft) (ft)
USDA Forest Service Gen. Tech. Rep. RMRS–GTR–6. 1998 17

to examine actual streambed changes at a monthly scale,

it is necessary to generate a time series of the thalweg or

minimum streambed elevation. Plots of the minimum

streambed elevation are developed in the same way that

MSBE plots are generated.

Figure 13 is a comparison of MINSBE and MSBE data

between 1962 to 1973. Both plots show net degradation

over multiple decades and annual scour and fill of the

streambed. However, the fills (bed elevation increases) of

the MSBE plot are not real and actually reflect large

changes in channel top width (figure 12). In contrast, the

MINSBE plot is based on actual measurements to the

streambed. Therefore, the bed elevation increases exhibited in the MINSBE plots represent true channel filling.

Because MSBE and MINSBE analyses provide strong

evidence of channel adjustability and are dependent upon

a common gage datum, it is imperative to have accounted

for all datum changes throughout the period of record.

Fortunately, failure to account for a datum change in the

analysis is rather obvious. Figure 14 is an MSBE analysis

of the Ashley Creek data without correcting for datum

changes. In this plot, unrecognized datum changes occur

as large, abrupt jumps in the data distribution. Consequently, if the plots show smooth trends and no abrupt

changes, it is likely that all datum changes have been

recognized. Close inspection of figure 10 reveals an abrupt

jump in 1957 that suggests a datum change. In this case, a

6228

6229

6230

6231

6232

6233

6234

TIME, IN WATER YEARS

1900 1950 2000

Figure 11. Plot of the mean streambed elevation (MSBE)

using only measurements made within 50 ft of the gage.

Since the plot shows the same trends as figure 12, the

analytical assumption that streambed adjustability is similar

above and below the gage is justified.

Figure 10. Plot of the mean streambed elevation (MSBE)

using all data. This plot depicts a streambed at a station

through time and shows that the streambed aggraded during

the early 1920s, was stable for approximately 38 years, and

then degraded rapidly during the early 1960s. The smooth

curve through the data delineates the temporal trend and

represents the application of a Stineman Function to the data.

The output of this function has geometric weight applied to the

current point and ±10% of the data range to arrive at the

smoothed curve.

6228

6229

6230

6231

6232

6233

6234

TIME, IN WATER YEARS

1900 1950 2000

Figure 12. The relationship

between mean streambed

elevations (MSBE) for high

and low flows along with the

minimum streambed elevation (MINSBE). This plot

shows how fluctuations in the

water level alone can result

in MSBE values that indicate

scour and fill. In contrast,

because MINSBE values are

always calculated using

measured depths to the

streambed, they reflect true

changes in the streambed.

HW=high water, LW=low

water, WSE=water surface.

ELEVATION IN FEET ABOVE SEA LEVELELEVATION IN FEET ABOVE SEA LEVEL

TIME IN WATER YEARS TIME IN WATER YEARS

LW Mean

Depth
18 USDA Forest Service Gen. Tech. Rep. RMRS–GTR–6. 1998

flood occurred, and the hydrographer noted that the channel had scoured; a scour event in 1957 is precisely what the

MSBE plot indicates. MSBE and MINSBE analyses quantify the magnitude of streambed adjustability, are sensitive enough to distinguish the effect of individual flood

events, and delineate discrete time periods of channel

change. In the Ashley Creek example, these time periods

are: 1917 to 1924, 1925 to 1961, 1962 to 1967, and 1976 to

1994. Similarly, the MINSBE plots show streambed adjustments on a month-to-month scale.

Hydraulic Geometry

The hydraulic geometry of a stream is a statistical

characterization that quantifies the channel dimensions

(Leopold and Maddock 1953). Hydraulic geometry analyses define the guiding relations of channel dimensions to

discharge, reveals which variables are most adjustable,

and further quantifies channel response to aggradation,

degradation, and stability. If the formative discharges of

the channel are altered, theory predicts a change in the

hydraulic geometry (Singh 1992). Standard hydraulic geometry relations include regression analyses of velocity,

width, and depth as a function of discharge. By comparing

the hydraulic geometry relations for the discrete intervals

of time as delineated by the MSBE analysis, it is possible

to quantify specific rates of adjustability that coincide

with periods of aggradation, degradation, and stability.

Such relations may be used as templates to assess whether

or not other reaches of the same stream are undergoing

aggradation, degradation, or relative stability.

Figure 15 shows hydraulic geometry plots for Ashley

Creek created from all data for the period of record. If the

data are sorted according to the time periods delineated

by the MSBE plots, the resultant hydrogeometric relations

can be compared and contrasted to quantify channel

response during the periods of aggradation, degradation,

and stability. Table 4 shows time-specific regression relations, and figure 16 shows the plots of these relations. In

general, these plots show that the hydraulic geometry has

changed only slightly since 1924 and that width and depth

exhibit the most variability. The plots also indicate that

periods of:

• rapid degradation (1962-1967) are characterized

by increases in the rate at which depth changes

with discharge;

• rapid aggradation are characterized by increases

in the rate at which width changes with discharge;

and

• stability are characterized by increases in the rate

at which velocity changes with discharge.

These regression comparisons are based on a visual

analysis and are therefore informal. More formal comparisons can be made by examining the regressions within

a rigorous statistical context as described by Neter et al.

(1989).

In addition to hydraulic geometry analyses, changes in

channel width and depth can be further examined through

time series analyses. Time series of depth (streambed

6228

6229

6230

6231

6232

6233

6234

TIME, IN WATER YEARS

1962 1965 1970 1973

Mean Streambed

Elevation (MSBE)

Minimum Streambed

Elevation (MINSBE)

Spikes are not Representative

of Channel Fill; They are Artifacts

from the Calculations

Figure 13. Comparison of mean streambed elevation (MSBE)

and minimum streambed elevation (MINSBE) plots for Ashley

Creek between 1962 and 1973, which was the most dramatic

period of streambed degradation. The MSBE plot shows

annual spikes that suggest channel filling. These spikes do

not represent real channel filling because the MSBE data is

based on calculations using channel top width. The MINSBE

plot is based on actual measurements to the streambed and,

therefore, the spikes exhibited in the MINSBE plot represent

true episodes of scour or fill.

Figure 14. Plot of the mean streambed elevation without

rectifying the gage heights. This plot contains 5 jumps

(arrows) in the data distribution that are indicative of the

datum changes (see figure 7).

6228

6230

6232

6234

6236

6238

6240

TIME, IN WATER YEARS

1900 1950 2000

ELEVATION ABOVE SEA LEVEL, IN FEET

TIME, IN WATER YEARS

ELEVATION ABOVE SEA LEVEL, IN FEET
USDA Forest Service Gen. Tech. Rep. RMRS–GTR–6. 1998 19

from up and downstream, is unjustified because the variability of stream width, up and downstream, for a specific

discharge can be significant. For example, stream widths

for a specific discharge along Ashley Creek can vary as

much as 30%. This variability is a reflection of the channel

complexity that is accentuated during low discharges and

1

10

100

1 10 100 1000 10000

DISCHARGE, IN CUBIC FEET PER SECOND

(c)

0.1

1

10

(a)

0.1

1

10

(b)

Figure 15. Hydraulic geometry plots of Ashley Creek. These

plots use all data for the entire period of record: (a) velocity

vs. discharge, (b) mean depth vs. discharge, and (c) width vs.

discharge.

elevation) were discussed in the MSBE and MINSBE analyses; temporal changes in width are discussed below.

Change in Width

The purpose of width analysis is to assess changes in

the bank-to-bank channel morphology. A straightforward

change-in-width-through-time analysis, using all DMs

1

10

100

1 10 100 1000 10000

1917-1924

1925-1961

1962-1967

1968-1972

1973-1976

1977-1994

(c)

DISCHARGE, IN CUBIC FEET PER SECOND

0.1

1

10

1917-1924

1925-1961

1962-1967

1968-1972

1973-1976

1977-1994

(a)

0.1

1

10

1917-1924

1925-1961

1962-1967

1968-1972

1973-1976

1977-1994

(b)

Figure 16. Temporal trends of the hydraulic geometry. These

plots are comparisons of the hydraulic geometry regression

relations for unique time periods of aggradation, stability, and

degradation: (a) velocity vs. discharge, (b) mean depth vs.

discharge, and (c) width vs. discharge. The points shown are

calculated values; their only purpose is to help distinguish the

trends of particular time periods.

VELOCITY, IN FEET PER SECOND MEAN DEPTH, IN FEET WIDTH, IN FEET

DISCHARGE IN CUBIC FEET PER SECOND

DISCHARGE IN CUBIC FEET PER SECOND

VELOCITY, IN FEET PER SECOND MEAN DEPTH, IN FEET WIDTH, IN FEET
20 USDA Forest Service Gen. Tech. Rep. RMRS–GTR–6. 1998

Table 4. Hydraulic geometry regression relations for specific time periods.

Time Periods Velocity Mean Depth Width

1917-1924 v = 0.33763*Q0.41938 d = 0.34764*Q0.24578 w = 8.5388*Q0.33311

1925-1961 v = 0.19547*Q0.52241 d = 0.35434*Q0. 25115 w = 14.916*Q0.21922

1962-1967 v = 0.18656*Q0.541 d = 0.16926*Q0. 38694 w = 31.608*Q0.073119

1968-1972 v = 0.254*Q0.49929 d = 0.42655*Q0.21701 w = 9.2339*Q0.28355

1973-1976 v = 0.18691*Q0.55255 d = 0.36968*Q0.23762 w = 14.878*Q0.20575

1977-1994 v = 0.2288*Q0.50287 d = 0.34115*Q0.25729 w = 13.359*Q0.23101

v = velocity, d = mean depth, w = width, Q = discharge

overbank flood flows. Therefore, changes in

width-through-time (WTT) analyses must exclude both

low-flow and overbank discharges.

The exclusion of low discharges is necessary because at

such flow, water edges are affected by the distribution of

instream features (such as channel bars), rather than the

channel banks. Similarly, the exclusion of flood-stage

discharges is necessary because overbank flow widths can

be highly variable. In both cases, the width measurements

are not the bankfull dimensions. Consequently, changes

in channel width are best demonstrated by DMs for a

range of medium to high discharges that nearly fill the

bankfull channel. In Ashley Creek, a range of discharges

between 40 and 85% of the mean annual flood were

suitable for width analysis. The need to restrict width

analysis to a range of discharges is shown in figure 17,

which indicates almost 20 ft of channel narrowing through

time. Channel narrowing is consistent with the MSBE,

MINSBE, and hydraulic geometry analyses, which show

that the channel has incised.

Cross Sections

As discussed, each DM includes a measured

cross-section. One of the more illustrative quantifications

of geomorphic change is to overlay cross-sections measured at the same location but at different times. Similarly,

contemporary surveys of historic cross-sections can also

be performed (figure 18). To perform these overlays, it is

necessary to know where the sections were measured. For

measurements made between permanent benchmarks that

can be relocated, such as a cableway, the overlays and

surveys are straightforward. More typically, DMs are

performed wherever the most accurate measurement can

be made, and precise locations are not recorded on the

DM. Instead, the distance from the gage is usually estimated, and notes such as “1/4 mile above,” “50 ft below

0

20

40

60

80

100

1900 1950 2000

(a)

0

20

40

60

80

100

TIME, IN WATER YEARS

1900 1950 2000

(b)

Figure 17. Stream width changes through time. The top plot

incorporates all width measurements for the period of record;

it shows slight narrowing and substantial scatter. The bottom

plot only uses width measurements associated with a range of

discharges between 500 and 1000 ft3

/sec and shows 15 to 20

ft of channel narrowing. WIDTH, IN FEET WIDTH, IN FEET

TIME, IN WATER YEARS

TIME, IN WATER YEARS
USDA Forest Service Gen. Tech. Rep. RMRS–GTR–6. 1998 21

gage,” and “at gage” are recorded. These cross-sections

are measured from one water edge to the other and are not

typically measured in relation to permanent benchmarks;

therefore, overlays and surveys of historic cross-sections

include elements of error with regard to location. The

error associated with estimating the distance from the

gage is assumed to increase the farther the hydrographer

was from the gage. Consequently, only historic sections

that were described as being within 20 ft of the gage or

cableway were compared. Typically, only cross sections

measured at the cableway were resurveyed. The error

associated with the laterally unconstrained aspect of the

historic sections appears to be uncorrectable.

Once a historic location has been selected for survey,

the distances from initial point and depth measurements

recorded on the particular DM are entered into the computer. This information is on the back pages of the DM

(figure 3). These depth measurements are relative to a

water-surface elevation that is defined by the gage-height

recorded on the DM. Thus, no matter where the section

was measured the only elevation reference is that of the

gage height recorded during the measurement. For purposes of cross-section overlays, the water surface elevation of the resurveyed section must be that of the gage

height at the time of resurvey. Once the original and resurveyed sections are entered in the computer spreadsheets,

they are plotted together. As indicated, the original section may be laterally unconstrained and a suitable horizontal depiction must be visually determined (figure 18).

In general, the replicated cross-sections should mimic

the changes determined in the MINSBE and WTT analyses. Moreover, the replications can provide insights into

the historic relation between the channel and discharge.

For example, a 1926 cross section measured at the cableway on Ashley Creek is compared with a 1995 resurvey

(figure 18). Both sections are plotted with lines indicating

discharges of 228 ft3

/sec and the mean annual flood. This

figure shows that before incision, the mean annual flood

(~bankfull) inundated the upper surface. Since the upper

surface is no longer inundated, it is now an abandoned

floodplain or terrace. Critical to this interpretation is that

flow velocity of these discharges during the different time

periods be essentially the same. Using the hydraulic geometry relations in table 4, the difference in flow velocity

at bankfull for both time periods is less than 2%. Thus, the

interpretation is supported and, like the other analyses,

this replication of cross-section data indicates channel

incision and narrowing.

Figure 18. Comparison of cross-sections measured in 1926 and 1995 at the Ashley Creek cableway. Although elevation control is

provided by the gage and reference marks, there are no lateral controls with which to fix the ends of the 1926 cross section.

Consequently, the overlay is fitted by eye. This figure shows both sections at a discharge of 288 ft3/sec, the 1926 level of the

mean annual flood, and the contemporary level of the mean annual flood. This figure indicates that before the channel degradation

of the early 1960s, mean annual flood flows represented incipient flooding of the valley flat.

6220

6225

6230

6235

6240

6245

6250

6255

6260

0 20 40 60 80 100 120 140 160

DISTANCE, IN FEET

1995

1926

288 ft 3/s

Contemporary Level

of the Mean Annual Flood

Terrace

1926 Level of the

Mean Annual Flood

ELEVATION ABOVE SEA LEVEL, IN FEET

DISTANCE, IN FEET
22 USDA Forest Service Gen. Tech. Rep. RMRS–GTR–6. 1998

Determination of Discharges

Once geomorphic change has been documented and

the timing of adjustment established, the geomorphic and

hydrologic histories can be compared and contrasted.

This is accomplished by comparing the MSBE, MINSBE,

or WTT plots with different hydrographs for the period of

record. Three of the more informative hydrographs to

develop are the: 1) annual total runoff volumes, 2) annual

instantaneous peak floods, and 3) daily mean discharges.

These hydrologic data sets are in the USGS Water Supply

Papers, CD-ROMs, and on the Internet. For example, the

MINSBE plot of Ashley Creek is combined with the annual

runoff volumes (figure 19) and peak flood data (figure 20).

Similarly, the MINSBE plot is compared with both daily

mean discharge data and peak flood data in figure 21.

Figure 19 shows that no anomalous increases or decreases

in the overall volume of water flowing through the channel have occurred over the period of record. Consequently,

the geomorphic changes recorded in the MiNSBE plot are

probably not the result of changes (i.e., regulation) in the

annual volume of water flowing through the channel.

0

50000

100000

150000

-3

0

3

TIME, IN WATER YEARS

1900 1950 2000

Figure 19. Comparison of minimum

streambed elevations to annual

runoff volumes. This plot shows no

dramatic increases or decreases in

volume of runoff and there is no

correlation between bed elevation

changes and years of high runoff.

0

1000

2000

3000

-3

0

3

TIME, IN WATER YEARS

1900 1950 2000

Figure 20. Comparison of minimum

streambed elevations to annual peak

discharges. This plot indicates that

changes in the streambed may be

related to changes in the hydrologic

regime, but peak flood events are

not directly responsible for streambed elevation changes. The

dashed horizontal line delineates the

mean annual flood of 1200 ft3

/sec.

ANNUAL VOLUME IN ACRE–FEET YEARLY PEAK DISCHARGE IN CUBIC FEET PER SECOND

BED ELEVATION CHANGE IN FEET BED ELEVATION CHANGE IN FEET

TIME, IN WATER YEARS

TIME, IN WATER YEARS
USDA Forest Service Gen. Tech. Rep. RMRS–GTR–6. 1998 23

 Figure 20 is the comparison of the MINSBE plot to the

annual instantaneous discharge peaks and some correlations are visible. Specifically, water years 1920 through

1923 were consecutive years of large peak flows that

corresponded with streambed aggradation. Between 1925

and 1963, peak discharges were relatively low and uniform. Coincidentally, no dramatic changes occurred in the

streambed. Between 1964 and 1968, the streambed degraded substantially, which is correlated with an abrupt

increase in the magnitude of peak floods. High peak

discharges occurred throughout the 1970s, 1980s, and

1990s, but large magnitudes of streambed change did not

occur. Thus, the same hydrologic conditions do not necessarily generate the same channel response in Ashley Creek,

and the role of large floods in affecting channel change is

variable.

A closer look at the data reveals that the substantial

channel degradation occurring in the mid 1960s was not

directly related to high discharges. Figure 21 shows the

changes in the Ashley Creek streambed between 1962 and

1973. As shown, the bed adjusts (fills and/or scours) as a

function of the rise and fall of the annual hydrograph. In

0

1000

2000

3000

-3

0

3

TIME, IN WATER YEARS

Mean Annual Flood

1962 1965 1970 1973

Figure 22. Comparison of minimum

streambed elevations to bankfull flow

days. This plot shows the MINSBE

data along with years that had

multiple days in which the daily mean

discharge equaled or exceeded the

mean annual flood of 1200 ft3

/sec.

Figure 21. Comparison of minimum

streambed elevations to annual

hydrographs from 1962 to 1973. The

hydrographs are generated using

daily mean discharge values. The

open circles are the instantaneous

peak floods for each year. Annual fill

and scour is indicated and a net

degradation of approximately 3 ft is

shown. Note that the degradation was

accomplished progressively by

frequently occurring flows and that

large-magnitude floods do not cause

large bed adjustments.

BED ELEVATION CHANGE IN FEET

DISCHARGE, IN CUBIC FEET PER SECOND

TIME, IN WATER YEARS

DAYS

TIME, IN WATER YEARS

BED ELEVATION CHANGE IN FEET

0

5

10

15

-3

0

3

1900 1950 2000
24 USDA Forest Service Gen. Tech. Rep. RMRS–GTR–6. 1998

particular, substantial degradation occurred incrementally over a number of years in response to a range of

frequently occurring flows. The degradation did not occur all at once in response to an infrequent large-magnitude flood.

The preceding paragraphs describe relatively simple

ways of estimating the discharges responsible for geomorphic adjustability. Greater precision, possible with

this data set, involves statistical time series analyses that

are beyond the scope of this report. However, one promising avenue of further analysis uses flow duration data.

For example, MINSBE plots can be compared with the

number of days per year that daily mean flows equaled or

exceeded the mean annual flood (figure 22). Figure 22 is a

plot of the Ashley Creek data that shows some visual

correlations between years of sustained high flows and

streambed response; however, a clear pattern is not indicated.

Detailed Site Characterizations

Detailed site characterizations of the contemporary

stream morphology link the historic record to the

present-day, serve as additional data points that extend

the historic record, and are tools that help extrapolate

findings to other stream reaches. More specifically, site

characterizations:

• accurately depict the spatial organization of the

geomorphic elements;

• can be used to assess the differences between DM

locations;

• are valuable in determining which cross-sections

to replicate;

• justify assumptions made during the historic

record analysis;

• quantify the relative errors associated with the

historic record analysis;

• examine the reasonableness of the conclusions

drawn from the historic record analysis; and

• provide a familiarity with the site that helps prevent interpretations of the historic record analyses from becoming too abstract.

The central element of a detailed site characterization is a geomorphic map. Other components include

cross-sections, longitudinal profiles, and sediment transport studies. Mapping the earth’s surface is “essential for

an understanding of spatial distributions and relationships” (McKnight 1990), and maps are the primary tool

used by geomorphologists. Leopold and Wolman (1957)

used detailed maps to quantify stream channel patterns,

and Lisle (1986) incorporated detailed channel morphology maps in his assessment of gravel bars in steep,

coarse-bedded mountain streams. Detailed channel morphology maps were developed by Keller and Tally (1979)

to quantify the impacts of large organic debris on channel

geometry, fish habitat, and patterns of erosion and deposition in mountain streams of northern California. In

addition, Madej (1984, 1995) mapped the channel in detail

to quantify sediment storage and channel stability in a

mountain watershed.

Detailed channel morphology maps facilitate contemporary decision-making and with time, become valuable

sources of historic data. Most importantly, detailed maps

of reference sites provide a means for extrapolating the

findings at those sites to other stream reaches. If the

geomorphic history and spatial organization of geomorphic elements (as depicted on maps) are understood at a

reference site, then these histories can be extrapolated to

other reaches that exhibit the same geomorphic organization. While the basic techniques of surveying and other

methods of stream channel characterization are well described in Harrelson et al. (1994), techniques of detailed

geomorphic mapping are not discussed.

Basic survey techniques using a surveyor’s level rely on

pace, tape, or indirect measurements of a stadia-rod for

horizontal distances, and horizontal angles are plotted by

hand. For third- and fourth-order streams, where typical

study reaches exceed 1,000 ft, surveying with a theodolite

is more efficient. For purposes of detailed mapping, it is

necessary to accurately survey a network of permanent

and temporary benchmarks that are within 100 ft of each

other. The permanent benchmarks are typically the ends

of cross-sections, cultural features, and definitive pieces

of the gage station. The temporary benchmarks include

knick points along the water’s edge marked with pin flags

or removable rebar, trees, and individual boulders. The

distance limitation is necessary because the mapping technique requires that a tape measure be stretched between

benchmarks. With an accurately surveyed base map of

permanent and temporary benchmarks, detailed geomorphic mapping is conducted in 2 phases. The first phase

characterizes the large-scale aspects of the fluvial landscape and the second phase characterizes the finer details.

Detailed Geomorphic Mapping - Phase I

Phase I mapping delineates the water edges, bars,

banks, and associated geomorphic features greater than

15 ft2. In addition, fences, structures, trees, and prominent

boulders are mapped for use as benchmarks during phase

II mapping. Phase I mapping is best accomplished by a
USDA Forest Service Gen. Tech. Rep. RMRS–GTR–6. 1998 25

mapper and an assistant. The assistant performs the measurements and the mapper draws the map. First, a 100 ft

fiberglass tape measure is stretched tight and fairly level

between 2 of the surveyed benchmarks in the field. This is

the baseline from which individual points will be measured. A line, representing the stretched tape, is drawn on

the map between the points that symbolize the surveyed

benchmarks. The mapping begins at one of the benchmarks and continues along the length of the tape to the

other benchmark. Thereupon, the fiberglass tape is

“leap-frogged” to the next benchmark, and the mapping

process continues in this manner all along the reach.

The particular points plotted to draw the map are

measured from the stretched tape with a retractable metal

tape (1-inch wide for rigidity) extended perpendicular to

the fiberglass tape. The mapper takes the free-end of a

metal tape and holds it to the point or feature to be

measured, taking care to maintain the metal tape fairly

level. The assistant slides the other end of the metal tape

along the stretched fiberglass until the metal tape is perpendicular to the stretched tape. The assistant first reports

the location of the metal tape along the stretched fiberglass tape, and then reports the distance recorded by the

metal tape. The mapper similarly scales these distances on

the map and plots the point. The mapper is responsible for

connecting the dots and drawing the map as each point is

measured. Phase I mapping can proceed in a timely fashion along the reach, and the assistant should never be idle

for more than one minute while the mapper draws.

Detailed Geomorphic Mapping - Phase II

Phase II mapping characterizes the geomorphic details

of the reach. During this phase, the bars, pools, riffles,

prominent boulders, eddies, and the flow pattern of the

active channel are mapped. In addition, meso- and

microscale topography, vegetation patterns, surficial geology, and high watermarks all along the riparian corridor are drawn on the map. As mapping proceeds, the map

is annotated in detail, bank materials are described, and

photograph stations are established. The measurement of

points for this phase of mapping is typically a combination of pace and compass and solo execution of the 2-person technique described above. Mapping at this detail

requires the use of simple symbols and colored pencils to

maintain map readability. Figure 23 is an explanation of

useful map symbols. Figure 24 is a detailed geomorphic

map of Ashley Creek. Phase II mapping requires concentration and objectivity. A goal of this mapping is to define

the active floodplain, but all geomorphic surfaces composed of alluvium are mapped. Subsequent analysis of the

map, cross-sections, and longitudinal profile projected

through the gage, are then used to define the active

floodplain and bankfull discharge.

Channel Morphology and

Bankfull Discharge

The elevation, stratigraphy, and vegetation characteristics of the geomorphic surfaces are analyzed using the

detailed geomorphic map and channel cross-sections (figure 25). The elevations of these surfaces are plotted on the

longitudinal profile (figure 26) so that the surfaces can be

correlated longitudinally. Theoretically, each geomorphic

surface is created by a specific discharge that is part of a

particular hydrologic regime (Leopold et. al 1964). By

drawing lines on the longitudinal profile that parallel the

bankfull water level and intersect the elevations of the

different geomorphic surfaces, it is possible to longitudinally correlate these surfaces and realize the average

water surface elevations necessary to inundate each surface. When these lines are drawn through a gaging station,

their intersection with the staff plate and an examination

of the rating relation allow for determination of discharges necessary to inundate, and likely form, the geomorphic surfaces. Once the discharges are known, the

recurrence interval curve (figure 5) is used to determine

how often the surfaces are inundated. This procedure is

Figure 23. Explanation of map symbols.
26 USDA Forest Service Gen. Tech. Rep. RMRS–GTR–6. 1998 Figure 24. Geomorphic map of Ashley Creek. The active floodplain is inset within the incised channel and is discontinuous.
USDA Forest Service Gen. Tech. Rep. RMRS–GTR–6. 1998 27

6240

6250

6260

6270

6280

Terrace

Mean Annual

Flood

Floodplain

Ashley Creek

Cross-Section AC-2

(a)

6230

6240

6250

6260

6270

Mean Annual

Flood

Floodplain

Terrace

Ashley Creek

Cross-Section AC-3

(b)

Figure 25. Representative cross-sections of Ashley Creek.

Plots (a), (b), and (c) are representative cross sections that

show similar alluvial surfaces (active floodplain and terrace),

which are longitudinally correlative.

6220

6230

6240

6250

6260

0 20 40 60 80 100 120 140 160

Mean Annual

Flood

Floodplain

Terrace

Road Fill

Ashley Creek

Cross-Section AC-7

(c)

6220

6230

6240

6250

6260

6270

0 200 400 600 800 1000 1200 1400

DISTANCE, IN FEET

Gage Height = 3.95 feet = 1200 ft 3 /s

USGS

Stream Gage

Water Surface

Floodplain

Terrace

Thalweg

Figure 26. Longitudinal

profile of Ashley Creek.

This profile shows a

longitudinally correlative

surface that intersects

the gage at 3.95 ft. A

gage height of 3.95 ft

corresponds to a

discharge of ~1200 ft3/

sec, which is the mean

annual flood with a

recurrence interval of

2.3 years. Because the

surface is relatively flat,

located adjacent to the

active channel, and

inundated by frequently

occurring flows, it is

considered to be the

active floodplain.

DISTANCE, IN FEET

ELEVATION ABOVE SEA LEVEL ELEVATION ABOVE SEA LEVEL

DISTANCE, IN FEET

DISTANCE, IN FEET

ELEVATION ABOVE SEA LEVEL

DISTANCE, IN FEET ELEVATION ABOVE SEA LEVEL

Gage Height = 3.95 feet = 1200 ft3/s
28 USDA Forest Service Gen. Tech. Rep. RMRS–GTR–6. 1998

further discussed by Leopold (1994) and Harrelson et al.

(1994).

At the Ashley Creek study site, 2 different surfaces

were longitudinally correlative (figures 24 and 25). Of

particular interest is a prominent surface adjacent to the

active channel that is inundated by the mean annual flood.

Field observations of newly deposited sand on these surfaces indicate that these surfaces are being constructed by

the current hydrologic regime. Therefore, this surface is

considered an active floodplain, and its elevation is correlative with the water level coincident with a discharge of

1200 ft3

/sec. Consequently, the mean annual flood is

representative of bankfull conditions. At the Ashley Creek

study site, the active floodplain is small, discontinuous,

and comprises less than 4% of the valley floor (figure 24).

These findings illuminate the inherent difficulty in identifying the active floodplain of mountain streams, and

thus, reinforce the importance of performing detailed site

characterizations.

Management Implications

The methods described in this report were developed

to measure historic stream channel changes and better

understand fluvial processes in mountainous regions.

This report explains how to analyze USGS gaging station

records and complete detailed site characterizations. The

methods are designed to reconstruct stream channel histories that can then be compared to histories of climate

change, stream regulation, and land-use. In turn, these

comparisons can be used to link geomorphic adjustments

to natural cycles, rare events, and land-use activities. With

such linkages, models of channel change can be developed to

assist resource managers in understanding the susceptibility of mountain streams to regulation and land use.

Literature Cited

Abrahams, A.D., G. Li, and J.F. Atkinson. 1995. Step-pool streams:

adjustment to maximum flow resistance, Water Resour. Res., 31, 2593-

2602.

Andrews, E.D. 1983. Entrainment of gravel from naturally sorted riverbed material, Geol. Soc. Am. Bull., 94, 1225-1231.

Andrews, E.D. 1984. Bed-material entrainment and hydraulic geometry

of gravel-bed rivers in Colorado, Geol. Soc. Am. Bull., 95, 371-378.

Andrews, E.D. 1994. Marginal bed load transport in a gravel bed stream.

Sagehen Creek, California, Water Resour. Res., 30, 2241-2250.

Andrews, E.D. and J.N. Nankervis. 1995. Effective discharge and the

design of channel maintenance flows for gravel-bed rivers, in Natural and Anthropogenic Influences in Fluvial Geomorphology, Geophy.

Monogr. Ser., vol. 89, edited by J.E. Costa, A.J. Miller, K.W. Potter, and

P.R. Wilcock, pp. 151-164, AGU, Washington, D.C.

Best, D.W. 1995. History of timber harvest in the Redwood Creek basin,

northwestern California. In: K.M. Nolan, H.M. Kelsey, and D.C.

Marron, eds. Geomorphic Processes and Aquatic Habitat in the

Redwood Creek Basin, Northwestern California. U.S. Geological

Survey Professional Paper 1454, U.S. Govt. Printing Office, Washington, D.C.: pp. C1-C7.

Bryan, K. 1928. Historic evidence of changes in the channel of Rio

Puerco, a tributary of the Rio Grande in New Mexico. Journal of

Geology, 36 (3): pp. 265-282.

Bunte, K. 1996. Analyses of the temporal variation of coarse bedload

transport and its grain size distribution, Squaw Creek, Montana,

USA, U.S. Dep. Agric. For. Serv. Gen. Tech. Rep. RM-GTR-288, 124 pp.

Burkham, D.E. 1972. Channel changes of the Gila River in Safford Valley,

Arizona. U.S. Geological Survey Professional Paper 655-G, U.S.

Govt. Printing Office, Washington, D.C:24 p.

Dominick, D.S. 1997. Effects of flow augmentation on channel morphology and riparian vegetation in the upper Arkansas River basin,

Colorado, M.S. thesis, Utah State Univ., Logan, 99 pp.

Erman, D.C. 1992. Historical background of long-term diversion of the

Little Truckee River. In: Hall, C.A., V. Doyle-Jones, and B. Widowski,

eds. The history of water: Eastern Sierra, Owens Valley, White-Inyo

Mountains. University of California Press, Berkeley, CA: pp. 415-427.

Germanoski, D. and S.A. Schumm. 1995. Changes in braided river

morphology resulting from aggradation and degradation. Journal of

Geology, 101: pp. 451- 466.

Gordon, N. 1995. Summary of technical testimony in the Colorado

Water Division 1 trial. Gen. Tech. Rept. RM-GTR-270. U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and

Range Experiment Station. 140 p.

Grant, G.E. and F.J. Swanson. 1995. Morphology and processes of valley

floors in mountain streams, Western Cascades, Oregon, in Natural

and Anthropogenic Influences in Fluvial Geomorphology, Geophy. Monogr.

Ser., vol. 89, edited by J.E. Costa, A.J. Miller, K.W. Potter, and P.R.

Wilcock, AGU, Washington, D.C. pp. 83-101.

Grant, G.E., F.J. Swanson, and M.G. Wolman. 1990. Pattern and origin of

stepped-bed morphology in high-gradient streams, Western Cascades, Oregon, Geol. Soc. Am. Bull., 102, 340-352.

Harden, D.R. 1995. A comparison of flood-producing storms and their

impacts in northwestern California. In: K.M. Nolan, H.M. Kelsey,

and D.C. Marron, eds. Geomorphic Processes and Aquatic Habitat in

the Redwood Creek Basin, Northwestern California. U.S. Geological

Survey Professional Paper 1454, U.S. Govt. Printing Office, Washington, D.C.: D1-D7.

Harrelson, C.C., C.L. Rawlins, and J.P. Potyondy. 1994. Stream channel

reference sites: an illustrated guide to field technique, Gen. Tech.

Rept. RM-245, U.S. Department of Agriculture, Forest Service. 61 p.

Jacobson, R.B. 1995. Spatial controls on patterns of land-use induced

stream disturbance at the drainage-basin scale--an example for

gravel-bed streams of the Ozark Plateaus, Missouri. In: J.E. Costa,

A.J. Miller, K.W. Potter, and P.R. Wilcock, eds. Natural and Anthropogenic Influences in Fluvial Geomorphology. American Geophysical Union Monograph 89: pp. 219-239.

James, L.A. 1991. Incision and morphologic evolution of an alluvial

channel recovering from hydraulic mining sediment. Geological

Society of America Bulletin, 103: pp. 723-736.

James, L.A. 1997. Channel incision on lower American River, California,

from streamflow gage records. Water Resources Research, 33(3): pp.

485-490.

Janda, R.J., K.M. Nolan, D.R. Harden, and S.M. Coleman. 1975. Watershed Conditions in the drainage basin of Redwood Creek, Humbolt,

County, California, as of 1973. U.S. Geol. Surv., Open-File Rept. 75-

568, 268 pp.

Janda, R.J. and K.M., Nolan. 1979. Stream sediment discharge in northwestern California. In: A Guidebook for a Field Trip to Observe

Natural and Management-Related Erosion in Franciscan Terrane of

Northern California, Cordilleran Section Meeting of the Geological
USDA Forest Service Gen. Tech. Rep. RMRS–GTR–6. 1998 29

Society of America, San Jose State University, San Jose, CA: pp. IV-1

to IV-27.

Keller, E.A. and T. Tally. 1979. Effects of large organic debris on channel

form and fluvial processes in the coastal redwood environment. In:

Rhodes, D.D., and G.P. Williams eds. Adjustments of the Fluvial

System. 10th Annual Geomorphology Symposium Proceedings,

Binghamton, New York: pp. 169-197.

Krug, W.R. and G.L., Goddard. 1986. Effects of urbanization on

streamflow, sediment loads, and channel morphology in Pheasant

Branch basin near Middleton, Wisconsin. Water Resources Investigations Rept. 85-4068. Madison, Wisconsin, U.S. Geological Survey,

U.S. Govt. Printing Office, Washington, D.C.: 82 p.

Leopold, L.B. 1994. A View of the River. Harvard University Press,

Cambridge, MA: 298 p.

Leopold, L.B. and T. Maddock. 1953. The hydraulic geometry of stream

channels and some physiographic implications. U.S. Geological

Survey Professional Paper 252, U.S. Govt. Printing Office, Washington, D.C.: 57 p.

Leopold, L.B. and M.G. Wolman. 1957. River channel patterns: braided,

meandering, and straight. U.S. Geological Survey Professional Paper

282-B, U.S. Govt. Printing Office, Washington, D.C.: 85 p.

Leopold, L.B., M.G. Wolman, and J.P. Miller. 1964. Fluvial Processes in

Geomorphology. Freeman, San Francisco, CA: 522 p.

Lisle, T.E. 1986. Stabilization of a gravel channel by large streamside

obstructions and bedrock bends, Jacoby Creek, northwestern California. Geological Society of America Bulletin, 97: pp. 999-1011.

Lisle, T.E. 1995. Particle size variations between bed load and bed

material in natural gravel bed channels, Water Resour. Res., 31, 1107-

1118.

Madej, M.A. 1984. Recent changes in channel-stored sediment, Redwood Creek, California. Redwood National Park Tech. Rept., 11,

U.S. National Park Service.: 54 p.

Madej, M.A. 1995. Changes in channel-stored sediment, Redwood Creek,

northwestern California. In: K.M. Nolan, H.M. Kelsey, and D.C.

Marron, eds. Geomorphic Processes and Aquatic Habitat in the

Redwood Creek Basin, Northwestern California. U.S. Geological

Survey Professional Paper 1454, U.S. Govt. Printing Office, Washington, D.C.: pp. O1-O27.

McCaffery, W.F., J.C. Blodgett, and J.L. Thornton, 1988. Channel morphology of Cottonwood Creek, near Cottonwood, CA, from 1940 to

1985. Water Resources Investigations Rept. 87-4251. U.S. Geological

Survey, U.S. Govt. Printing Office, Washington, D.C: 33 p.

McKnight, T.L. 1990. Physical geography: a landscape appreciation, 3rd

ed. Prentice Hall, Englewood Cliffs, NJ.: 610 p.

Montgomery, D.R. and J.M. Buffington. 1993. Channel classification,

prediction of channel response, and assessment of channel condition. Report TFW-SH10-93-002, Washington State Department of

Natural Resources, Olympia WA: 84 p.

Nakamura, F., and F.J. Swanson, 1993. Effects of coarse woody debris on

morphology and sediment storage of a mountain stream system in

western Oregon, Earth Surface Processes Landforms, 18, 42-61.

National Park Service, 1985. Water resources management plan, Redwood National Park. National Park Service: 103 p.

Neter, J., W. Wasserman, and M.H. Kurtner. 1989. Applied Linear

Regression Models, 2nd ed. Homewood, Il.; Richard D. Irwin, 667 p.

Nolan, K.M., H.M. Kelsey, and D.C. Marron. 1995. Summary of research

in the Redwood Creek basin 1973-83. In: K.M. Nolan, H.M. Kelsey,

and D.C. Marron, eds. Geomorphic Processes and Aquatic Habitat in

the Redwood Creek Basin, Northwestern California. U.S. Geological

Survey Professional Paper 1454, U.S. Govt. Printing Office, Washington, D.C.: pp. A1-A7.

Nolan, K.M. and D.C. Marron. 1995. History, causes, and significance of

channel geometry of Redwood Creek, Northwestern California

1926-82. In: K.M. Nolan, H.M. Kelsey, and D.C. Marron, eds. Geomorphic Processes and Aquatic Habitat in the Redwood Creek Basin,

Northwestern California. U.S. Geological Survey Professional Paper

1454, U.S. Govt. Printing Office, Washington, D.C.: pp. N1-N22.

Parker, G. and P.C. Klingeman. 1982. On why gravel bed streams are

paved, Water Resour, Res., 18, 1409-1423.

Parker, G., P.C. Klingeman, and D.G. McLean. 1982. Bedload and size

distribution in paved gravel-bed streams, J. Hydraul, Div. Am. Soc.

Civ. Eng., 108, 544-571.

Rantz, S.E. and others. 1982. Measurement and computation of

streamflow: volume q. measurement of stage and discharge.

Water-Supply Paper 2175, U. S. Geological Survey, U.S. Govt. Printing Office, Washington, D.C.: 631 p.

Rogers, G.F., H.E. Malde, and R.M. Turner. 1984. Bibliography of repeat

photography for evaluating landscape change. University of Utah

Press, Salt Lake City, UT: 179 p.

Rosgen, D.L. 1994. A classification of natural rivers. Catena, 22(3): pp.

169-199.

Schmidt, K.H. and P. Egenzinger. 1994. Recent developments and perspectives in mountain river research. In: Schmidt, K.H., and

Egenzinger, P. eds. Dynamics and Geomorphology of Mountain

Rivers, Lecture Notes in Earth Sciences, 52: pp. 3-11.

Schumm, S.A. and R.W. Lichtey. 1963. Channel widening and flood-plain

construction along Cimarron River in southwestern Kansas. U.S.

Geological Survey Professional Paper 352-D, U.S. Govt. Printing

Office, Washington, D.C.: 88 p.

Simon, A. 1994. Gradation processes and channel evolution in modified

west Tennessee streams: process, response, and form. U.S. Geological Survey Professional Paper 1470, U.S. Govt. Printing Office,

Washington, D.C.: 84 p.

Singh, V.P. 1992. Elementary hydrology. Prentice Hall, NJ: 973 p.

Trimble, S.W. and S.W. Lund. 1982. Soil conservation and the reduction

of erosion and sedimentation in the Coon Creek basin, Wisconsin.

U.S. Geological Survey Professional Paper 1234, U.S. Govt. Printing

Office, Washington, D.C.: 35 p.

Williams, G.P. and M.G. Wolman. 1984. Downstream effects of dams on

alluvial rivers. U.S. Geological Survey Professional Paper 1286, U.S.

Govt. Printing Office, Washington, D.C.: 83 p.

Wohl, E.E. 1992. Gradient irregularity in the Herbert Gorge of Northeastern Australia, Earth Surf. Processes and Landforms, 17, 69-84.

Wolman, M.G. 1967. A cycle of sedimentation and erosion in urban river

channels. Geographica Annular, 49-A: pp. 385-395.

Wolman, M.G. and J.C. Miller. 1960. Magnitude and frequency of forces

in geomorphic processes. Journal of Geology, 68: pp. 54-74.

Acknowledgments

This study was funded by the USDA Forest Service Rocky Mountain Research Station through

the Stream Systems Technology Center under cooperative agreements with Utah State

University (28-CCS3-007). The study would have been impossible without the valuable

assistance of the U.S. Geological Survey (USGS) in Salt Lake City, Utah, and Riverton,

Wyoming. In particular, Julane Muldar, David Allen, Sherry Green, and William Baughm were

instrumental in locating and making available the historic gaging station records. In addition,

Mike Remillard, Larry Kova, David Allen, and Pamela Hamburg provided helpful insights on

how to analyze the USGS records. Rudy King (USDA Forest Service Rocky Mountain

Research Station) provided statistical review comments that improved the manuscript.
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found worldwide.

Research Locations

Flagstaff, Arizona

Fort Collins, Colorado*

Boise, Idaho

Moscow, Idaho

Bozeman, Montana

Missoula, Montana

Lincoln, Nebraska

* Station Headquarters, 240 West Prospect Road, Fort Collins, CO 80526

The U.S. Department of Agriculture (USDA) prohibits discrimination in all its

programs and activities on the basis of race, color, national origin, gender,

religion, age, disability, political beliefs, sexual orientation, and marital or familial

status. (Not all prohibited bases apply to all programs.) Persons with disabilities

who require alternative means for communication of program information (Braille,

large print, audiotape, etc.) should contact USDA’s TARGET Center at (202)

720-2600 (voice and TDD).

To file a complaint of discrimination, write USDA, Director, Office of Civil

Rights, Room 326-W, Whitten Building, 14th and Independence Avenue, SW,

Washington, D.C. 20250-9410, or call (202) 720-5964 (voice or TDD). USDA is

an equal opportunity provider and employer.

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Reno, Nevada

Albuquerque, New Mexico

Rapid City, South Dakota

Logan, Utah

Ogden, Utah

Provo, Utah

Laramie, Wyoming