U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2010–5057

Prepared in cooperation with the Susquehanna River Basin Commission and Lycoming County

Development of Flood-Inundation Maps for the West Branch 

Susquehanna River near the Borough of Jersey Shore, 

Lycoming County, Pennsylvania
Front cover—Aerial photograph of Jersey Shore, Pa., and Long Island during flooding of September 18, 2004. Photograph taken by the 

Pennsylvania Civil Air Patrol and used with their permission. 
Development of Flood-Inundation Maps for 

the West Branch Susquehanna River

near the Borough of Jersey Shore,

Lycoming County, Pennsylvania

By Mark A. Roland and Scott A. Hoffman

Prepared in cooperation with the Susquehanna River Basin Commission and 

Lycoming County

Scientific Investigations Report 2010–5057

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

KEN SALAZAR, Secretary

U.S. Geological Survey

Marcia K. McNutt, Director

U.S. Geological Survey, Reston, Virginia: 2011

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reproduce any copyrighted materials contained within this report.

Suggested citation:

Roland, M.A., and Hoffman, S.A., 2011, Development of flood-inundation maps for the West Branch Susquehanna 

River near the Borough of Jersey Shore, Lycoming County, Pennsylvania: U.S. Geological Survey Scientific Investigations Report 2010–5057, 9 p.
iii

Contents

Abstract...........................................................................................................................................................1

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

Study Area Description........................................................................................................................2

Purpose and Scope ..............................................................................................................................2

Hydrologic Analysis.......................................................................................................................................2

Hydraulic Analysis.........................................................................................................................................2

Development of Flood-Inundation Maps ...................................................................................................5

Comparison of Flood-Inundation Map to Aerial Photograph .................................................................6

Summary..........................................................................................................................................................6

Acknowledgments.........................................................................................................................................8

References Cited............................................................................................................................................8

Figures

1. Map showing study area for development of flood-inundation maps for the

West Branch Susquehanna River near the Borough of Jersey Shore, Pa. .......................3

2. Graph showing HEC-RAS water-surface profile for a gage height of 28.0 feet,

West Branch Susquehanna River at Jersey Shore, Pa. ........................................................5

3. Map showing simulated areas of inundation at a stage of 28.0 feet for the U.S. 

Geological Survey streamgage 01549760, West Branch Susquehanna River at

Jersey Shore, Pa...........................................................................................................................7

4. Aerial photograph of Jersey Shore, Pa., and Long Island during flooding of

September 18, 2004.......................................................................................................................8

Table

1. U.S. Geological Survey streamgage 01549760 rating-table stage with

corresponding elevations and discharge estimates for the West Branch

Susquehanna River at Jersey Shore, Pa. .................................................................................4
iv

Conversion Factors and Abbreviations

Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)

inch (in.) 25.4 millimeter (mm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

square mile (mi2

) 259.0 hectare (ha)

square mile (mi2

) 2.590 square kilometer (km2)

Flow rate

cubic foot per second (ft3

/s) 0.02832 cubic meter per second (m3/s)

Vertical coordinate information is referenced to the North American Vertical Datum of 1988 

(NAVD 88).

Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83).

List of Acronyms

AHPS Advanced Hydrologic Prediction Service

DEM digital elevation model

FEMA Federal Emergency Management Agency

FIRM flood-insurance rate map

FIS flood-insurance studies

GIS geographical information system

HEC-RAS Hydrologic Engineering Center River Analysis System

LiDAR Light Detection and Ranging

NFIP National Flood Insurance Program

NOAA/NWS National Oceanic and Atmospheric Administration’s National Weather Service

PaDCNR Pennsylvania Department of Conservation and Natural Resources

SFFWS Susquehanna Flood Forecast and Warning System

SRBC Susquehanna River Basin Commission

USGS U.S. Geological Survey
Development of Flood-Inundation Maps for the West 

Branch Susquehanna River near the Borough of Jersey 

Shore, Lycoming County, Pennsylvania

By Mark A. Roland and Scott A. Hoffman

Abstract

Streamflow data, water-surface-elevation profiles 

derived from a Hydrologic Engineering Center River Analysis System hydraulic model, and geographical information 

system digital elevation models were used to develop a set 

of 18 flood-inundation maps for an approximately 5-mile 

reach of the West Branch Susquehanna River near the 

Borough of Jersey Shore, Pa. The inundation maps were 

created by the U.S. Geological Survey in cooperation with 

the Susquehanna River Basin Commission and Lycoming 

County as part of an ongoing effort by the National Oceanic 

and Atmospheric Administration’s National Weather Service 

to focus on continued improvements to the flood forecasting 

and warning abilities in the Susquehanna River Basin and to 

modernize flood-forecasting methodologies. The maps, ranging from 23.0 to 40.0 feet in 1-foot increments, correspond 

to river stage at the U.S. Geological Survey streamgage 

01549760 at Jersey Shore. The electronic files used to 

develop the maps were provided to the National Weather 

Service for incorporation into their Advanced Hydrologic 

Prediction Service website. The maps are displayed on this 

website, which serves as a web-based flood-warning system, 

and can be used to identify areas of predicted flood inundation associated with forecasted flood-peak stages. During 

times of flooding or predicted flooding, these maps can be 

used by emergency managers and the public to take proactive steps to protect life and reduce property damage caused 

by floods.

Introduction

Floodwaters can present real dangers in the form of 

loss of life and (or) property. According to the Susquehanna 

River Basin Commission (SRBC), the Susquehanna River 

Basin continues to be one of the most flood-prone areas 

in the country (Susquehanna River Basin Commission, 

2009). Since 1889, the West Branch of the Susquehanna 

River has exceeded the flood stage1

 of 26.0 ft no fewer than 

nine times (National Oceanic and Atmospheric Administration, National Weather Service, 2009b); the most recent 

major flood2

 occurred on September 18, 2004, when a gage 

height of 30.74 ft was recorded at the U.S. Geological Survey 

(USGS) streamgage 01549760 at Jersey Shore. Areas within 

and around the Borough of Jersey Shore are designated by the 

Federal Emergency Management Agency (FEMA) as being 

within the 1-percent annual chance flood-hazard area. While 

the development of flood-response and damage-reduction programs in flood-prone communities is instrumental to minimizing the potential impact associated with floods, the effectiveness of such programs can be diminished without adequate 

forecast lead times.

The SRBC coordinates an interagency committee that 

maintains and operates the Susquehanna Flood Forecast and 

Warning System (SFFWS). The purpose of the SFFWS is 

to provide timely and accurate information to reduce flood 

damages and prevent loss of life due to flooding within the 

basin. To assist with the accomplishment of this mission, 

a subcommittee was established with representation from 

the National Oceanic and Atmospheric Administration’s 

National Weather Service (NOAA/NWS), SRBC, and USGS 

to focus on continued improvements to the flood forecasting 

and warning abilities in the Susquehanna River Basin. An 

example of a continued improvement is the modernization 

of NOAA/NWS flood-forecasting methodologies through 

the implementation of the Advanced Hydrologic Prediction 

Service (AHPS) in the Susquehanna River Basin. AHPS is the 

NWS’s ongoing effort to modernize NWS hydrologic services that will provide improved river and flood forecasts and 

water information across America to protect life and property 

1

Flood Stage is defined by the National Oceanic and Atmospheric Administration’s National Weather Service as an established gage height for a given 

location above which a rise in water-surface level begins to create a hazard to 

lives, property, or commerce.

2

Major flood is defined by the National Oceanic and Atmospheric Administration’s National Weather Service as a general term including extensive 

inundation and property damage. A major flood is usually characterized by 

the evacuation of people and livestock and the closure of both primary and 

secondary roads.
2 Development of Flood-Inundation Maps for the West Branch Susquehanna River near the Borough of Jersey Shore

(National Oceanic and Atmospheric Administration, National 

Weather Service, 2009a).

A priority of the SFFWS interagency committee is the 

enhancement of AHPS through the development of flood-inundation maps that graphically depict expected areas of inundation relative to stage at specific flood-forecasting locations 

in the Susquehanna River Basin. A cooperative agreement 

between Lycoming County, SRBC, and the USGS was enacted 

to develop flood-inundation maps for the NWS flood-forecast 

point at Jersey Shore, Pa. Emergency managers and the public 

will have access on the AHPS website to mapped information of inundated areas in addition to forecasted river stage(s). 

During times of predicted flooding, these data may be used 

for evacuation purposes and identification of potential roadclosure points.

Study Area Description

The West Branch Susquehanna River Basin is in northcentral Pennsylvania (fig. 1). The study area is an approximately 5-mi reach from the confluence of Pine Creek extending downstream past the Borough of Jersey Shore to the 

confluence of Larrys Creek. The Borough of Jersey Shore 

is approximately 15 mi southwest of Williamsport, Pa., in 

southern Lycoming County; the population of the Borough is 

approximately 4,500 (U.S. Census Bureau, 2009).

The approximate mid-point of the study reach is Long 

Island, where the West Branch Susquehanna River changes 

flow direction from a generally easterly direction to a northerly direction with flow splitting into an east and west channel 

for approximately 1 mi. State Route 44 (SR 44) crosses Long 

Island, and two bridges span the river. USGS streamgage 

01549760, West Branch Susquehanna River at Jersey Shore, 

Pa., is located on Long Island near the western SR 44 bridge 

and is a flood-forecasting point for the NWS. The landscape 

on Long Island consists primarily of agricultural fields with 

several residential structures; the perimeter of the island is 

lined with light brush and trees.

Flood-plain areas in the upstream part of the study reach 

are characterized by steep, forested banks on the southern side 

of the river; the flood plain on the northern side of the river is 

low relief with agricultural fields. At the approximate midpoint of the study reach (near Long Island), the flood plains 

begin to flatten out with the Borough of Jersey Shore situated 

to the western side of the river; landscape on the eastern side 

of the river is primarily agricultural fields with sparse residential structures. The flood-plain areas in the downstream part 

of the study reach are characterized by a sparsely populated 

residential area with open grassy areas on the immediate 

left overbank; U.S. Route 220 parallels the river at the base 

of steep forested banks on the far left flood plain. Agricultural fields dominate the downstream flood plain on the right 

overbank area of the study reach and include the presence of a 

local landing airstrip.

Purpose and Scope

This report describes the methods and results of hydrologic and hydraulic analyses and geographic information 

system (GIS) data-processing techniques used to develop 

flood-inundation maps for selected water-surface stages at the 

NWS flood-forecast point on the West Branch Susquehanna 

River at Jersey Shore, Pa., for incorporation by the NWS 

into their AHPS website. The USGS, in cooperation with the 

Susquehanna River Basin Commission and Lycoming County, 

Pa., developed flood-inundation maps and water-depth maps 

(or grids) to estimate areas and depths of anticipated flooding 

at 18 water-surface stages.

Hydrologic Analysis

The flood-inundation maps prepared for this study range 

from the action stage of 23.0 ft at 1-ft increments up to a stage 

of 40.0 ft, which is approximately 2 ft higher than the stage of 

maximum flow of 38.2 ft observed on June 23, 1972. Therefore, flows were estimated at 18 different gage heights.

A rating table developed for USGS streamgage 01549760 

was used to derive flow estimates that are based on stage 

for use in the hydraulic model (table 1). This streamgage 

was established as a staff gage in October 1938. Recording 

equipment was installed in March 2000 for operation as a 

stage-only gage. On October 1, 2004, it was established as a 

continuous-record annual peak site. The existing rating table 

for the Jersey Shore streamgage went up to a gage height of 

32.0 ft with a corresponding discharge of 200,000 ft3

/s. The 

upper end of this rating was initially extended from 32.0 ft 

to 38.2 ft (with a corresponding discharge of 257,000 ft3

/s), 

which was the maximum observed stage at this location for 

the June 1972 flood. This rating extension was based on a 

discharge-per-square-mile correlation with USGS streamgage 

01551500, West Branch Susquehanna River at Williamsport, for the June 1972 flood event. Streamgage 01551500 

is downstream from Jersey Shore, shares similar hydrologic 

basin characteristics as streamgage 01549760, and has been 

in operation since 1895. The drainage areas of streamgages 

01549760 and 01551500 are 5,225 and 5,682 mi2

, respectively. 

The rating was subsequently extended from 38.2 ft to 40.0 ft 

(with a corresponding discharge of 273,300 ft3

/s) on the basis 

of a straight-line extension.

Hydraulic Analysis

The hydraulic-analyses computations were performed 

using the U.S. Army Corps of Engineer’s Hydrologic Engineering Center River Analysis System (HEC-RAS), version 

3.1.1 (U.S. Army Corps of Engineers, Hydrologic Engineering 

Center, 2002). HEC-RAS is a one-dimensional step-backwater 

model designed for application in flood-insurance studies 
Hydraulic Analysis 

3

L

arrys

Creek

West Branch Susquehanna River

Long Island

44

150

Pine Creek

PORTER

PIATT

NIPPENOSE

WAYNE

PINE CREEK

WATSON

Jersey Shore

Avis

CRAWFORD

220

0 1 2 MILES

0 1 2 KILOMETERS

Jersey

Shore

LYCOMING

COUNTY

PENNSYLVANIA

•

EXPLANATION

POPULATION CENTERWATERWAYSMUNICIPAL BOUNDARY

U.S. HIGHWAY 220

STATE HIGHWAY 44FLOW DIRECTIONAL ARROWU.S. GEOLOGICAL SURVEYSTREAMGAGE

41°14'41°12'41°10'

77°14' 77°16' 77°18'

Roads, population centers, county and municipal boundaries: Commonwealth of Pennsylvania, 2009Waterways: U.S. Geological Survey, 2009

West Branch Susquehanna River

at Jersey Shore, Pa.

(01549760)

Figure 1.—Study area for development of flood-inundation maps for the West Branch Susquehanna River near the Borough of Jersey Shore, Pa.
4 Development of Flood-Inundation Maps for the West Branch Susquehanna River near the Borough of Jersey Shore

Table 1. U.S. Geological Survey streamgage 01549760 rating-table stage with corresponding elevations and discharge estimates for 

the West Branch Susquehanna River at Jersey Shore, Pa.

[Vertical coordinate information is referenced to the North American Vertical Datum of 1988 (NAVD 88). The hydraulic analyses computations were performed 

using the U.S. Army Corps of Engineer’s Hydrologic Engineering Center River Analysis System (HEC-RAS), version 3.1.1 (U.S. Army Corps of Engineers, 

Hydrologic Engineering Center, 2002). ft3/s, cubic feet per second]

Stage, 

gage datum 

(feet)

Discharge 

(ft3

/s)

HEC-RAS 

Profile

Elevation, 

NAVD 88 datum 

(feet)

HEC-RAS modeled 

water-surface 

elevation 

(feet)

Elevation 

difference 

(feet)

23.00

24.00

25.00

26.00

27.00

28.00

29.00

30.00

31.00

32.00

33.00

34.00

35.00

36.00

37.00

38.00

39.00

40.00

114,700

123,200

132,000

141,000

150,300

159,700

169,500

179,400

189,600

200,000

208,900

217,900

227,100

236,300

245,600

255,100

264,100

273,300

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

535.53

536.53

537.53

538.53

539.53

540.53

541.53

542.53

543.53

544.53

545.53

546.53

547.53

548.53

549.53

550.53

551.53

552.53

535.75

536.70

537.65

538.61

539.58

540.63

541.68

542.76

543.75

544.68

545.59

546.55

547.51

548.49

549.47

550.43

551.38

552.30

0.22

.17

.12

.08

.05

.10

.15

.23

.22

.15

.06

.02

-.02

-.04

-.06

-.10

-.15

-.23

(FIS) and flood-plain management and is accepted by FEMA 

for use in the National Flood Insurance Program (NFIP).

Hydraulic models from two FISs were obtained and 

combined into one HEC-RAS hydraulic model for use in 

this study. The effective FIS for the Borough of Jersey Shore 

(Federal Emergency Management Agency, 2004) was completed in 1975 by the SRBC and the effective FIS for the 

Township of Piatt (Federal Emergency Management Agency, 

2004) was completed in 1979 by Michael Baker, Jr., Inc., 

under subcontract to SRBC, each using a HEC-2 hydraulic 

model (U.S. Army Corps of Engineers, 1984). The data input 

to each of these models and the associated FIS were reviewed 

to verify accuracy (e.g., location, spacing, and ground elevations of cross sections). During the review process, it was 

discovered that a cross section existed in each of the models 

that was common to both—the farthest upstream cross section in the Township of Piatt FIS was the same as the farthest 

downstream cross section in the Borough of Jersey Shore FIS. 

This common cross section was used to effectively join both 

models together such that the study reach could be evaluated 

using one model. In 1985, the eastern SR 44 bridge (connecting Long Island to Antes Fort) was replaced. The merged 

HEC-RAS hydraulic model was updated to reflect the new 

bridge location and geometry (Pennsylvania Department of 

Transportation, written commun., 1985).

USGS streamgage 01549760 was used as the calibration 

point for this model. The 18 rating-table discharges identified in table 1 were incorporated into the HEC-RAS model 

with their accompanying rating-table stages, which were 

converted to water-surface elevations. Initially, these watersurface elevations were entered into the model as known 

starting water-surface elevations at the farthest downstream 

cross section. Eighteen computed water-surface profiles were 

subsequently generated for the study reach. On the basis of 

the slope of these profiles, revised initial water-surface elevations were estimated at the farthest downstream cross section 

and entered into the hydraulic model. This method provided 

a means to establish reasonable starting water-surface elevations from which the model subsequently required additional 

calibration to match the corresponding rating-table stages 

at the streamgage cross section. For example, at a stage of 

28.0 ft (540.53 ft NAVD 88), the corresponding discharge 

according to the USGS streamgage 01549760 rating table is 

159,700 ft3

/s. This discharge was entered into the model and 

a water-surface profile (fig. 2) was generated throughout the 

study reach. This water-surface profile subsequently required 

calibration to correspond with a 28.0 ft stage (540.53 ft 
Development of Flood-Inundation Maps 5

0 10,000 20,000 30,000 40,000 50,000

490

500

510

520

530

540

550

560

ELEVATION, IN FEET

MAIN CHANNEL DISTANCE, IN FEET FROM DOWNSTREAM MODEL BOUNDARY

Calculated water surface

Land surface

Pine Creek 

confluence

Larrys Creek 

confluence

Eastern span 

State Route 44 bridge

Western span

State Route 44 bridge U.S. Geological Survey 

streamgage 01549760

480

Figure 2.—HEC-RAS water-surface profile for a gage height of 28.0 feet, West Branch Susquehanna River at Jersey Shore, Pa.

NAVD 88) at the modeled location of the streamgage. In this 

case, model calibration consisted of adjusting the channel and 

overbank roughness-coefficient values such that the predicted 

water-surface profiles would best match the stages identified 

in the rating table. To ensure reasonableness of the roughnesscoefficient values, field reconnaissance of the study area was 

conducted, and orthophotography was examined. This model 

calibration process was repeated for each of the 18 discharges 

and their corresponding stages (table 1). Consequently, this 

was an iterative process because any change to the model (for 

example, adjustment of roughness coefficients) had the potential to alter any of the water-surface profiles. The resultant 18 

water-surface profiles for the study reach (table 1) were within 

+/- 0.23 ft for each of the 18 corresponding stages at the 

streamgage location.

Development of Flood-Inundation Maps

The flood-inundation maps were developed using a Light 

Detection and Ranging (LiDAR) based digital elevation model 

(DEM) from data collected by the Pennsylvania Department 

of Conservation and Natural Resources (PaDCNR) and USGS 

as part of PAMAP, which is a program designed to create a 

new electronic map of Pennsylvania using high-resolution 

aerial photography, elevation data collected using LiDAR 

technology, and existing spatial data from local, state, and federal sources (Pennsylvania Department of Conservation and 

Natural Resources, 2009). Each PAMAP data set is organized 

into blocks representing 10,000 ft by 10,000 ft on the ground 

(Pennsylvania Spatial Data Access, 2009). These blocks do 

not have gaps or overlapping areas, which allow a seamless 
6 Development of Flood-Inundation Maps for the West Branch Susquehanna River near the Borough of Jersey Shore

mosaic of multiple blocks of data. Six individual DEM blocks 

were mosaicked together using ArcGIS (Environmental 

Systems Research Institute, Inc., 2009) software to cover the 

Jersey Shore model area. The resulting raster data set, or grid, 

covered approximately 21.5 mi2 with a horizontal ground 

resolution of 3.2 ft, for the elevation data. Horizontal accuracy 

is documented at 5 ft or better and vertical accuracy is 7.3 in. 

(Pennsylvania Spatial Data Access, 2009).

A study-area polygon, shown on figure 3, was created to 

assist in the GIS processing for each water-surface-elevation 

profile. This polygon boundary included the modeled area 

from Pine Creek downstream to Larrys Creek. The west bank 

of Pine Creek was used for the upstream limit of the polygon, 

and the downstream terminus was between 500 and 1,000 ft 

downstream from the east bank of Larrys Creek. The width of 

the study-area polygon was determined by digitizing two lines 

using the ends of cross-section lines that were digitized using 

FEMA’s flood-insurance rate map (FIRM) data as a guide. 

These lines were then expanded by using a buffer of 500 ft to 

insure the edge-of-water could be seen at each modeled watersurface profile. The structure of grid-formatted data allowed 

fast and efficient processing and analyzing of large LiDAR 

data sets. Bare-earth DEMs generated from LiDAR data are 

large gridded data sets that do not include data related to manmade objects (Maune, 2007). To represent the impact of flood 

levels on infrastructure, the DEM was corrected to show the 

elevations of those areas where bridges and overpasses were 

located. Cell-elevation values were manually changed using 

surveyed bridge-deck elevations as references, where possible. 

In most bridge locations, the bare-earth elevations from roads 

leading up to the bridges were used and applied to cells across 

the surface of the bridge.

Each FIRM digitized cross-section line used for the study 

area was attributed with a HEC-RAS calculated water-surface 

elevation for each of the 18 profiles (table 1). The flood 

surfaces were generated using an iterative finite-difference 

interpolation technique found in the ArcGIS, TopoToRaster 

tool. This tool is unique because it is the only ArcGIS interpolation routine designed to work intelligently with contour 

data and combines locally efficient interpolation methods with 

global surface-continuity routines (Environmental Systems 

Research Institute, Inc., 2009). Inputs into the tool are as follows: contour data using the digital cross sections attributed 

with the NAVD 88 elevation, in feet, and boundary data using 

the study-area polygon. Depth of water grids were generated by subtracting the flood water-surface elevation from the 

study-area DEM.

Comparison of Flood-Inundation Map 

to Aerial Photograph

After the HEC-RAS hydraulic model was calibrated to 

the USGS streamgage 01549760 stage and discharge data and 

the inundation maps were generated, visual comparison was 

made between distinguishable inundated or near-inunadated 

areas (Areas 1 through 4) identified on the inundation map 

at stage 28.0 ft (fig. 3) and an aerial photograph (fig. 4) of a 

flood event to judge the relative accuracy of the model. Aerial 

photography of the September 18, 2004, Hurricane Ivan flood 

event was taken by the Civil Air Patrol Composite Squadron 

401 at various flood-affected communities throughout Lycoming County, including the Borough of Jersey Shore. The peak 

gage height from the September 18, 2004, event was 30.74 ft 

recorded at USGS streamgage 01549760. Although a time 

stamp was not associated with the aerial photograph of the 

Jersey Shore flooding, it was estimated on the basis of shadows from structures and trees to have been taken in the early 

afternoon when the corresponding recorded stage was approximately 28 ft.

Areas 1 to 4 (figs. 3 and 4) show similar inundated or 

near-inundated areas. Area 1 on the eastern side of Long 

Island near the approach to the SR 44 bridge and the bridge 

itself were not inundated. Similarly, Area 2 on the western side 

of Long Island near the approach to the SR 44 truss bridge 

and the bridge itself are not inundated. Area 3 identifies an 

agricultural field south of the Borough showing what appears 

to be a combination of backwater and channelized flow around 

a topographical high point in the field. Area 4 shows inundated 

areas within the northern portion of the Borough possibly 

caused by a combination of small tributaries draining the 

local area and backwater from a culvert pipe that discharges to 

the river.

In addition to aerial photograph comparison, a review of 

flood-inundation maps was performed by County and Borough personnel and residents who indicated that the modeled 

inundated areas appeared to present reasonable delineations of 

flooded areas at various stages. These evaluations were based 

primarily on personal experiences during times of flooding.

Summary

The mission of the Susquehanna Flood Forecast and 

Warning System in the Susquehanna River Basin is to provide 

timely and accurate information to reduce damages and prevent loss of life during flood events within the basin. Continued improvements and modernization of National Oceanic and 

Atmospheric Administration’s National Weather Service floodforecasting methodologies with the implementation of the 

Advanced Hydrologic Prediction Service can assist with the 

achievement of this mission. The development of flood-inundation maps that graphically depict areas of expected inundation relative to stage at flood-forecast points can enhance 

the Advanced Hydrologic Prediction Service. In cooperation 

with the Susquehanna River Basin Commission and Lycoming County, the U.S. Geological Survey used streamflow data, 

modeled water-surface-elevation profiles, and GIS digital 

elevation models to develop a set of 18 flood-inundation 

maps for an approximately 5-mi reach of the West Branch 
Summary 7

77°16' 77°15' 77°14' 77°13'

AREA 2 AREA 1

AREA 3

AREA 4

Jersey Shore

Long 

Island

Pine Creek

Larrys Creek

State Route 44

Interstate 180

0 0.5 1 MILE

0 10.5 KILOMETER

Aerial Photography: Pennsylvania Mapping Program, 2006

Road Network: TeleAtlas of North America, 2009

Streamgage Location: U.S. Geological Survey, Pennsylvania Water Science Center 

Map Projection: Pennsylvania State Plane, South, NAD 1983

41°13'

41°12'

41°11'

41°10'

SIMULATED INUNDATED AREA

AT A FLOOD STAGE OF 28 FEET

STUDY-AREA BOUNDARY

FLOW DIRECTIONAL ARROW

U.S. OR STATE ROUTE

LOCAL ROAD

U.S. GEOLOGICAL SURVEY 

STREAMGAGE 01549760

EXPLANATION

Figure 3.—Simulated areas of inundation at a stage of 28.0 feet for the U.S. Geological Survey streamgage 01549760, West 

Branch Susquehanna River at Jersey Shore, Pa. (Areas 1 through 4 are inundated and near-inundated areas used for 

comparison with aerial photograph, figure 4.)
8 Development of Flood-Inundation Maps for the West Branch Susquehanna River near the Borough of Jersey Shore

AREA 1

AREA 2

AREA 3

AREA 4

Long Island

Figure 4.—Aerial photograph of Jersey Shore, Pa., and Long Island during flooding of September 18, 2004. (Photo taken by 

Pennsylvania Civil Air Patrol and used with their permission.) (Areas 1 through 4 are inundated and near-inundated areas used for 

comparison with flood-inundation map, figure 3.)

Susquehanna River near the Borough of Jersey Shore, Pa. The 

surface-water elevations depicted in this set of maps range 

from a stage of 23.0 ft to a maximum stage of 40.0 ft (approximately 2 ft higher than the stage of maximum observed flow), 

in 1-ft stage increments. In addition to river stage, emergency 

managers and the public have access to the mapped information on inundated areas on the Advanced Hydrologic Prediction Service website. During times of predicted flooding, these 

maps may be used to take proactive steps to protect life and 

reduce property damage caused by floods.

Acknowledgments

For their cooperation throughout this study, special 

thanks are extended to Frances Jones, and John Lavelle of 

Lycoming County, Pa., and Benjamin Pratt, Susquehanna 

River Basin Commission, who also provided a technical and 

editorial review. Thanks are also due to Jeff Levan, Pennsylvania Department of Transportation, for providing information 

relative to the bridges within the study reach. Critical reviews 

and suggestions were provided by Edward Koerkle (USGS 

Pennsylvania Water Science Center) and Matt Whitehead 

(USGS Ohio Water Science Center). Reviews of GIS-derived 

data sets were performed by Silvia Terziotti (USGS North 

Carolina Water Science Center).

References Cited

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Products—ArcGIS: accessed October 20, 2009, at 

http://www.esri.com/products/index.html.

Federal Emergency Management Agency, 2004, Flood Insurance Study, Lycoming County, Pennsylvania: FIS number 

42081CV003, March 16, 2004 [variously paged].

Maune, D.F., 2007, Digital elevation model technologies and 

applications—The DEM users manual (2d ed.): Bethesda, 

Md., American Society for Photogrammetry and Remote 

Sensing, 655 p.
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Weather Service, 2009a, Advanced Hydrologic Prediction 

Service (AHPS): Silver Springs, Md., accessed November 

30, 2009, at http://www.floodsafety.noaa.gov/ahps.shtml.

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Pennsylvania: Harrisburg, Pa., accessed May 27, 2009, at 

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http://www.srbc.net/pubinfo/brochures.htm.

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Prepared by the West Trenton Publishing Service 

Center.

For more information concerning this report, contact:

Director

U.S. Geological Survey

Pennsylvania Water Science Center

215 Limekiln Road

New Cumberland, PA 17070

dc_pa@usgs.gov

or visit our Web site at:

http://pa.water.usgs.gov
Roland and Hoffman—Development of Flood-Inundation Maps for the W.B. Susquehanna River near Jersey Shore—Scientific Investigations Report 2010–5057