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Flood-Hydrology Data for the Potomac River and Selected Tributaries in the Vicinity of the Chesapeake and Ohio Canal National Historical Park, Maryland, West Virginia, and the District of Columbia

By Edward J. Doheny

Conversion Factors and Abbreviations
Multiply By To obtain
foot(ft) 0.3048 meter
square foot (ft2) 0.0929 square meter
foot per second (ft/s) 0.3048 meter per second
cubic foot per second (ft3/s) 0.02832 cubic meter per second
square mile (mi2) 2.590 square kilometer

Sea level: In this report, "sea level" refers to the National Geodetic Vertical Datum of 1929-a geodetic datum derived from a general adjustment of the first-order level nets of the United States and Canada, formerly called Sea Level Datum of 1929.

Table of Contents

Abstract
Introduction
Purpose and scope
Acknowledgments
Flood-hydrology data for the Potomac River
Basic data
Peak flows and recurrence intervals
Selected discharge measurements
Flood-hydrology data for selected tributaries
Basic data
Peak flows and recurrence intervals
Additional information and resources
Flood studies and reports
Indirect flood-discharge measurements
Streamflow-gaging stations on the Chesapeake and Ohio Canal
Other discharge measurements on the Chesapeake and Ohio Canal
Summary
References cited
Appendix
U.S. Geological Survey streamflow-gaging stations with surface-water flow data in the vicinity of the Chesapeake and Ohio Canal National Historical Park

Figures

  1. Map showing the locations of U.S. Geological Survey streamflow-gaging stations on the Potomac River and selected tributaries in the vicinity of the Chesapeake and Ohio Canal National Historical Park, Maryland West Virginia, and the District of Columbia
  2. Flood hydrograph for U.S. Geological Survey streamflow-gaging station 01638500, Potomac River at Point of Rocks, Maryland, during the flood of January 19-21, 1996.
  3. Flood hydrograph for U.S. Geological Survey streamflow-gaging station 01614500, Conococheague Creek at Fairview, Maryland, during the flood of January 19-21, 1996.

Tables

  1. Basic data for Potomac River streamflow-gaging stations in the vicinity of the Chesapeake and Ohio Canal National Historical Park.
  2. Peak-flow data and approximate recurrence intervals for Potomac River streamflow-gaging stations in the vicinity of the Chesapeake and Ohio Canal National Historical Park.
  3. Selected discharge-measurement data for high flows at U.S. Geological Survey streamflow-gaging station 01603000, North Branch Potomac River near Cumberland, Maryland.
  4. Selected discharge-measurement data for high flows at U.S. Geological Survey streamflow-gaging station 01610000, Potomac River at Paw Paw, West Virginia.
  5. Selected discharge-measurement data for high flows at U.S. Geological Survey streamflow-gaging station 01613000, Potomac River at Hancock, Maryland.
  6. Selected discharge-measurement data for high flows at U.S. Geological Survey streamflow-gaging station 01618000, Potomac River at Shepherdstown, West Virginia.
  7. Selected discharge-measurement data for high flows at U.S. Geological Survey streamflow-gaging station 01638500,Potomac River at Point of Rocks, Maryland.
  8. Selected discharge-measurement data for high flows at U.S. Geological Survey streamflow-gaging station 01646500, Potomac River at Little Falls near Washington, D.C.
  9. Calculated ranges of Manning's roughness coefficient values for selected discharges and flow conditions at Potomac River streamflow-gaging stations.
  10. Basic data for streamflow-gaging stations on tributaries to the Potomac River in the vicinity of the Chesapeake and Ohio Canal National Historical Park.
  11. Peak-flow data and approximate recurrence intervals for selected streamflow-gaging stations on tributaries to the Potomac River in the vicinity of the Chesapeake and Ohio Canal National Historical Park.

Abstract

This report presents flood-hydrology data for the Potomac River and selected tributaries in the vicinity of the Chesapeake and Ohio Canal National Historical Park (C & O Canal NHP). Data were compiled for the floods of (1) March 17-19, 1936; (2) June 22-24, 1972; (3) November 4-7, 1985; (4) January 19-21, 1996; (5) September 6-8, 1996; and (6) the peak of record for 6 U.S. Geological Survey (USGS) streamflow-gaging stations on the Potomac River and 10 streamflow-gaging stations on selected tributaries to the Potomac River. Peak discharge, peak gage height, the date and time of the peak, and approximate recurrence interval are presented for each flood event at these streamflow-gaging stations.

Data compiled from selected high-flow discharge measurements at the six Potomac River streamflow-gaging stations are presented. The gage height, top width, cross-sectional area, mean velocity, maximum velocity, and discharge are presented for each selected discharge measurement. Any corresponding discharge on the C & O Canal that was measured or estimated during these discharge measurements is presented. Ranges of Manning's roughness coefficient were computed for the range of selected discharge measurements based on estimates of water-surface slope or the channel-bed slope.

An inventory of selected flood studies and reports, and additional USGS data collected along the Potomac River and the C & O Canal NHP also are presented. Included are (1) a listing of selected flood studies and reports, and (2) a listing of USGS indirect flood-discharge measurements that have been made at the six Potomac River streamflow-gaging stations in the vicinity of the C & O Canal NHP. Information on historical streamflow-gaging station records and discharge measurements on the C & O Canal also is presented.

Introduction

The Chesapeake and Ohio Canal National Historical Park (C & O Canal NHP) is operated by the U.S. Department of the Interior, National Park Service (NPS). The park extends from Cumberland, Md., to Georgetown in the District of Columbia. The C & O Canal and its towpath are located well within the flood plain of the Potomac River. The towpath is a historic structure that serves as an important corridor for visitor recreation, including horse, bicycle, and pedestrian uses.

The C & O Canal NHP is often impacted by flooding on the Potomac River. Since being established in January 1971, the park has experienced four major flood events--in June 1972, November 1985, January 1996, and September 1996--causing significant damage to the C & O Canal, towpath, and other park infrastructure. The costs associated with park repairs has risen into the tens of millions of dollars. Flooding and subsequent damage to the C & O Canal NHP has emphasized a need for the NPS to begin (1) correlating park-related flood damage with specific flood events in the Potomac River Basin, (2) predicting expected inundation and subsequent damage based on the magnitude and frequency of flood events, and (3) prioritizing park structures for protection from future flood damage. In order to assist NPS in meeting these objectives, the U.S. Geological Survey (USGS), in cooperation with NPS, initiated a study in November 1996 to (1) compile hydrologic data from specific flood events on the Potomac River and selected tributaries in the vicinity of the C & O Canal NHP, and (2) inventory selected resources and flood-study information along the Potomac River and the C & O Canal NHP.

Purpose and Scope

This report presents hydrologic data on flooding of the Potomac River and selected tributaries to the Potomac River in the vicinity of the C & O Canal NHP. An inventory of selected reports, flood studies, and additional USGS data along the Potomac River and C & O Canal NHP is presented.

This report presents data that were compiled for the floods of (1) March 17-19, 1936; (2) June 22-24, 1972; (3) November 4-7, 1985; (4) January 19-21, 1996; (5) September 6-8, 1996; and (6) the peak of record for 6 USGS streamflow-gaging stations on the Potomac River and 10 USGS streamflow-gaging stations on selected tributaries in the vicinity of the C & O Canal NHP (fig. 1). The peak discharge, peak gage height, the date and time of the peak, and approximate recurrence interval are presented for each flood event.

Data compiled from selected high-flow discharge measurements at the six Potomac River streamflow-gaging stations are presented. Gage height, top width, cross-sectional area, mean velocity, maximum velocity, mean depth, and discharge are presented for each selected discharge measurement. Any corresponding estimates or measurements of discharge on the C & O Canal are also presented for each selected discharge measurement. Ranges of Manning's roughness coefficient (Manning's n) were computed for the range of selected discharge measurements based on estimates of water-surface slope or the channel-bed slope. These data will be used for subsequent hydraulic studies by engineers for maintenance, protection, or restoration of the C & O Canal.

The report also provides an inventory of selected flood studies and reports related to the Potomac River Basin in the vicinity of the C & O Canal NHP. A listing of USGS indirect flood discharge measurements that have been made at the six Potomac River streamflow-gaging stations in the vicinity of the C & O Canal NHP is provided. Information on historical streamflow-gaging station records and discharge measurements on the C & O Canal also is presented.

Acknowledgments

The author would like to thank Patrick L. Toops of the National Park Service, C & O Canal NHP, for planning assistance. Special thanks are extended to the U.S. Geological Survey, West Virginia District, for providing additional data and technical information on streamflow-gaging stations near the Potomac River in West Virginia.

Flood-Hydrology Data for the Potomac River

Flood-hydrology data were compiled for six USGS streamflow-gaging stations on the Potomac River in the vicinity of the C & O Canal NHP. The streamflow-gaging stations are (1) Station 01603000, North Branch Potomac River near Cumberland, Md.; (2) Station 01610000, Potomac River at Paw Paw, W. Va.; (3) Station 01613000, Potomac River at Hancock, Md.; (4) Station 01618000, Potomac River at Shepherdstown, W. Va.; (5) Station 01638500, Potomac River at Point of Rocks, Md.; and (6) Station 01646500, Potomac River at Little Falls near Washington, D.C. Data compiled for these streamflow-gaging stations include (1) basic data regarding the drainage basin and the station, (2) peak-flow data and recurrence intervals for selected flood events, and (3) flow characteristics that were defined in selected discharge measurements made at the stations.

Basic Data

Basic data compiled for each of the six Potomac River streamflow-gaging stations include the (1) latitude and longitude of the station, (2) period of gage record, (3) drainage area at the station, (4) percentage of the total basin drainage area, and (5) mean sea level datum of the station in relation to the National Geodetic Vertical Datum (NGVD) of 1929. This information is listed in table 1.

Peak Flows and Recurrence Intervals

Peak-flow data and approximate recurrence intervals were compiled for the six Potomac River streamflow-gaging stations for the floods of (1) March 17-19, 1936; (2) June 22-24, 1972; (3) November 4-7, 1985; (4) January 19-21, 1996; and (5) September 6-8, 1996. Data for the peak of record also were compiled if the peak occurred during a different flood event than those listed above. The peak-flow data that were compiled included the peak gage height, peak discharge, and the date and time of the peak. An approximate recurrence interval for each event was determined from the station data, and techniques described by the Interagency Advisory Committee on Water Data (1982) and Dillow (1996).

The recurrence interval of a specific flood is the average number of years between floods equal to or greater than that specific flood. It is emphasized that this is an average number of years and does not imply that it will be that many years before another event of that magnitude occurs. Similar or greater events can occur in the same year, as demonstrated by the 1996 floods on the Potomac River. The reciprocal of the recurrence interval is the probability of the event occurring in any one year. For instance, a 100-year flood has a 0.01 probability, or 1 percent chance, of occurring in any year (Lescinsky, 1987).

Peak-flow data and approximate recurrence intervals for the six Potomac River streamflow-gaging stations during the specified flood events are shown in table 2. A flood hydrograph for the streamflow-gaging station on the Potomac River at Point of Rocks, Md., during the flood of January 19-21, 1996, is shown as an example (fig. 2).

Selected Discharge Measurements

Data from selected historical discharge measurements were compiled for the six USGS streamflow-gaging stations on the Potomac River in the vicinity of the C & O Canal NHP. Twelve to thirteen measurements were selected for each streamflow-gaging station that represented a range of high-flow events. The date of the measurement, the sequential measurement number, gage height, top width, cross-sectional area, mean velocity, maximum velocity, mean depth, and discharge are presented for each selected discharge measurement. If any corresponding flow in the C & O Canal was estimated or measured during the measurement, this value also is presented. The maximum velocity is presented in two ways. The section maximum mean velocity is presented as the maximum mean velocity measured in any measurement subsection along the cross section. When discharge measurements are made, the mean velocity in each measurement subsection is determined as the average of point velocities measured at 0.2 and 0.8 of the depth of the subsection at that point, provided that the depth is 2.5 ft or greater at that point. If the depth of the measurement subsection is less than 2.5 ft, the mean velocity for the measurement subsection is determined by measuring a point velocity at 0.6 of the depth of the subsection at that point. The section maximum point velocity is presented as the maximum point velocity measured at any point in any measurement subsection along the cross section. Tables 3 through 8 summarize selected discharge-measurement data for high flows at the six USGS streamflow-gaging stations on the Potomac River in the vicinity of the C & O Canal NHP.

Table 1. Basic data for Potomac River streamflow-gaging stations in the vicinity of the Chesapeake and Ohio Canal National Historical Park
[°= degrees, `= minutes,″= seconds; % = percentage]
Station no. Station name and location Latitude
(° ` ″)
Longitude
(° ` ″)
Period of record
(years)
Drainage area at gage
(square miles)
Percentage of total basin drainage area
(%)
Station datum (feet above sea level)
01603000 North Branch Potomac River near Cumberland, Md. 39 37 18 78 46 24 1929 to present 875 6.0 585.22
01610000 Potomac River at Paw Paw, W. Va. 39 32 20 78 27 24 1938 to present 3,109 21.2 487.88
01613000 Potomac River at Hancock Md. 39 41 49 78 10 39 1932 to present 4,073 27.8 383.68
01618000 Potomac River at1 Shepherdstown, W. Va. (a) 39 26 04 77 48 07 1928-53
1964-93
5, 936 40.5 281.00
01638500 Potomac River at Point of Rocks, Md. 39 16 25 77 32 35 1895 to present 9,651 65.8 200.63
01646500 Potomac River at Little Falls near Washington, D.C. 38 56 58 77 07 40 1930 to present 11,560 78.8 37.95
(a)1    Annual maximum discharges were recorded from 1954 to 1964.

The discharge in a uniform-flow channel can be determined by use of the following empirical formula:

Q = (1.49/n) x (A) x (RH)2/3 x (S)1/2

where

Q is the discharge, in cubic feet per second;
n is the dimensionless Manning roughness coefficient, or Manning's n;
A is the cross-sectional area of the channel cross section, in square feet;
RH is the hydraulic radius of the channel cross section, in feet; and
S is the channel-bed slope or the water-surface slope.
Table 2. Peak-flow data and approximate recurrence intervals for Potomac River streamflow-gaging stations in the vicinity of the Chesapeake and Ohio Canal National Historical Park
[An asterisk (*) indicates the peak of record for the gaging stations; > = greater than]
Date of peak Time of peak
(hours)
Peak gage height
(feet)
Peak discharge
(cubic feet per second)
Recurrence interval
(years)
01603000 North Branch Potomac River near Cumberland, Maryland
06/01/1889* Unknown 29.20 89,000 >100
03/17/1936 2330 29.10 88,200 >100
06/23/1972 1800 14.55 17,400 2
11/05/1985 0915 18.85 25,500 4
01/19/1996 1545 25.56 59,200 50
09/07/1996 0515 22.48 42,300 20
01610000 Potomac River at Paw Paw, West Virginia
03/18/1936* 0800-1000 54.00 240,000 >100
06/23/1972 2100 28.83 64,500 5
11/06/1985 2215 53.60 235,000 >100
01/20/1996 1030 40.86 122,000 35
09/07/1996 1830 43.45 140,000 60
01613000 Potomac River at Hancock, Maryland
03/18/1936* 1800 47.60 340,000 >100
06/23/1972 0800 30.79 112,000 8
11/06/1985 0630 41.20 207,000 50
01/20/1996 1515 36.29 152,000 20
09/08/1996 0200 35.81 148,000 20
01618000 Potomac River at Shepherdstown, West Virginia
03/19/1936* 0600 42.10 335,000 >100
06/23/1972 2330 31.58 187,000 25
11/07/1985 0030 31.44 187,000 25
01/1996 Gaging station discontinued
09/1996 Gaging station discontinued
01638500 Potomac River at Point of Rocks, Maryland
03/19/1936* 0930 41.03 480,000 >100
06/23/1972 2330 37.43 347,000 55
11/07/1985 0330 36.28 309,000 35
01/21/1996 0430 36.54 313,000 40
09/08/1996 1500 36.32 310,000 40
01646500 Potomac River at Little Falls near Washington, D.C.
03/19/1936* 1645 28.10 484,000 90
06/24/1972 0330 22.03 359,000 35
06/24/1972 0330 22.03 359,000 35
11/07/1985 1315 18.00 317,000 23
01/21/1996 1230 19.29 347,000 30
09/08/1996 2315 17.84 314,000 23

Figure 2. Flood hydrograph for U.S. Geological Survey streamflow-gaging station 01638500, Potomac River at Point of Rocks, Maryland, during the flood of January 19-21, 1996.

When uniform flow is assumed in an open channel, the longitudinal lines of the channel bed and water surface are parallel to each other, and the slopes of these parallel lines are equal (Hwang and Hita, 1987). If estimates of water-surface slope or channel-bed slope can be made in the vicinity of a streamflow-gaging station, discharge-measurement data can be used to determine an approximate Manning's n value for the measured flow conditions.

Ranges of Manning's n were calculated for the ranges of discharge and flow conditions presented in tables 3 through 8, based on the assumption of uniform flow conditions. The calculations were made using estimates of water-surface slope that were based on previous flood studies (Somervell, 1930), and flood insurance studies (Federal Emergency Management Agency, 1981, 1985, 1989). Where information on water-surface slope was not available, channel-bed slopes were determined by use of USGS topographic maps. These channel-bed slopes were used as an estimate of water-surface slope. The calculated values of Manning's n apply to the entire cross section that was used during the discharge measurement. Insufficient data exist to calculate Manning's n values for flows in the C & O Canal for these discharge measurements. However, approximations can be made using accepted hydraulic design practices. Table 9 summarizes the general ranges of Manning's n values for the selected discharges and flow conditions presented in tables 3 through 8.

Table 9 shows a large range of Manning's n values for the selected flow conditions at most gaging stations. Direct measurements of water-surface slope during discharge measurements could serve to (1) provide a means to directly calculate Manning's n for any discharge measurement, and (2) provide a means to calibrate the ranges of Manning's n values presented in table 9.

Flood-Hydrology Data for Selected Tributaries

Flood-hydrology data were compiled for 10 USGS streamflow-gaging stations on selected tributaries to the Potomac River in the vicinity of the C & O Canal NHP. The streamflow-gaging stations are (1) Station 01601500, Wills Creek near Cumberland, Md.; (2) Station 01608500, South Branch Potomac River near Springfield, W. Va.; (3) Station 01609000, Town Creek near Oldtown, Md.; (4) Station 01610155, Sideling Hill Creek near Bellegrove, Md.; (5) Station 01611500, Cacapon River near Great Cacapon, W. Va.; (6) Station 01614500, Conococheague Creek at Fairview, Md.; (7) Station 01619500, Antietam Creek near Sharpsburg, Md.; (8) Station 01636500, Shenandoah River at Millville, W. Va.; (9) Station 01643000, Monocacy River at Jug Bridge near Frederick, Md.; and (10) Station 01645000, Seneca Creek at Dawsonville, Md. Data compiled for these streamflow-gaging stations include (1) basic data regarding the drainage basin and the station, and (2) peak-flow data and recurrence intervals for the five selected flood events and the peak of record.

Basic Data

Basic data compiled for each of the 10 Potomac River tributary streamflow-gaging stations include the (1) latitude and longitude of the station, (2) period of gage record, (3) drainage area at the station, (4) percentage of the total basin drainage area, and (5) mean sea level (NGVD) datum of the station. This information is listed in table 10.

Peak Flows and Recurrence Intervals

Peak-flow data and approximate recurrence intervals were compiled for the 10 Potomac River tributary streamflow-gaging stations for the five selected flood events and for the peak of record. For some stations, data were not available for some flood events because the station was not in operation at the time of the specified flood event. Peak-flow data and approximate recurrence intervals for the 10 Potomac River tributary streamflow-gaging stations during the specified flood events are shown in table 11. A flood hydrograph for the streamflow-gaging station at Conococheague Creek at Fairview, Md., during the flood of January 19-21, 1996, is shown as an example (Figure 3).

Table 3. Selected discharge-measurement data for high flows at U.S. Geological Survey stream flow-gaging station 01603000, North Branch Potomac River near Cumberland,Maryland [ft = feet; ft2= square feet; ft/s = feet per second; ft3/s= cubic feet per second; --, no data available]
Date Measurement no. Gage height
(ft)
Top width
(ft)
Cross-sectional area
(ft2)
Mean velocity
(ft/s)
Maximum mean velocity
(ft/s)
Maximum point velocity
(ft/s)
Mean depth
(ft)
River discharge
(ft3/s)
C & O Canal discharge
(ft3/2)
02/14/1984 603 14.54 374 3,540 5.08 7.54 7.97 9.47 18,000 --
04/03/1970 464 13.12 247 2,720 5.26 8.00 8.90 11.01 14,300 --
03/07/1967 428 18.59 399 4,730 5.41 9.30 9.89 11.85 25,600 --
04/30/1964 376 13.37 249 2,770 5.52 8.16 9.07 11.12 15,300 --
05/09/1960 328 13.84 303 3,180 4.87 7.88 8.68 10.50 15,900a --
05/06/1958 304 14.08 240 2,940 5.14 7.62 8.71 12.25 15,100 --
08/19/1955 275 22.24 302 4,840 5.99 9.78 10.16 16.03 32,200a --
12/30/1954 266 13.70 303 3,000 4.83 7.02 7.57 9.90 14,500 --
06/14/1951 221 14.53 237 3,070 5.10 8.02 8.99 12.95 15,400 --
04/27/1937 58 17.14 382 4,230 4.92 8.62 8.95 11.07 20,800a --
05/13/1932 25 15.40 382 3,700 4.98 7.32 8.04 9.69 18,400a --
05/12/1932 24 14.26 382 3,320 4.92 8.57 8.57 8.69 16,300a --

a   Discharge adjusted for rapidly changing stage during measurement.

Table 4. Selected discharge-measurement data for high flows at U.S. Geological Survey streamflow-gaging station 01610000, Potomac River at Paw Paw, West Virginia [ft =feet; ft2 = square feet; ft/s = feet per second; ft3/s = cubic feet per second;--, no data available]
Date Measurement no. Gage height
(ft)
Top width
(ft)
Cross-sectional area
(ft2)
Mean velocity
(ft/s)
Maximum mean velocity
(ft/s)
Maximum point velocity
(ft/s)
Mean depth
(ft)
River discharge
(ft3/s)
C & O Canal discharge
(ft3/2)
08/01/1996 364 18.85 330 4,820 6.58 8.72 9.46 14.64 31,700 --
02/23/1971 264 22.10 414 6,730 6.29 9.54 10.61 16.26 42,300 --
04/30/1964 210 23.21 540 7,270 6.12 9.21 10.36 13.46 44,500 --
02/26/1961 193 24.80 531 7,770 6.73 10.86 11.10 14.63 52,300 --
08/19/1955 161 34.40 557 12,600 6.68 11.22 13.00 2.62 84,200 --
03/23/1955 156 21.42 414 5,830 6.24 8.68 10.34 4.08 36,400 --
06/14/1951 120 25.17 345 6,884 7.33 9.96 11.34 19.95 50,400 --
12/08/1950 116 24.13 337 6,617 7.31 9.78 11.11 19.64 48,400 --
06/19/1949 97 32.13 549 11,470 6.65 11.20 12.46 20.89 76,300 --
05/17/1942 34 17.96 328 4,760 5.58 7.42 8.77 14.50 26,500 --
02/04/1939 13 28.72 351 9,436 6.96 13.61 13.61 26.90 65,700 --
01/31/1939 8 19.10 378 5,481 5.54 7.76 8.91 14.50 30,400a --

a   Discharge adjusted for rapidly changing stage during measurement.

Table 5. Selected discharge-measurement data for high flows at U.S. Geological Survey streamflow-gaging station 01613000, Potomac River at Hancock, Maryland [ft = feet;ft2 = square feet; ft/s = feet per second, ft3/s= cubic feet per second; --, no data available]
Date Measurement no. Gage height
(ft)
Top Width
(ft)
Cross-sectional area
(ft2)
Mean velocity
(ft/s)
Maximum mean velocity
(ft/s)
Maximum point velocity
(ft/s)
Mean depth
(ft)
River discharge
(ft3/s)
C & O Canal discharge
(ft3/s)
03/21/1996 402 15.34 623 8,210 4.20 5.78 7.26 13.18 34,500a --
04/26/1983 360 18.13 600 8,850 4.78 7.88 8.54 14.75 42,300a --
02/23/1971 305 19.41 490 9,100 5.25 8.40 8.78 18.57 47,800 --
03/08/1967 280 26.54 1,350 16,500 5.06 10.25 10.97 12.22 83,500 --
05/10/1960 231 17.76 635 9,040 3.99 7.30 7.95 14.24 38,300a --
04/06/1960 230 19.87 631 10,050 4.43 7.96 8.87 15.93 44,500a --
08/20/1955 202 24.71 830 11,100 5.33 8.58 13.60 13.37 67,800 --
10/17/1954 192 24.92 1,005 15,600 3.85 7.31 9.23 15.52 68,300 --
06/14/1951 160 23.59 685 11,100 5.99 9.72 10.27 16.20 66,500 --
10/16/1942 67 36.27 1,380 30,200 5.03 11.89 12.15 21.88 153,300 100
10/30/1937 37 17.39 675 9,110 4.40 6.73 7.55 13.50 40,100a --
10/30/1937 36 21.66 736 11,100 5.34 8.53 8.78 15.08 59,300 0
10/29/1937 35 31.35 762 19,600 6.07 10.70 11.07 25.72 119,000 50b

a Discharge measured by use of horizontal angle coefficients.
b Estimated discharge.

Table 6. Selected discharge-measurement data for high flows at U.S. Geological Survey streamflow-gaging station 01618000, Potomac River at Shepherdstown, West Virginia [ft= feet; ft2 = square feet; ft/s = feet per second, ft3/s= cubic feet per second;--, no data available]
Date Measurement no. Gage height
(ft)
Top Width
(ft)
Cross-sectional area
(ft2)
Mean velocity
(ft/s)
Maximum mean velocity
(ft/s)
Maximum point velocity
(ft/s)
Mean depth
(ft)
River discharge
(ft3/s)
C & O Canal discharge
(ft3/s)
03/18/1982 316 14.70 640 10,600 4.76 5.87 6.54 16.56 50,400 --
03/15/1978 297 18.02 670 12,600 6.06 7.61 8.17 18.81 76,400 --
02/24/1971 273 16.88 680 12,400 5.49 7.10 7.26 18.24 68,100 --
03/07/1963 220 19.17 673 12,900 6.19 7.40 7.79 19.17 79,800 --
10/17/1954 219 21.97 673 14,800 6.73 8.32 8.82 21.99 99,700 80
06/14/1951 198 17.84 700 12,300 6.04 7.36 7.52 17.57 72,800a --
12/31/1942 111 21.17 758 15,000 6.66 8.04 8.61 19.79 99,900 50
10/17/1942 108 27.52 850 20,700 7.15 9.37 10.17 24.35 148,000 --
10/16/1942 106 32.54 880 25,300 7.63 11.90 12.29 28.75 193,000 --
05/14/1932 31 23.81 566 15,000 7.27 10.20 11.81 26.50 108,000 50b
04/18/1929 8 18.14 563 11,800 5.95 10.16 10.21 20.96 70,200 --
04/18/1929 7 21.70 567 14,100 6.71 11.18 11.50 24.87 98,600 --

a Discharge adjusted for rapidly changing stage during measurement.
b Estimated discharge.

Table 7. Selected discharge-measurement data for high flows at U.S. Geological Survey streamflow-gaging station 01638500, Potomac River at Point of Rocks, Maryland [ft= feet; ft2 =square feet; ft/s = feet per second, ft3/s= cubic feet per second;--, no data available]
Date Measurement no. Gage height
(ft)
Top Width
(ft)
Cross-sectional area
(ft2)
Mean velocity
(ft/s)
Maximum mean velocity
(ft/s)
Maximum point velocity
(ft/s)
Mean depth
(ft)
River discharge
(ft3/s)
C & O Canal discharge
(ft3/s)
03/06/1993 355 23.99 1,464 30,300 4.92 7.80 8.17 20.73 149,000 --
02/16/1984 342 26.00 1,434 32,900 5.26 8.35 9.89 22.97 173,000 --
10/10/1976 324 25.10 1,451 32,642 4.99 8.82 9.46 22.50 163,000 --
09/27/1975 319 23.55 1,362 29,300 4.11 6.41 7.33 21.49 120,300 --
06/23/1972 311 36.49 1,564 48,200 5.98 10.26 11.53 30.80 288,000 --
08/20/1955 246 28.73 1,462 37,500 5.55 9.56 11.25 25.64 208,000 --
06/15/1951 219 17.47 1,255 20,400 5.00 7.68 8.53 16.26 102,000 --
10/18/1942 133 19.46 1,355 24,800 4.40 6.44 8.22 18.28 109,000 --
10/17/1942 132 35.24 1,565 47,700 6.12 11.28 11.66 30.50 292,000 --
04/28/1937 103 -- 1,543 38,300 6.08 10.59 10.59 24.82 233,000a 315
05/14/1932 87 22.36 1,255 27,600 5.25 9.04 11.02 21.96 145,000 241
03/30/1924 65 19.90 1,260 25,300 5.24 10.08 10.08 20.06 132,500 --

a Measurement was made at Brunswick, Maryland. Gage height and discharge at Point of Rocks were 30.50 ft and 244,000 ft3/s. Discharge for Point of Rocks was determined by correcting measured discharge for storage and inflow between Brunswick and Point of Rocks.

Table 8. Selected discharge-measurement data for high flows at U.S. Geological Survey streamflow-gaging station 01646500, Potomac River at Little Falls near Washington, D.C.[ft = feet, ft2 = square feet; ft/s = feet per second, ft3/s= cubic feet per second; --, no data available; Note: All measurements were made at the 14th Street Bridge, Washington, D.C., except for measurement 326, which was made at the Key Bridge, Washington, D.C.]
Date Measurement no. Gage height
(ft)
Top Width
(ft)
Cross-sectional area
(ft2)
Mean velocity
(ft/s)
Maximum mean velocity
(ft/s)
Maximum point velocity
(ft/s)
Mean depth
(ft)
River discharge
(ft3/s)
C & O Canal discharge
(ft3/s)
09/09/1996 330 15.75 2,195 45,200 6.12 8.09 9.07 20.60 271,000 --
09/09/1996 330 15.75 2,195 45,200 6.12 8.09 9.07 20.60 271,000 --
03/06/1993 326 12.10 940 26,700 6.85 8.98 9.46 28.40 183,000 --
11/07/1985 316 17.95 2,153 47,700 6.45 9.27 10.36 22.16 308,000 --
02/27/1979 307 12.94 2,022 46,000 4.51 7.36 8.17 22.75 204,900 --
09/27/1975 289 13.17 2,024 40,100 4.86 8.25 9.07 19.81 194,700 --
06/24/1972 285 21.58 2,260 48,440 7.18 11.56 11.93 21.43 348,000 --
06/22/1972 284 13.58 2,108 38,030 4.89 7.02 7.85 18.04 186,000 --
10/18/1942 56 17.25 1,976 44,100 4.78 7.33 -- 22.32 210,800 --
10/17/1942 55 25.64 2,058 54,920 7.20 9.81 -- 26.69 394,200 --
03/23/1936 26 10.07 2,047 36,600 2.50 3.44 4.08 17.88 87,200 --
03/21/1936 25 11.90 2,058 38,900 2.99 4.26 5.16 18.90 122,500 --
03/20/1936 24 22.10 2,149 50,000 6.52 10.52 10.74 23.27 314,000 --
03/19/1936 23 27.75 2,145 53,000 8.83 13.48 13.67 24.71 473,000 --
Table 9. Calculated ranges of Manning's roughness coefficient values for selected discharges and flow conditions at Potomac River streamflow-gaging stations
Station no. Station name and location Manning's roughness coefficient range
01603000 North Branch Potomac River near Cumberland, Md. 0.035-0.043
01610000 Potomac River at Paw Paw, W. Va. 0.033-0.045
01613000 Potomac River at Hancock, Md. 0.032-0.051
01618000 Potomac River at Shepherdstown, W.Va. 0.031-0.039
01638500 Potomac River at Point of Rocks, Md. 0.036-0.052
01646500 Potomac River at Little Falls near Washington, D.C. 0.021-0.047
Table 10. Basic data for streamflow-gaging stations on tributaries to the Potomac River in the vicinity of the Chesapeake and Ohio Canal National Historical Park [°= degrees, `= minutes, ″= seconds; % = percentage]
Station no. Station name and location Latitude
(° ′ ″)
Longitude
(° ′ ″)
Period of Record
(years)
Drainage area at gage
(square miles)
Percentage of total basin drainage area (%) Station datum (feet above sea level)
01601500 Wills Creek near
Cumberland, Md.
39 40 07 78 47 18 1905 to 1906,
1929 to present
247 97.2 640.89
01608500 South Branch
Potomac River near
Springfield, W. Va.
39 26 49 78 39 16 1894 to 1896,
1899 to 1902,
1903 to 1906,
1928 to present
1,471 98.9 562.02
01609000 Town Creek near
Oldtown, Md.
39 33 12 78 33 19 1928 to 1935,
1967 to 1981
148 94.9 547.97
01610155 Sideling Hill Creek
near Bellegrove, Md.
39 38 58 78 20 40 1967 to 1977 102 98.5 440.41
01611500 Cacapon River near
Great Cacapon, W. Va.
39 34 43 78 18 34 1922 to 1995 677 99.4 456.78
01614500 Conococheague Creek
at Fairview, Md.
39 42 57 77 49 28 1928 to present 494 87.7 391.85
01619500 Antietam Creek near
Sharpsburg, Md.
39 27 01 77 43 52 1897 to 1905,
1928 to present
281 96.2 311.05
01636500 Shenandoah River at
Millville, W. Va.
39 16 55 77 47 22 1895 to 1909
1928 to present
3,040 99.5 293.00
01643000 Monocacy River at
Jug Bridge near
Frederick, Md.
39 24 13 77 21 58 1929 to present 817 84.2 231.92
01645000 Seneca Creek at
Dawsonville, Md.
39 07 41 77 20 13 1930 to present 101 78.3 214.02
Table 11. Peak-flow data and approximate recurrence intervals for selected streamflow-gaging stations on tributaries to the Potomac River in the vicinity of the Chesapeake and Ohio Canal National Historical Park [An asterisk (*) indicates the peak of record for the gaging stations; > = greater than]
Date of peak Time of peak
(hours)
Peak gage height
(feet)
Peak discharge
(cubic feet per second)
Recurrence interval
(years)
01601500 Wills Creek near Cumberland, Maryland
03/17/1936 2300 20.20 38,100 >100
06/23/1972 1245 10.06 11,300 7
11/05/1985 0830 9.10 8,970 4
01/19/1996* 1330 22.58 44,500 >100
09/07/1996 0000 11.54 14,900 13
01608500 South Branch Potomac River near Springfield, West Virginia
03/18/1936 0530 34.20 143,000 100
06/23/1972 1600 17.87 31,500 3
11/05/1985 * Unknown 44.22 240,000 >100
01/20/1996 0430 28.36 93,500 50
09/07/1996 1000 34.99 147,000 >100
01609000 Town Creek near Oldtown, Maryland
03/17/1936 * 2400 19.08 27,000 >100
06/22/1972 1515 14.13 11,700 30
11/1985 Gaging station discontinued
01/1996 Gaging station discontinued
09/1996 Gaging station discontinued
01610155 Sideling Hill Creek near Bellegrove, Maryland
03/1936 Gaging station not yet in operation
06/22/1972 * 0915 12.44 14,200 100
11/1985 Gaging station discontinued
01/1996 Gaging station discontinued
09/1996 Gaging station discontinued
01611500 Cacapon River near Great Cacapon, West Virginia
03/18/1936 * 0800 30.10 87,600 >100
06/22/1972 2300 22.17 45,500 20
11/05/1985 2330 21.95 44,500 20
01/1996 Gaging station discontinued
09/1996 Gaging station discontinued
01614500 Conococheague Creek at Fairview, Maryland
03/18/1936 0500 13.27 13,700 10
06/23/1972 * 1700 24.50 32,400 >100
11/05/1985 1445 7.92 4,760 1
01/20/1996 0430 14.49 15,300 20
09/07/1996 0915 10.32 7,970 2
01619500 Antietam Creek near Sharpsburg, Maryland
03/18/1936 1400 8.88 3,930 4
07/20/1956 * 1700 16.73 12,600 80
06/23/1972 1400 14.30 9,880 40
11/05/1985 0445 4.93 1,210 1
01/19/1996 1500 13.71 8,960 25
09/06/1996 2145 7.03 2,600 2
01636500 Shenandoah River at Millville, West Virginia
03/18/1936 2030 26.36 151,000 50
10/16/1942 * 1500 32.40 230,000 >100
06/23/1972 1200 21.89 103,000 15
11/06/1985 1900 25.60 142,000 40
01/20/1996 2130 23.61 121,000 25
09/08/1996 0800 26.82 156,000 55
0164300 Monocacy River at Jug Bridge near Frederick, Maryland
03/18/1936 1230 9.95 8,640 1
06/23/1972 * 0600 35.90 81,600 >100
11/05/1985 0830 8.02 5,610 1
01/20/1996 1230 23.67 37,400 15
09/07/1996 2030 17.74 21,600 3
01645000 Seneca Creek at Dawsonville, Maryland
03/18/1936 0230 3.99 820 1
06/22/1972 * 0200 16.40 26,100 100
11/05/1985 0445 4.27 862 1
01/19/1996 2200 10.41 9,290 11
09/07/1996 0415 9.48 6,370 6

Figure 3. Flood hydrograph for U. S. Geological Survey streamflow-gaging station 01614500, Conococheague Creek at Fairview, Maryland during the flood of January 19-21, 1996.

A list of additional USGS streamflow-gaging stations with surface-water data in the vicinity of the C & O Canal NHP also was prepared. This list is shown in the appendix.

Additional Information and Resources

A search was conducted of (1) the libraries of the USGS Maryland-Delaware-D.C. District office and the Interstate Commission on the Potomac River Basin, and (2) original USGS data files, to compile information and resources related to flooding in the Potomac River Basin in the vicinity of the C & O Canal NHP. Records at these locations are among the most complete available. An inventory of significant flood studies and reports pertaining to the Potomac River Basin in the vicinity of the C & O Canal NHP is presented in the following section. USGS indirect flood-discharge measurements that have been made at the six USGS streamflow-gaging stations on the Potomac River in the vicinity of the C & O Canal NHP also are listed. Information on historical streamflow-gaging station records and discharge measurements on the C & O Canal is summarized.

Flood Studies and Reports

The following inventory of flood studies and reports on the Potomac River Basin in the vicinity of the C & O Canal NHP is sorted by category. Report categories include (1) USGS Annual Water-Resources Data Reports, (2) USGS Water-Supply Papers, (3) other flood studies and reports, and (4) flood-insurance studies.

USGS Annual Water-Resources Data Reports: The USGS releases an annual water-resources data report for each water year, which runs from October 1st of one year to September 30th of the next. For example, October 1, 1996 to September 1, 1997 is referred to as "Water Year 1997". These reports have been published for Maryland and West Virginia on a yearly basis since 1961. The reports summarize flow conditions at all active USGS streamflow-gaging stations for the given water year. This includes such information as mean daily discharges for each day of the water year, mean annual discharge, and the instantaneous peak gage height and discharge at each streamflow-gaging station for the given water year (U.S. Geological Survey, 1961-95).

USGS Water-Supply Papers: Prior to 1961, USGS streamflow-gaging station records were published as part of a report series entitled "Water-Supply Papers." Water-Supply Papers are publications that are intended to present significant interpretive results of hydrologic investigations that are broader than local interest. Specific Water-Supply Papers (WSP) that were used in the preparation of this report include:

  1. WSP 800, The Floods of March, 1936, Part III, Potomac, James, and Upper Ohio Rivers (Grover, 1937).
  2. WSP 971, Surface Water Supply of the United States, 1943, part 1B, North Atlantic Slope Basins, New York to York River (Parker and others, 1945).
  3. WSP 1302, Compilation of Records of Surface Waters of the United States through September, 1950, part 1B, North Atlantic Slope Basins, New York to York River (Wells and others, 1960).
  4. WSP 1432, Surface Water Supply of the United States, 1956, part 1B, North Atlantic Slope Basins, New York to York River (Wells and others, 1959).
  5. WSP 1672, Magnitude and Frequency of Floods in the United States, part 1B, North Atlantic Slope Basins, New York to York River (Tice, 1968).
  6. WSP 1722, Compilation of Records of Surface Waters of the United States, October 1950 to September 1960, part 1B, North Atlantic Slope Basins, New York to York River (Hendricks and others, 1964).

Other Flood Studies and Reports: Often studies are conducted and reports are prepared in the aftermath of major floods. These studies and reports usually document peak gage heights and peak discharges for streamflow-gaging stations during a specific flood event. Some studies and reports may present estimated flood profiles for specific flood events or for flood events of a certain magnitude or frequency. Others may contain descriptive material about specific flood events. The subjects and authors of notable studies and reports related to flooding in the Potomac River Basin in the vicinity of the C & O Canal NHP are listed below in chronological order.

  1. Development of Great Falls for Water Power and Increase of Water Supply for the District of Columbia (U.S. Army Corps of Engineers, 1921).
  2. Report to the Chief of Engineers, U.S. Army on the Potomac River and its Tributaries, Including Occoquan Creek (Somervell, 1930).
  3. Floods of 1936 and 1937 (Pennsylvania Railroad Company, 1937).
  4. Flow Data and Draft Storage Curves for Major Streams, 1929-1937 (Maryland Water Resources Commission, State Planning Commission, 1940).
  5. Storm and Flood of October 16, 17, 18, 1942 (U.S. Army Corps of Engineers, 1942).
  6. Joint Reconnaissance Survey and Study of the Chesapeake and Ohio Canal, Between Great Falls, Maryland and Cumberland, Maryland (Bureau of Public Roads and National Park Service, 1950).
  7. Storms and Floods of August, 1955 (U.S. Army Corps of Engineers, 1955).
  8. The Water Resources of Carroll and Frederick Counties (Beall and Meyer, 1958).
  9. Maryland Streamflow Characteristics; Flood Frequency, Low Flow Frequency, and Flow Duration (Darling, 1962).
  10. Tropical Storm Agnes--June, 1972, Basins of the Susquehanna and Potomac Rivers and Maryland Portions of Chesapeake Bay and Atlantic Coast, Post Flood Report, Volume 1, Meteorology and Hydrology (Prepared by Gannett, Fleming, Corddry, and Carpenter Engineers for the U.S. Army Corps of Engineers, Baltimore District, 1974).
  11. Flood Plain Information, Frederick County, Potomac River, Maryland (U.S. Army Corps of Engineers, 1975).
  12. USGS Professional Paper 924, Hurricane Agnes Rainfall and Floods, June-July, 1972 (Bailey and others, 1975).
  13. Historic Structure Report, Chesapeake and Ohio Canal Dam Number 2 and Associated Structures (Unrau, 1976a).
  14. The Major Floods of the Potomac River and Their Effect on the Chesapeake and Ohio Canal: 1828-1936 (Unrau, 1976b).
  15. Tropical Storm Eloise, September, 1975, Susquehanna and Potomac River Basins, Post Flood Report (U.S. Army Corps of Engineers, 1976).
  16. Flood Plain Information, Washington County, Potomac River, Maryland, Part 1, (U.S. Army Corps of Engineers, 1977).
  17. Floodplain Reconnaissance Study, November 1985 Flood, Potomac River Basin (Scatena, 1986).
  18. USGS Open-File Report 86-486, Flood of November, 1985 in West Virginia, Pennsylvania, Maryland, and Virginia (Lescinsky, 1987).
  19. USGS Water-Resources Investigations Report 88-4213, Floods in West Virginia, Virginia, Pennsylvania, and Maryland, November 1985 (Carpenter, 1988).
  20. C & O Canal: The Making of a Park (MacKintosh, 1991).

Most of these studies and reports provide hydrologic data, peak-flow data or descriptive information for certain flood events. A few of the U.S. Army Corps of Engineers' publications provide flood profiles for certain flood events or cross sections of the Potomac River in various locations.

Flood-Insurance Studies: The Federal Emergency Management Agency (FEMA) publishes flood-insurance studies for Maryland counties and some specific towns and communities along the Potomac River. The reports for these studies contain various hydrologic and hydraulic data for streams and rivers within the study area. Cross-sectional data are usually obtained from USGS topographic maps or from field surveys. Hydraulic data and flood profiles are usually determined by use of step-backwater hydraulic modeling. Most FEMA flood-insurance studies present drainage areas, peak-flow data, and recurrence-interval information, as of the most recent date that the information was updated. Channel widths, cross-sectional areas, and mean velocities are presented for different segments of each stream or river that is studied. Flood profiles are presented for each stream or river that is studied for the 10-year, 50-year, 100-year, and 500-year recurrence intervals.

FEMA flood-insurance studies for counties and towns in the vicinity of the C & O Canal NHP include the Town of Hancock, Md. (FEMA, 1981), the City of Cumberland, Md. (FEMA, 1983), the District of Columbia (FEMA, 1985), and Allegany County, Md. (FEMA, 1989). These reports contain data and flood profiles for the North Branch Potomac River and Potomac River. Reports are available for Frederick County, Md. (FEMA, 1991), Washington County, Md. (FEMA, 1992a), and Montgomery County, Md. (FEMA, 1992b), but data and flood profiles for the Potomac River are not included in these reports. A flood-insurance report was published for the Town of Williamsport, Md. (U.S. Department of Housing and Urban Development, Federal Insurance Administration, 1976), but was not available for review.

Indirect Flood-Discharge Measurements

The discharge of streams and rivers is usually measured directly using a current meter. During floods, however, it is sometimes impossible or impractical to measure the discharge by this method. Consequently, some peak discharges must be determined after the passage of the flood by indirect methods, such as slope-area, contracted-opening, flow-over-dam, and flow-through-culvert, rather than by direct current-meter measurement (Benson and Dalrymple, 1967).

Indirect methods of determining flood discharge are based on hydraulic equations which relate the discharge to the water-surface profile and geometry of the channel. A field survey is made after the flood to determine the location of high-water marks and the physical characteristics of the channel (Benson and Dalrymple, 1967). Hydraulic equations that are most appropriate for the study reach are then solved based on the field data to determine the peak discharge for the study reach.

Indirect flood-discharge measurements can provide information such as (1) records of high- water marks, (2) cross-section geometry and diagrams, (3) estimates of Manning's n, and (4) calculations of water-surface slopes. The data files of the USGS Maryland-Delaware-D.C. District were searched to inventory indirect flood-discharge measurements that have been made at the six USGS streamflow-gaging stations on the Potomac River in the vicinity of the C & O Canal NHP. The results of the search are listed below.

Station 01603000, North Branch Potomac River near Cumberland, Md.--An indirect measurement of peak discharge was made for the flood of March 17-19, 1936. The peak discharge was determined to be 88,200 ft3/s, including documentation of flow in the overbank areas.

Station 0161000, Potomac River at Paw Paw, W. Va.--An indirect measurement of peak discharge was made for the flood of March 17-19, 1936. The peak discharge was determined to be 240,000 ft3/s, including documentation of flow in the overbank areas and the C & O Canal. The results indicated that a peak discharge of approximately 3,000 ft3/s was carried in the C & O Canal for this event.

Station 01613000, Potomac River at Hancock, Md.--An indirect measurement of peak discharge was made for the flood of March 17-19, 1936. The peak discharge was determined to be 340,000 ft 3s, including documentation of flow in the overbank areas and the C & O Canal. The results indicated that a peak discharge of approximately 1,700 ft3s was carried in the C & O Canal for this event.

An indirect measurement of peak discharge was also made for the flood of April 27, 1937. The peak discharge was determined to be 153,000 ft3s, including documentation of flow in the overbank areas. The flow for this event did not overtop the C & O Canal as it did in March 1936. However, the water surface at the peak was nearly level with the top of the towpath.

Station 01618000, Potomac River at Shepherdstown, W. Va.--High watermarks were documented for the flood of April 27, 1937. An indirect measurement of peak discharge was made for the flood of October 16-18, 1942. The results indicated a peak discharge of 190,000 ft3s, including documentation of flow in the overbank areas and the C & O Canal. Estimates of flow in the C & O Canal ranged from 1,280 ft3/s to 1,780 ft3/s depending on the location and hydraulic characteristics of the measured cross sections.

Station 01638500, Potomac River at Point of Rocks, Md.--An indirect measurement of peak discharge was made for the flood of March 17-19, 1936. The peak discharge was determined to be 480,000 ft3/s, including documentation of flow in the overbank areas and the C & O Canal. Estimates of flow in the C & O Canal ranged from 1,700 ft3/s to 3,630 ft3/s depending on the location and hydraulic characteristics of the measured cross sections.

Streamflow-Gaging Stations on the Chesapeake and Ohio Canal

The USGS previously operated two streamflow-gaging stations on the C & O Canal. Streamflow-gaging station 01602000, on the C & O Canal at Cumberland, Md., was in operation from October 1929 to September 1934. Streamflow-gaging station 01620000, on the C & O Canal at Point of Rocks, Md., was in operation from August 1931 to November 1935.

Data and related information that are available for these streamflow-gaging stations include (1) mean daily discharges, (2) summaries of discharge measurements, (3) rating curves and tables of gage height versus discharge that were valid during the period of record, and (4) descriptions of the stations and their locations. The maximum known discharge and gage height during the period of record for the streamflow-gaging station on the C & O Canal at Cumberland, Md., was 104 ft3/s at a gage height of 9.85 ft on May 16, 1930. This maximum discharge did not occur during a flood event on the North Branch Potomac River. The maximum known discharge and gage height during the period of record for the streamflow-gaging station on the C & O Canal at Point of Rocks, Md., was 146 ft3/s at a gage height of 2.64 ft (approximately 227.64 ft above sea level) on May 13, 1932. This maximum discharge occurred during a flood event on the Potomac River during May 13 and 14, 1932. The peak discharge and gage height at streamflow-gaging station 01638500 (Potomac River at Point of Rocks) were 158,000 ft3/s and 23.34 ft (223.97 ft above sea level), respectively. The recurrence interval for this flood event was approximately 5 years.

Other Discharge Measurements on the Chesapeake and Ohio Canal

Between 1923 and 1995, over 250 discharge measurements were made on the C & O Canal at several locations. Many of these discharge measurements were made in the vicinity of the Potomac River at Chain Bridge because the C & O Canal diverts flow from the Potomac River at this location. Since discharge measurements for station 01646500, Potomac River at Little Falls near Washington, D.C., are often made at Chain Bridge, the diversion of flow from the Potomac River requires an estimate or measurement of flow in the C & O Canal at this location to obtain the total discharge. Other locations where discharge measurements have been made on the C & O Canal include Cumberland, Md.; Hancock, Md.; Harpers Ferry, W. Va.; and Brunswick, Md. These discharge measurements document the same types of data variables that were presented for the Potomac River streamflow-gaging stations in tables 3 through 8, including the channel width, cross-sectional area, mean and maximum velocities, and discharge.

Summary

This report presents flood-hydrology data for the Potomac River and selected tributaries in the vicinity of the Chesapeake and Ohio Canal National Historical Park. Data were compiled for selected flood events at 6 USGS streamflow-gaging stations on the Potomac River and 10 streamflow-gaging stations on selected tributaries to the Potomac River. Peak discharge, peak gage height, the date and time of the peak, and approximate recurrence interval are presented for each flood event at these streamflow-gaging stations.

Data compiled from selected high-flow discharge measurements on the six Potomac River streamflow-gaging stations are presented. The gage height, top width, cross-sectional area, mean velocity, maximum velocity, and discharge are presented for each selected discharge measurement. Any corresponding discharge on the C & O Canal that was measured or estimated for these discharge measurements is presented. Ranges of Manning's n were computed for the range of selected discharge measurements based on estimates of water-surface slope or the channel-bed slope.

An inventory of flood studies, reports, and additional USGS data collected along the Potomac River and the C & O Canal NHP is also presented. Included are (1) a listing of selected flood studies and reports, and (2) a listing of USGS indirect flood-discharge measurements that have been made at the six Potomac River streamflow-gaging stations in the vicinity of the C & O Canal NHP. Information on historical streamflow-gaging station records and discharge measurements on the C & O Canal is also presented.

References Cited

Bailey, J.F., Patterson, J.L., and Paulhus, J.L.H., 1975, Hurricane Agnes rainfall and floods, June-July 1972: U.S. Geological Survey Professional Paper 924, 403 p.

Beall, R.M., and Meyer, Gerald., 1958, The water resources of Carroll and Frederick Counties: State of Maryland, Board of Natural Resources, Department of Geology, Mines, and Water Resources, Bulletin 22, 355 p.

Benson, M.A., and Dalrymple, Tate, 1967, General field and office procedures for indirect discharge measurements: U.S. Geological Survey Techniques of Water-Resources Investigations, book 3, chap. A1, 30 p.

Bureau of Public Roads and National Park Service, 1950, Joint reconnaissance survey and study of the Chesapeake and Ohio Canal, between Great Falls, Maryland, and Cumberland, Maryland: Washington, D.C., House Document No. 687, 81st Congress, 2nd Session, 87 p.

Carpenter, D.H., 1988, Floods in West Virginia, Virginia, Pennsylvania, and Maryland, November 1985: U.S. Geological Survey Water-Resources Investigations Report 88-4213, 86 p.

Darling, J.M., 1962, Maryland streamflow characteristics: Flood frequency, low flow frequency, and flow duration: State of Maryland, Board of Natural Resources, Department of Geology, Mines and Water Resources, Bulletin 25, 136 p.

Dillow, J.J. A., 1996, Technique for estimating magnitude and frequency of peak flows in Maryland: U.S. Geological Survey Water-Resources Investigations Report 95-4154, 55 p.

Federal Emergency Management Agency, 1981, Flood insurance study, Town of Hancock, Maryland, Washington County: Federal Emergency Management Agency, Washington, D.C., 15 p.

_____ 1983, Flood insurance study, City of Cumberland, Maryland, Allegany County: Federal Emergency Management Agency, Washington, D.C., 35 p.

_____ 1985, Flood insurance study, District of Columbia: Federal Emergency Management Agency, Washington D.C., 23 p.

_____ 1989, Flood insurance study, Allegany County, Maryland, Unincorporated areas, Volume 1 of 2: Federal Emergency Management Agency, Washington D.C., 48 p.

_____ 1991, Flood insurance study, Frederick County, Maryland, Unincorporated areas: Federal Emergency Management Agency, Washington D.C., 56 p.

_____ 1992a, Flood insurance study, Washington County, Maryland, Unincorporated areas: Federal Emergency Management Agency, Washington D.C., 67 p.

_____ 1992b, Flood insurance study, Montgomery County, Maryland, Unincorporated areas, Volume 1 of 6: Federal Emergency Management Agency, Washington D.C., 155 p.

Gannett, Fleming, Corddry, and Carpenter Engineers, 1974, Tropical Storm Agnes, June 1972, Basins of the Susquehanna and Potomac Rivers and Maryland portions of Chesapeake Bay and Atlantic Coast, Post flood report, Volume 1, Meteorology and hydrology: Consultant's report prepared for the U.S. Army Corps of Engineers, Baltimore District, Harrisburg, Pa., 64 p.

Grover, N.C., 1937, The floods of March 1936; Part 3; Potomac, James, and Upper Ohio Rivers: U.S. Geological Survey Water-Supply Paper 800, 351 p.

Hendricks, E.L., and others, 1964, Compilation of records of surface waters of the United States, October 1950 to September 1960, Part 1-B, North Atlantic slope basins, New York to York River: U.S. Geological Survey Water-Supply Paper 1722, p. 451-546.

Hwang, N.H.C., and Hita, C.E., 1987, Fundamentals of hydraulic engineering systems: Englewood Cliffs, N.J., Prentice-Hall, Inc., 370 p.

Interagency Advisory Committee on Water Data, 1982, Guidelines for determining flood flow frequency: Water Resources Council Bulletin 17B, 28 p.

Lescinsky, J.B., 1987, Flood of November 1985 in West Virginia, Pennsylvania, Maryland, and Virginia: U.S. Geological Survey Open-File Report 86-486, 33 p.

MacKintosh, Barry, 1991, C & O Canal: The Making of a Park: Washington D.C., History Division, National Park Service, U.S. Department of the Interior, 208 p.

Maryland Water Resources Commission, State Planning Commission, 1940, Flow data and draft storage curves for major streams, 1929-1937: Baltimore, Md., The Johns Hopkins University, 136 p.

Parker, G.L., and others, 1945, Surface water supply of the United States, 1943, Part 1, North Atlantic slope basins, New York to York River: U.S. Geological Survey Water-Supply Paper 971, p. 538-585.

Pennsylvania Railroad Company, 1937, Floods of 1936 and 1937: Philadelphia, Pa., Cuneo Eastern Press, 150 p.

Scatena, F.N., 1986, Floodplain reconnaissance study, November 1985 flood, Potomac River Basin: Baltimore, Md., The Johns Hopkins University, 45 p.

Somervell, Brehon, 1930, Report to the Chief of Engineers, U.S. Army, on the Potomac River and its tributaries including Occoquan Creek, Volume 2, Section 2: United States Engineer Office, Washington, D.C., 178 p.

Taylor, K.R., James, R.W., Jr., and Helinsky, B.M., 1984, Travel time and dispersion in the Potomac River, Cumberland, Maryland, to Washington, D.C.: U.S. Geological Survey Open-File Report 83-861, 55 p.

Tice, R.H., 1968, Magnitude and frequency of floods in the United States, Part 1-B, North Atlantic slope basins, New York to York River: U.S. Geological Survey Water-Supply Paper 1672, 585 p.

U.S. Army Corps of Engineers, 1921, Development of Great Falls for water power and increase of water supply for the District of Columbia: Government Printing Office, Washington, D.C., 179 p.

______ 1942, Storm and flood of October 16, 17, 18, 1942: Office of the District Engineer, U.S. Army Corps of Engineers, Washington, D.C., 18 p.

_____ 1955, Storms and floods of August 1955: Office of the District Engineer, U.S. Army Corps of Engineers, Washington, D.C., 14 p.

_____ 1975, Flood plain information, Frederick County, Potomac River, Maryland: U.S. Army Corps of Engineers, Baltimore District, Baltimore, Md., 22 p.

_____ 1976, Tropical Storm Eloise, September 1975, Susquehanna and Potomac River Basins post flood report: U.S. Army Corps of Engineers, Baltimore District, Baltimore, Md., 40 p.

_____1977, Flood plain information, Washington County, Potomac River, Maryland, Part 1: U.S. Army Corps of Engineers, Baltimore District, Baltimore, Md., 24 p.

U.S. Department of Housing and Urban Development, Federal Insurance Administration, 1976, Flood insurance study, Town of Williamsport, Washington County, Maryland: Washington D.C., variously paged.

U.S. Geological Survey, 1962-65, Surface water records of Maryland and Delaware, water years 1961-64; U.S. Geological Survey Water-Data Reports MD-61 to MD-64 (published annually).

_____ 1966-75, Water resources data for Maryland and Delaware, 1965-74--Part 1. Surface-water records: U.S. Geological Survey Water-Data Reports MD-65-1 to MD-74-1 (published annually).

_____ 1976-89, Water resources data, Maryland and Delaware, water years 1975-88; U.S. Geological Survey Water-Data Reports MD-75-1 to MD-88-1 (published annually).

_____ 1990-91, Water resources data, Maryland and Delaware, water years 1989-90, Volumes 1 and 2; U.S. Geological Survey Water-Data Reports MD-DE-89 to MD-DE-90 (published annually).

_____ 1992-96, Water resources data, Maryland and Delaware, water years 1991-95--Volume 1. Surface-water data: U.S. Geological Survey Water-Data Reports MD-DE-91-1 to MD-DE-95-1 (published annually).

Unrau, H.D., 1976a, Historic structure report, Chesapeake and Ohio Canal Dam Number 2 and associated structures: Denver, Co., Historic Preservation Division, National Park Service, Denver Service Center, 84 p.

______ 1976b, The major floods of the Potomac River and their effect on the Chesapeake and Ohio Canal: 1828-1936, Chapter 10; Chesapeake and Ohio Canal National Historical Park Historic Resource Study: Denver, Co., National Park Service, Denver Service Center, 288 p.

Wells, J.V.B., and others, 1959, Surface water supply of the United States, 1956, Part 1-B, North Atlantic slope basins, New York to York River: U.S. Geological Survey Water-Supply Paper 1432, p. 463-557.

Wells, J.V.B., and others, 1960, Compilation of records of surface waters of the United States through September 1950, Part 1-B, North Atlantic slope basins, New York to York River: U.S. Geological Survey Water-Supply Paper 1302, p. 552-648.

Appendix

Appendix: U.S. Geological Survey streamflow-gaging stations with surface-water flow data in the vicinity of the Chesapeake and Ohio Canal National Historical Park
[misc. meas. = miscellaneous measurement]
Station no. Station name and location Period of record Data type
01601500 Wills Creek near Cumberland, Md. 1929-present discharge, other
01602000 Chesapeake and Ohio Canal at Cumberland, Md. 1929-34 discharge
01603000 North Branch Potomac River near Cumberland, Md. 1929-present discharge
01604000 Evitts Creek near Cumberland, Md. 1929-32 discharge, other
01604150 Collier Run at Spring Gap, Md. 1964-74 low flow
 
01605425 Mill Run at Oldtown, Md. 1975-77 low flow
01605475 Seven Springs Run at Oldtown, Md. 1975-81 low flow
01605600 Friends Run near Franklin, W. Va. 1969-77 discharge
01606000 North Fork South Branch Potomac River at Cabins, W. Va. 1940-61 discharge
01607000 Big Spring at Masonville, W. Va. 1946-59 discharge
 
01608050 Fort Run near Moorefield, W. Va. 969-77 discharge
01608400 Buffalo Creek near Romney, W. Va. 1969-77 discharge
01608500 South Branch Potomac River near Springfield, W. Va. 1 1928-present discharge, other
01608975 Maple Run near Town Creek, Md. 1977-78, 80-81 low flow
01609000 Town Creek near Oldtown, Md. 1928-35, 67-81 discharge, other
 
01609500 Sawpit Run near Oldtown, Md. 1948-58 discharge, other
01609800 Little Cacapon River near Levels, W. Va. 1966-77 discharge
01610000 Potomac River at Paw Paw, W. Va. 1938-present discharge
01610030 Potomac River at Magnolia, W. Va. 1958-67 high flow
01610065 Deep Run near Little Orleans, Md. 1975-77 low flow
 
01610075 Fifteen Mile Creek at Little Orleans, Md. 1975-79 low flow
01610155 Sideling Hill Creek near Bellegrove, Md. 1967-77 discharge, other
01610170 Potomac River tributary at Woodmont, Md. 1985-86 low flow
01610200 Lost River at McCauley near Baker, W. Va. 1972-80 discharge
01610300 Cacapon River above Wardensville, W. Va. 1972-73 discharge
 
01610500 Cacapon River at Yellow Spring, W. Va. 1940-52 discharge
01611200 North River at North River Mills, W. Va. 1960-64, 69-70 low flow
01611500 Cacapon River near Great Cacapon, W. Va. 1922-95 discharge
01612500 Little Tonoloway Creek near Hancock, Md. 1947-63 discharge, other
01613000 Potomac River at Hancock, Md. 1932-present discharge, other
 
01613100 Tonoloway Creek at Hancock, Md. 1985-86 low flow
01613150 Ditch Run near Hancock, Md. 1965-86 high flow, low flow
01613160 Potomac River tributary near Hancock, Md. 1965-76 high flow
01613400 Sleepy Creek near Berkeley Springs, W. Va. 1960-64, 70 low flow
01613545 Licking Creek near Pectonville, Md. 1985-86 low flow
 
01614000 Back Creek near Jones Springs, W. Va. 1928-74 discharge
01614050 Little Conococheague Creek near Charlton, Md. 1985-86 low flow
01614500 Conococheague Creek at Fairview, Md. 1928-present discharge
01614625 Meadow Brook at Conococheague, Md. 1976-79, 81-82, 85-86 low flow
01614705 Conococheague Creek at Williamsport, Md. 1985-86 low flow
 
01614850 Potomac River near Falling Waters, W. Va. 1958-67 high flow
01616500 Opequon Creek near Martinsburg, W. Va. 1 1947-present discharge
01617000 Tuscarora Creek above Martinsburg, W. Va. 1949-63, 68-77 discharge
01617600 Downey Branch near Downsville, Md. 1976-79, 81 low flow
01617780 St. James Run at Spielman, Md. 1977-79, 81-82, 85-86 low flow
 
01617800 Marsh Run at Grimes Md. 1963-present discharge
01617850 Potomac River at Lock 40 near Mondell, Md. 1957-67 high flow
01618000 Potomac River at Shepherdstown, Md. 1928-93 discharge, high flow
01619500 Antietam Creek near Sharpsburg, Md.1 1928-present discharge, other
01619525 Sharmans Branch near Antietam, Md. 1977-79, 81 low flow
 
01620000 Chesapeake and Ohio Canal at Point of Rocks, Md. 1931-36 discharge
01636500 Shenandoah River at Millville, W. Va.1 1928-present discharge
01636650 Potomac River at Weverton, Md. 1958-70 high flow
01636690 Piney Run near Lovettsville, Va. 1968-69 low flow
01636730 Israel Creek at Weverton, Md. 1975-77 low flow
 
01636850 Little Catoctin Creek near Brunswick, Md. 1977-81 low flow
01638480 Catoctin Creek at Taylorstown, Va. 1971-present discharge
01638500 Potomac River at Point of Rocks, Md. 1895-present discharge
01638600 Tuscarora Creek at Tuscarora, Md. 1975-77 low flow
01643000 Monocacy River near Frederick, Md. 1929-present discharge
 
01643495 Bennett Creek tributary at Park Mills, Md. 1992-93 discharge
01643500 Bennett Creek at Park Mills, Md. 1 1966-present discharge
01643550 Potomac River at Lock 27 near Dickerson, Md. 1957-68 high flow
01643580 Monocacy River near Dickerson, Md. 1975-77, 79-83 misc. meas.
 
01643585 Potomac River tributary near Lucketts, Va. 1979-80 low flow
01643590 Limestone Branch near Leesburg, Va. 1968-69 misc. meas.
01643600 Limestone Branch tributary near Leesburg, Va. 1979-80 low flow
01643615 Broad Run near Elmer, Md. 1975-82 low flow
01644000 Goose Creek near Leesburg, Va. 1 1930-present discharge
 
01644100 South Fork-Sycolin Creek near Leesburg, Va. 1966-77 high flow
01644115 Dry Mill Branch near Leesburg, Va. 1969 misc. meas.
01644277 Beaverdam Run near Ashburn, Va. 1979-81 misc. meas.
01644283 Potomac River tributary No. 2 near Sterling, Va. 1979-80 misc. meas.
01645000 Seneca Creek at Dawsonville, Md. 1930-present discharge
 
01645050 Dry Seneca Creek near Seneca, Md. 1975-82 low flow
01645080 Seneca Creek near Seneca, Md. unknown misc. meas.
01645500 Potomac River at Great Falls, Md. 1886-1891 discharge
01645975 Rocky Run near Great Falls, Va. 1961-67 high flow
01646000 Difficult Run near Great Falls, Va. 1934-present discharge
01646200 Scott Run near McLean, Va. 1961-73 high flow
01646220 Rock Run near Cabin John, Md. 1964, 66-67 low flow
01646500 Potomac River near Washington, D.C. 1930-present discharge
01646550 Little Falls Branch near Bethesda, Md. 1944-59, 62-79 discharge
01646700 Pimmitt Run at Arlington, Va. 1961-68 high flow
 
01646750 Little Pimmitt Run tributary at Arlington, Va. 1962-66 high flow
01646755 Little Pimmitt Run tributary at Arlington, Va. 1962-69 high flow
01646800 Little Pimmitt Run at Arlington, Va. 1961-66 high flow
01647600 Potomac River at Wisconsin Avenue at Washington, D.C. 1935-present tide gage
01648000 Rock Creek at Washington, D.C. 1929-present discharge
 
01649000 Rock Creek at Q Street at Washington, D.C. 1892-1895, 1930-1933 discharge
01652580 Oxen Run at Washington, D.C. 1980-82 low flow

1 Station contains other shorter periods of record prior to current period of record.


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