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Improving Time of Concentration Estimates for Small Rural Watersheds in the Appalachian Plateaus Physiographic Province, West Virginia

Scientific Investigations Report 2024-5051
Prepared in cooperation with West Virginia Department of Transportation, Division of Highways
By: , , , and 
https://doi.org/10.3133/sir20245051

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Abstract

The U.S. Geological Survey (USGS), in cooperation with the West Virginia Department of Transportation, Division of Highways, compared time of concentration (Tc) and related runoff characteristics measured at four field sites in West Virginia to estimates of these values made using accepted methods. These four sites were selected to represent a range of basin size, length, and slope, and a range of estimated Tc. Instrumentation included a rain gage and a streamgage at all sites. Two streamgages, USGS station number (no.) 03159718 Grasslick Creek tributary above Interstate 77 near Fairplain, West Virginia, (referred to as Fairplain in this report) and USGS station no. 03159823 Grass Run tributary above Interstate 77 near Ripley, W. Va., (referred to as Ripley in this report) were near each other in northwestern West Virginia at the outlets of small basins with moderate slope. The largest, longest, and flattest basin in the study was upstream from USGS station no. 03190307 Hedricks Creek Tributary above US–19 near Hico, W. Va. (Hico). The final gaged basin in the study, that of USGS station no. 03197062 Cookman Fork at Interstate 79 near Wallback, W. Va., (Wallback) in central West Virginia, had a drainage area nearly as large as Hico, but the basin was more compact.

Precipitation and streamflow data were collected at the streamgages between October 2017 and July 2020. Storms were identified and classified through an iterative process relying on inspecting graphs created from the precipitation and streamflow data. Three hydrograph time metrics that represent Tc were computed for this study: time to rise, time to recede from a high point on the hydrograph to an inflection on the recession, and the time between an inflection on the hyetograph and an inflection on the recession of the hydrograph (precipitation inflection to recession inflection or PI-to-RI).

Hico had the slowest time metrics: the streamgage had an average Tc of 34 and 32 minutes for time to rise and time to recede, respectively. The time between the PI-to-RI at Hico, 38 minutes, was the longest for any of the characteristics at any of the streamgages. Wallback had the second slowest time metrics. At Wallback, average Tc for time to rise and time to recede was similar, 23 and 25 minutes, respectively. The average time between the PI-to-RI for Wallback was greater than its time to rise or time to recede, 32 minutes. At Fairplain and Ripley, time to rise was 18 and 19 minutes, time to recede was 14 and 16 minutes, and time between the PI-to-RI was 22 and 27 minutes, respectively. At Ripley, PI-to-RI and time to rise were significantly different from each other. Differences in metrics were not statistically significant (p ≤0.05) among streamgages.

At all streamgages, predictions made with the “Rational Method” were within one average standard deviation of the overall mean Tc. The Rational Method was applied following two different procedures— (1) channel geometry was estimated using professional judgment and (2) channel geometry estimates were adjusted using regional equations. The three different time metrics had an inconsistent relation with the estimates. Some of the predictions differed from individual hydrograph time metrics by more than one standard deviation. Predicted values for the 10-year storm were within the interquartile range (IQR) for 4 of 12 combinations of streamgages and time metrics. Adjusted Tc predictions were within the IQR of PI-to-RI for Fairplain and Wallback, longer than the IQR of observed PI-to-RI at Hico, and shorter than the IQR of observed PI-to-RI at Ripley. The adjusted predictions of Tc were within the IQR of time-to-rise for Hico and Fairplain and were longer than the IQR for Ripley and Wallback. At Ripley, the predictions were not within the IQR for either PI-to-RI or time to rise, but instead, were between them. These lines of evidence do not indicate large, systematic errors in Tc estimates.

Suggested Citation

Messinger, T., Holmes, D.A., Scott, J.D., and Kirk, D.W., 2024, Improving time of concentration estimates for small rural watersheds in the Appalachian Plateaus physiographic province, West Virginia: U.S. Geological Survey Scientific Investigations Report 2024–5051, 34 p., https://doi.org/10.3133/sir20245051.

ISSN: 2328-0328 (online)

Study Area

Table of Contents

  • Acknowledgments
  • Abstract
  • Introduction
  • Study Design and Site Selection
  • Methods of Data Collection and Quality Assurance
  • Precipitation and Streamflow Results
  • Storms and Storm Characteristics
  • Summary
  • References Cited
  • Appendix 1. Instrumentation for U.S. Geological Survey Station Grasslick Creek Tributary Above Interstate 77 near Fairplain, West Virginia, Number 03159718
  • Appendix 2. Instrumentation for U.S. Geological Survey Station Grass Run Tributary Above Interstate 77 near Ripley, West Virginia, Number 03159823
  • Appendix 3. Instrumentation for U.S. Geological Survey Station Hedricks Creek Tributary Above U.S.–19 near Hico, West Virginia, Number 03190307
  • Appendix 4. Instrumentation for U.S. Geological Survey Station Cookman Fork at Interstate 79 near Wallback, West Virginia, Number 03197062
Publication type Report
Publication Subtype USGS Numbered Series
Title Improving time of concentration estimates for small rural watersheds in the Appalachian Plateaus physiographic province, West Virginia
Series title Scientific Investigations Report
Series number 2024-5051
DOI 10.3133/sir20245051
Year Published 2024
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Virginia and West Virginia Water Science Center
Description Report: vii, 34 p.; Data Release
Country United States
State West Virginia
Other Geospatial Appalachian Plateaus Physiographic Province
Online Only (Y/N) Y
Additional Online Files (Y/N) N
Google Analytic Metrics Metrics page
Additional publication details