Flood and Drought Data for the Big Laurel-Whitetop Laurel Creek Watershed

 

(Note that this blog entry will be updated with more information after the 2025 Federal Government shutdown is over.)

The Big Laurel Creek – Whitetop Laurel Creek watershed recently experienced a catastrophic flood event due to the remnants of Hurricane Helene during 23-28 September 2024.  (The watershed has not experienced a drought as far as I can tell from the historical records available.)

 An excellent presentation of the aftermath of Hurricane Helene is:  Helene in Southern Appalachia, One year later: An event analysis and how we move forward, by the NOAA National Centers for Environmental Information, Asheville, North Carolina, September 17, 2025 https://storymaps.arcgis.com/stories/8887acbd2dbd4d28a68e79fe53cbfaa3

 The United States Geological Survey (USGS) stream gage station nearest to the Big Laurel Creek – Whitetop Laurel Creek watershed outfall is gage number 03473000, named S(outh) F(ork) HOLSTON RIVER NEAR DAMASCUS, VA, location 36.652, -81.844, a continuous record gage from 10/01/1931 to the present.  The relative location of the USGS gage to the Big Laurel-Whitetop Laurel Creek watershed is shown in this picture.



The peak annual streamflow for this gage (https://streamstats.usgs.gov/ss/?gage=03473000&tab=info ) is shown here

 


As shown on this chart, the peak annual streamflow for Hurricane Helene was 26,400 cubic feet per second (cfs) that occurred on 9/27/2024. 

 Additionally, the Office of Water Prediction, National Weather Service, National Oceanic and Atmospheric Administration, U.S. Department of Commerce, Silver Spring, Maryland produced a report “Hydrometeorological Design Studies Center Progress Report for Period 1 July to 30 September 2024” that covered the time frame of the flood events of Hurricane Helene.  The following map shows the Annual Exceedance Probabilities (AEPs) for the Highest 3-day Rainfall Perion for Hurricane Helene from 23-28 September 2024, with the Big Laurel Creek – Whitetop Laurel Creek watershed indicated by a yellow bordered rectangle.   This report is available at https://www.weather.gov/media/owp/oh/hdsc/docs/202410_HDSC_PR.pdf

 


In analyzing the flood regime for this watershed, I performed a one-dimensional (1-D) U.S. Army Corps of Engineers Hydrologic Engineering Center's (CEIWR-HEC) River Analysis System (HEC-RAS) model of the Whitetop Laurel Creek watershed from the confluence of Whitetop Laurel Creek and Green Cove Creek, to the confluence of Whitetop Laurel Creek and Laurel Creek (that flows from Tennessee).  The modeled maximum flow was the Annual Exceedance Probability (AEP) of 0.01, corresponding to the “100-year design flood”.  The output from this analysis is shown on the following slides.

 























The 1-D HEC-RAS model demonstrated that extreme flood event flows are very constrained in the narrow Whitetop Laurel Creek watershed, and that the entire valley flood plain is inundated during extreme flood event flows. 

Location: Whitetop Laurel Creek near Damascus, VA, USA

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