Accession Number : AD1037437

Title :   Unit Hydrograph Peaking Analysis for Goose Creek Watershed in Virginia: A Case Study

Descriptive Note : Technical Report

Corporate Author : U.S. Army Engineer Research and Development Center Vicksburg United States

Personal Author(s) : Loney,Drew ; Pradhan,Nawa R

Full Text :

Report Date : 01 May 2017

Pagination or Media Count : 34

Abstract : Existing U.S. Army Corps of Engineers (USACE) policy suggests unit hydrograph peaking factor (UHPF), the ratio of an observed event unit hydrograph peak to the modeled one for a catchment, ranges between 1.25 and 1.50 to ensure dam safety. It is pertinent to investigate the impact of extreme flood events on the validity of this range through physically based rainfall-runoff models not available during the planning and design of most USACE dams. The UHPF range was analyzed by deploying the Gridded Surface Subsurface Hydrologic Analysis model in the Goose Creek, VA, watershed to develop a peaking factor relationship with excess rainfall for National Oceanic and Atmospheric Administration rainfall depths across various return-period events as well as the National Weather Service probable maximum precipitation event. The effect of statistical uncertainty on UHPF at Goose Creek was determined by applying the 5% and 95% confidence interval precipitation depths to the watershed in addition to the 50% value. This study concluded that a design event with a return period greater than 5-year is required for the unit hydrograph to ensure dam safety. Goose Creek unit hydrograph was designed from 25-year return period rainfall and therefore ensures dam safety given the current UHPF guidance.

Descriptors :   dams , floods , flood control , precipitation , runoff , watersheds , army corps of engineers , policies , safety , military engineering , drainage basins

Subject Categories : Hydrology, Limnology and Potamology
      Civil Engineering

Distribution Statement : APPROVED FOR PUBLIC RELEASE