Date of this Version
Nelson, M.J. (2017). Impact of Using Spatially Distributed Soils Information on Flood Hydrograph Simulation with HEC-HMS (Master’s Thesis). University of Nebraska-Lincoln
Hydrologic rainfall-runoff models employ numerical equations to simulate the soil absorption of rainfall and resulting runoff. A number of methods have been developed to model these processes, but the parameters used to define these methods can be difficult to directly measure due to the variable nature of soil properties. They often rely on estimation of hydraulic and hydrologic parameters and calibration to produce accurate results.
A challenge with runoff method parameterization is the need for oversimplification using a lumped modeling approach. While distributed hydrologic modeling techniques are now available, distributed runoff methods are limited in use due to the tradition of lumped modeling and lack of widely available runoff parameter datasets. This study sought to define modeling parameters for three runoff methods based on physical soil data contained within the Soil Survey Geographic (SSURGO) database for lumped and distributed modeling approaches. These parameters were defined for 1-foot and 3-foot soil depths for estimating controlling influences on infiltration. The methods investigated are the Deficit and Constant method, the Green and Ampt method, and the SCS Curve Number method.
The Salt Creek Basin located in southeast Nebraska was the pilot basin for this study. The basin was modeled using the Hydrologic Engineering Center-Hydrologic Modeling System (HEC-HMS) software package. The model was adapted to the basin using ArcGIS and the HEC-GeoHMS extension. Three different precipitation events were modeled with the simulated runoff hydrographs at seven locations compared to the observed data to assess the model performance.
Several trends in the quality of loss parameters were observed. First, Deficit and Constant and Green and Ampt runoff methods produced runoff hydrographs that closely matched observations. Second, distributed loss parameters for these two methods produced more accurate results than their lumped counterparts. Third, the shallower soil depth parameters produced marginally better hydrographs than their counterparts. Finally, the SCS Curve Number method was able to produce accurate peak flow and runoff volume estimates, but performed poorly with the hydrograph timing.
Advisor: Ayse Kilic