Simulation of Rainfall-Runoff in the Deep Hollow Lake Watershed Using an Integrated Surface-Subsurface Flow Model

Research has pointed out that subsurface contributions may play an important role in predicting surface runoff and water depth during a rainfall event. A fully implicit coupled surface-subsurface flow model designed for hydrologic evaluation in wetlands and other fields is presented in this paper. In the model, the modified horizontal two-dimensional diffusion wave equation governing surface flow is solved with three-dimensional variably saturated subsurface flow equation in a coupled way. The coupled system of equations governing surface and subsurface flows is discretized using the finite volume method in space and the implicit backward scheme in time. The modified Picard procedure is used to linearize the surface and subsurface flow equations. The discretized algebraic equation system is solved using Stone's Strongly Implicit Procedure. The established model is used to simulate the storm event in the Deephollow Lake watershed, which is located within the Yazoo River Basin, North Mississippi. The lake is in the center of an agricultural watershed and surrounded by approximately 232 acres of cotton and soybean fields and wooded area. The numerical solution shows that the developed integrated surface-subsurface flow model is able to predict the hydrological response in surface and subsurface domains due to rainfall.