HR: 1330h
AN: H42G-1158    [PDF]
TI: Using Green and Ampt with Redistribution to Simulate Recharge for Saturated Groundwater Modeling in Support of Surface Water Applications
AU: * Downer, C W
EM: Chuck_Downer@nps.gov
AF: National Park Service, South Florida Ecosystem Office 950 N. Krome Avenue 3rd Floor, Homestead, FL 33030 United States
AB: The Gridded Surface Subsurface Hydrologic Analysis Model (GSSHA) employs a one-dimensional finite difference approximation of the head based form of Richards' equation to calculate groundwater recharge for saturated groundwater simulations needed for groundwater/surface water interaction studies. When used to simulate sharp wetting fronts, solution of Richards' equation can be computationally very expensive. This computational cost may not be justified if Richards' equation is being solved merely to provide estimates of groundwater recharge for saturated groundwater simulations. For large problems, the computational cost may preclude the used of automated calibration methods which allow a more complete exploration of the parameter space but may require hundreds of simulations to do so. In addition to the Richards' equation solution the GSSHA model also includes Green and Ampt based infiltration models. These Green and Ampt approaches have historically been used to compute infiltration under Hortonian conditions, where saturated groundwater has little influence on surface water flows. It is hypothesized that the Green and Ampt based method of computing infiltration may prove adequate for computing groundwater recharge for use in saturated groundwater simulations. The GSSHA model is modified to allow the Green and Ampt with Redistribution model of infiltration to provide values of groundwater recharge for saturated groundwater simulations. The formulation results in infiltrated water immediately becoming recharge. The modified model is employed in two studies where groundwater surface water interaction is critical to the prediction of stream flow. In both cases the model is able to produce acceptable results in terms of predicting stream flow. The method appears useful for determining values of groundwater recharge for use with saturated groundwater simulations. The reduced simulation times with the method make the use of automated calibration methods possible.
DE: 1829 Groundwater hydrology
DE: 1875 Unsaturated zone
SC: Hydrology [H]
MN: 2003 Fall Meeting