HR: 09:25h
AN: H21I-05    [Abstracts]
TI: Distributed Watershed Modeling: Incorporation of a Free-Surface Overland Flow Boundary Condition and Land Surface Parameterization Scheme Into a Parallel, Variably Saturated Groundwater Flow Model
AU: * Kollet, S J
EM: kollet2@llnl.gov
AF: Atmospheric, Earth, and Energy Sciences Department, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550 United States
AU: Maxwell, R M
EM: maxwell5@llnl.gov
AF: Atmospheric, Earth, and Energy Sciences Department, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550 United States
AB: Interactions of the land surface with the subsurface are important in hydrologic and energy budget considerations on the watershed scale. In many subsurface flow models, the linkage of the energy and the hydrologic budget through the process of evaporation (latent heat) is often neglected, which constitutes a major simplification. In the hydrologic budget, surface groundwater interactions are of great significance and must be incorporated into hydrologic modeling tools that may be used for management and prediction purposes. In this study, we incorporated a two-dimensional overland flow simulator into the parallel, variably saturated subsurface flow code ParFlow to account for coupled surface-subsurface flow. The overland flow simulator is fully integrated into ParFlow as a new free-surface overland flow boundary condition without relying on the conductance concept (no distinct interface separating the surface from the subsurface domains is presumed). We additionally integrated CLM, a land surface parameterization scheme, into ParFlow to account for the energy fluxes at the land surface. Both, the overland flow simulator and CLM exploit the efficient parallelism implemented into ParFlow. Simulation examples are presented that demonstrate the usefulness of our approach and focus on the interaction of surface-subsurface flow. The influence of heterogeneity in the subsurface hydraulic properties on overland flow and the energy fluxes at the land surface is also examined. The efficient parallelism, which is demonstrated in a parallel efficiency study, makes this model especially suitable for watershed scale modeling, where the use of large computational resources is important. This work was conducted under the auspices of the U. S. Department of Energy by the University of California, Lawrence Livermore National Laboratory (LLNL) under contract W-7405-Eng-48 and Lawrence Berkeley National Laboratory (LBNL) under contract DE-AC03-76F00098.
DE: 1814 Energy budgets
DE: 1830 Groundwater/surface water interaction
DE: 1836 Hydrological cycles and budgets (1218, 1655)
DE: 1847 Modeling
DE: 1879 Watershed
SC: Hydrology [H]
MN: Fall Meeting 2005