HR: 1340h
AN: H33C-0483    [Abstracts]
TI: Incorporating Sub-grid Spatial Variabilities Into Subsurface Flow Parameterizations For Land Surface Modeling In Ungauged Basins
AU: * Huang, M
EM: huangmy@berkeley.edu
AF: University of California, Department of Civil and Environmental Engineering, Berkeley, CA 94720
AU: Liang, X
EM: liang@ce.berkeley.edu
AF: University of California, Department of Civil and Environmental Engineering, Berkeley, CA 94720
AU: Leung, R L
EM: Ruby.Leung@pnl.gov
AF: Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA 99352
AB: An adequate representation of subsurface flow processes is very important for land surface modeling at the large scales. At the regional scale, for example, the amount of annual averaged subsurface flow is an important component of the water budget used to manage water resources. However, the understanding of the impacts of subgrid spatial variability on subsurface flow processes at the large spatial scales is very limited. Most land surface models use simple parameterizations to estimate the subsurface flow where groundwater discharge is related to a lumped soil moisture state (i.e., the unsaturated zone and saturated zone are lumped), while some models incorporate the effects of landscape and lateral flow partially into the subsurface flow calculation using the framework of TOPMODEL. In this study, we propose a new wetness index for developing a new subsurface flow parameterization. The new wetness index incorporates the concept of dynamic contributing area, spatial variability of the topography, and spatial variability of recharge. Numerical experiments will be carried out to investigate the impacts of different types of spatial variabilities on subsurface flow simulations at two study sites: (1) the Tarrawara catchment in the southeastern Australia, and (2) the Usadievskiy catchment at Valdai, Russia, both of which have multiple measurements on water fluxes. To enable the proposed parameterization to be applied to ungauged basins, efforts are made to keep the number of parameters in the new subsurface flow parameterization as few as possible.
DE: 1829 Groundwater hydrology
DE: 1833 Hydroclimatology
DE: 1860 Runoff and streamflow
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting