HR: 09:00h
AN: H11H-05    [Abstracts]
TI: Simulation of vegetation, soil characteristics, and topography effects on soil water distribution and streamflow timing over a semi-arid mountain catchment
AU: * Grant, L E
EM: lauragrant@mail.boisestate.edu
AF: Department of Geosciences Department of Geosciences, 1910 University Dr , Boise, ID 83725 United States
AU: Seyfried, M S
EM: mseyfrie@nwrc.ars.usda.gov
AF: Northwest Watershed Research Center ARS-USDA, 800 Park Blvd , Boise, ID 83712 United States
AU: Marks, D
EM: danny@nwrc.ars.usda.gov
AF: Northwest Watershed Research Center ARS-USDA, 800 Park Blvd , Boise, ID 83712 United States
AU: Winstral, A
EM: awinstra@nwrc.ars.usda.gov
AF: Northwest Watershed Research Center ARS-USDA, 800 Park Blvd , Boise, ID 83712 United States
AB: Soil water ($\theta$, m$^{3}$m$^{-3}$) and soil characteristics act as intermediaries, along with plants and climate, modifying and modulating streamflow timing and quantity-the majority in the intermountain US west resulting from spring-melt events of accumulated winter snow. The antecedent soil water conditions also predispose different patterns and dynamic responses, especially in semiarid, mountain regions. The context of soil water, analyzed using modeling, is necessary to describe the processes of soil water dynamics. In this research, two years of neutron probe soil water data from a small, semiarid mountain catchment were evaluated using a vertical flow, combined snowmelt-soil water, capacitance-parameter model with available snowmelt data and climate data as driving inputs. Model parameters were vegetation characteristics and soil properties. Results at the point scale show good fit at many locations while a few have poor simulation results at depth. The discrepancies are hypothesized to be due to lack of understanding of parameters such as rooting depth of trees; heterogeneity of parameters within the soil layers; using capacitance parameters that treat some variables as constants; exclusion of lateral flow processes that must occur in some locations due to basin geometry and nature of soil-fractured bedrock interface; and rising water table effects that can be seen in the gleying of clayey soils near drainage lines. Driving parameters were then distributed over the 0.36 km$^{2}$ catchment using the regional 10 m DEM, soil maps, remotely sensed color-infrared imagery, and the spatiotemporal distributions of soil water from previous research. The model was run discretely at each pixel. Results matched point data simulations well. Simulated throughflow, totaled over the watershed, compared well with weir measured streamflow in timing and quantity indicating accurate representation of parameters over the watershed, proper calibration, and well described processes.
DE: 1818 Evapotranspiration
DE: 1860 Runoff and streamflow
DE: 1863 Snow and ice (1827)
DE: 1866 Soil moisture
DE: 1884 Water supply
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting