HR: 1340h
AN: H33C-0486    [Abstracts]
TI: Complexities Involved in One-Dimensional Infiltration Models for Predicting the Soil Moisture Content for a Hillslope
AU: * Kalra, A
EM: ajaykalra@cc.usu.edu
AF: Dr.David G.Chandler, Department of Plants, Soils and Biometeorology, Utah State University , Logan, UT 84322 United States
AU: Chandler, D G
EM: david.chandler@usu.edu
AF: Dr.David G.Chandler, Department of Plants, Soils and Biometeorology, Utah State University , Logan, UT 84322 United States
AU: McNamara, J P
EM: jmcnamar@boisestate.edu
AF: Dr.J.P.McNamara, Department of Geosciences Boise State University, 1910 University Dr., Boise, ID 83725 United States
AB: Most operational hydrologic models use one-dimensional representations of infiltration and soil moisture redistribution. However several field studies have shown lateral flow under unsaturated and near saturation conditions to make a significant contribution to hydrologic response for hillslopes. There is not consensus on a robust technique to predict the occurrence of neither bypass flow nor the volumetric division between matrix flow and bypass flow from hillslopes. This study investigates whether the popular one-dimensional infiltration models based on Richard's equation adequately represent the spatial and temporal patterns of soil moisture content on a hillslope. Two spring rain events of different intensities were chosen to compare the translation of precipitation to changes in soil moisture and streamflow. The soil moisture predicted by numerical approximation of the Richard's equation using Hydrus 1D and by manual computation of the Green-Ampt equations was compared to soil moisture measured by TDR for several locations on north and south facing hill slopes in the Dry Creek watershed, near Boise ID. The streamflow records for the two events differed in lag of time to peak and that the low-constant flux event had one peak and the high-variable flux event had two. Both models replicated the pattern of the measured soil moisture values for the low-steady flux rainfall event, and for the first peak of the high-variable flux event, although the moisture content was overestimated. For the second hydrograph peak of the high-variable flux event the models did not capture the second peak in the measured soil moisture at shallow depths, indicating that shallow lateral flow occurred in response to the higher input flux during that event.
DE: 1800 HYDROLOGY
DE: 1860 Runoff and streamflow
DE: 1866 Soil moisture
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting