HR: 1340h
AN: H33C-0482    [Abstracts]
TI: Simulation of Crust Effects on Infiltration and on Runoff Generation at Arid Micro-catchments
AU: * Ben-Zvi, A
EM: arieb20@water.gov.il
AF: Negev Academic College of Engineering, P.O. Box 45, Beer Sheva, Isr IL-84100 Israel
AU: Carmi, G
EM: genadi@bgumail.bgu.ac.il
AF: J. Blaustein Inst. for Desert Research, Ben Gurion Univ. Of the Negev, Wyler Dept. for Dryland Agriculture, Sde Boker, Isr IL-84990 Israel
AU: Berliner, P
AF: J. Blaustein Inst. for Desert Research, Ben Gurion Univ. Of the Negev, Wyler Dept. for Dryland Agriculture, Sde Boker, Isr IL-84990 Israel
AU: Ben-Asher, J
EM: benasher@bgumail.bgu.ac.il
AF: J. Blaustein Inst. for Desert Research, Ben Gurion Univ. Of the Negev, Wyler Dept. for Dryland Agriculture, Sde Boker, Isr IL-84990 Israel
AB: Generation of runoff in arid areas was studied by analysis and modeling of rainfall - runoff relations over a cluster of six micro-catchments whose total area is about 0.25 km2. The state of the crust, formed by raindrop impact on the soil surface, was found to substantially affect infiltration and runoff. These effects pertain, almost entirely, to overland processes, because channel flow is minimal in the micro-catchments. The experimental catchments lie at Avdat, Israel, where mean depth of precipitation is about 85 mm/y and mean depth of potential evapotraspiration exceeds 2500 mm/y. Rainfall was recorded by two gauges, situated at the margins of the catchments' cluster, and was considered uniformly distributed over their area. Runoff was separately recorded for each catchment. Infiltration rates, for the different geo-morphological units prevailing in the study area, were measured for incrusted conditions. Runoff generation and magnitude were simulated by use of the physical, event-based, distributed, model called KINEROS. Data analysis applied the ™ index and the UH models. An order of magnitude difference was found between measured final infiltration rates for incrusted conditions and the values of hydraulic conductivity obtained in the calibration of the KINEROS model for the actual crusted conditions. The calibration required values of capillary drive substantially smaller than those commonly used to the actual soil types. In addition, the model was found very sensitive to antecedent soil moisture. Fit of ™ index abstraction rates corroborated to the final infiltration rates obtained by the model. The results indicate that the selected model can be used for predicting runoff over and infiltration through crusted surfaces in arid watersheds with assumed soil characteristics for the crust only, and without taking into consideration the underlying conditions. The linearity of unit hydrographs, found for some cases at the micro-catchments, indicates that the thin flow over the crusted soil is either laminar or reached terminal velocity.
DE: 1821 Floods
DE: 1836 Hydrologic budget (1655)
DE: 1860 Runoff and streamflow
DE: 1866 Soil moisture
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting