Co-Authors:
Chen, L., Division of Hydrologic Sciences, Desert Research Institute, Las Vegas, NV 89119, United States
Sela, S., Department of Geography and Environmental Development, Ben-Gurion University of the Negev, Beer Sheva, Israel
Svoray, T., Department of Geography and Environmental Development, Ben-Gurion University of the Negev, Beer Sheva, Israel
Assouline, S., Department of Environmental Physics and Irrigation, Institute of SoilWater and Environmental Sciences, A.R.O.-Volcani Center, Bet Dagan, Israel
Abstract:
The hydrological response of semiarid watersheds to short but intense rainfall events is complex due to feedbacks among water fluxes, vegetation patches, topography, and soil properties. This paper seeks to quantify the combined impact of soil-surface sealing, microtopography, and vegetation patches on surface hydrologic processes on a semiarid hillslope. A modeling approach using a two-layer conceptual infiltration model and two-dimensional surface runoff model was developed to study rainfall-runoff relationships. This combined model is applicable to heterogeneous areas with spatially varying soil properties, landscape, and land-cover characteristics. Data from a semiarid site in southern Israel was used to evaluate the model and analyze fundamental hydrologic mechanisms. Our results indicate that seal layer, microtopography, and vegetation play important roles in dry land runoff processes: seal layer controls runoff generation; vegetation patches affect overland flow by enhancing local infiltration rates; microtopography has a small impact on the total amount of runoff, but shapes the spatial pattern of overland flow. The presence of vegetation patches amplifies the effect of microtopography by increasing spatial variability of infiltration and runoff. Results also show that water resource allocation favors vegetation patches through surface runoff, with maximum local cumulative infiltration one order of magnitude higher than the amount of water available from rainfall. This suggests a sophisticated system of water resource distribution in semiarid ecosystems through complex interactions among environmental factors. Key Points 2D overland flow and two-layer infiltration for complex rainfall-runoff modeling Surface seal and vegetation patches conjunctively determine runoff volume Local infiltration at vegetation patches much higher than rainfall depth ©2013. American Geophysical Union. All Rights Reserved.
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