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Title: Simulation of a Heavily Buffered Watershed Using the SWAT Landscape Model

item Bosch, David - Dave
item Arnold, Jeffrey
item VOLK, MARTIN - Helmholtz Centre

Submitted to: Annual International SWAT Conference
Publication Type: Abstract Only
Publication Acceptance Date: 4/22/2009
Publication Date: 8/5/2009
Citation: Bosch, D.D., Arnold, J.G., Volk, M. 2009. Simulation of a Heavily Buffered Watershed Using the SWAT Landscape Model. Annual International SWAT Conference, August 5-7, 2009, Boulder, Colorado.

Interpretive Summary: Conservation practice programs supported by the Government have played a large role in maintaining environmental health throughout rural regions in the U.S. Watershed scale natural resource models are being used to quantitatively evaluate the benefits of these programs. However, one shortcoming of these models is their inability to accurately represent water flow and transport from higher positions in the landscape to lower positions. The Soil Water Assessment Tool, SWAT, has been revised to properly describe this transport process. The revised watershed model was tested for a hillslope in a small Georgia watershed. The model simulates important changes in the hydrologic water balance as the water moves from the field area at the top of the hillslope, through grass and wooded buffers, and eventually into the stream. While additional testing is necessary, the revised model holds considerable promise as a tool for watershed management.

Technical Abstract: Accurate representation of landscape processes in natural resource models requires distributed representation of basin hydrology and transport processes. To better represent these processes, SWAT was modified to represent runoff processes occurring in different parts of the landscape. The SWAT landscape model consists of a three component system, consisting of hill-top, upland, and near stream sections. The model addresses flow and transport across hydrologic response units prior to concentration in streams, and is capable of simulating flow and transport from higher landscape positions to lower positions within a single river basin. The SWAT landscape model was tested using data collected from a heavily vegetated riparian buffer system near Tifton, Georgia, USA. The watershed has been well characterized, with significant information concerning the hydrologic and water quality impacts of the stream buffers. Simulations of surface runoff, lateral subsurface runoff, and groundwater flow for the upland divide, hillslope, and floodplain were generated. Model results indicated that surface runoff was dominated by the upland divide while groundwater flow was dominated by the hillslope and the floodplain. These results agree with general observations from the watershed. Evapotranspiration estimates from the model were not very sensitive to the changes in vegetation occurring in the three different landscape positions. While additional calibration and testing is necessary, the results are encouraging. The results demonstrate the applicability of the model to simulate filtering of surface runoff, enhanced infiltration, and water quality buffering typically associated with riparian buffer systems.