Submitted to: Transactions of the ASABE
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/15/2010
Publication Date: 10/15/2010
Citation: Arnold, J.G., Allen, P.M., Volk, M., Williams, J.R., Bosch, D.D. 2010. Assessment of different representations of spatial variability on SWAT model performance. Transactions of the ASABE. 53(5):1433-1443. Interpretive Summary: Watershed models are commonly used tools to access the impact of management practices on water quality. Most existing watershed models do not account for landscape position, or whether the field is on hill top or in the floodplain. We developed a landscape model and incorporated it into a watershed model called SWAT (Soil and Water Assessment Tool). This will give decision makers a planning tool that can determine the impact of management from fields near streams and those on hilltops, thus making conservation planning more efficient and equitable.
Technical Abstract: Most existing river basin scale models use subwatersheds to account for heterogeneity but do no account for landscape position within subbasins. Landscape delineation tools were developed to divide a subwatershed into three landscape units: divide, hillslope, and flood plain. Process models were developed to route surface runoff, lateral soil flow, and shallow ground water flow from the divide, through the hillslope, to the floodplain and eventually to the stream. The landscape model was incorporated into the SWAT watershed model and tested it at the USDA-ARS Y2 experimental watershed in Riesel, Texas. Simulated soil moisture was compared to measured soil moisture for each landscape unit with reasonable agreement. Future work will also compare runoff, lateral soil flow, and ground water well heights.