TopoSWAT Source

Topography exerts critical control on many hydrologic, geomorphologic, and environmental biophysical processes. In order to properly model such dynamics in the Soil and Water Assessment Tool (SWAT), we explicitly integrate topography into the initialization procedure with a purpose-built extension. This ArcMap® toolbox (TopoSWAT) interfaces directly with ArcSWAT, to create multiple SWAT data layers, update the SWAT databases and generate the lookup tables required by the model. User defined data layers are processed in a single-step toolbox and include, aspect, elevation, and topographic index (TI), which are then intersected with the vector FAO Global Soils dataset. The toolbox then builds a soil raster layer at the resolution of the project’s base Digital Elevation Model and creates the ArcSWAT required ‘usersoil’ database table along with the corresponding soil lookup table required to map the specific raster soil values to the soil parameters in the ‘usersoil’ database table. This toolbox effectively creates a new soil dataset that incorporates topographic features. This standardized method and toolset allows SWAT modelers to easily incorporate topographic features they believe are important for their catchments without requiring any changes to the current ArcSWAT initialization system.  Some of the topographic features may be necessary for process-based routines that one may want to incorporate into SWAT, e.g., energy-budget snowmelt modeling.  However, such routines will need to be added to the SWAT model source code. This SWAT toolbox adds flexibility to SWAT modeling with little extra effort on the part of modelers.