SWAT is an open source model that can be used with GIS data to simulate hydrological processes in basins. The SWAT complement is a tool to evaluate soil and water and basin management. The QGIS interface is called QSWAT. The latest version is QSWAT 1.4 which was released on Feb. 2, 2017.
This model is used to predict the effects of land use and management in water flow, amount of sediments and chemistry in basins, mainly in basins that do not have previous monitoring information. It is also used in big and complex basins that have a variety of different types of soils and management practices.
Originally, SWAT was developed in the early 90s by the Agricultural Research Service (ARS) of the U.S. Department of Agriculture (USDA). Now it is currently developed by USDA-ARS and Texas A&M AgriLife Research, part of The University of Texas.
This complement can simulate the water cycle in basins to determine the impacts in a period of time taking into account multiple variables. In general, when using this plugin, it is needed to follow these 4 steps:
- Basin delimitation
- Creation of HRUs (Hydrologic Response Units)
- Set and run SWAT
- Results visualization
However, the database preparation can be considered as the step "0" (zero) because it is important to have data of the region we are studying. We will need to create a new file based on the structure used by SWAT, which originally comes with a U.S. database.
To obtain a higher precision in the simulation, the SWAT model requires a variety of spatial data related to soils, topography, climate, etc., being the main input data the following:
- Lateral sub superficial flow
- Tributary channels
- Plants cover
- Agricultural management
- Hydrological transit
Download QSWAT here.
Download QGIS here.