QGIS
The free, open-source GIS that has become the default spatial platform for water engineers worldwide.
The QGIS interface for SWAT+ — delineate, discretise and build a watershed model without leaving the GIS.
by Texas A&M AgriLife / USDA-ARS
Install
QGIS → Plugins → Manage and Install Plugins → "QSWAT+"QSWAT+ is the official QGIS plugin for building SWAT+ models: watershed delineation from a DEM (via TauDEM), landscape-unit and HRU discretisation from soils and land use, channel and reservoir setup, and visualisation of model outputs back on the map.
It replaced the old ArcSWAT/ArcGIS dependency with an entirely free chain — QGIS + QSWAT+ + SWAT+ — which matters for the global user base in agencies and universities that never had Esri licences. If you are starting with SWAT+ today, this is the intended front door.
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Click anywhere on earth, get the upstream watershed in seconds — free delineation in the browser.