Basin delineation in HEC HMS

Watershed delineation in HEC-HMS involves defining the drainage boundaries, stream networks, and subbasins that contribute flow to a common outlet. This process is typically performed using Digital Elevation Models (DEM) and GIS tools like HEC-GeoHMS or QGIS with TauDEM, which identify flow accumulation paths and divide the watershed into hydrologically connected subbasins. Proper delineation ensures accurate hydrologic modeling by capturing terrain influences, streamflow direction, and watershed storage characteristics.