Watershed delineation and hydrological response unit (HRU) analysis of the Banas River Basin using the SWAT model

The present study aims to delineate the Banas River Basin of south-eastern Rajasthan, India, to generate hydrological response units (HRUs) using the Soil and Water Assessment Tool (SWAT) in a geographic information system (GIS) environment. The objective of the research is to develop a reliable spatial framework that represents basin heterogeneity for future hydrological simulation and water resource planning in a semi-arid region. Watershed delineation was carried out using the Shuttle Radar Topography Mission (SRTM) Digital Elevation Model, while land use/land cover, soil and slope layers were integrated through the ArcSWAT interface to derive HRUs. Threshold values of 20 % for land use, 10 % for soil and 10 % for slope were applied to balance spatial detail and computational efficiency. The analysis resulted in the delineation of 33 sub-basins and 580 HRUs, reflecting significant spatial variability within the basin. Agricultural land was found to be the dominant land use (approximately 55 %), followed by forest and pasture areas, while silt loam soils and gentle slopes (0–10 %) prevailed across large portions of the basin. These physiographic characteristics indicate moderate runoff potential with localised erosion risk. The outcomes of this study provide a robust spatial foundation for hydrological modelling, soil and water conservation planning and assessment of land-use and climate change impacts in the Banas River Basin.