Hydrological Response of Two Adjoining Subtropical Catchments – Iril and Thoubal of the Manipur River Basin in the Indian Himalayan Region

The Thoubal river catchment (TRB) and Iril river catchment (IRB), which are two major adjoining sub-basins of the Manipur river basin in India, were selected for this study. A GIS-based semi-distributed hydrologi­cal model soil and water assessment tool (SWAT) was used to derive the hydroclimatic parameters such as surface run-off, evapotranspiration. The present study aims to calibrate and validate the SWAT model using streamflow and satellite soil moisture data, as well as to examine the hydroclimatological responses in the two adjacent basins, and compare the relative changes in treating the Iril–Thoubal river basin jointly and as two separate entities. The model was calibrated and validated using the SUFI-2 tool. During calibration and validation, both IRB and TRB showed good model performance. This study shows that in a poorly gauged river basin with scarce data, remotely sensed soil moisture data may be effectively applied for the calibration and validation of hydrological models. The novel aspect of this study is the efficient calibration and validation of a hydroclimatic model for subtropical river sub-basins with limited hydrological ground data reinforced with open-source satellite-derived soil moisture datasets.