Impact estimation of landuse/land cover changes and role of hydrological response unit in hydrological modelling in a watershed of Mahanadi river basin, India

Aim of the water balance study is to evaluate the distribution of hydrological responses towards water balance components for a watershed. The present study highlights the water balance study for a watershed of Mahanadi river basin of India. Impact estimation of Landuse Land Cover (LULC) on runoff using Soil and Water Assessment Tool (SWAT) model under varying levels of hydrological response unit (HRU) has also been determined. For the purpose, LULC maps are prepared and utilized in decadal intervals for the years 1994, 2004 and 2014. The sensitivity analysis was performed using local and global methods, where eight most sensitive parameters have been utilized for calibration and validation. The model showed good agreement between observed and estimated time scale and showed satisfactory results during calibration and validation. As per impact estimation of LULC during 1994 to 2014, it was noticed that significant percentage of runoff has been increased from 27.6 to 30.95%, respectively. It was also noticed that the annual average ground water contribution decreased with LULC, from 20.1% (1994) to 15.24% (2014). Sub-watershed (SWS-6) and SWS-2 have been identified as high priority for implementation of conservation measures and better water management. Because these sub-watersheds yielded maximum runoff. The HRU role in hydrological modelling revealed that a greater number of HRUs simulate runoff more precisely and more accurately useful for water management studies.