Evaluation of the Impact of LULC Changes on Water Balance Components

This study assesses the impact of historical (1987–2018) and projected future (2018–2033) land use and land cover (LULC) changes on the water balance components of the Subarnarekha River Basin (SRB). The 2033 LULC spatial pattern was projected using the CA-Markov model, achieving a k-standard value of 0.7969, indicating high reliability for spatial and temporal change modelling. The SWAT model was employed to evaluate these impacts, calibrated and validated for 1987–2005 and 2006–2013, respectively. Model performance showed strong agreement between observed and simulated streamflow, with Nash-Sutcliffe efficiency ranging from 0.73 to 0.91 during calibration and 0.71 to 0.84 during validation across three sub-basins: Muri, Jamshedpur, and Ghatshila. Analysis revealed significant LULC changes, with dense and open forest areas declining from 17.49% to 6.71% and 11.60% to 8.04%, respectively, while settlement and agricultural areas expanded from 2.35% to 6.48% and 45.47% to 57.53%. These changes substantially impacted water balance components, leading to notable reductions in groundwater recharge and percolation, minimal changes in evapotranspiration and streamflow, and a considerable increase in annual surface runoff. Despite these shifts, changes in average annual water yield were minimal, underscoring the significant role of LULC dynamics in shaping hydrological processes within the SRB.

Keywords: LULC changes, SWAT model, water balance, CA-Markov model.