Assessing Hydrological Impacts of Deforestation and Land Use Change in the Tel River Basin

Land use and land cover changes (LULCC) alter catchment hydrology by changing how water moves between the land surface and the atmosphere. This study examines how land use change between 1985 and 2015 affected the water balance of the Tel River basin, a sub-basin of the Mahanadi system in eastern India. Land cover maps for 1985, 1995, and 2005 were obtained from the national decadal LULC database, and a 2015 map was prepared from Landsat 8 imagery using a Random Forest classifier on Google Earth Engine (GEE) and later validated against NRSC data. The 2015 map reached an overall accuracy of 78.6 % (Kappa 0.68) against independent reference data. Forest and agriculture were mapped reliably, while the smaller classes of built-up land, bare land, and water body were combined into one less reliable category. Hydrological response was simulated with the Variable Infiltration Capacity (VIC) model for 1980 to 2018, using a one-factor-at-a-time design that holds climate constant so that only land use varies. Forest cover fell by 13.02% over the period, with most of the loss going to agriculture (about 1575 km2). With climate held fixed, lower evapotranspiration (about 16 mm/year, or 1.7%) was passed almost entirely into higher surface runoff (about 7 mm, 2.0%) and higher base flow (about 9 mm, 4.6%), while long-term soil water storage stayed essentially unchanged. A pixel-level analysis shows that runoff rises in some parts of the basin and falls in others, so the basin average understates the local change in flood and erosion risk. The results point to the value of catchment-scale water management that accounts for where land use is changing within the basin.