Impact of land-use change on the water resources of the Upper Kharun Catchment, Chhattisgarh, India

Reliable information on the water balance components today and their future changes is a prerequisite for foresightful and sustainable water management. Basically, these components are under the strong influence of land-use dynamics. The Upper Kharun Catchment (UKC) is a typical example featuring considerable population growth, expansion of urban areas, industrialization, and dynamic changes in irrigation practices (extension, intensification). This research combines the Soil and Water Assessment Tool (SWAT) and an advanced procedure for spatio-temporal land-use mapping that integrates the intra-annual variation within a single map and hence better represents an area with different levels of urbanization and multiple crop rotations. Due to its relevant impact on the water balance, special attention is paid to aspects of irrigation. The land-use map scenarios are prepared for 1991, 2001, 2011, and 2021. The study reveals that an increasing pumping rate of groundwater for irrigation is the main reason for decreasing the groundwater contribution to streamflow and subsequently a lowering in discharge and water yield. On the other hand, annual surface runoff has increased significantly by an expansion in built-up areas over the decades in the respective parts of the study area. On the UKC scale, the impact of land-use change on the water balance until 2021 is small. However, the impact on water resources is clearly visible and significant at sub-catchment level (increase: surface runoff; decrease: percolation; decrease: groundwater contribution to streamflow, and increase: actual evapotranspiration), where expanding urban areas and intensification of groundwater irrigated areas were observed and assessed as the major drivers. The results facilitate the introduction of best water and land-use management practices and conceiving of supportive infrastructure.