Assessment of Blue and Green Water Availability in the Upper Ghatprabha River Basin under Climate Change Impacts

The study focuses on assessing the impact of climate change on water balance components in the Upper Ghatprabha River Basin in India. The Soil Water Assessment Tool (SWAT) is utilized to simulate streamflow in the basin. Calibration and validation of SWAT are performed across multiple sites using the Sequential Uncertainty Fitting Algorithm (SUFI 2). Performance assessment relied on metrics such as the Nash-Sutcliffe efficiency (NSE) and coefficient of determination (R2). Future climate projections are based on an ensemble mean of 13 bias-corrected GCM models for the Shared Socioeconomic Pathways (SSP) scenarios SSP245 and SSP585. The simulation of future basin water balance components involves segmenting the entire timeframe into S1 (2015-2040), S2 (2041-2070), and S3 (2071-2100). Projections indicate an increase in maximum and minimum temperatures, with precipitation potentially rising by up to 47% in the basin under the SSP245 scenario by the end of the century. Hydrological simulations reveal increased surface runoff and evapotranspiration under the SSP245 scenario compared to historical data. The percentage change in blue water components under both SSP scenarios shows an increase of more than 50% compared to the historical data. In comparison, that of green water components only increases to a maximum of 8% in all the timeframes (S1, S2 and S3). Notably, the impact of climate change is more pronounced under the SSP585 scenario compared to SSP245. These changes significantly impact the water resources of the Upper Ghatprabha River Basin; necessitating focused attention on future planning and management strategies for water resources.