Water footprint analysis for the upper Baitarani River basin, India

The water footprints (WFs) or freshwater availability components such as blue water flow (water yield plus deep aquifer recharge), green water flow (actual evapotranspiration), and green water storage (soil moisture) at spatial (sub-basin) level with temporal (monthly) time-steps are assessed for the Upper Baitarani River Basin (UBRB) of India. This study uses the modeling framework of the Soil Water Assessment Tool (SWAT) and the Sequential Uncertainty Fitting version 2 (SUFI-2) in SWAT-Calibration and Uncertainty Programs (SWAT-CUP) for automatic calibration of the hydrological model. In addition, the climate change impacts on the monthly soil moisture levels in the (UBRB) were assessed using five general circulation models (GCMs) under representative concentration pathways (RCPs) 4.5 and 8.5 scenarios. Model performance was evaluated using several statistical parameters. For calibration (1991–2006), the coefficient of determination (R2) was obtained as 0.86, and for validation (2007–2011) was 0.94. The Nash–Sutcliffe (NS) efficiency in the calibration was 0.85 and was obtained as 0.93 in the validation. The percentage bias (PBIAS) for calibration was − 11 and for the validation, the period was − 10.40. A good agreement among the simulated and observed data was found in both calibration and validation of the models. The average annual amount of water resources in the UBRB was 4749.59 million m3, of which the blue water resources were 1691 million m3, and the green water resources were 3058 million m3. The results summarize the spatiotemporal distribution of blue and green water resources and provide comprehensive information on water availability status in the study region for better planning management.