Impact of Climate Change on Runoff using SWAT for Malwa Region of Madhya Pradesh in Central India

The selected area, Malwa region of Madhya Pradesh is plagued with groundwater overexploitation and experiences prolonged dry spells during cropping season which coincides with the seed formation stage of soybean and maize. This region has high runoff potential and hence its harvesting and utilization for supplemental irrigation can improve the crop yield considerably. In this study, the runoff was estimated with SWAT model due to limited number of gauging stations available at Malwa. The model was calibrated (R2=0.9) and validated (R2=0.96) for the study area. The Nash-Sutcliffe efficiency during calibration and validation were determined as 0.89 and 0.93 respectively and the model performed satisfactorily. The mean annual rainfall ranged from 474 to 1302 mm over the years and runoff varied from 10.7 to 27.0% with a mean of 18.3% of rainfall. The annual rainfall varied spatially from 585 to 1187 mm and the runoff from majority of the area varied spatially from 7.6 to 25.6% of rainfall. The rainfall during normal years varied spatially from 658 to 939 mm and the runoff varied from 12.1 to 27.0% of rainfall. It is predicted that the mean maximum and minimum temperature under medium emission scenario may increase by 2.3 and 2.6°C and runoff is predicted to increase by 0.8 to 1.8% of rainfall by 2080’s. The runoff potential available under the current scenario itself is quite sufficient for rainwater harvesting. In addition to this, the increase in rainfall and runoff predicted for this area under changing climatic scenarios showed more potential for rainwater harvesting and supplemental irrigation in near future also.