Estimation of Runoff Sensitivity to Climate Change Using MIKE11 NAM Model at Parvati Catchment of Rajasthan, India

Climate change has a significant impact on water resources, particularly on runoff. In the present study, impact of climate change on runoff under different shared socio-economic pathways (SSPs) of CMIP6 is analysed over the Parvati catchment of Rajasthan using MIKE11 NAM model. The ensemble of best 3 global climate models (GCM) out of 13 GCMs is taken to generate future climate projections of rainfall, maximum temperature (Tmax), and minimum temperature (Tmin). MIKE11 NAM model is used for runoff simulation. The results showed a good match between observed and model simulated runoff with Nash-Sutcliff efficiency, percent of bias, coefficient of determination, and root mean square error as 0.79, - 2%, 0.79, and 4.95 during model calibration (2005-2013) and 0.67, - 12.4%, 0.68, and 0.83 during model validation (2014-2020). The changes in runoff during three future periods FP1 (2023-2039), FP2 (2046-2064), and FP3 (2081-2099) under three SSPs (SSP1-2.6, SSP2-4.5, and SSP5-8.5) are compared with base period (2005-2020). The projected rainfall, Tmax, and Tmin showed an increasing trend in future. Similarly, future simulated runoff is also found to increase by 2.08-3.78, 3.47-5.15, and 3.13-5.82% during FP1, FP2, and FP3, respectively. The runoff is found to increase during monsoon and pre-monsoon season, whereas decrease in runoff is found during post-monsoon and winter season. These changes in the runoff pattern suggest the need to develop better irrigation management strategies for crop planning and may help planners and policy-makers for effective water resources management.