Simulating the Performance of the Pong Reservoir in India under Climate Change Perturbations

This paper assessed the implications of plausible climate change perturbations on the performance characteristics of the Pong Reservoir on the Beas River, Himachal Pradesh, India. Simulated historic and climate-change runoff series developed using the HYSIM rainfall-runoff model of the snowy catchment, formed the basis of the analysis. The climate perturbations used delta changes in temperature (from 0 degrees C to +2 degrees C) and precipitation (from -10% to +10% of annual rainfall). Reservoir simulations were then carried out, forced with the simulated runoff records, guided by rule curves derived by a coupled sequent peak algorithm and genetic algorithm optimiser. The resulting performance was summarised in terms of reliability, resilience, vulnerability and sustainability. The results show that when the runoff increases in the future due to higher rainfall, the performance of the reservoir will improve. Of notable importance is the vulnerability or water shortfall, which more than halved for a 5% increase in rainfall and completely disappears if the rainfall increases by 10%. Decreases in the rainfall produced the opposite effect, i.e. caused the vulnerability to worsen. Increases in the temperature (and the additional runoff generated from snowmelt) appeared to partially annul the effect of reduced rainfall on the runoff causing the performance of the reservoir to improve as the temperature rises. Ways of ameliorating the water shortage difficulties are suggested, including better operational practices that manage the available water through hedging.