Climate Change Adaptation in Multi-Reservoir Systems through Revising Operation Policies

Many river-reservoir systems have been significantly affected by climate change. Karun and Dez multi¬ reservoir system is the largest reservoir system in Iran, which has experienced significant decline of surface runoffs in the past 10 years. Currently, the system contains six multi-purpose hydropower reservoirs and 8 more dams have been studied to be built on these two rivers. In this study, potential impacts of climate change on the optimal operation policies of the reservoirs were assessed. For this purpose, time series of reservoir inflows under A2, B1 and A1B emission scenarios were projected using outputs of HadCM3, CGCM3 and ECHAM5 Atmosphere-Ocean General Circulation Models (AOGCM). In order to formulate the optimal operation policies for the Karun-Dez multi-reservoir system, a stochastic optimization model, namely Stochastic Dual Dynamic Programming (SDDP), was utilized. Comparison between the simulation of operation policies proposed based on the historical and projected inflows, showed that by considering the climate change projections, the performance of the policies could be improved by up to 30%. The results also showed that a relatively important share of negative impacts of climate change on Karun and Dez multi-reservoir system can be mitigated by utilizing the operation policies derived based on the climate change projections.