Modelling of future hydropower generation using WEAP: A case study in Ceyhan Basin

Abstract

Electricity demand is expected to increase globally in the future. Unfortunately, climate change is a threat to countries that are heavily dependent on hydroelectric energy. Turkey, recognized as vulnerable to the potential impacts of climate change, encounters greater risk. Within Turkey, Ceyhan Basin is one of the regions that is most vulnerable to the effects of climate change. It currently hosts several numbers of reservoirs and is important for agricultural activity due to its fertile lands. Therefore, much research on how projected climate change impacts precipitation patterns, temperature variations, water flows as well as hydropower generation within the basin is necessary for future water and energy planning. The objective of this study is to assess the impact of climate change on the hydropower generation at Menzelet Dam, both in the near and far future periods. Initially, a hydrology model was developed utilizing the Water Evaluation and Planning (WEAP) tool to characterize the hydrological dynamics of the Ceyhan Basin. Subsequently, station measurement data specific to the region were integrated into the model, to produce time series data for streamflow. The model's statistical performance was assessed by comparing the simulated flow data with the observed flow time series recorded at the measurement station within the same measurement intervals. Then, artificial components, such as dams and water demand, were introduced to the model. Simultaneously, dynamically downscaled climate datasets corresponding to RCP4.5 and RCP8.5 scenarios of the MPI-ESM-MR global climate model were obtained from the Turkish State Meteorological Service (MGM). To enhance precision, a delta-change bias correction was applied to these time series, and the adjusted parameters were incorporated into WEAP for the projection of future scenarios. The results of the study indicate that the Menzelet and upstream sub-basin will experience a temperature increase and reduction in rainfall that will reduce water resources in the area. The projections showed that under the two scenarios, the Menzelet Dam basin would be warmer overall, however precipitation would slightly increase in near future (NF, 2030-2050) and then decrease in far future (FF, 2051-2070). There is a declining trend in streamflow observed in both periods. Hydropower sectors will be negatively affected as stream flows are expected to decrease in the future. The average energy generation of Menzelet hydroelectric dam is 375.3 GWh/year in the reference period (1971-2000) calculated by WEAP and is expected to decrease by 32.1% and 35.9% in the NF and by 26.1% and 44.9% in the FF, respectively, under the RCP4.5 and RCP8.5 scenarios. According to both scenarios, hydropower generation decreased more in the FF than in the NF. These results will help the energy sector to develop strategies to maximize benefits and cope with the impacts of climate change in the near and long-term future.