Today, despite the effects of climate change and the widespread growth of industries and populations in the world, there are problems in water resources management. In this context, prior modeling for water resources management, based on the conditions in the historical period, has been ineffective and future changes have posed some challenges in this regard. This issue has become more important in the management and planning of dams reservoirs as the most important sources of water supply in many basins of the country. Therefore, one of the most important issues in the management of watersheds is the study of the effects of climate change on optimal utilization and allocation of reservoirs. Therefore, in this study, upstream catchment of Zayandehrood Dam as one of the areas involved with these problems and having an effective role in providing water for Zayandehrood Dam has been evaluated. To evaluate the effects of climate change on optimal utilization of Zayandehrood Dam reservoir, 6 GCM models have been used which, based on PERSIANN-CDR dataset, have the best performance in estimating climate parameters in this region. These models estimate rainfall and minimum and maximum temperature parameters over the 30-year period from 2020 to 2049 under RCP4.5 and RCP8.5. These models are weighted according to their accuracy in estimating climatic parameters and are finely downscaled using the “Change Factor” method. Then, using the information obtained from these models at 10 selected stations in the upstream of Zayandehrood Dam basin, the amount of runoff produced over the next 30 years is calculated using the HEC-HMS rainfall-runoff model. On the other hand, the new multi-objective optimization algorithm f-MOPSO / WP, which is obtained by eliminating the pre-optimization step from the f-MOPSO algorithm steps, has been used. This algorithm is evaluated in two states “with mutation” and “without mutation” which is first applied to historical data of the region; and in the next step and after assuring the performance of these algorithms, for the next 10 years and considering the effects of climate change is estimated in Zayandehrood Dam. To analyze the performance of these algorithms, their results were compared at each stage with the results of the NSGA II, which shows the superiority of the f-MOPSO/WP algorithm for both periods in terms of percent response to needs and realistic volume of water in the tank f-MOPSO/WP. In the coming period, the input under the RCP4.5 and RCP8.5 scenarios increased by 36.67% and 44.25%, respectively. Because the RCP4.5 scenario input is more critical than the RCP8.5 scenario, the first scenario is used to optimize the recovery of the Zayandehrood Dam reservoir in the future. After running the algorithms, Compromise Progrmming method is used to select the best execution in each algorithm. Consequently, for the historical period, the f-MOPSO / WP “without mutation” with 82.44% responsiveness was needed and in the next period, the f-MOPSO / WP with mutation 95.47% had the best performance.