Climate changes have impacted to many sectors including water resources in Vietnam. Vietnam is agricultural development country having a lot of reservoirs. These reservoirs play a very important role in flow regulation for water supply to economic sectors. In the context of undesirable impacts of climate change such as increasing temparature, evaporation, and changing rainfall and rainfall pattern, water demands and inflow to reservoirs change. This leads to changes of resevoir exploitation effects that needs to be assessed for adaptation solutions. This arcticle summaries the development of a tool for quick assessement of climate change impacts on exploitation effect of reservoir in central provinces of Vietnam.