Evaluation of climate change impacts on reservoirs in water supply system is essential for a dry city in an arid state like Adelaide, South Australia. Myponga Reservoir, known as one of the principal water supply sources for residents living in the south area of this city was selected as the case study. To achieve the rainfall data related to forecasting behaviors of climate change under various scenarios, the Climate Futures Exploration tool (CFET) from the Climate Change in Australia website (https://www.climatechangeinaustralia.gov.au) was used. This web-based tool is specially developed for predicting the trends of climate change over regions in Australia. Two Global Climate Models (GCMs), including CESM1-CAM5 and CNRM-CM5 in combination with three Representative Concentration Pathways (RCPs) scenarios were selected to produce predications regarding future rainfall trends in this research. Results showed that the annual and monthly rainfall will likely to decrease, ranging from -25.4% to +7.4% and -46.6% to +58.4%, respectively during three future time spans (2030s, 2050s and 2070s). A hydrological model was developed for the study catchment using the Personal Computer Stormwater Management Model (PCSWMM) to simulate streamflows in different climate scenarios and then compare to the baseline data (1993-1998). The monthly average inflows of Myponga Reservoir tended to be stable in summer and autumn and decrease in winter and spring. Results also revealed that Myponga Reservoir is likely to face more droughts that reduce its ability to supply water over the next decades. Water supply planners and managers and regulators can apply these findings of this study in enhancing the effectiveness of their supply and management plans or adaptive policies against climate change.
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