Water resources sustainability considering climate change and future demands in five Peruvian watersheds

Abstract

Climate change and increases in human activities are constantly threatening water availability in Peru. This study provides a tool for the evaluation of future scenarios on five watersheds located in the Arequipa Region, southern Peru. Future climate change analysis using calibrated hydrologic models for available streamgages and reservoir volumes is provided. A semi-distributed approach was executed for each watershed and an innovative simulation splitting approach was used, which allowed having different starting dates for the simulations using all available data obtained from different sources. Furthermore, water uses for each watershed were evaluated against predicted reservoir inflows and streamflows for near and far future periods. In addition to the above, 12 climate change models with four Shared Socioeconomic Pathways (SSP) were ensembled for the five watersheds. The results indicate that the region expects increased flows during the wet season, and no significant changes occur during the dry season. This pattern is similar for all five watersheds, which is expected because of the large spatial resolution of the climate change models. Reservoir inflows are expected to increase by up to 42\% and 216\% for the lowest and highest greenhouse gas emission SSP evaluated, respectively. Similarly, streamflows were predicted to increase by up to 295 and 704\% for these two different SSPs. Future hydrology simulations combined with future water demands suggest that significant water deficits are not expected for the watersheds under study. This could not be true because the flows were found to be higher during the wet season and steady during the dry season. Moreover, important volumes of water can be lost during the wet season by natural drainage; hence, if future water sustainability is desired, storage and irrigation efficiencies need to be improved.