Assessing water demands and coverage sensitivity to climate change in the urban and rural sectors in central Chile

Abstract

Snow dominated basins in the subtropics are susceptible to climate change, since evaporation and streamflows are affected, impacting key water sectors and increasing the risk of water shortages. This paper shows an integrated assessment of the impacts of climate change on the major water users in the Maipo Basin of Chile, allowing a direct comparison between competing sectors, describing their sensitivity to future climate changes instead of focusing on individual scenarios, and assessing the effect of likely responses, such as pumping, that impact groundwater levels. We developed a statistical downscaling mechanism to correct biases in global circulation model projections and ran a hydrological model to determine the impacts of climate change on the ability of the system to meet water demands. Mean coverage and minimum coverage of urban and agricultural sectors are sensitive to climate change, particularly to larger changes in precipitation. The urban sector is less sensitive because of higher reliability standards and holds a greater fraction of water-use rights in comparison to actual withdrawals. In addition, groundwater pumping represents an additional source of water to meet population demands. However, this favorable condition could no longer be present if climate change also affects aquifer recharge dynamics.