Potential climate change impacts on the water balance of regional unconfined aquifer systems in South-Western Australia

Abstract

Abstract. This study assessed climate change impacts on water balance components of the regional unconfined aquifer systems in South-Western Australia, an area that has experienced a marked decline in rainfall since the mid 1970s and is expected to experience further decline due to global warming. Compared with the historical period of 1975 to 2007, reductions in the mean annual rainfall of between 15 and 18% are expected under a dry variant of the 2030 climate which will reduce recharge rates by between 33 and 49% relative to that under the historical period climate. Relative to the historical climate, reductions of up to 50% in groundwater discharge to the ocean and drainage systems are also expected. Sea-water intrusion is likely in the Peel-Harvey area under the dry future climate and net leakage to confined systems is projected to decrease by up to 35% which will cause reduction in pressures in confined systems under current abstraction. The percentage of net annual recharge consumed by groundwater storage, and ocean and drainage discharges is expected to decrease and percentage of net annual recharge consumed by pumping and net leakage to confined systems to increase under median and dry future climates.