Climate change impact on water and salt balances: an assessment of the impact of climate change on catchment salt and water balances in the Murray-Darling Basin, Australia

Byline: Jenet Austin (1), Lu Zhang (1), Roger N. Jones (2), Paul Durack (3), Warrick Dawes (1), Peter Hairsine (1) Abstract: Climate change has potentially significant implications for hydrology and the quantity and quality of water resources. This study investigated the impacts of climate change and revegetation on water and salt balance, and stream salt concentration for catchments within the Murray-Darling Basin, Australia. The Biophysical Capacity to Change model was used with climate change scenarios obtained using the CSIRO DARLAM 125 (125 km resolution) and Cubic Conformal (50 km resolution) regional climate models. These models predicted up to 25% reduction in mean annual rainfall and a similar magnitude of increase in potential evapotranspiration by 2070. Relatively modest changes in rainfall and temperature can lead to significant reductions in mean annual runoff and salt yield and increases in stream salt concentrations within the Basin. The modelled reductions in mean annual runoff were up to 45% in the wetter/cooler southern catchments and up to 64% in the drier/hotter western and northern catchments. The maximum reductions in salt yield were estimated to be up to 34% in the southern catchments and up to 49% in the northern and western catchments. These changes are associated with average catchment rainfall decreases of 13 to 21%. The results suggest that percentage changes in rainfall will be amplified in runoff. This study demonstrates that climate change poses significant challenges to natural resource management in Australia. Author Affiliation: (1) CSIRO Land and Water, Private Bag 5, Wembley, WA 6913, Australia (2) Centre for Strategic Economic Studies, Victoria University, Melbourne, Australia (3) CSIRO Marine and Atmospheric Research, Hobart, Tasmania Article History: Registration Date: 07/09/2009 Received Date: 09/01/2008 Accepted Date: 28/07/2009 Online Date: 07/11/2009