August 26, 2009
Graph of the Day: Annual Inflow to Perth Dams, 1911-2009
Changes in rainfall combined with increased potential evaporation are expected to result in reduced runoff across most of Australia. In some cases reductions could be be severe. For example, by 2050 average streamflow is projected to drop 7-35% in Melbourne, 10-25% in the Murray-Darling Basin and 31% in the Stirling catchment (WA). These estimates of future impacts are consistent with regional observations in recent decades. In southwest WA, mean rainfall has declined dramatically from the late 1960s, in a series of steps. However reduction in river flows, and hence dam inflows, has been magnified nearly threefold from the reduction in mean rainfall. An average rainfall decline of 10-20% caused a 40-60% decline in dam inflow.
