Multi-year streamflow drought in eastern Australia

Abstract

Streamflow drought characteristics were calculated for 123 coastal and inland catchments in eastern Australia. The characteristics for each catchment were determined by stochastic generation of 2000 years of daily rainfalls, which were converted to streamflows using the AWBM rainfall-runoff model. Droughts were calculated from the 2000 years of generated streamflow for durations of 1, 2, 3, 5 and 10 years, and expressed as a percentage of mean annual flow to facilitate comparisons among the catchments. There were six river basins with five or more catchments in the basin - three coastal basins in northern New South Wales and three inland basins in the Murray-Darling drainage division. These showed more variation within each basin than between basins. A long sequence of 100,000 years of streamflow was generated on one catchment, which showed that the severity of droughts increased with average recurrence interval to the limit of the generated data. There was no evidence of any regional influence on or geographical pattern of drought severity. The main result was the large variability of drought severity from catchment to catchment even within river basins.