SEASONAL STREAMFLOW FORECASTING IN EASTERN AUSTRALIA AND THE EL-NINO SOUTHERN-OSCILLATION

Previous studies have identified a strong link between climate variabi lity in Australia and the El Nino-Southern Oscillation (ENSO). This pa per describes the development and use of a seasonal streamflow forecas t model based on an optimal linear combination of forecasts derived fr om climatology, persistence, the Southern Oscillation index (SOI), and equatorial Pacific sea surface temperatures (SST). The model builds o n the work of the Australian Bureau of Meteorology and that of other r esearchers who have investigated southeast Australian rivers. The mode l is tested using 66 years of unimpaired streamflow data from 10 easte rn Australian catchments. Results from testing the model further suppo rt the ENSO-hydroclimate link, showing that eastern Australia generall y receives below normal streamflow during El Nino conditions ana above normal streamflow during La Nina conditions. In southeast Australia t he SOI is a better predictor for July-September and October-December s treamflow and the SST a better predictor of January-March and April-Ju ne streamflow. For many of the seasons and stations, the skill associa ted with the cross-validation forecast is better than that drawn from the baseline condition of climatology.