A RECONSTRUCTION OF LATE QUATERNARY PALEOHYDROLOGY OF THE LAKE EYRE BASIN, ARID CENTRAL AUSTRALIA USING GIS TECHNIQUES

Lake Eyre, a closed-basin intermittent lake, receives the majority of its moisture from the summer monsoon. In times of increased monsoon intensity, generally associated with the La Nina phase of the ENSO cycle, the lake experiences significant flooding. But Lake Eyre has not always been an ephemeral lake. It was a perennial lake during several phases of increased monsoon activity during the late Quaternary (esp. 125 ka, 80 ka, 65 ka, 40 ka). Elevated shorelines mapped around Lake Eyre and the Frome-Gregory system, to the southeast, reflect these paleo-highstands. Using the age and elevation data from past research, we are able to use digital elevation models to map these paleo-lakes. Areas and volumes were calculated and the paleohydrologic processes, including the flow direction of spillovers, were reconstructed by incrementally filling each lake meter by meter. At the peak 125 ka filling, the Frome-Gregory system rose to more than +18 m AHD and overflowed to Lake Eyre which filled to +10 m AHD. Together they covered more than 35,000 km², more than three times the area of the modern Lake Eyre playa, and they held 430 km³ of water. By comparison, the deepest historic filling (1974) held 30 km³.