Topographic data reveal a buried fluvial landscape in the Simpson Desert, Australia

Buried river channels and valleys have proven to be valuable economic and agricultural resources. Often they are ecologically important refugia and in some instances, such as in the Sahara Desert, serve as dramatic reminders of the climatic changes that have taken place. Here we report the determination of a fluvial landscape that is substantially buried under the Simpson Desert using a digital elevation model (DEM) specifically derived for this purpose. The DEM is a grid of ground-level elevation points with a spacing of 9 s in longitude and latitude (~250 m). It was calculated by applying the ANUDEM gridding algorithm to national spot height elevation data taken from 1:100 000 scale topographic maps. The ANUDEM algorithm includes a drainage enforcement algorithm that has been found to reliably discern drainage structure from minimally sampled point elevation data in central Queensland and broad-scale paleodrainage structure in Western Australia. To avoid erroneously highelevation information, source elevation data were only selected from between dunes in the Simpson Desert region, providing a more accurate basis for determination of the general surface topography and its underlying paleodrainage structure that existed prior to the development of the dunefields. The DEM reveals the broader, low-frequency topography in the Simpson Desert, reflecting the landscape buried up to 35 m below the sand surface. The paleodrainage analysis is in good agreement with data from the Shuttle Radar Topographic Mission (SRTM). It is now possible to trace a network of topographic lows that are likely to represent paleochannels through the driest desert in Australia and plot the former courses of the world's oldest rivers prior to their burial