Hope, P.K., Nicholls, N., and McGregor, J.
The rainfall response to permanent inland water in Australia

Schemes to produce permanent inland water surfaces in central Australia to ameliorate the climate in agricultural areas have been suggested since the late 19th Century. A thorough examination of the expected meteorological response to such an imposed water expanse was undertaken by Warren (1945) and the general conclusion was that there would be limited change to the climate. Here we use data and techniques not available to Warren (1945), to assess the likely impact of large permanent inland water surfaces on Australian climate. Studies of the rainfall response to extensive areas of irrigation in other countries generally conclude that there is little discernible difference in the rainfall amount, and the rainfall pattern does not change. Inland Australia is arid, with strong potential evaporation and only intermittent rainfall from modifications to the large-scale flow, often linked with positive phases of the El Nino - Southern Oscillation (ENSO). ENSO is also strongly linked with rainfall in eastern Australia, most likely swamping any signal from an inland water source. The large-scale interaction between the atmosphere and the land surface in central Australia is weak, and is not affected by whether large lakes such as Lake Eyre are full. Mesoscale and global climate models show that large water expanses do have local effects including a large local increase in surface latent heat flux and a decrease in temperature. In some cases this reduces rainfall over the water surface. However, across the rest of Australia there is no consistent or significant response in rainfall. We conclude, as did Warren (1945) that there is no evidence that large-scale permanent water surfaces in inland Australia would result in widespread climate amelioration.

Warren H.N. 1945, Bradfield scheme for `watering the inland'. Meteorological aspects: a) Possibilities of climatic amelioration; and b) Rainfall characteristics of river basins proposed to be harnessed. Bulletin 34, Commonwealth Meteorological Bureau, J. J. Gourley, Government Printer, Melbourne. 82pp