Climatic background to past and future floods in Australia

摘要: Rainfall variability in Australia is generally among the highest world, largely due to dominant influence of El Nin˜o–Southern Oscillation. Australian climate has been characterized by wet and dry periods with sometimes sudden transitions from one mode other. Synoptic explanations teleconnections are discussed, an emphasis on Murray–Darling Basin (MDB). Floods two types: local ‘‘flash floods’’ widespread basin flooding. The latter often start upper reaches MDB tropical low‐pressure systems, slowly move downstream. smaller subcatchments can be rapid intense heavy thunderstorms or other instability exacerbated by topography. Global warming human activities occurring. Observed rainfall trends may partly natural but origin. Possible changes rain‐bearing systems associated midlatitude will along land cover change possible effects runoff, erosion, sediment loading. general picture for MDB, despite significant uncertainties, that frequency small catchment flash flooding likely increase, especially autumn winter summer over northern southern (but not central) areas MDB. Large floods increase magnitude parts of Basin, less do so south, where average decrease. Increased fire risk decreased ground lead greater loading erosion during floods, although reforestation could slow runoff decrease magnitudes catchments.