From Drought to Flood: The Life Cycle of Drought

Australia’s climate is widely recognised as oscillating between drought and flood, with these cycles potentially intensifying under climate change. To reduce the impacts of both, being better prepared for, and more resilient to climate extremes is required . To develop management strategies that address these issues, improved prediction and an understanding of both drought onset and termination is required. Here, a whole-catchment assessment of drought from onset through to propagation and then termination for a 585 km² agricultural catchment in eastern Australia was conducted. Meteorological and hydrological measurements of drought were combined with vegetation and soil moisture data to assess how the catchment responded to drought and then recovered during drought termination. Thirteen meteorological drought periods persisting more than six months were identified during this period. During these, vegetation health, soil moisture and streamflow declined, however, all indicators recovered quickly when rainfall surplus returned. Drought onset was tightly coupled to the combined state of large-scale ocean-atmosphere climate drivers and termination was caused by synoptic-scale events. The combination of climatic factors, topography, soils and vegetation are believed to be what makes the study catchments more resilient to drought than others in eastern Australia. The study diversifies traditional approaches to assessing hydrological extremes at the catchment-scale by examining the drought to flood cycle using a range of globally available measures. This is a key step towards improved drought prediction and management.