Based on a survey of OECD countries the incidence and severity of flood and droughts has been increasing for the majority of countries (Figure 1.2). Many of these countries also project that with climate change the incidence and severity of flood and drought events may continue to increase, while other research also supports an ongoing intensification of the hydrologic cycle (Huntington, 2006; IPCC 2008). This applies to rain fed farming systems, but is especially relevant to irrigated areas where upstream extractions and storage reduce the quantity available for environmental services, floodplains, and other uses downstream, including irrigation (Productivity Commission, 2006).