How water is managed is emerging as one of the core challenges of sustainable development and earth system governance (Pahl-Wostl, Gupta, & Petry, 2008a; Biermann et al., 2009). Floods and droughts already have a huge impact on human development and well-being. Adaptation to existing climate variability to reduce water insecurities is already a pressing need (Pielke, Prins, Rayner, & Sarewitz, 2007). Securing access to safe drinking water, allocating sufficient water to grow food, protecting life and property from floods, as well as maintaining river and floodplain ecosystems as countries develop economically, however, is a complex set of interlocking and dynamic challenges.