Maximizing joint economic and ecological robustness in floodplain planning

Climate nonstationarity and uncertainty raise important issues related to design and planning within the water sector. In addition, the water sector has acknowledged the need for improved methods of incorporating impacts of water resources development on ecosystems into project evaluation. We present a decision analytic approach to selecting flood management portfolios that maximize robustness to climate change of both economic and ecological objectives. Robustness is measured according to the breadth of possible change in climate variables that can occur while maintaining acceptable economic and ecological performance of the flood management system and floodplain. A satisficing criterion is used for performance assessment, in which thresholds in quantifiable economic and ecological performance metrics delineate acceptable performance. The model is applied to choose combinations of infrastructural and non-structural, options-based flood management interventions on the Iowa River. Present value of expected net cost is used as the economic performance metric, while a hydrologically-based index representing floodplain activation measures ecological performance. Results demonstrate the tradeoffs between the high level of flood protection afforded through levee construction and low-regret reservoir re-operation strategy, which would expedite reservoir storage reduction and restore mid-magnitude flows downstream of a flood control dam