Ecological Decision Scaling: A Framework For Incorporating Ecological Principles in Water Management Decision Making

Abstract:

Large water infrastructure projects have fueled the economies of developed countries and led to the widespread degradation of freshwater ecosystems. Proposed dams promise to similarly transform the economies and environment of developing countries. Yet with rapidly changing climate, traditional water infrastructure design carries with it an increased risk of failure if climate conditions shift beyond design parameters. Environmental concerns have long been at the periphery of water management decision-making. However, the destabilizing effect of climate change on traditional engineering practices, coupled with increased societal interest in sustainable water management, now present an opportunity to better integrate ecological principles in water infrastructure planning and design. Here we operationalize sustainable water management by incorporating ecological performance metrics with traditional engineering performance criteria in a decision-analysis framework. We adapt the decision-scaling risk assessment approach to evaluate ecological consequences of water management decisions and quantify tradeoffs and synergies among economic and environmental objectives. We apply the framework to the Iowa River system, where recent changes in flood intensity have prompted managers to consider alternative flood control strategies, including new infrastructure and reservoir operation rules. The system was modeled to quantify flood damages (to Iowa City and agricultural lands) and the ecological benefits of river floodplain inundation under alternative management and climate scenarios. We found that raising levees substantially reduced economic damages under wetter and more variable climate futures, but provided limited ecological benefits relative to the status quo. In contrast, changes in reservoir operations did not reduce the risk of catastrophic flood damage, but provided significant ecological benefits associated with increased floodplain inundation. The management option that provided the greatest ecological and economic benefits over the widest range of future climates involved raising existing levees and allowing for controlled floodplain inundation.