Feedback Between Reservoir Operation and Floodplain Development: Implications for Reservoir Benefits and Beneficiaries

Currently, reservoir operation researchers and decision makers weigh the trade-off between water conservation and flood control at the event and seasonal scales but have neglected the role of socioeconomic dynamics which unfold over longer time scales. However, ongoing advances in understanding human-flood interactions provide an exemplary opportunity to diverge from this traditional treatment and instead incorporate feedbacks from downstream floodplain development in reservoir operation decisions. To do so, we modify and couple existing mathematical frameworks for optimal reservoir operation and leveed floodplain dynamics. The new coupled model demonstrates that, where reservoir operation persistently maximizes event- to seasonal-scale benefits (i.e., the status quo), most reservoir-floodplain systems will coevolve toward states of high preference for flood protection and highly developed floodplains. Further, under the status quo operation strategy, less benefits can be achieved as time goes on, benefits shift from water conservation consumers to floodplain inhabitants, and risk is transferred from floodplain inhabitants to water conservation consumers. We compare the status quo operation strategy to a strategy which stabilizes the floodplain development level and show that allowing excess (i.e., more than is optimal at the seasonal scale) flooding now preserves future water conservation benefits by disincentivizing floodplain development. Finally, we illustrate this coevolution and its ramifications at two U.S. reservoir-floodplain systems where floodplain development has seemingly undermined hydropower production. The insights from this study fill a knowledge gap for floodplain managers and reservoir operators tasked with achieving economically efficient use of floodplains and reservoir storage.