Environmental Planning of River Corridors Considering Climate Change: A Brief Perspective

Abstract

Water reservoirs interrupt the supply of sediment to river reaches and floodplains downstream of dams. Consequently, reservoirs are sediment sinks, with accumulation rates that reflect the combined effects of local and regional hydroclimatology, prevailing landscape-scale erosion rates, and land-use practices. Sediment supply interruption has profound implications for the quality of downstream aquatic habitat, river bed architecture, and infrastructure safety. Resource managers attempt to address downstream impacts through a broad set of direct actions, which includes downstream habitat enhancement, sediment bypass or reintroduction downstream of dams, and complete dam removal. When confronted with climate change and uncertainty regarding precipitation projections, the environmental planning process used to review direct actions involving dams and reservoirs becomes more challenging. Specifically, if several different precipitation projections provide unique future hydroclimates, how do scientists, engineers and environmental planners decide which projection(s) to use within supporting technical analyses? Here, we offer a brief perspective on the need for the broader community to develop clear criteria on how to incorporate climate change information into the environmental planning process of rivers corridors. We frame our perspective around an approach used in evaluating the impacts associated with granular sediment release from a reservoir located on the central California coast, USA. We close with a review of limitations associated with our example approach and suggested directions for future research.