Mapping the future of flood risk in the Snohomish and Stillaguamish basins

Recent studies have begun clarifying both the mechanisms driving changes in flood risk and the best practices for advancing climate-resilient planning. Although invaluable for local planning, these studies lack the spatial coverage needed to support regional planning and prioritization. Here we present on a recent effort to quantify changes in the depth and extent of flooding for the Snohomish and Stillaguamish watersheds. Leveraging recent studies to estimate changes in streamflow, precipitation, and sea level rise, this effort represents a novel and relatively inexpensive approach to estimating the future impacts of flooding, with potential for expansion to all of western Washington and beyond. In addition, models like these can be used to evaluate the downstream reductions in flood risk that could result from major restoration efforts. In this talk we will describe our approach, validation, and the resulting maps of changing flood risk for the two watersheds, as well as its integration into the Snohomish Conservation District’s Agriculture Resilience Plan