The California Department of Water Resources (DWR) is exploring development of climate change risk-informed floodplain mapping. This study will support the goals of improving the understanding of changing flood risks to the communities in the face of climate change and identifying the most appropriate resilience actions to enable better risk-informed decision-making. The intensity, magnitude, and frequency of extreme rainfall events are projected to intensify due to climate change and may further exacerbate flooding risks. Evaluation of changing flood risks due to climate change requires analysis of climate change projections and simulating the effects of changes in long-term precipitation and temperature on the flood flows using hydrologic and hydraulic models. Some of the key challenges associated with this type of analysis include many choices of climate models available, wide range of uncertainties in climate change projections, various downscaling methods, multiple emission scenarios, and determining probabilities of future flood flows. In this presentation, we will present the modeling approaches being developed to address the above challenges to analyze and quantify the impacts of climate change on flood flows and to describe and map prototype 100-year flood delineation for future conditions. An overview will be presented on the communication approaches being developed to describe changes to flood risk over time due to changing climate. A summary will be presented on how these approaches can help federal, state, and local agencies in developing policies, procedures, and communication material for climate risk-informed floodplain mapping.
