Climate Extremes and Adaptive Flood Management in the Central Valley, California

Abstract:

Current evaluations of Central Valley, California flood control improvements are based on climate and hydrologic conditions that occurred over the past 100 years. This historical period includes significant flood events caused by intense precipitation, rapid snowmelt, and watershed conditions that, in combination, result in the hydrologic conditions that have shaped the current flood infrastructure and management.

Future climate projections indicate the potential for increased flood peak flows and flood volumes in the Central Valley that will likely exceed the current capacity of existing flood control systems. Preliminary estimates of potential changes in flood flows have been developed for all the major watersheds in the Central Valley through the use of regionally downscaled climate projections and hydrologic modeling. Results suggest increasing flood risks that are dependent on spatial climate change patterns, individual watershed characteristics, and existing infrastructure investments.

In many areas, the increasing flood risks cannot be managed through traditional flood infrastructure alone, and more adaptive measures are needed to improve resilience under climate extremes. Planning approaches are being applied to consider the full range of flood risks, and include tiered interventions for events beyond the floods-of-record. The on-going flood risk planning efforts demonstrate new, and sensible approaches toward improving resilience for uncertain and evolving climate extremes.