CAN WE SAVE THE CALIFORNIA DELTA IN THE FACE OF SEA LEVEL RISE?

ABSTRACT Sea level rise would profoundly affect low‐lying coastal and estuary regions of the world and especially the Sacramento–San Joaquin delta in California. This delta, the largest on the west coast of the US, has about 120 000 ha below sea level, protected by levees, many on weak peat soil. The delta is also the hub of water transfer from north to south for two big water projects, which are vulnerable to ocean saltwater intrusion. Sea level has been rising slowly and is projected to rise more in the next 100 years. This, coupled with continued subsidence, will make it more difficult to protect low‐lying delta lands from inundation. The biggest threat is during high water storm events, but also a few summer dry season breaks have affected water exports. Since current rates of ocean rise are slow, a modest continuing effort in levee strengthening to handle a rise of 0.3 to 0.5 cm yr‾¹ could maintain present levels of flood protection for decades. Eventually hard choices will have to be made on which islands to save as costs rise and with better estimates of ocean rise. More than farmland is involved; much infrastructure, such as roads and pipelines, is as well. Copyright © 2011 John Wiley & Sons, Ltd.