I agree with this article from the California Water Blog, that we would be well served to give rivers more room than current levee structures permit; but since that is impossible without removing substantial developed housing and commercial building wealth, we need to examine other ways to recharge groundwater storage.
A little publicized but highly curious part of the emergency drought legislation signed by Gov. Jerry Brown last month advances hundreds of millions of dollars to shore up and replace aging levees in flood prone areas of the state.
Drought relief through better flood control? Really?
As it turns out, some flood protection projects are important during droughts. Strategically removing sections of old levees or rebuilding them hundreds or thousands of feet from their original riverbank sites can significantly replenish aquifers during wet years, providing badly needed supplies during droughts.
The drought relief package accelerates the appropriation of $660 million from a 2006 flood protection bond act (Proposition 1E) that specifically authorizes construction of such “setback levees” because of the groundwater recharge value and other benefits they provide.
Setback levees are not new. The Dutch have them to improve flood control; allowing floodwaters to spill onto undeveloped or farmed floodplains lowers the flood risk for communities downstream. Their use in California, however, has been much more limited. Local flood control and reclamation districts have focused more on keeping century-old levees intact (Suddeth, 2010).
Some agencies are beginning to rethink this approach as growing numbers of studies point to the multiple economic and environmental benefits of reconnecting rivers with their walled-off floodplains.
It’s easy to forget the Central Valley was once a vast wetland (Whipple et al, 2012). Before we built dams and straightjacketed rivers with levees and riprap, floodwaters would swell onto floodplains (Mount, 1995). The water would percolate into the ground and refill local aquifers. Inundated floodplains also served as nurseries for fish, with abundant insect food and ideal water temperatures for growing bigger and faster – improving their odds of survival in the ocean (Jeffres et al, 2008).
Today, with only 5 percent of the floodplains left undeveloped, California affords few opportunities for floodwaters to restock local aquifers (Hanak et al, 2011). The levees built in the late 1800s and early 1900s to hold back floodwaters from cities and farms now stand as barriers to residents and farmers needing to expand groundwater supplies for drinking water and irrigation.
Retrieved April 14, 2015 from http://californiawaterblog.com/2015/04/09/making-every-drop-count-in-drought-and-deluge/