Helping Wildlife Could Ease California’s Drought
Flood control systems such as levees often prove environmentally destructive, destroying wildlife habitat. But they just might be the key to helping alleviate California’s worsening drought.
Researchers at the University of California, Davis, have found that moving back levees to allow more rainwater to soak the state’s flood plains helps recharge aquifers and increases the groundwater supply. The work is part of a project led by Graham Fogg, a UC-Davis hydrology professor who is researching how better flood control can be used to manage the state’s record-breaking drought.
As an added bonus, California would regain riparian habitat destroyed by flood control systems, which could lead to the return of wildlife.
Much of the state’s current water systems and flood plains have been relegated to concrete or rock-stacked ditches—high and narrow—that swiftly move rainwater and runoff downriver and out to sea.
Once it hits the ocean, it’s gone—unless your county is constructing a billion-dollar desalinization plant.
But Fogg and Joshua Viers, a University of California, Merced, environmental engineering professor, are working on a different approach: Instead of pushing rainwater down the drain, we should be flooding land to recharge increasingly tapped-out aquifers.
If the levees are moved back, spreading out the surface water area, rainwater and snowmelt would be able to spread out and percolate into the soil.
Viers used the setback of levees along the Cosumnes River in Northern California to test out the theory.
Over the past three years, he’s been monitoring the effects of the setback on the newly established 500-acre floodplain. The rearranged levees allowed for groundwater replenishment and also made space for row crops to grow, which actually reduced flood risk for local landowners.
“In wetter years, it even improves the salmon fishery because the floodplain is like an incubator,” Viers said in statement. “It provides the right food and water temperature for juvenile salmon. Spending time there helps them grow larger faster, and gives them places to hide from predators so there are more of them.”
One problem: Reconstructing levees is an expensive proposition.
In Sutter County, plans to construct a 3,400-foot-long setback structure and restore a riparian habitat along the lower Feather River is expected to cost $20 million.
California Gov. Jerry Brown, however, recently signed off on a $1 billion drought relief package, including $660 million in flood protection efforts. It may sound strange to appropriate more than two-thirds of a drought bill for flood safety, but with the warming weather, scientists expect increasingly severe storms to trigger more flooding.
And while most of the flood money will to go toward rehabilitating current infrastructure, there is a chance the funds could be used in levee setback projects as well.
“Under climate change, we anticipate more extreme wet weather and hence more winter flooding when we cycle out of drought conditions,” Fogg said. “These high river flow events will likely create significant opportunities for recharging groundwater if we can devise mechanisms for getting the water underground, such as via floodplain recharge.”