California’s dilemma: How can you harness massive amounts of rain when water is scarce? Scientists say let it sink in.



CNN

California went from severe drought to severe flooding in a matter of days. On Monday, 90% of the state’s population was under flood watch as another round of storms passed. However, it was just last week when several counties in the state were experiencing quite the opposite—an exceptional drought, which the U.S. Drought Observatory considers the most severe category.

California’s parade of heavy rain storms didn’t quite reverse the deep-seated drought. Scientists warn it still has a long way to go to erase unfavorable rainfall trends and overuse of water supplies.

But the sudden shift from drought warnings to flood warnings highlights the dilemma California faces: How does it manage a massive amount of rain when water is scarce? And is it possible to harness that water to be available in the dry summer months?

Part of the solution, climate scientists told CNN, is to withdraw dams to allow rivers more room to flood safely into surrounding lands.

“We have to let the rivers flow differently, let the rivers flood a little bit more and recharge the groundwater in the wet seasons,” Peter Glick, a climate scientist and co-founder of the Pacific Institute in Oakland, told CNN. “Instead of thinking we can control all floods, we have to learn to live with them.”

Dams have effectively protected communities in the past, Glick said, but they are not designed for the challenges of climate change today.

“We need new thinking, we need to operate that infrastructure differently, we need to change some of the characteristics of that infrastructure,” Glick said. “This will allow us to capture more of these flood flows, store them underground in aquifers, and then use the groundwater resources when we need them in dry years.”

Many climate experts agree that using dams to prevent flooding during the rainy season means less water is available to seep into the aquifers. A vital source of drinking, bathing, and farming water across California’s Central Valley, these aquifers are drying up.

Cars were inundated with floodwaters after torrential rain lashed across Windsor, California, on Monday.

But giving rivers more room to flood has a benefit. This means entire communities will need to relocate; The process is known as a managed rollback.

Nicholas Painter, a researcher and professor of applied geosciences at the University of California, Davis, acknowledged that managed retreat is a daunting task, but noted that other countries are doing it.

“We’re behind the curve on this,” Pinter told CNN. Europeans in the 1990s started to do just that. They have invested billions of euros to restore the dams.”

Painter said the United States has always leaned toward building the infrastructure to provide protection.

“We’ve always had an engineering mindset with strong equity,” said Pinter. “There is also intense resistance from property owners when it comes to giving up their property rights.”

There is also a risk of opposition from political leaders worried about losing property tax revenue and losing land for building and development, Painter said.

A concept like a managed retraction, Glick said, requires a shift in mindset that will be very difficult to achieve. “These changes are absolutely easier said than done but they must be done.”

Pinter and Gleick both said that a managed retreat is just one tool in the box when it comes to adapting to more inclement weather. Glick noted that there are a host of other policies that countries need to consider.

“We have to redesign insurance policies so that we don’t rebuild homes once they are damaged in the same places where they will flood again,” Glick said. “We have to design flood insurance policies to encourage people to move away from floodplains, so we can open up those floodplains So when we get these floods, it will be less harmful.”

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