The state has to provide rivers greater room to flood safely, according to experts, as climate change delivers more heavy rains. But there are significant challenges.
Jan 5 2023, updated 1:56 p.m. ET
California is battling a second week of torrential rain and snow that have flooded cities, destroyed levees, and downed power lines, and the state is debating whether its strategy for dealing with destructive storms is appropriate given the challenges posed by the 21st century's climate change.
Levees and dams were constructed in California for many years by state and federal planners to store water and keep it at bay. However, academics and some legislators are advocating a different strategy: allowing rivers to overflow, as climate change raises the danger of heavier and more catastrophic storms, like the one that was wreaking havoc on Northern California on Wednesday.
Levees may be moved further away from streams, protecting people and property from flooding while allowing more precipitation and snowmelt to infiltrate into subterranean aquifers, where it is basically stored in reserve to aid during times of drought. However, doing so frequently necessitates public entities purchasing riverfront property, which is challenging in a state where land prices are high and public resources are limited.
The state organisation that is in charge of managing floods in California's huge agricultural heartland, the Central Valley Flood Protection Board, Jane Dolan said, "You've got to find the room, you've got to find the support, and you've got to pay it."
Warmer air retains more moisture as the earth continues to warm due to human activities. Because of their lengthy form and enormous water carrying capacity, storms that pass across California most winters are more likely to be particularly powerful.
Rapid-fire atmospheric rivers, like those that have been sweeping through California since late December, can be especially hazardous. Flooding and landslides are more likely because the land and streams that have already been soaked by one rainstorm cannot hold the additional water from the subsequent one. The worst flooding in California's recent history occurred during the winter of 1861, when several weeks of intense storms wreaked havoc along the West Coast. According to climate experts, as the Earth warms, the likelihood of storm sequences of a comparable strength is increasing.
According to Larry Schick, a meteorologist who once worked for the Army Corps of Engineers, rivers eventually run out of time to ebb. "That's when danger begins,"
Dams, levees, and other "grey infrastructure," so named for its dependence on concrete and man-made buildings, contributed to California's economic success. Agriculture in the Central Valley, which produces nearly a quarter of the country's food, drives a large portion of the state's economy. But that triumph wasn't without a price.
According to Jeffrey Mount, a senior scholar at the research group Public Policy Institute of California, levees can foster an excessive sense of security, promoting the development of residences and businesses near them. State law limits property tax increases, so the best way to generate new tax revenue is to approve new homes. Local officials have a financial incentive to permit that development.
The need to build as much grey infrastructure as you can is being driven by the urge to expand, according to Dr. Mount. The risk of devastation if such levees break rises along with growth.
According to Joshua Viers, a watershed scientist at the University of California, Merced, extensively relying on levees has additional costs. The amount of water that California's underground aquifers receive as a result of its efforts to control its rivers has decreased. These aquifers are the ones that farmers and towns are increasingly relying on during droughts.
When surface water percolates through the soil, the groundwater that supplies California's drinking wells and many of its irrigation pumps is recharged. Levees obstruct that process by reducing the width of rivers, so reducing the amount of ground that water can reach and filter through.
According to Dr. Viers, "We've shut off the very process through which groundwater recharge used to happen."
Water Whiplash in California
The state has already made some policy changes to at least tacitly admit that levees and other infrastructure cannot completely avoid flooding and that it is necessary to guarantee that flooding only occurs in locations where it won't be very disastrous.
Since 2007, California has required a two-tier system of levees throughout the Central Valley. They must be made to survive floods, which have a 1-in-200, or 0.5 percent, probability of occuring in more populous locations. However, levees in rural regions are not need to be as strong.
The dual standard aids in prioritising investment in the most populous areas of the valley. In certain river systems, though, it also denotes an unwritten method of regulating floods: During intense storms, agricultural regions upstream are more likely to flood first, soaking up water so that towns downstream can escape the worst of the flooding.
Some regions of the state have been experimenting with relocating development and habitation from waterways. A new "setback" levee, which is effectively a second levee farther from the river, has given the Sacramento River in the city of West Sacramento greater freedom to flow.
Homes and fields were just below the main levee before the restoration began in 2011, leaving them vulnerable to floods. Currently, at times of high river levels, water instead flows through the area between the two levees that is covered with trees, as it did during this week's storms.
The Army Corps of Engineers, which is in charge of planning and engineering levees financed by the federal government, has grown increasingly receptive to the idea of expanding river space.
The Sacramento District of the Corps of Engineers, which covers a large portion of the state's central and northern regions, has a deputy district engineer named Beth Salyers who claims her organisation is increasingly embracing "engineering with nature."
Ecosystem restoration is something we're beginning to see implemented as we work on our flood projects, according to Ms. Salyers. "We learn and develop as time goes on."
It's unclear how much of the Corps' pledged assistance for flood management initiatives have really materialised.
Levee removal from rivers is a difficult endeavour. According to Paul Dirksen, the city's flood protection planner, in order to finish the setback levee project in West Sacramento, the city had to evacuate about a dozen homes close to the river. There were several difficult discussions with property owners.
One example sticks out in Mr. Dirksen's memory very well. It was a beautiful home, he said. "And that individual believed they would spend the rest of their lives there. As a result, they were really emotional about that.
According to Julie Rentner, president of River Partners, an environmental organisation that focuses on floodplain restoration projects in the state of California, local politicians might be reluctant to remove farms near rivers from production. "Land that's providing animal habitat and flood relief pays lower property taxes than land that's producing a product like milk, almonds, or walnuts," she said.
The Dos Rios Ranch Preserve, a 2,100-acre floodway enlargement close to the junction of the San Joaquin and Tuolumne rivers, was developed with significant assistance from River Partners. Previously a dairy and cow enterprise, the region is now a lush home for wildlife including birds and fish. The plot can safely be submerged by water if the rivers overflow their banks, lowering the risk of a downstream flood.
However, it took years to finish the project and a great deal of careful effort to piece together government money, according to Ms. Rentner. River Partners started negotiating with the family that owned Dos Rios Ranch in 2006, according to the source. It was completed in 2012.
She said that it had taken six years to find the funds to complete a single land deal. “Absurd.”
According to Dr. Viers of the University of California, altering how the state perceives its connection with nature may be the largest barrier to creating space for rivers.
"We've tried to control nature in the West for 150 years," he remarked. "Letting nature go goes against 150 years of convention. The difficult aspect is that.
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