As a series of major winter storms hit the West Coast this week, anxious Californians remember the flash floods and “thousand-year” deluge that hit San Diego a week ago and Oxnard a few weeks earlier, wondering what will happen next.
Starting Tuesday night, and then again on Sunday, two “atmospheric river” systems will bring strong winds and heavy rain to Northern California, along with at least two feet of snow in the Sierra, followed by moderate to moderate rainfall. strong in central and southern California. , with a real risk of local flooding. And there are still at least two months left in our rainy season.
We should welcome the wet climate because most of California's annual water supply depends on winter storms that come across the Pacific or come in from Alaska. However, as cars driving through the flooded streets of the city of San Diego vividly demonstrated, the state is not adequately prepared to deal with extreme weather events, especially the turbocharged storms that human-caused climate change can bring.
Last year's severe winter (nine atmospheric rivers in just a few weeks in December and January) was both a reminder of the threat of a megastorm, the so-called ARkStorm, like the one that flooded the entire Central Valley in the winter of 1861 .62 killing thousands of people and a preview of the vulnerabilities California faces when facing extreme weather events.
Last year we were lucky in two ways. Although massive rainfall from the storms (the state's total rainfall was 141% of the annual average) packed deep snow in the mountains, abnormally cold temperatures allowed it to slowly melt throughout the spring and summer. The rapid thaw, with its risk of flooding, is a nightmare scenario for disaster planners.
The other saving grace was that California's reservoirs were relatively empty after three years of drought, providing space to store flood water for winter rains and snowmelt.
Even with those advantages, the southern San Joaquin Valley experienced spring river flows that overwhelmed some reservoirs and river capacity and caused reflooding of former Tulare Lake, which had been dry for decades due to water diversions for the agriculture.
This winter, our major reservoirs are at or above normal levels, so a long series of especially wet storms could still require emergency releases from major dams and some stress on the part of water managers.
What do we need to do to be better prepared? We have to manage water for tomorrow's climate, not yesterday's.
We have channeled and dammed California's rivers and then built homes and businesses in the floodplains, exposing them to costly damage. Now we need to move levees back, widen floodplains, slow our rivers, and better capture precipitation that falls as rain, not snow, in a warmer climate.
We have massively overpumped and degraded aquifers across the state while reducing nature's ability to recharge them. Groups like Sustainable Conservation is partnering with farmers, environmental organizations and the agricultural industry to pilot projects that will allow lands along rivers to flood during the winter, reducing flooding and improving groundwater recharge in the Central Valley. There are even charging sites along the mostly canalized Los Angeles River and in other urban areas of the state. These programs need to be drastically expanded.
Insurance policies, including those of the National Flood Insurance Program, They need to be renovated to protect vulnerable communities while discouraging construction (and reconstruction) in floodplains.
And the state must update its building codes and standards to make homes and entire communities more resilient.
The California Department of Water Resources has language developed to modify local regulations in coordination with model ordinances prepared by the Federal Emergency Management Agency in 2020. The new rules would require strengthening and elevating buildings, expanding flood setbacks, reducing the risk of repetitive losses, and requiring developers in high-risk areas risk that they reserve open areas and parks. that can be flooded without endangering lives or property.
Building resilience against extreme weather conditions will take time, but that just means we have to work fast. And yes, it will be expensive, but spending now to prepare for very wet and very dry seasons will cost much less than having to pay for future disasters. In May, Governor Newsom proposed nearly $500 million for one-time flood relief, but consistent, long-term funding is needed.
Atmospheric rivers and arid droughts are like earthquakes and wildfires: challenges Californians must face. We know they are coming; We just don't know exactly when or where. An earthquake-resistant home or a more flood-resistant community won't stop the ground from shaking or rain from falling, but it can mean the difference between weathering the storm or cleaning up after a disaster.
Peter Gleick is a hydroclimatologist, a senior fellow at the Pacific Institute in Oakland, and the author of “The Three Ages of Water.”
