Explainer: How much will all this rain help the California drought?

California has endured a devastating multi-year drought that has depleted reservoirs, forced officials to beg residents to conserve water, and limited the supply of vital farmland.

Suddenly, a series of severe storms hit the state, and more are expected in the coming days. Rain soaks a state that desperately needs water, even as it causes devastating loss of life. Experts say it will help in drought conditions, but it’s not yet clear how much. And rain and snow won’t be enough to solve some of California’s long-term water problems that climate change is exacerbating.

“We are moving towards a warmer and drier climate,” said Ginny Jones, interstate resources manager for the California Department of Water Resources.

Here’s how the storms will affect California’s long struggle with drought:

Where does rain help?

California has experienced six atmospheric rivers in recent weeks and is poised for three more, with wild weather set to continue for at least another week, Gov. Gavin Newsom of Santa Cruz County, where raging ocean water has damaged the iconic river, said Tuesday. wooden pier.

Storms brought massive amounts of water to the state, especially in central California, including the San Francisco Bay Area and the Sacramento Valley. According to official data, the amount of precipitation is 138% of the average for this time of year. The storms also brought snow to the Sierra Nevada, which runs along California’s eastern border.

Some depleted bodies of water have begun to fill, especially near the hard-hit Sacramento region and parts of the Sierra Nevada. The reservoirs are needed to irrigate the Central Valley, a productive area of ​​farmland that grows large quantities of fruits, nuts and grains. The reservoirs also supply water to millions of people living in coastal cities.

The latest in a relentless string of California storms has been flooding roads, eroding coastlines with heavy surf, turning rivers into raging flood zones, and forced the evacuation of thousands of people in cities that have already experienced deadly landslides.

For example, a small reservoir in Sonoma County, which at Christmas was about half its historical average, rose to 80% of that average by Monday.

“What we have at the moment allows us to be in good shape, probably for at least the next year,” said Alan Haynes, a hydrologist in charge of the California Nevada River Prediction Center.

It is also one of the best years in recent decades for snow accumulation, according to government officials. Snowpack is a special type of reservoir that stores moisture, which ideally slowly melts into reservoirs, supplying residents with water during the drier summer and autumn months. In addition to rain, storms have shed snow, resulting in total snow cover more than double the average for this time of year.

Where can storms be imperfect?

Winter is still early and it is unclear what the next few months will bring. Last year, snow cover across the state around this time also looked promising. But then followed several warm and dry months, and when the peak of snow cover was supposed to occur in early April, it was only 38% of the historical average.

“We’re not out of the drought yet,” said Laura Feinstein, who leads climate and environmental resilience at SPUR, a non-profit public policy organization.

Also, storms didn’t bring that much water down on northern California. The Shasta Lake reservoir, which was 55% of its historical average at Christmas, had risen to 67% by Monday, an improvement but still well below the historical average due to years of water shortages, Haynes said.

Atmospheric rivers do not hit everywhere. They move “like a garden hose if you spray it all over the yard,” said David Gochis, an expert on the effects of water on weather at the National Center for Atmospheric Research in Boulder, Colorado.

A major storm heading into Northern California could impact San Diego in different ways, but state officials want the entire state to be on top of resources, according to NBC 7’s Kelvin Henry.

“These largest reservoirs are so large that it will probably take some time for them to fill up,” he said. Some of the largest and most important reservoirs may require five or six such pours, he says.

David Novak, director of the National Weather Service’s Weather Prediction Center, says atmospheric rivers that are yet to come are likely to be weaker. The problem is that the already wet ground will not be able to absorb more water, which will create runoff problems. In about 10 days, weather conditions could change and finally “turn off the tap,” he said.

And the Colorado River, the main source of water in Southern California, has also been hit by a drought that has depleted major reservoirs along that river. Recent storms will not solve this problem.

What about long term issues like climate change?

Many farmers in California are pumping water from underground, which draws vast amounts of water from aquifers, depleting groundwater. Some wells dry up. This is an ingrained problem, experts say, and will not be addressed by a short-term series of storms.

And California is facing a long-term problem. Although there have been several rainy years, California’s drought continues for about two decades. Climate change is creating drier and hotter conditions. Water evaporates faster. California authorities predict that there will be less water in the state in the future.

“So in that overall picture, this series of storms is really just a drop in the ocean,” Jones said.

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Associated Press writers Seth Borenstein of Denver and Kathleen Ronaine of Sacramento contributed.