But even in a time of plenty, when Lake Sonoma is slowly filling and the Russian River may soon overflow its banks, water managers and scientists are unwilling to declare the drought over.
“We had such a big hole to dig out of to get this started,” said Grant Davis, general manager of Sonoma Water, as rain drenched Santa Rosa, the county seat. “We as water managers face something we call whiplash – meaning extremes at the dry end and extremes at the wet end.”
Scientists say the apparent paradox of dangerous floods amid the historic drought shows how climate change has intensified California’s intense climate — making the drylands drier and the periods wetter, with neither season completely counteracting the other effects.
Although California has improved its water management system in recent years, it was not built to handle storms this intense, experts say. Even if every drop can be captured and stored in a reservoir, it will take much more rain to wipe out the country’s years-long water deficit. And rain is only one part of the equation.
“We’re in a flood emergency while we still have an active drought emergency,” Carla Nemeth, director of the California Department of Water Resources, said in an interview. “That pretty much says it all about the new normal we have with climate change.”
Human greenhouse gas emissions, mostly from burning fossil fuels, have raised California’s average air temperatures by about 2.5 degrees Fahrenheit, according to the state’s Environmental Protection Agency. These warmer conditions increase water evaporation from vegetation and soil and thin the mountain snowpack that the state relies on for 30 percent of its water storage.
According to the U.S. Drought Monitor, there hasn’t been a week where some part of California hasn’t been abnormally dry or worse since 2011. Last year was particularly bad: Wells ran dry, and cities became dependent on bottled water as the state saw its second driest year on record.
“We’re starting from a position of really severe deficit,” said Noah Diffenbaugh, a climate scientist at Stanford’s Durr School of Sustainability. “If you don’t get paid for a few months, and then your employer gives you one regular monthly paycheck, most people won’t feel like their bank account is back to normal.”
When it rains, climate change does It’s much more intense and destructive, studies show – and, in turn, harder for water systems to absorb. The atmosphere holds 7 percent more moisture for every degree Celsius increase in temperature, which means any given storm will be much wetter in a warmer world.
If the forecasts for the next two weeks hold, 22 trillion liters of water May fall on California in the next 15 days, according to meteorologist Michael Snyder’s calculations. That’s enough to fill Like immediately more than twice.
“We are now in a climate where we are much more likely to have severe water deficits as opposed to wet conditions,” Diffenbaugh said.
The rise in temperatures means more than that Precipitation falls as rain instead of snow. Instead of accumulating on mountaintops, where it will gradually melt into waterways and ecosystems, the water immediately washes into rivers and streams. That can flood water systems that weren’t designed to handle such sporadic, heavy rains, Diffenbaugh said. In a 2019 study in the journal Water Resources Research, he and his colleagues found that flood risk worsens exponentially as precipitation shifts from snow to rain.
In California this week, the showers soaked soils and caused the collapse of drought-stressed trees. Officials fear that landscapes recently scorched by fire could dissolve into a sodden debris flow. Water managers once worried about critically low reservoirs are now considering releases to prevent dangerous floods.
Although dangerous, the deluge of recent storms has helped ease the country’s long-standing water shortage.
Sierra Nevada snowpack is nearly 180 percent of its normal volume for this point in the season — the highest level in 10 years. Scientists hope that the weather in California will not warm up too quickly in the coming months. This will allow the snow to slowly melt and trickle into the communities into the summer.
As of January 3, the US Drought Monitor classified the entire country as “abnormally dry”. California’s more than 200 reservoirs are about 33 percent below their historical average levels. Monitoring wells show that the country’s underground aquifers, which account for more than half of the country’s water supply during drought years, contain only two-thirds of their normal amount of water.
Now, some parts of the country are seeing up to an inch of rain per hour. But instead of slowly percolating through ecosystems and soils, the rain glistens over saturated soil in a devastating flood. Instead of replenishing depleted groundwater, the flood exceeds the limited capacity of rivers and reservoirs, causing an overflow.
This forces water managers in flood-prone areas into a delicate balancing act. Water is the country’s most valuable resource, and managers should hold on to as much of it as possible. But repeated heavy storms mean they need to reserve space to absorb floodwaters.
Those facing the worst drought conditions have other problems. In early December, Lake Sonoma’s bill was running painfully low, Davis said. The reservoir was below 40 percent of its capacity, just under 100,000 acre feet in volume. As of this week, it has passed 120,000, a good sign, but only about half of what the lake can comfortably hold.
Faced with unprecedented challenges, Davis said he is nonetheless Optimistic and that the country is “better prepared than we have ever been” to deal with extreme weather. One source of his hope is a pilot program that uses improved forecasting and modeling to make decisions about keeping or releasing water from reservoirs.
Sonoma used the system, known as Reservoir Operations Prediction, at one of its smaller reservoirs, and Davis credited it with saving thousands of acre-feet of water.
“This is going to be the way water managers are going to get through these extreme events,” he said.
Meanwhile, a wet December and early January are no guarantee that all that water will last until spring. Look no further than last year’s weather, said Ellen Hank, director of the Water Policy Center at the Public Policy Institute of California. The state saw similar winter storms, before an exceptionally warm and dry stretch wiped out most of the snowpack.
“Last year was not a good year, even though we started wet,” Hanak said.
California’s traditional rainy season runs from October to April, so much will change in the coming months.
“We still have a few months to play here,” Hanak said. “But this A blessed beginning.”
A key factor in navigating long-term drought conditions—and ensuring the nation’s well-being—will be finding new ways to harness floodwaters from future megastorms, effectively using one climate disaster to mitigate another.
Hanak and other experts see promise in underground water storage, which has been used in some parts of the country but may become increasingly popular as snowpack becomes less reliable.
Jane Dolan, president of the Central Valley Flood Protection Board, has pushed state and local governments to widen floodways and restore wetlands as a way to protect against heavy storms and recharge groundwater basins. The recent storms in California show the urgent need to do both, she said.
“We’re paying now to make things more resilient and protect people’s lives and property, or we’re going to pay later by fixing the massive damage that’s happening,” Dolan said in Chico, the state’s largest city north of Sacramento, where she spent time. decades in local government.
“Water is the number one issue in California,” she said. “We have too Too much of it, or not enough.”