This winter was a record one. Snow piled up so high in California’s mountains that collapsed roofs and extended the ski season into summer.
California officials are now keeping an eye on the weather, worrying that parts of the state, especially the southern Central Valley, could experience devastating flooding. Because that rich snow mass begins to melt, running down the saturated ground and into the already swollen rivers. In some areas, the snow is thicker than it has been in generations, so it’s hard to say how quickly it will melt, and it’s hard to predict how it will turn out.
Jeffrey Mount, Senior Fellow, Center for Water Policy, California Institute of Public Policy, said: How bad the snowmelt will be depends on how warm it gets and how fast it goes.
“It’s a big unknown — when and how long,” Mount said. “We know the total volume that needs to come out of these mountains is an all-time record.”
The thaw is less of a threat to the major waterways that flow around the state capital and down the Delta and San Francisco Bay. The Sacramento River is a large, well-protected waterway with a robust flood control system, and although current snowfall levels flowing in from the central Sierra are high, they are not unprecedented.
But the San Joaquin River and the southern Sierra, which flows into the southern Central Valley, see record snowfall, and many of the smaller waterways that run through agricultural areas are ill-equipped to handle such currents.
Statewide snowfall is 249% of normal so far. But the snow is falling harder in the south. The Northern Sierra is currently at 209% of normal, the Central Sierra is at 243% of normal, while the Southern Sierra is currently at 320% of normal, according to the California Department of Water Resources.
Already, heavy winter rains have resurfaced Lake Tulea, a dry freshwater lake in the southern San Joaquin Valley, once the largest freshwater lake west of the Mississippi River, for the first time in a quarter of a century, spurring small farming communities. It was flooded. .
“Perseverance is a daily word in Allensworth,” said Kayode Cadara, who lives in Tulare County’s Central Valley community. “The community has experienced a much-needed break from the rain. However, work has yet to be completed to protect the area from the historic spring and summer thaws.”
State officials said Tuesday that reservoir managers are working to ensure that as much water as possible is conserved in a state that has endured three years of drought until this winter, while protecting communities from flooding. He said he was adjusting the water levels to keep them under control as much as possible.
“After three very harsh years and five years of drought before that, when nature decided to do us a favor, the long-term goal was to maximize storage while minimizing impact. That’s what it is,” said David Rizzardo, manager of the Department of State’s Hydrology Division for Water Resources.
But DWR state climatologist Michael Anderson told reporters on Tuesday, “How this year unfolds will depend on the weather and how quickly it warms.”
And it’s hard to say.
“We don’t really know how the snow will melt,” said Jenny Fromm, head of water management for the U.S. Army Corps of Engineers. “If we could predict the future, we probably wouldn’t be in this industry.” .”
“We expect these exceptional snow levels to lead to high flows,” said Jeremy Arrich, who manages DWR’s Flood Management Division.
“There are so many parameters in that calculation that we are not in a position to predict where the water will go,” says Arrich. “There are a lot of moving parts and parts.
In addition to the Tulare Basin, there are also concerns about the Eastern Sierra, Mount said.
“Flooding in the San Joaquin Valley is a concern as the levees are not very good, the river is already nearing flood stage and the water has nowhere to go in the Tulare Basin,” Mount said. “It just sits there and many farms have to stop producing.
Finally, he said: What is (the country) going to do for them? ”
https://www.eastbaytimes.com/2023/04/11/california-officials-gird-for-potential-disaster-when-and-where-will-the-record-melting-snow-go/ California officials prepare for potential snowmelt disaster