[New post] California officials gird for potential disaster: When and where will the record melting snow go?
gqlshare posted: "This winter has been one for the record books — snow piled so high across California's mountain ranges that it's collapsed roofs and extended ski season into summer.Now California officials are anxiously eyeing the weather and girding for potentially disa" The Ukiah Daily Journal
This winter has been one for the record books — snow piled so high across California's mountain ranges that it's collapsed roofs and extended ski season into summer.
Now California officials are anxiously eyeing the weather and girding for potentially disastrous flooding in parts of the state — especially the southern Central Valley — as that bountiful snowpack begins to melt, flows down saturated ground and pours into already swollen rivers. Because the snow is thicker in some areas than it's been in generations, it's hard to say how quickly it will melt and difficult to predict what will happen as it does.
"We're in uncharted territory for the southern Sierra because we've never measured snowpack this thick," said Jeffrey Mount, a senior fellow at the Public Policy Institute of California's Water Policy Center. How bad the snowmelt will be depends on how warm it gets and how fast, which affects when the snowpack "ripens," or thaws.
"That is the big unknown — when and how much," Mount said. "We know the total volume that has to come out of those mountains is an all-time record."
The snowmelt isn't so much a threat to the major waterways that flow around the state capital and down through the Delta and San Francisco Bay. The Sacramento River is a large and well-protected channel with robust flood-control systems, and current snow levels that feed into it from the central Sierra are high but not unprecedented.
But the southern Sierra that drains into the San Joaquin River and southern Central Valley has seen record snow, and many of the smaller waterways through the agricultural region are less equipped to handle such flows.
A drone view of flooded fields and properties south of Corcoran in Kings County on March 24, 2023. (Photo: Josh Baar/California Department of Water Resources)
Statewide snowpack is 249% of normal to date. But that snow has fallen more heavily to the south. While the northern Sierra is 209% of normal to date and the central Sierra 243% of normal to date, the southern Sierra is at 320% of normal to date, according to the California Department of Water Resources.
Already, heavy winter rains have caused Tulare Lake, a freshwater dry lake in the southern San Joaquin Valley that once was the largest freshwater lake west of the Mississippi, to reappear for the first time in a quarter century, and small farm communities have been inundated.
"Perseverance is the word of the day in Allensworth," said Kayode Kadara, a resident in the Central Valley community in Tulare County. "The community has experienced a much-needed break from the rain; however, the work to protect the community from the spring and summer historic snowpack melt is far from complete."
State officials said Tuesday that reservoir managers are coordinating to manage stream flows and water levels as best they can to ensure they save as much water as possible in a state that before this winter endured three years of punishing drought while protecting communities from flooding.
"When nature decides to give us a bounty after a really tough three years and previous drought of five years, the long goal is to try to maximize storage … while trying to minimize the impacts," said David Rizzardo, manager of the state Department of Water Resources' hydrology branch.
But Michael Anderson, the state climatologist at DWR, told reporters Tuesday that "how this year plays out depends on the weather, how quickly we warm up."
And that's hard to say.
"We don't actually know how the snow is going to melt," said Jenny Fromm, chief of the water management section for the U.S. Army Corps of Engineers. "If we could predict the future, we probably wouldn't be in this business."
Jeremy Arrich, who manages DWR's flood management division, said that "we do expect these exceptional snowpack levels will lead to high flows."
A drone view of floodwaters from the March storms that have flooded a field south of Corcoran in Kings County on March 23, 2023. (Photo: Josh Baar/California Department of Water Resources)
Snow melts in the Sierra Nevada mountains after another storm system brought heavy snowfall to higher elevations on March 30, 2023 near Mammoth Lakes, Calif. (Photo: Mario Tama/Getty Images)
A drone view of flooded fields and properties south of Corcoran in Kings County on March 23, 2023. (Photo: Josh Baar/California Department of Water Resources)
"We're not in a position to be able to predict where water may go, because there are so many parameters that go into that calculation," Arrich said. "There's a lot of moving parts and pieces. It's very complicated. We'll continue to put all our energy into this planning effort."
In addition to the Tulare Basin, there also are concerns about the Eastern Sierra, Mount said.
"We're concerned about flooding in the San Joaquin Valley because the levees are not very good, the rivers are already near flood stage, and the water's got nowhere to go in the Tulare Basin," Mount said. "It's just going to pool there, and a lot of farms are going to have to come out of production.
Ultimately, he said, "this is almost always a social justice question for these poor rural communities. What (is the state) going to do for them?"
No comments:
Post a Comment