The Sacramento Delta is very susceptible to slight rises in sea level, and the problems the salt water would cause for much of the state’s fresh drinking water, which flows through the Delta.
This was the motive for the Peripheral Canal, part of the Central Valley Project of the Bureau of Reclamation and still the best solution.
You can read a nice history of it at http://www.usbr.gov/dataweb/html/delta.html
And did you know that the Delta is one of the world’s great wind surfing destinations?
An excerpt.
Still awash in doubt
Delta residents fear storms -- and now climate change, too
By Matt Weiser -- Bee Staff WriterPublished 12:01 am PDT Monday, August 28, 2006
SHERMAN ISLAND -- On New Year's weekend, Barbara Flores went three days without sleep, and not because she was partying.
Flores and other anxious residents of Sherman Island, on the western edge of the Sacramento-San Joaquin Delta, spent the opening days of 2006 battling one of the biggest storms they'd ever seen.
Waters rose to the crest of the island's levees. Wind-whipped spray from crashing waves blew over the levee in a stinging fusillade, threatening to flood the island.
"We came close. Real close," said Flores, manager of Sherman Lake Resort on the island's western tip. "The only reason it didn't flood is because the wind stopped."
The Sacramento and San Joaquin rivers converge at Sherman Island, putting Flores in the cross hairs of the Delta's biggest wind and waves. This makes Sherman Lake Resort, humble and weather-worn though it is, one of the world's top windsurfing destinations.
But the resort has another distinction: It would be highly vulnerable to a rise in sea level from global warming.
The resort sits at one of the lowest levee points in a flood-control system that protects the Delta as a freshwater supply for 23 million Californians -- from computer wizards in Silicon Valley to financial gurus of Los Angeles.
If these critical levees on the Delta's front line failed, seawater would rush into the Delta, poisoning the estuary with ocean salts and forcing water export pumps and canals to be shut down.
This is a big enough threat in the conventional 100-year storm that flood managers plan against.
But new research suggests climate change makes this troubling scenario even more likely.
Warmer temperatures could cause a 1-foot sea level rise in the Delta by 2050, according to a new report by the state Department of Water Resources.
Added to severe winter storm conditions, the report finds, this would likely overtop not just Sherman Island, but also Webb Tract and Jersey Island, nearby islands also considered vital to Delta water quality.
Global warming is also expected to reduce the Sierra snowpack. This would mean less water stored for summer runoff but would boost winter river flows, putting additional strain on levees throughout the Central Valley, including Sacramento's.
And that's not all. Climate scientists estimate sea levels could go up another 16 inches by 2100.
"We are not, at this point, doing anything about it -- at our peril," said Jeffrey Mount, a geology professor at UC Davis who has documented additional threats to the Delta from earthquakes and weak levees. "There is little doubt the situation is changing, and changing very rapidly, and we have got to come up with a strategy to adapt."
There is broad agreement among scientists that these effects will come to pass. Sea levels are trending upward, rising 8 inches in the past century. But uncertainty lingers about how fast change will come, and how big it will be.
At first, swollen rivers would pose a bigger threat than a rising sea level, said Dan Cayan, a climate scientist at the Scripps Institution of Oceanography in San Diego.
"Later on, what happens is that sea level rises so much that you hardly even need a storm to create an event that is kind of exceptional," said Cayan, who studied the issue for the California Climate Change Center. "They're potentially bad events and they could overtop structures."
