California's Central Valley Subsidence Accelerating, But No Comprehensive Survey Since 1970s
EDIT
Joseph Poland of the U.S. Geological Survey used a utility pole to document where a farmer would have been standing in 1925, 1955 and where Poland was then standing in 1977 after land in the San Joaquin Valley had sunk nearly 30 feet.
Groundwater now supplies about 60 percent of the state’s water, with the vast majority of that going to agriculture. Tens of thousands of groundwater pumps run day and night, sucking up about 5 percent of the state’s total electricity, according to a Reveal analysis of the increased pumping resulting from the historic drought. That’s an increase of 40 percent over normal years – or enough electricity to power every home in San Francisco for three years.
The sinking is starting to destroy bridges, crack irrigation canals and twist highways across the state, according to the U.S. Geological Survey. Two bridges in Fresno County – an area that produces about 15 percent of the world’s almonds – have sunk so much that they are nearly underwater and will cost millions to rebuild. Nearby, an elementary school is slowly descending into a miles-long sinkhole that will make it susceptible to future flooding.
The wall of a canal (left) cracks as the earth around it sinks. The top of a well (right) is pushed up and out of the ground as the ground around it sinks.
Private businesses are on the hook, too. One canal system is facing more than $60 million in repairs because one of its dams is sinking. And public and private water wells are being bent and disfigured like crumpled drinking straws as the earth collapses around them – costing $500,000 or more to replace. The sinking has a technical name: subsidence. It occurs when aquifers are drained of water and the land collapses down where the water used to be.
The last comprehensive survey of sinking was in the 1970s, and a publicly funded monitoring system fell into disrepair the following decade. Even the government’s scientists are in the dark. “We don’t know how bad it is because we’re not looking everywhere,” said Michelle Sneed, a hydrologist with the geological survey. “It’s frustrating, I’ll tell you that. There is a lot of work I want to do.” Some places in the state are sinking more than a foot per year. The last time it was this bad, it cost the state more than a billion dollars to fix.
EDIT
https://www.revealnews.org/article/california-is-sinking-and-its-getting-worse/
