Why is California sinking? (Hint: drought)

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California’s four-year drought is causing the state to sink.

Many of the state’s farmers have turned to drilling deeper and deeper down in order to find groundwater for their crops, resulting in a higher risk of flooding.

According to the Center for Investigative reporting, nearly half of America’s fruits, vegetables and nuts are produced in California. As farmers dig deeper down to find water, the land gradually starts to cave in, an effect scientists refer to as subsidence. Some parts of California are settling lower at a rate of two inches a month.

Johnny Andrews, a fourth-generation farmer in California’s Central Valley, is worried about the flood risks associated with subsidence. “We’re talking about the state and feeding the people in the state. If that flood is bad enough, it will wipe out the next year’s farming, or a lot of it,” he said.

According to Michelle Sneed of the United States Geological Survey, the area being permanently affected by subsidence is enormous, stretching about 1,200 square miles, roughly the size of the state of Rhode Island.

Subsidence also has serious effects on California’s infrastructure, including roads and bridges, as well as the state’s flood control system. Chris White with the Central Irrigation District pointed out that the levees in one part of California are six feet lower than they were historically, which causes them to be weaker as well.

Last year, California lawmakers passed legislation to control groundwater drilling, but regulators are not required to limit pumping for another 25 years.

California Department of Water Resources’ Jeanine Jones said subsidence is not regulated under California law and that the state does not have data on how much damage subsidence may cost Californians. Independent groups, including California Water Foundation, said the damage could be in the billions.

Geologist Sneed said one way to prevent subsidence is to stop lowering water levels, but as farmers try to ensure a healthy harvest, cutting back on drilling remains a challenge.

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 Vocab

subsidence – the gradual caving in or sinking of an area of land

groundwater – the water present beneath Earth’s surface in soil pore spaces and in the fractures of rock formations

irrigation – the artificial application of water to the land or soil

Warm up questions

1. What is a drought?
2. What do you know about the drought in California?
3. What kinds of industries do droughts hurt the most?

Critical thinking questions

1. If California needs rain so badly, then why are farmers still worried about potential flooding?
2. What should be done to respond to the threat of subsidence?
3. What effect would there be on the rest of the country if California’s farmland dried up?

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http://www.pbs.org/newshour/extra/daily_videos/why-is-california-sinking-hint-drought/