캘리포니아 지역을 덮친 4년간의 가뭄과 지하수 펌핑에 대한 높은 의존도는 주 일부가 내려앉는 원인이 됐다. 지반이 가라앉음으로써 요구되는 인프라 보수는 수십 억 달러의 비용이 들어갈 것으로 예상된다.

몇몇 지역에서 연간 최대 1피트 이상 내려앉은 캘리포니아의 지반침하는 주 내 과도한 지하수 사용에 기인한 것으로 보이며 최근 몇 년간 주 전체의 가뭄으로 인해 가속화됐다.

 

 

 

Four years of drought and heavy reliance on pumping of groundwater in California have caused parts of the state to sink. The repairs to infrastructure required by the sinking is said to be costing billions of dollars.

 

California's land subsidence - which adds up to more than one foot a year in some places - can be attributed to the pumping of groundwater in the state; sped up in recent years due to state-wide drought. As pumping and well-drilling increases, aquifers below the surface become depleted, causing the land to sag in areas.

 

Major areas affected include the San Joaquin Valley, where half of the land is prone to sinking, according to a 1975 U.S. Geological Survey.

 

Long-term costs of repairs are hard to pinpoint, in large part because irrigation districts don't often single out repairs required by subsidence from general upkeep, but some experts estimate the final bill to be somewhere in the billons. Replacing one bridge that now sits below the waterline in Los Banos, for instance, is expected to cost $2.5 million.

 

The problem of sinking land in California is ongoing and accelerating. Researchers at NASA found that land near Corcoran sank 13 inches over eight months last year alone. Parts of the California Aqueduct, a massive canal that delivers water 400 miles to Southern California, also sank by nearly 13 inches, the NASA research shows.

 

[출처 = Water World / 2015년 12월 30일]