Subsidence

California, tumbles into the sea

That'll be the day I go

Back to Annandale... 

Remember those lyrics from the Steely Dan song, My Old School?  (Well, probably not.)  Anyway, California isn't exactly falling into the sea, but vast areas of the Central Valley are sinking as massive amounts of groundwater are pumped during this historic drought.   

Basically, when water is taken out of the soil, the ground collapses and drops, threatening highways, bridges and structures. Sinking land is nothing new for the San Joaquin Valley. In the four decades prior to 1970, portions of the valley sank 28 feet. 

 Soil cracking and slumpage, 1970

We hadn't really heard of this until we watched a PBS News segment on California land subsidence. The bottom line is, no one really knows what to do about it. Or has any idea what this will ultimately cost.  In some places, the sinking rate has increased to almost 2 inches a month.

Subsidence from ground water pumping in the San Joachim Valley has been called "the greatest human alteration of the earth's surface."

And that's saying something...