LOS ANGELES — As pumps hum on wells and send vast quantities of water flowing to farms in the San Joaquin Valley, the dropping water levels are leaving underground spaces in layers of gravel, sand and clay, causing the ground to collapse and sink.
Satellite measures have tracked the worsening problem, known as land subsidence. In parts of the valley, the land has been sinking about 1 foot each year. The shifting ground has damaged canals and wells, and threatens to do more costly damage in the years to come.
In a new study, researchers at Stanford University examined the sinking in one area of the San Joaquin Valley over 65 years and projected that subsidence will likely continue for decades or centuries, even if aquifer levels were to stop declining. They also found, however, that if aquifers recover with a significant rise in water levels, that could slow or stop the sinking within a few years.
