Loss of both groundwater and water stored in surface reservoirs in the drought-striken western U.S. isn't just expensive and contentious: it's evidently making the earth's crust rise in the West
. Scripps researchers say that the average rise across a wide stretch of the West Coast is approximately one sixth of an inch.
Scientists came to this conclusion by studying data collected from hundreds of GPS sensors across the Western U.S., installed primarily to detect small changes in the ground due to earthquakes. But the GPS data can also be used to show very small changes in elevation. The study specifically examined GPS stations on bedrock or very thin soil because it provides the most accurate measurement of groundwater loss, said Duncan Agnew, professor of geophysics at the Scripps Institution of Oceanography. Areas with thick soil, such as farms, can see the ground sinking as the soil dries out. But Agnew said the bedrock underneath that soil is actually rising.
The highest uplift of the Earth occurred in California's mountains because there is so much water below them, Agnew said. The uplift was less in Nevada and the Great Basin.