Researchers at the California Institute of Technology compiled hundreds of satellite images collected between 1992 and 2011 to measure how the ground in California rises and falls during the wet and dry seasons. When the images are put together, the result is a dramatic animated graphic showing the land seeming to inhale and exhale water, writes Live Science.
“What we see through the rising and falling of the ground surface is the elastic response of the land to regular changes in groundwater level,” Bryan Riel, lead author, and geophysicist at NASA’s Jet Propulsion Laboratory said in a statement.
Riel and his colleagues compiled 18 years of publicly available radar data captured by the European Space Agency. They focused on the area between San Fernando, northwest of Los Angeles, down to Irvine, in Orange County. The aquifers in this area are heavily tapped throughout the year to meet the water demands of the millions of residents and abundant farms in the region. The graphic the researchers made reflects the annual fluctuation of high and low groundwater levels that correspond with California’s wet and dry seasons.
The researchers point out that the fluctuation appears less dramatic in more recent years as water management authorities began focusing on replenishing the aquifers and avoiding depletion. The trend occurred after the passage of the Sustainable Groundwater Management Act that California Gov. Jerry Brown signed into law in 2014, which dictates that groundwater managers must avoid permanent ground lowering.
But subsidence, or ground lowering, has already occurred on a more permanent level in many parts of the area by several dozen feet, according to the U.S. Geological Survey, and groundwater levels are likely to continue declining in the future.
The new results were published April 20 in the journal Water Resources Research.