Satellites weigh California water
Nasa satellites have weighed the water lost by the US State of California’s heartland since 2003. The Sacramento and San Joaquin River Basins which support the highly productive Central Valley have shed over 30 cubic km of water in that time.
The data comes from the Grace mission which detects changes in gravity caused by water as it cycles between the sea, the atmosphere and the land. It illustrates the impact of a drought but also excessive irrigation use. Source