Though Congress is hammering the country’s on-the-ground monitoring programs, it still supports gathering data from space. Several recent NASA satellite missions are providing high-quality data.
The GRACE mission, launched in 2002, uses changes in gravity to detect changes in water storage. The data have revealed groundwater depletions in the Great Plains and California’s Central Valley. These trends can be used to predict floods and droughts.
A thermal sensor on the latest Landsat mission tracks evaporation and the amount of water used to grow crops.
And later this year, two additional water-related satellites – to measure soil moisture and precipitation – will be launched.
Though beneficial for assessing large-scale trends, the satellites do not replace the data gathered from a dense network of sensors placed in rivers and streams, which conveys the changes in a specific place.