The traditional way of measuring groundwater levels is labor-intensive. You drill a bunch of wells in different locations, take measurements over time and combine the data to understand groundwater levels and flows.
The Minnesota Department of Natural Resources is working on mapping groundwater in the state, but there are still hundreds -- if not thousands -- of wells yet to be drilled. An understanding of groundwater quantity is crucial -- three-quarters of Minnesotans get their drinking water from groundwater, and it's also used to irrigate crops in parts of the state.
That's what makes a special satellite used by a professor at the University of California, Irvine so exciting. Jay Famiglietti, also a senior water scientist at NASA's Jet Propulsion Laboratory in Pasadena, is using the satellite to measure changes in mass on land. From those measurements, researchers can figure out how much water is there, he said.
"We can literally put together maps regionally and globally of the places that are gaining and losing water each month," said Famiglietti, who will talk tonight about the research at a lecture sponsored by the Freshwater Society.
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The satellite can zero in on an area the size of a large aquifer -- about 60,000 square miles -- but it can't pinpoint areas as small as the three regions in Minnesota where DNR officials are looking at managing groundwater more closely. Famiglietti said using additional data can allow researchers to focus in on an area of about 20,000 square kilometers, and two other similar satellites to be launched in the future will likely be able to focus in on even smaller areas.
The satellite doesn't tell researchers how much water is groundwater versus surface water, so the data must be combined with other measurements being taken on the ground, he said. Still, it offers the ability to measure water levels much faster than traditional methods, he said.
And because groundwater is such a critical part of our water supply, it's important to be able to keep tabs on how much is there, he said.
"It hasn't been well-measured or monitored. The general public is not even really aware of how important it is to our water supply," Famiglietti said.
In addition to identifying shortages, the satellite data can help find areas that are prone to flooding. Famiglietti said the next step for researchers is to work with the state and regional agencies that manage water to incorporate the data into flood forecasts and regional drought monitors.