Gravity and Groundwater: Satellites that measure changes in gravity can alert us to potential floods.

Using gravity to predict floods… it’s a weighty topic…. on this CurrentCast.

NASA satellites monitor changes in the earth’s gravity field. Yes – gravity changes!  JT Reager of the NASA Jet Propulsion Laboratory says shifting water masses play a role.

Reager: “If you have more water in a region, you have more mass there. And more mass is associated with more gravity. And therefore changes in water can cause changes in gravity.”

So think of river basins as buckets. When they’re almost full of snow, soil moisture, and groundwater, the NASA satellites will measure a small increase in gravity – alerting us that the system is saturated and more likely to flood with added precipitation.

Reager says that by combining gravity measurements with weather forecasts, we could see floods coming about five months in advance.

CurrentCast is produced in partnership with Cornell’s Atkinson Center for a Sustainable Future. Learn more online at

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