A Flood of Surprising Info About Gravity

Using gravity to predict floods is a weighty topic. So when satellites that measure gravity have something to say, we listen:

By the GRACE of satellites, scientists can now predict flooding! (via NASA)

NASA satellites monitor changes in the earth’s gravity field. Yes—gravity changes! So what does that have to do with flooding? JT Reager of the NASA Jet Propulsion Laboratory says shifting water masses play a role in gravity change.

“If you have more water in a region, you have more mass there,” he explains. “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. That lead time could be huge for farmers and public safety planners working to defend against extreme weather.