Space Lends a Hand to Early Flood Warnings

Satellite monitoring data that can detect tiny changes in the gravitational field of river basins may be able to give up to 11 months' warning of disastrous floods, according to a new study published Sunday.

"This gives the background on what's on the ground before the rain even gets there," study author J.T. Reager, an earth scientist at the University of California, Irvine, told Live Science.

Using data from a NASA gravity-monitoring satellite called GRACE, researchers mapped out the Mississippi River basin and found that minute increases in the gravitational pull pointed to higher "wetness" of the land.

The drier the land is, the better it can soak up and store water. But if the ground is already saturated, the water will quickly run off into the river and potentially cause flooding,

"Just like a bucket can only hold so much water, the same concept applies to river basins," Reager added.

Reager and his colleagues looked at past satellite data from the May-June 2011 flooding of the Missouri River - a disaster that statistically occurs only once ever 500 years, Phys.org reported.

Their technique proved effective at predicting such major floods from six to 11 months ahead of time. Though, the more advanced the warning, the less reliable the data was.

The team used GRACE to look at all potential water sources, including snow, surface water, soil moisture and groundwater, according to Live Science.

One drawback to the method is that it only works for certain types of floods, and can't foresee flash floods caused by sudden rain, for instance.

Reager hopes his new approach will eventually help forecasters prepare reliable flood warnings several months earlier.

"It would be amazing if this could have a positive effect and potentially save lives," he said.

However, the team notes that GRACE satellite data cannot be obtained for three months after measurements are taken, limiting potential flood predictions. That's the same amount of time it takes for current on-the-ground advanced warning systems. NASA is working on ways to speed up its data delivery to 15 days, Reager added.

The research was published in the journal Nature Geoscience.