Forget NOAA; NASA’s GRACE Protects You from Floods

The GRACE satellites. Image from

Or is that spelled Noah?  Anyway, NASA has a pair of 12-year old satellites from their Gravity Recovery And Climate Experiment (GRACE), and it’s NASA’s GRACE that might save you from flooding.  The two satellites are orbiting the Earth in a polar Low Earth Orbit (LEO) and are 220 kilometers (140 miles) apart from each other.  They were designed to measure and map the variations in the Earth’s gravity.

“Um,” says the astute reader of this post, “doesn’t flooding have more to do with water?  Wouldn’t a satellite that measures water be better for this?”  Gold star for you.  However, these satellites do measure water, in a way.  The GRACE satellites were designed to measure variations in the Earth’s gravity through measuring the changes in mass, such as the loss of ice from glaciers and the poles (example of Greenland ice loss below), as well as the water that flows through aquifers (as shown in groundwater depletion video, also below).  If there’s more mass detected, that means there’s more, in this case, water.


Since the satellites have been orbiting the Earth for so long, it’s fairly simple to build up a baseline of what an area’s normal water content is.  But if there’s an increase of the mass of water in that area, be that in the soil (indicating saturation of the soil), or in glaciers, then the GRACE satellites detect that.  With some more analysis of that kind of data, the information can provide residents of an observed area fairly accurate data of the likelihood of flooding near them.

What gives NASA the confidence to say they can help with flood prediction using GRACE?  They simply used data they had on hand to see if they could have predicted a pretty bad flood–the 2011 Missouri River flooding.  At least according to this little tidbit from the Nature Geoscience site, it looks as if the GRACE satellites detected the gradual increases in water mass leading to the flooding.

Apparently the data is so solid, the folks working on this study feel as if they can predict flooding as early as 11 months from [before] the event.  Although a 5-month lead, which would give better fidelity to their analysis, would probably be acceptable to most folks anxiously, and perhaps unwisely, living in those zones prone to flooding.  But, it also sounds like the data analysis infrastructure and methods will need to be changed.  Right now, according to this Yahoo! News article, NASA needs three months to analyse the data for flood prediction.  But NASA thinks they can cut down the analysis time to 15 days (!!), which means that even the shortest lead of 5 months would still be given in plenty of time for required actions.

Understand, the nature of how these satellites detect the water build-up will not allow for detecting flash flooding during monsoons.  That’s for NOAA’s weather satellites.  But it’s another possible and nifty capability to keep property and people safe.  And if anyone on NASA’s GRACE team starts building an ark, it might be good to follow their lead.


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