Gravity Variations Foretell Flood Risk Months in Advance Written by Science News
Thursday, 10 July 2014
Satellites can monitor saturated river basins to forecast disasters Small gravitational tugs from waterlogged river basins could give scientists a big advantage in predicting devastating floods, researchers report July 6 in Nature Geoscience.
Hydrologist J.T. Reager and colleagues from the University of California, Irvine looked at data from GRACE, a duo of NASA satellites that detect small changes in Earth’s gravity. As a river basin soaks up water, the satellites record a stronger gravitational pull. Wetter ground is more liable to flood when hit by a surge of rain or snowmelt.
The researchers studied GRACE data collected during the months before the May–July 2011 catastrophic flooding along the Missouri River. The team found that the region’s gravity increased leading up to the floods, and the researchers showed that the uptick could have been used to predict the 2011 flood five months in advance. Field measurements of snowmelt and soil moisture can offer at most two months of warning.
While promising, Reager’s team says the approach can’t predict flash floods brought on by sudden torrential rain, such as the deadly July 2010 typhoon that flooded parts of Pakistan.
Citations
J.T. Reager, B.F. Thomas and J.S. Famiglietti. River basin flood potential inferred using GRACE gravity observations at several months lead time. Nature Geoscience. Published online July 6, 2014. doi: 10.1038/ngeo2203.
Further Reading
J. Shugart. Flood damage to cost up to $1 trillion per year by 2050. Science News Online, August 16, 2013.
E. Wayman. Extreme storm surges may occur more often. Science News. Vol. 183, April 20, 2013, p. 18.
S. Perkins. Johnstown Flood matched volume of Mississippi River. Science News. Vol. 176, November 21, 2009, p. 10.
Source: Science News
http://www.amerisurv.com/content/view/12835/2/.........................................
Satellite Data Enables Early Flood Predictions
by Michelle Jones
July 07, 2014, 12:40 pm
Studying water levels
In the study, researchers took measurements of how much water was in a river basis before the spring flooding season came. Then they looked at historical satellite data, using it to take measurements about the amount of water that saturated the ground ahead of the Missouri River flooding in 2011. They found that the statistical model they developed gave strong indicators that a major flood was about to happen five months before it did. Researchers said they may be able to predict a major flood up to 11 months out, although predictions that far ahead of time would be less reliable.
The 2011 Missouri River flood lasted months, soaking farmland, closing nuclear plants and shutting down highways. A month before the floods rolled in, the National Weather Service issued flood warnings
NASA’s GRACE satellites
The data researchers used for the study came from the two GRACE satellites launched by NASA. Their orbits around Earth were affected slightly due to changes in the planet’s gravitational pull. Scientists say these small pulls indicate that the planet’s mass is changing slightly due to impacts from a buildup of water and / or snow. NASA originally launched the satellites to keep an eye on ice sheet melting.
At this point, researchers have only used their statistical method to examine past floods. In addition, they said only some types of floods can be predicted using their model. Flash flooding caused by sudden downpours, like what happens during monsoon season in India, could not be predicted.
Scientists also said it takes about three months for researchers to gather data from the two satellites, which means they can only predict floods two or three months ahead of time. That’s not much different than the amount of time current ground methods of measurements provide. However, NASA is looking at ways to speed up how fast its data is delivered, bringing it down to 15 days.
http://www.valuewalk.com/2014/07/satellite-data-enables-early-flood-predictions/..................................
http://austriantribune.com/informationen/144044-researchers-say-satellite-data-may-predict-floods-earthResearchers say that Satellite Data May Predict Floods on the Earth
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The findings were published on July 6 in the Nature Geoscience journal.
http://www.nature.com/ngeo/index.htmlLetter | 6 July 2014
River flood potential inferred using GRACE observations at several months lead time
J. T. Reager et al.