Skip to comments.The Gravity of Water: A novel and much-needed view of Earth’s water supplies
Posted on 09/20/2012 11:04:09 AM PDT by null and void
Measurements of underground water storage (aquifers) rather than surface water (lakes, rivers, etc.) reveal the long-term effects of drought. This map shows ground water conditions in the U.S. during the week of November 28, 2011, compared to the long-term average. (Map by Chris Poulsen, National Drought Mitigation Center, based on data from the GRACE science team.)
Measurements of underground water storage (aquifers) rather than surface water (lakes, rivers, etc.) reveal the long-term effects of drought. This map shows ground water conditions in the U.S. during the week of November 28, 2011, compared to the long-term average. (Map by Chris Poulsen, National Drought Mitigation Center, based on data from the GRACE science team.) The signature of drought was easy to read in the southern United States in the summer of 2011. It was in the brown, wilted crops and the bare fields. It was in the clouds of dust that rolled across the sky and in the shrinking reservoirs. It was in the fires that raced through crisp grasslands and forests, devouring homes and wilderness. It was in the oppressive heat that returned day after day.
Drought was harder to see as 2011 drew to a close. With the return of winter, rains began to fall and temperatures dropped. But the drought was still there, lingering beneath the surface. It was still apparent to hydrologists who test the wells that plunge deep into underground aquifers.
This lingering, subtle drought was also visible to a highly unusual pair of satellites.
In Nebraska, Brian Wardlow and colleagues at the National Drought Mitigation Center watched the drought long before and after the average citizen paid heed. Wardlow develops satellite-based products that experts use along with more traditional ground observations to assess the severity of drought. Looking at measurements from the satellites, Wardlow could see broad-scale changes in groundwater supplies at varying depths over large swaths of the South.
After a year without much rain, it was no surprise that the drought lingered below the lands surface. Groundwater takes a long time to be depleted, but it takes a long time to be recharged as well, says Wardlow, a remote sensing specialist at the University of Nebraska-Lincoln. From experience, he expected regional groundwater supplies to be diminished. But, this time, he could see it in greater detail than traditional well measurements had ever provided.
Observing the water buried beneath layers of soil and rock was no small thing. When the twin satellites known as the Gravity Recovery and Climate Experiment, or GRACE, were launched in March 2002, few hydrologists believed they could see no less measure changes in groundwater. But at least two scientists did: Jay Famiglietti and his graduate student Matt Rodell, who were working at that time at the University of Texas at Austin (UT-Austin).
Now a scientist at NASAs Goddard Space Flight Center, Rodell has spent the past decade studying groundwater with GRACE and working to make those measurements useful to decision-makers. Thanks largely to Famiglietti, Rodell, and a handful of other scientists, GRACEs measurements of groundwater, ice, and oceans are now so essential that NASA is preparing to launch a follow-on mission.
Thank you for posting.
Question: How can 5% of the country be in the 2nd percentile?
5% of the country has less than 2% of the water?
Heck I don’t know, I just repost ‘em!
Seems to me those aquifers would show a lot of variation depending on what time of the year you measured their levels, and then compared them to the long-term average.
Heck I dont know, I just repost em!
I take it to be read as 2% of the long term average value for a specific location. In this case it looks like the "specific location" is a grid cell that is about the size county or so.
Each grid cell's current value would be compared to the long term average value for that grid cell making each relatively independent of the others...
Just my interpretation though.
That’s where Lake Woebegone is located.
As Global Warming and peak oil falls apart as a philosophy of control, the next drive by the central planner party shall be water.
Surprise TN is neutral. We have a lot of ground water as well as a gazillion waterways.
Water doesn't disappear in a few years, it just moves around a bit.
Remember the huge, destructive floods on the Misouri and Mississippi rivers?
I wondered if we could build a canal down the East slope of the Rockies or across the high plains to move that excess water to irrigate or refill aquifers?