While a drought may quickly become evident in inhabited regions that depend on regular rain, when remote parts of the world undergo a dry spell it might not become obvious for a long time, if ever. To build a more complete picture of drought-stricken areas, NASA has developed its first global groundwater map, which it hopes will become useful way of monitoring water supplies as the world contends with ever-hotter temperatures.
NASA developed the new tool together with researchers from the University of Nebraska-Lincoln, with the team drawing on data from the Gravity Recovery and Climate Experiment Follow On (GRACE-FO) satellites. Launched last year, these spacecraft circle the Earth to map its gravitational field, and by detecting variations in that gravitational field, can reveal the shifting of mass, such as the global flow of water and ice.
The GRACE-FO observations were mixed with computer models that simulate water and energy cycles to spit out time-varying maps of water distribution at different depths. This includes the moisture of the soil at the surface, root zone soil moisture that takes up the top 3 feet of soil, and shallow groundwater, with the water distribution presented in the form of weekly global maps.
“The global products are important because there are so few worldwide drought maps out there,” said hydrologist and project lead Matt Rodell of NASA’s Goddard Space Flight Center. “Droughts are usually well known when they happen in developed nations. But when there’s a drought in central Africa, for example, it may not be noticed until it causes a humanitarian crisis. So it’s valuable to have a product like this where people can say, wow, it’s really dry there and no one’s reporting it.”
A clearer picture of groundwater around the world could become an important tool in managing water security as the global population continues to grow and climate change makes for hotter and drier landscapes.
“Drought is really a key [topic]… with a lot of the projections of climate and climate change,” said professor Brian Wardlow from the University of Nebraska-Lincoln. “The emphasis is on getting more relevant, more accurate and more timely drought information, whether it be soil moisture, crop health, groundwater, streamflow—[the GRACE missions are] central to this. These types of tools are absolutely critical to helping us address and offset some of the impacts anticipated, whether it be from population growth, climate change or just increased water consumption in general.”
The researchers also leveraged the data to develop new one- to three-month groundwater forecasts for the US.
The video below offers an overview of the new global groundwater maps.
Source: NASA
