NASA Follows Changing Freshwater from Space


We live on a water planet. From millions of miles away, Earth shines blue, with almost 70% of its surface covered in water. But most of that water is in the oceans, it’s salty. On Earth, only about 3% of water is fresh — the stuff we drink and use to feed our crops — and it’s constantly moving: Through the atmosphere, soil, aquifers deep underground, and even living things. That’s where NASA satellites come in. Taking a global look at freshwater provides important information about droughts, floods and water quality around the globe. The more we know about water and its availability, the better decisions we can make about how to manage it. From identifying food insecurity before aquifers run dry, to pinpointing when and where rivers will flood, tracking water from space gives us an advantage in using it. For example: Looking deep underground, the Gravity Recovery and Climate Experiment, or GRACE mission, measured water stored in aquifers. When human activity and drought drain aquifers, they can be replenished by sufficient precipitation…but they aren’t always. GRACE watched how water moved in and out of aquifers from 2002 to 2016. Closer to our feet, water in the soil changes quickly in response to precipitation. We can see soil get wetter in response to rainfall, and about a month later, watch as vegetation blooms where the soil is sufficiently moist. We can track all of these steps with satellites, which help us predict where food insecurity may crop up before it becomes a problem. Satellites help us track rivers and lakes, too. Reservoirs can become contaminated by blooms of algae, which grow in response to fertilizer running off from farms and cities. In the upper Midwestern U.S., there are hundreds of lakes, so it can be difficult to track them all individually. A view from space helps us keep an eye on lakes with blooming algae. Rivers are an important source of water for communities around the globe, and often, these rivers originate as snow high in the mountains. Snowpack, or the amount of snow and accumulates on the ground, feeds rivers on a seasonal basis. Earlier snowmelt can affect how and where water is available for irrigation. And as the climate continues to warm, snowpack is disappearing at lower altitudes, and what does exist is melting faster. Our planet is constantly in motion, with freshwater shifting around the globe. Those changes are happening faster in a warming world, with precipitation falling in different places, and rivers flowing new speeds. NASA’s view of where freshwater is, and how it moves, is even more important than ever. From deep below the ground up into the atmosphere, we’re helping manage their water better. EXPLORE
EARTH
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