Gravity. It keeps Earth
orbiting around the Sun, satellites in Earth’s orbit and all of us
standing on the ground. Gravity also allows us to track how
water moves around our home planet. By measuring minute
changes in gravity from space, the Gravity Recovery and Climate Experiment,
or GRACE mission, and its successor, GRACE Follow-on, have helped us
follow water moving on and below Earth’s surface for more than 15 years.
Now, integrating these and other measurements
into advanced computer models allows researchers to distinguish water
in the soil, root zone and deeper in the ground – and to forecast
into the future. Working with the National Drought Mitigation Center,
NASA scientists are providing global water availability maps
and U.S. forecasts to the public. The forecasts look
30. 60 and 90 days into the future and allow farmers.
community managers and researchers to prepare for flash droughts and floods.
The ability to forecast where water will be comes from knowing
where water has been, measuring soil moisture and how much water has been gained
or lost from aquifers. Using the models to separate the water
into layers, we can better predict events like flash floods, which are more likely
when the surface soil is already saturated, and anticipate droughts
as aquifers run out of water and take time to recharge.
Among the layers, surface soil moisture responds most rapidly to the weather,
while root zone soil moisture – the water available to plants – changes more
slowly, and groundwater – a vital resource for drinking water
and agriculture – evolves over months and longer.
Like here in the Okavango Delta. In the 25 years before
GRACE launched, the region experienced a prolonged drought.
Around the time GRACE started collecting data in 2002
precipitation picked back up. While the soil moisture quickly responded, it took longer
for the aquifers to refill.Although groundwater is not immediately
immediately affected by drought, it also takes longer to recover from drought.
In Australia, a historic drought in the early 2000s impacted
all of the layers. Another drought at the end of 2019
was seen by the GRACE-FO mission and dried out vegetation in the region,
leading to intense fires that burned through early 2020.
Let’s take another look at Europe. A heatwave scorched western Europe,
melting glaciers and drying out the region. Soil moisture dries
up almost immediately, while the root zone, which crops rely on, takes
longer to catch up. This computer model, by assimilating
satellite observations, helps monitor drought and wetness conditions.
NASA scientists originally developed the capability for the United States,
but it is now providing valuable information on the whole world.
Combining NASA’s spaceborne view with research and high end computing
helps us better prepare for extremes in water availability.
EXPLORE EARTH
NASA