Satellites Can Now Forecast Droughts Months in Advance

We no longer have to wait for signs on the ground to know there is a drought. The tools we have used in the past, like monitoring rainfall, are useful but have a short timescale and climate modes do not last long. The ability to forecast water availability months into the future just don’t exist – until now.

That’s because advanced scientific satellites have given us the ability to track groundwater reserves and researchers are now working on using this data to accurately predict drought conditions months in advance.

The satellites were launched in 2002 as a joint American and German space project called Gravity Recovery and Climate Experiment (GRACE). The space mission placed two satellites into a polar orbit with the mission to map the Earth’s gravitational field. The satellites have since been decommissioned but they collected a wealth of data that is still being utilized.

In layman’s terms, the satellites worked together to map variations in the planet’s gravity with very sensitive instruments that reveal tiny fluctuations that could have been caused by mountains, shifting magma under the Earth’s crusts, or the impact of earthquakes.

They also measured the changes in the amounts of water stored in the ground through the differences in gravitational pull. A study in 2012 revealed a pattern that showed Earth’s groundwater reserves were declining and this information led an Australian research team from ANU to delve further. Their study about forecasting dryland vegetation months in advance was recently published in Nature Communications.

“What GRACE doesn’t tell you is whether it is deep water, soil moisture of surface water,” study author Dr Paul Tregoning told New Atlas. “It does give you the change in the total water column. The other measurement that we’ve used is from a soil moisture satellite mission called SMOS [Soil Moisture and Ocean Salinity] and that gives you a measure of the amount of water in the top five centimeters [2 in] of soil.”

Utilizing data from both GRACE and SMOS gave the research team a much better idea of how much water was available – if any – and how deep it was. They also analyzed how the different types of vegetation worldwide can access the groundwater and can predict the state of that vegetation months in advance.

“So, if you looked at say August 2016 and how much water was there in the shallow soil or in the deeper soil, and then we looked at which particular level of water was important for grassland or for forested regions, we would predict the state of vegetation up to many months in advance,” Tregoning said. “And these predictions turned out to be much more accurate than what had been done previously.”

The researchers told The Atlas that the results were so accurate that they were “mind-boggling” and “unprecedented.”

Combining this unprecedented research with computer modeling, the researchers say, can help predict the declining conditions of grazing areas and crops in advance and can even show areas that are at heightened fire risk.

“We have always looked up at the sky to predict droughts – but not with too much success,” Professor van Dijk from the ANU Fenner School of Environment and Society told New Atlas. “This new approach – by looking down from space and underground – opens up possibilities to prepare for drought with greater certainty. It will increase the amount of time available to manage the dire impacts of drought, such as bushfires and livestock losses.”

Climate change is making droughts more likely, but this diagnostic tool gives us a crystal ball view of the future. Through the computer model, we can anticipate droughts and allocate water, food, and firefighting equipment to the places that will need them.