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Underground water measured from space can predict drought

Mark Dunn and Donna Coutts, February 3, 2019 5:30PM Herald Sun

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Twin GRACE-FO satellites follow each other in orbit around the Earth. Picture: NASA media_cameraTwin GRACE-FO satellites follow each other in orbit around the Earth. Picture: NASA

environment

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Measuring underground water on Earth from space can help predict droughts and bushfire intensity* up to five months before the events, according to new Australian research.

Scientists have studied information from satellites to measure water levels below the Earth’s surface with amazing accuracy.

“The way these satellites measure the presence of water on Earth is mind-boggling*,” Australian National University Research School of Earth Sciences’ Siyuan Tian said.

Dr Tian said the team knew they needed to move into space to get closer to understanding and predict drought.

They used information about gravity sent back from the GRACE-FO satellites, which orbit in a pair.

“We’ve been able to use them to detect variations in water availability that affect the growth and condition of grazing land, dryland crops and forests, and that can lead to increased fire risk and farming problems several months down the track.”

The ANU team designed computer models of water cycles and plant growth to build a picture of below-ground water distribution* and likely impacts on plants months later, co-researcher Professor Albert van Dijk said.

“We have always looked up at the sky to predict droughts, but not with too much success,” he said.

“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.”

Darling River Community Feel Effects Of Alleged Murray-Darling Basin Mismanagement media_cameraSheep rushing to be fed at drought-affected Louth, NSW. Picture: Jenny Evans/Getty Images

Dr Paul Tregoning from the ANU Research School of Earth Sciences said the GRACE space gravity mission provided a measurement of changes in total water storage anywhere on Earth for the first time.
THE SATELLITES
The satellites that collect the information for this research are called GRACE-FO.

They launched on May 22, 2018.

media_cameraGRACE-FO launch onboard a SpaceX Falcon 9 rocket, Tuesday, May 22, 2018, from Space Launch Complex 4E at Vandenberg Air Force Base in California, US. Picture: AFP/ NASA/Bill Ingalls

GRACE-FO stands for Gravity Recovery and Climate Experiment Follow-On.

Most of Earth’s mass (soil, rocks, mountains) hardly moves at all. Water, however, is constantly moving. It evaporates, flows, freezes, melts, rains and snows.

When a mass of water moves it affects that area’s gravitational pull.

The two satellites orbit 220km apart and they measure the difference in gravitational pull between them. This tells scientists where there is water and how much there is, even when it is deep underground.
The satellites are part of a project by NASA and German Research Centre for Geosciences and Australian researchers. ANU Professor Daniel Shaddock led the Australian team.

The research is published in the science journal Nature Communications.

GLOSSARY

  • intensity: how strong or powerful something is
  • mind-boggling: so huge or amazing you can’t imagine it
  • dire: very serious or urgent
  • livestock: farm animals

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QUICK QUIZ

  1. What is collecting the information for the scientists to analyse?
  2. What Australian university is involved?
  3. What computer models did the researchers build?
  4. When did the GRACE-FO pair launch?
  5. How far apart is their orbit?

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CLASSROOM ACTIVITIES
1. Make a model or diagram
Create a model or diagram of the GRACE-FO satellites. Add three or more factual pieces of information to display with your model or diagram that help explain what it does.

Time: allow 25-45 minutes to complete this activity
Curriculum Links: English, Science

2. Extension
Satellites help us in many different ways. Perform your own research to create a list of as many different uses for satellites as you can find.

Time: allow 15 minutes to complete this activity
Curriculum Links: Science, Digital Technologies

VCOP ACTIVITY
Vocabulary
There are many ambitious pieces of vocabulary in this article. Pick one of these words. Draw a grid on a blank page so it is divided into four squares. Write the word you have chosen in big letters somewhere on the page, such as at the top or in the centre. Label the four squares: 1. write the definition, 2. use it in a sentence, 3. write a synonym and antonym for the word and 4. draw a picture.

See if you can use your chosen work in a piece of text you are writing this week.

Challenge: Swap a completed grid with a classmate and see if you can add another synonym and antonym to their grid.

HAVE YOUR SAY: What on Earth would you like to see from space? Why?
No one-word answers. Use full sentences to explain your thinking.

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