InSAR for climate change

Did you know that 50% of our drinking and irrigation water comes from underneath the earth? Understanding and managing these water resources is critically important as we prepare to tackle challenges such as population growth and man-made climate change in the 21st century.

The goal of my research is to combine data from satellites with computer models to help us understand more about the groundwater on our planet.

The surface of the earth moves all of the time, for example, when two tectonic plates move during an earthquake. But did you know that the surface of the earth also moves up and down all of the time depending on how wet it is?

You can think of the earth as being a bit like a sponge. It is elastic, meaning that when it is loaded it deforms, and when it is unloaded it returns to the same position. It is also porous, so water can flow and be stored in small spaces inside the rock. Elasticity and porosity are coupled, so when we squeeze the rock, water flows out of it. The mathematical theory of poroelasticity gives us a model that can help us predict this movement.

By using this theory we can build a model of the flow of water in the Earth and underground deformation on a computer. But to make this model useful we need real data about the earth as input. Incredibly, modern satellite systems can give us data about how the surface of the earth moves to centimetre or even millimetre accuracy.

Every six days a satellite from the Sentinel-1 mission passes over Belval, and every other place on the planet. The satellite sends down a burst of radar that reflects off the Earth’s surface, and the satellite receives this information back.

By comparing two radar signals, we can precisely measure the distance by which the ground has risen, or sunk. So we can produce data describing the surface displacement everywhere and every time.

By combining the data from the satellite with the computer model, we will be able to reveal the hidden world of water under our feet.