A new research project between GEUS and NASA provides more information about the Earth’s water cycle

Published 18-12-2019

Water is essential to all life on Earth and the topic on which hydrologist, Julian Koch, at Geological Survey of Denmark and Greenland (GEUS) is an expert. In the research project ALL-WET, he has used data from NASA to develop a hydrological model, which reveals new insight into changes in the Earth’s water cycle.

Foto: Rasmus Fensholt

The rising global temperatures caused by climate changes affect the Earth’ water cycle, which result in for instance extreme rain periods and severe droughts. This is why it is important that we have the most updated information on how the water cycle is being affected – and this is exactly what researcher Julian Koch studies in his new research project ALL-WET.

New satellite data increase insight into the Earth’s water cycle
In his research project, ALL-WET, Julian Koch uses a hydrological model to study the Earth’s water cycle focusing on water evaporation. A hydrological model is a simplification of the real-life water cycle calculating the hydrological processes.

In his research, Julian Koch uses satellite data from the American Space Administration (NASA) and the US Department of Agriculture (USDA). For the first time, the data are based on microwaves improving Koch’s model and in this way our information about the Earth’s water cycle:

Traditionally, hydrological research has relied on thermal satellite data to study evaporation. This method, however, depends on a cloudless sky as the clouds will otherwise block the signal,” Julian Koch says, and he continues:

“The new satellite data from NASA and USDA are based on microwaves allowing us to conduct our research in almost all kinds of weather. This is a huge improvement as it has been difficult to acquire data using the traditional thermal observations in tropical and subtropical regions due to, for example, the rainy season and a dense cloud cover. Now we get data that are more representative of the entire water cycle and a complete picture of the evaporation and water balance, allowing us to understand changes in the Earth’s water cycle.

Senegal shows the way for the rest of the world
The case in the ALL-WET research project is the Senegal River in the Sahel region in Africa. The area has been exposed to periods of severe drought, and here the more representative data can make a difference:

”The drought in the Sahel region, where the Senegal River is located, has led to drastic changes in the vegetation in the area with a very negative effect on both animals and people. The model can increase our knowledge about how and why the evaporation has changed over the period,” Koch explains and he adds:

“The Senegal River project can show the way to a better understanding of the water evaporation and how the water cycle works. The potential of the new method not only lies in Senegal, it can also be used all over the world in different climates – for instance in Denmark where clouds often limit the use of satellite data for hydrological research”.

The figure below shows the preliminary results of the model study:


Julian Koch
Senior Researcher

More about ALL-WET

See the video 'On a sunny day' about the exiting research project ALL-WET and researcher Julian Koch here .