The old continent has suffered from a severe and persistent drought since 2018 and is increasingly lacking groundwater. This is confirmed by a study by the Institute of Geodesy at Graz University of Technology, Austria. Institutions from Germany, Spain, France, Finance, Holland and Switzerland also participated in the work.
While extreme weather events with flooding temporarily paint a different picture, Europe is suffering from a severe drought. Groundwater levels in Europe have been consistently low since 2018. The beginning of this tense situation is documented in a study conducted by the Institute of Geodesy at the Graz University of Technology (Austria) and other European institutions, published in the journal Geophysical Research Cards
The research notes that there was a notable water shortage in Central Europe during the summer months of 2018 and 2019. Since then, levels have remained consistently low. This is demonstrated by data analyzes carried out by Torsten Mayer-Gürr and Andreas Kvas from the Institute of Geodesy at the Graz University of Technology.
As part of the EU’s Global Gravity-based Groundwater Product (G3P) project, they used satellite gravimetry to observe the world’s groundwater resources and document their changes over recent years. The effects of this prolonged drought became visible in Europe in the summer of 2022.
Dry beds, stagnant waters that gradually disappeared and, with them, countless impacts on nature and people. The energy shortage worsened and many aquatic species lost their habitat and dry soils caused many problems for agriculture. Nuclear power plants in France lacked the cooling water to generate enough electricity, and hydroelectric power plants couldn’t do their job without enough water either.
Measuring groundwater from space
At the heart of the G3P project are twin satellites called Tom and Jerry, which circle Earth in a polar orbit at an altitude of nearly 300 miles. The distance between the satellites, about 200 kilometers, is important. Who is behind should not reach what is in front, so they received the name of Tom and Jerry in reference to cartoon characters.
The speed of satellites increases in proportion to the mass of land over which they fly. For example, if they pass under a mountain, the front satellite will start to go faster than the one behind and then slow down again. Then the same thing happens with the rear satellite. When both have cleared the mountain, their relative speed stabilizes again. These distance changes are the main measurement variables for determining the Earth’s gravitational field and are verified with micrometer precision.
With an average speed of around 30,000 km/h, the two satellites make 15 Earth orbits a day, which means that in a month they cover the entire surface of the Earth. Therefore, TU Graz can provide a gravitational map of the Earth every month. “The computational and processing effort here is quite large. We have a distance measurement every five seconds and therefore about half a million measurements per month. From them we determine maps of the gravitational field“explains Torsten Mayer-Gürr.
Europe has problems with persistent droughts and water shortages
However, the gravity map still does not determine the amount of groundwater because satellites show all mass changes and do not distinguish between sea, lakes or groundwater. This requires cooperation with all other partners in the EU’s G3P project. Torsten Mayer-Gürr and his team provide the total mass, from which mass changes in rivers and lakes are subtracted, soil moisture, snow and ice are also subtracted, and finally, only groundwater remains. .
Each of these other masses has its own specialists, who come from different European countries and who provide their data here. The result of this cooperation shows that the water situation in Europe is very precarious. Torsten Mayer-Gürr did not expect it on such a large scale. “A few years ago, I would never have imagined that water would be a problem here in Europe, especially in Germany or Austria. Here we are having water supply problems; we have to think about it“, explain. From your point of view, you need to document the drought with data and have continuous satellite missions in space.
Collaborating entities from Austria (Graz University of Technology, Vienna University of Technology, Earth Observation Data Center), Germany (Geo Forschungs Zentrum in Potsdam), Switzerland (University of Bern, University of Zurich), France (Collection Localization Satellites , Laboratoire d’ Etudes en Géophysique et Océanographie Spatiales LEGOS, Magellium), Spain (FutureWater), Finland (Finnish Meteorological Institute) and the Netherlands (International Center for Groundwater Resources Assessment).
Reference:
Boergens, E. et al “Quantifying Central European Droughts in 2018 and 2019 with GRACE Follow-On”. Geophysical Research Records (2020).