Through these ESA projects, the Hydrology Group of the Italian National Research Council has developed an innovative approach using satellite observations of terrestrial water storage, soil moisture and precipitation to predict runoff and river discharge – with the results published in the EGU Geoscientific Model Development journal.

Stefania Camici of the National Research Council of Italy, said, “Our Stream approach is innovative because it takes advantage of the new possibilities offered by satellite observations.”

Their research included using soil moisture data from ESA’s Climate Change Initiative and total water storage data from NASA’s Gravity Recovery and Climate Experiment, GRACE, mission.

Dr Camici continued, “From space, we can obtain information on soil moisture content and terrestrial water storage that is not available from ground-based monitoring networks. By using these observations in a newly-designed hydrological model, we have been able to develop a robust and reliable system for predicting runoff and river discharge.”

The model has already been applied to a number of large river basins, in different parts of the world and the first results are now available for Europe.

The large map above shows annual runoff trend over 20 years, between 2002 and 2022. This throws up some intriguing findings.

It is evident that runoff over central Europe – Germany, France, Austria, Czech Republic – is strongly decreasing, as one would expect given drought conditions over the last years. Runoff is also decreasing in parts of southern Europe, such as Spain and Greece.

On the other hand, runoff is increasing in Denmark and northern Europe.

But curiously, runoff is also increasing parts of southern Europe, including central Italy, Sardinia, Corsica and the in the Pyrenees.