2023

Floor Hermans: "Power plants and shipping are particularly affected by low river flows"

How will climate change affect the flow regime of the Meuse? How much water will still flow through the river in the coming decades and in which economic sectors can we expect issues in particular? The now-graduated Floor Hermans talks about the results of her graduation internship.

Last year, KNMI published the 2023 KNMI climate scenarios for the years 2050, 2100 and 2150. In them, the organisation translated what the findings of the sixth report of the United Nations Intergovernmental Panel on Climate Change (IPCC) mean for the Netherlands. As mentioned in the previous article, Deltares used these KNMI scenarios to analyse the impact of climate change on the Meuse flow regime: the amount of water flowing through the Meuse in a given period.

With these insights, Floor Hermans of Wageningen University & Research (WUR), working with research firm HKV Lijn in Water and RIWA-Meuse, investigated what these flow regimes could mean for the various users of Meuse water. Indeed, climate change is expected to make the flow regime more extreme: in wetter winters much more water will flow through the Meuse and in drier summers much less. 

Issues

For her research, Hermans, who specialises in hydrology and water management, looked at where issues may start to arise in the river basin, and also which economic sectors would suffer. "This way, we can see what we should focus on in the future."

The study focused on the Franco-Belgian part of the Meuse river basin. This upstream part of the Meuse obviously has a lot of influence on the situation in Flanders and the Netherlands. Hermans zoomed in on 40 locations. Of these, 13 are designated as problematic with the current climate. This means that at least one day a year less water is available than needed for all sectors and groups that use water. Under all the scenarios calculated, not only does the number of issues increase, the water shortage itself also worsens.

Lower flow rate

The KNMI works with six different scenarios in 2050, 2100 and 2150. The scenarios vary and depend on the amount of CO2 we continue to emit, Hermans explains. There is a low, moderate and high scenario and there is a wet and a dry version for each scenario. "One extreme is when our winters become significantly wetter and the other extreme is when summers become very dry." The scenarios are all possible futures - there is no single, most-likely scenario.

Hermans also compared the 2014 and 2023 KNMI climate scenarios in her study. "The old scenarios showed a much wider distribution in the minimum flow," she says. "Now we know that the minimum flow is getting lower in any event because of climate change. All scenarios now show a decline, but it is less extreme than in the old scenarios. So it's not too bad."

The study showed that the number of issues will increase in the future. And especially in the dry scenarios. The higher the emissions scenario, the greater the water shortage and therefore the more extreme the problems.  

What do the sectors use?

The RIBASIM model (RIver BAsin SImulation Model) for the Meuse River was used for the study. This was developed in 2022 by Deltares on behalf of RIWA-Meuse, Rijkswaterstaat and the drinking water companies. Hermans explains: "RIBASIM is a water equilibrium model. I looked at how much water goes in and out under different climate scenarios."

In doing so, she examined both the effect of climate change on the number of problems, more or less rainfall and what that means for the flow rates, as well as the abstractions. In other words, how much water different sectors use: agriculture, industry, energy, shipping and drinking water consumers. To do so, she used data from the 2017 Delta scenarios. These scenarios, provided by Deltares and others, give a picture of how much water these sectors use, what the consequences of climate change will be in 2050 and what problems they will pose for these sectors.

Energy and shipping

Two issues stood out in particular in the study by Hermans and her colleagues. First, power plants. These use the largest amount of Meuse water, namely as cooling water, although they eventually discharge most of the water back into the river. Hermans: "When little water flows through the river, power plants may not have enough water for cooling. Or the temperature of the water could be too high." In this context, she points to the importance of developments in the energy sector: "By using more solar and wind energy and less fossil fuels, you will reduce the water consumption by the current power plants."

The second major issues lies in shipping. "The locks in the Flemish canals are already faced with water shortages," says Hermans. "Low water flows compromise the proper functioning of the locks."

The Nete Canal (Flanders) is a bottleneck for drinking water, the study also found. "In the current climate, this is already a bottleneck, but under the dry scenarios it will become a serious bottleneck." It means the demand for water will be as much as twice the supply.

Water quality

Hermans thinks her research provides good initial insights into where problems are going to occur. But, she says: "This study dealt with issues relating to water quantity, not the impact of climate change on water quality. If you have little water, the concentration of dissolved substances obviously increases, because there is much less dilution. That in turn creates other kinds of problems." She therefore recommends follow-up research on water quality issues.

In a follow-up study, Deltares will first look at what issues there are in the amount of water in the Dutch part of the Meuse river basin. This study will be based on a new version of the RIBASIM model. It will also takes into account the groundwater that agriculture uses extensively. "If you extract a lot of groundwater, the groundwater flow to the river decreases," explains Hermans. "That may affect the bottlenecks. Possibly more than we have mapped out now."

Hermans expects the bottleneck analysis to be useful in discussions on water availability with the various users of the Meuse water. "Hopefully, with this overview, we can start an international dialogue on how to tackle these problems together," she said.

Want to read more about this research? Read it on the RIWA-Meuse website.

Photo 10: Sampling in 1982 near the source of the Meuse in Val-de-Meuse, France.