2021

The climate is changing, and this impacts the flow rate in the Meuse. In 2021, the water balance model RIBASIM was developed for the international Meuse River basin. "By using this tool, we are better able to drive the discussion on the approach needed for action," contemplates Harold van Waveren of Rijkswaterstaat. "But first there has to be sufficient support for the use of the model."

Low water

Rijkswaterstaat senior consultant Harold van Waveren is one of the five chairs of the National Coordination Committee on Water Allocation (LCW), part of the Netherlands Water Management Centre. It is a cooperative arrangement among Rijkswaterstaat, the Water Boards, the Ministries of Defence and of Infrastructure and Water Management, representatives of the provinces and of certain regional cooperative arrangements.

"There are five chairpersons because we work with an on-call service. Normally speaking, we don't have much to do, until extreme circumstances arise. These could be related to too much water or conversely a water shortage, or an environmental incident." In the Netherlands, a water report is drawn up every day. "This is a core task of the Water Management Centre. In crisis situations, this work is scaled up."

The LCW is a crisis advice group for water shortages. When is this the case? "This is the case when the demand for water (use for drinking water, agriculture, shipping and nature) is greater and the supply (precipitation and the supply via the rivers). The LCW is already active when a water shortage is threatened, so that preparations can be made in good time in case real water shortages arise."

High water

Harold is not only Chair of the LCW, but also of the National Coordination Committee for Flood Threats (LCO). The LCO was founded to inform the Minister and network partners to warn them in case of extreme situations in good time, when floods may possibly occur. The LCO also works with national water reports. Harold was actively involved with the high-water situation in the Meuse in 2021, and so already knows a lot about the consequences of extreme weather. "They say that the weather is becoming ever more extreme, but I say that we are confronted with it already."

According to Harold, climate change is not something that will happen tomorrow, we are already in the middle of it. “Compared to 1950, year-averaged, 20 per cent more precipitation is falling in the Netherlands. Let's do something beneficial with it. We need to look for a new balance between too much and too little water. If you do this together with your partners right from the start, you can also arrive at solutions.”

Climate change

Do you notice that the LCW and LCO must go into action more due to climate change?

"This changes from year to year. At the LCW there’s indeed action every year if the weather is nice for longer. We then often go into action for threatened water shortages. If you're talking about actual water shortages at a national scale, this luckily doesn't happen very often. The last time this happened was in 2018, and before that in 2011 and 2003.

At regional scale, a water shortage can indeed arise more rapidly. Particularly on the high sandy soils where we can't supply any water. There we’re completely dependent on precipitation. In these areas, we've seen that in the three dry summers in a row (2018, 2019 and 2020), water shortages arose quickly. The spring of 2022 was also very dry.

We can clearly notice that something’s going on with the climate. This is also substantiated by figures from the KNMI (Royal Netherlands Metrological Institute). The change in spring and summer is not so much in the shifting of precipitation, but rather in the shifting of evaporation. Particularly inland, where this has increased significantly in the last 50 years. Finally, the point is the difference between precipitation and evaporation because this determines whether there is a precipitation shortage.

The precipitation pattern itself is also peculiar because the annual average precipitation is increasing. Warm air can after all contain more water. But precipitation is not equally divided through the year. In summer, we see that precipitation reduces or conversely falls in extreme downpours, so that it does not end up in the groundwater but runs away over the surface. Due to this, shortages can therefore arise more often."

Water balance models

Water balance models are crucial to allow the dialogue regarding water availability in relation to climate change to be conducted. One example is the RIBASIM model for the Meuse. Were you involved in its development, and in what role?

“I had a fairly modest advisory role. The real work was done by RIWA-Meuse together with Rijkswaterstaat Zuid-Nederland, and Deltares who conducted the work. It's important that such models become available. In the book ‘Van Regen tot Meuse’ (From Rain to Meuse), Marcel de Wit recommended that a cross-border instrument was needed to calculate the effects of climate change and to be able to discuss them.

The question of climate change in relation to the flow rates of the rivers, and what this means for our drinking water is an important subject. This theme must be discussed nationally and internationally, and then preferably based on fact-based policy. In other words, factually substantiated administration and management is needed so that you conduct the discussion based on the same facts. For this, computer models, such as the water balance model for the Meuse, are very important."

Aleksandra Jaskula from Rijkswaterstaat Southern Netherland was also closely involved in the development of the water balance model. She adds to Harold's remarks: "Fact-based policy is indeed an important departure point, but it's not the start of cross-border cooperation. First, parties must mutually agree on the input to the model. This means particularly that the climate scenarios used must be accepted. In practice, each country works with its own climate scenarios. Until now, there was no inclination to agree to make use of another country's scenarios. This is therefore an important point for follow-up actions.”

Harold concludes: “Once you finally reach an agreement about the facts, you can then start to discuss their meaning. And what we can do. For example, how we can best invest to reduce water scarcity and preferably prevent it."

New insights

The study regarding the water balance for the Meuse River basin was conducted in 2021. If we consider the conclusions and recommendations, what's the most relevant outcome that has stayed with you most?

"I've been working on the dossier for a while, so the conclusions weren't new. But the most important thing for me remains the fact that in all the climate scenarios that were analysed, water availability becomes less. The trend is clear: the flow rate of the Meuse is decreasing. In all cases, even for the most optimistic scenario. This is unusual. The situation on the Rhine is different. There we see the water level increasing a little in the coming years in some scenarios due to the melting of the glaciers.

It is important to consider that the water in the Meuse will, because we already have water shortages now. Hence, this future scenario is coming on top of that. In other words: if you know that there are already regular water shortages now and that we must work hard together to deal with this situation, and you also then see that in all scenarios there is a falling trend on top of this, it's clear that we must seriously consider how we're going to deal with this and what we can do.

This set of measures could for example concern water quantity. If you could ensure that you retain more of the water flow, that would be good. Such a set could also consider water usage; we could after all use it more sparingly. But it could also concern the impact of water shortages on water quality. Chemical substances are now discharged with the idea that they are sufficiently diluted. But this assumption disappears now that the climate is changing. In other words: we ought to have to consider whether the way in which we now have the water system set up needs to be altered."

Perspective for Action

Is the water balance model for the Meuse (RIBASIM) the suitable instrument for this, or more needs to be done?

"There are still a couple of steps needed. You can't drop this model into the international discussions just like that. The crucial thing is that we create support, together with international counterparts, about the importance of this type of model.

Once we have support from the neighbouring countries, it's then important to dive into the content. We need to jointly ask the question of whether the quality of the model is sufficient for the type of issues that we want to analyse together. I am optimistic about this. It would be nice to be able to add water quality to the model as well as water quantity. Because, with drinking water, it's always about the question of whether there is sufficient water of the right quality.

In the coming time, we all just need to get on with it. In my view, if there are still question marks, these are in fact opportunities to further develop the model – together with other parties. For example, in the context of European climate research programmes for which there are also subsidies."