News

Together with Astrid Blom (TU Delft), Ralph is supervising Claudia Ylla Arbos (TU Delft) and Kifayath Chowdhuryen (TU Delft). The PhD students are working on the studies of soil erosion in the Upper Rhine Delta and the distribution of water and sediment at the bifurcation points. The first insights are already known. “Through Claudia’s research on the Upper Rhine Delta, we now know that soil erosion that was already occurring is because we tinkered with the rivers in the past. The river responds by cutting in. This behavior will continue in the coming decades and climate change is exacerbating it. These insights are especially important for river-dependent functions: what does it mean for safety, shipping, groundwater levels and freshwater supplies?”

Kifayath’s research also shows that the changing discharge distribution around the bifurcation points is affecting safety in the area, the study shows. “More and more water is going to the Waal. This can have huge consequences, for example for the dikes.” Ralph thinks this research has revealed the cause. “The cause is the high water in 1993 and 1995. With the insights you get a picture of how to prevent this in the future; there are probably more high waters to come. If we can see this coming, we can anticipate this behavior.”

The separation between policy and science

Ralph has a double involvement. He collaborates from RWS, but also works at the university. At times the insights intersect with the measures. “We know from ourselves that we reason from science, but at some point a policy advisor comes along who may think differently.” In addition to the aforementioned studies, major studies on the future of the river basin are currently underway within the Integrated River Management (IRM) program. Ralph especially wants the insights gained to land in IRM, specifically so that they do not become measures that work against the system. He cites two examples: “One of the insights from the Upper Rhine Delta study is that the river still wants to lower the bottom. If you take measures on that, it probably doesn’t make much sense. As for the junction points, it appears that the discharge distribution is skewed, but what can we do about that? The measure that comes out of this we also bring to attention.”

A view on the future

Whereas RWS is concerned with short- and medium-term management, the ministry is concerned with long-term vision. “Will we still be able to go around the rivers in 2100, or might there be no shipping for months due to low water discharge? With the insights already obtained, we can already partially answer that. We now want to focus mainly on measures to make the system naturally robust and climate-proof.”

The request to continue the research on the Upper Rhine Delta has already been submitted. The model developed from the research can describe the entire river system including changes, such as climate change. “We are now able to quickly make predictions about what the system will look like in, say, 2100, what measures you can take and what the consequences will be.” In this regard, the timing for the follow-up research is perfect. KNMI is coming out with new climate scenarios at the end of this year that can be included, and the follow-up research is running parallel to the IRM: this keeps the discussion going.

The collaboration between Rivers2Morrow and TU Delft

Ralph sees enormous added value in the program through both the valuable insights for RWS and the enthusiasm at the universities. “You see at the university an increasing sense of social relevance and questions from practice: you notice then that the students are extra on. They can work on socially relevant problems, take science further and also really make the Netherlands a bit nicer.” Ralph therefore sees added value for Rivers2Morrow in the future. “We need to look at topics that we can tackle in such a way, so that we can also implement them quickly in the organization.”