Broad analysis of river management accelerates natural solutions

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Managers of the Rhine face major challenges: due to a declining river bed, the discharge from the IJssel to the Waal is shifting (which has consequences for the filling of the IJsselmeer, among other things) and climate change is increasing the risk of low and high water levels. Restoration of ecological quality is also lagging behind.

To tackle these challenges, new plans are being developed in the Room for the River 2.0 programme.

Social cost-benefit analysis

Sien Kok, researcher at Deltares and WUR, compares different strategies for river and floodplain management in a comprehensive social cost-benefit analysis (SCBA). In addition to the effects on water safety, shipping and freshwater supply from the IJsselmeer, she includes a broader range of “ecosystem services”, such as water purification and greenhouse gas storage, recreation, landscape quality and the value that people attach to nature, even if they do not use it directly (the “non-use value”).

The most important finding: the scope of the assessment can influence the preferred strategy. It became clear that a relatively inexpensive strategy that only addresses drought and high water problems (“Robust River”) scores best when the SCBA has a narrow scope.

If a broader range of ecosystem services is included in the SCBA, the preferred strategy shifts. In that case, the most ambitious, nature-based strategy (‘Room for Delivering Rivers +’), in which floodplains are widened and rewetted and agriculture makes way for nature, delivers the greatest social added value. So-called cultural ecosystem services are particularly decisive in this regard.

Benefits of NbS

Koks' research shows that a broader SCBA can lead to different choices in future river management. By explicitly including the value of nature, the preferred alternative can change fundamentally and provide more insight into the broad benefits of natural solutions or Nature-based Solutions.

If we want to give Nature-based Solutions a fair chance in water management, we must fully incorporate the broad societal benefits they deliver into our assessment frameworks, such as cost-benefit analyses.

Sien Kok, environmental and economic expert at Deltares

Restoring freshwater ecosystems

Sien Kok's PhD research is part of the European MERLIN project, which looks at where and how the restoration of freshwater ecosystems is necessary and possible for both people and nature in Europe.