Valkenburg water defense to cost €80 million; Will prevent severe flooding like 2021

A proposed high-water tunnel beneath the Geul River in Valkenburg, estimated to cost about 80 million euros, is being studied as part of a broader package of measures to prevent a repeat of the devastating 2021 floods, when extreme rainfall in a short period inundated streets in the town’s center.

The tunnel, described as a “flood bypass,” would serve as an additional outlet to divert excess water during heavy rainfall.

The plan is part of the Waterveiligheid en Ruimte Limburg (WRL) program, launched by the province, Waterschap Limburg, the national government and municipalities in Limburg to improve protection against extreme water events. Both the national government and regional authorities have each allocated 300 million euros for water safety measures.

Research commissioned by the program identified the tunnel as a feasible option. Engineering firm Witteveen+Bos concluded that the most viable design consists of two tunnel tubes, each 3.5 meters wide, constructed about 20 meters below ground.

The tunnel would run more than 1.2 kilometers and partially follow the course of the Geul. Construction is expected to take about three years.

According to the researchers, the tunnel could more than double the river’s discharge capacity in Valkenburg, which would virtually entirely protect the center of the tourist destination from flooding caused by extreme rainfall.

Flood bypass systems of this kind do not currently exist in the Netherlands, but they are more common in Alpine countries such as Switzerland, representatives of the WRL program said during a presentation in Valkenburg.

Authorities are also examining additional measures in the Geul basin, including water buffers, rainwater trenches and more far-reaching interventions such as transverse dams designed to retain water. Twenty potential locations have been identified for such dams.

“But that would be a major intrusion into this landscape,” said WRL area manager Maarten van der Sande. “How high do you want them and do you want them at all? Those are considerations we have to go through in this process.”

Provincial executive Michael Theuns (CDA) said further research is needed to determine which flood protection measures are the most feasible and desirable in the Geul area.

Officials are assessing which combination of measures offers the most effective solution. A preferred option will be selected and further developed by the end of 2027, and is intended to result in a comprehensive package of water safety measures.