Flood prevention in the Denderbassin

The Molenbeek is a tributary of the Dender. It rises in the municipality of Brakel and flows via the municipality of Lierde towards the municipality of Geraardsbergen. In Zandbergen the Molenbeek flows into the Dender. Very recently, the Molenbeek caused again large flooding problems downstream. Within the framework of the WAVE-project, the VMM designed two floodplains to protect the citizens from extreme flooding in the future. These floodplains will both have a flow opening in the dike crosswise the valley.

1. Floodplain Molenbeek
The floodplain Molenbeek will have a capacity of 300 000 m³ water, which will increase with 200 000 m³ water with the shutter weir.
End of 2010 most of the land was acquired and on 1st March 2011 the works started in Smeerebbe-Vloerzegem.

Because the soil where the passage construction isn’t firm enough, the VMM expects setting. Therefore a thick layer of soil and drainage poles will be placed where the construction will come, to set the soil at a maximum before the start of the building process. In september 2011 the VMM started building the passage construction (n°1 on the map).

2. Floodplain Ophasseltbeek

The floodplain Ophasseltbeek can keep 65 000 m³ water capacity. This floodplain will be built with an extra sedimentary deposit, to avoid sediment due to domestic discharge and soil erosion. Sediment deposits in waterways and decreases the drainage and storage capacity, which increases the possibility of flooding. The passage construction is already realised.

3. Communication

Even tough the construction works will cause few problems for the local residents, the VMM organised an informationmoment to inform them about the timing and execution of the works. This encourages the residents to ask questions and contributes to a better cooperation in the future of the project. October 17th, the Flemish minister Joke Schauvliege visted the construction sites of both flood plains an expressed her support for the project.