Royal HaskoningDHV has been selected by Rijkswaterstaat (the executive agency of the Dutch Ministry of Infrastructure and Water Management) for the Houtrib dike reinforcement. To strengthen the natural values in the area, the dyke between Enkhuizen and Trintelhaven is reinforced with sand. The mud, which is released during sand extraction, is used for the construction of the nature reserve Trintelzand. This innovative use of sandy foreshores for the reinforcement of the Houtrib dike has been nominated for the Water Innovation Prize 2019. Trough the development of the Trintelzand nature reserve, the dike reinforcement offers opportunities for nature and contributes to the water quality in the Markermeer.

Need for reinforcement

The Houtrib dike in its current condition does no longer meet the current standard for water safety and must be reinforced. The Houtrib dike separates lake Marken from lake IJssel and connects the cities Enkhuizen and Lelystad. Royal HaskoningDHV has been selected by Rijkswaterstaat (the executive agency of the Dutch Ministry of Infrastructure and Water Management) for the reinforcement of the Houtrib dike.

Dike reinforcement combined with the development of nature reserve Trintelzand

Royal HaskoningDHV has worked out a design for the dike reinforcement within the 2012-2015 planning phase and prepared the planning procedures.

The design for the dyke is created in close collaboration with all stakeholders. We investigated opportunities to combine assignments from existing policy frameworks and spatial initiatives in the region with the dike reinforcement. As the Houtrib dike does not directly protect land, an overflow-proof dyke design was chosen.

To improve the natural value of the area, the dyke is reinforced with sand between Enkhuizen and Trintelhaven. The sand was extracted from Lake Marken. The mud that was released during the sand extraction is used to construct the nature reserve Trintelzand. This nature reserve is partly located below and partly above the water surface and offers opportunities for different species including mussels, snails, insects and fish. The sand extraction pit functions as mud trap which has a beneficial effect on the water quality of the lake.

The section between Trintelhaven and Lelystad is reinforced with penetrated rubble. Reinforcement with sand is less feasible at this location due to the greater depth in combination with a less favourable location with respect to the prevailing wind and waves.

At the moment, Royal HaskoningDHV advices Rijkswaterstaat for the construction of the design and about methods to monitor the development of the nature reserve.

Innovative dike reinforcement which contributes to the natural value of lake Marken.

The innovation with sandy foreshores used for the dike reinforcement of the Houtrib dike was nominated for the Water Innovation Price 2019. Through the development of the nature reserve Trintelzand the dike reinforcement offers opportunities for nature and contributes to the water quality of lake Marken. A global scoop that makes the region safer and increases biodiversity.