Reinforcement IJsselmeerdijk (dike) with a foreshore

The IJsselmeerdijk (dike located in the Netherlands, next to the lake ‘IJsselmeer’) needs to be reinforced to ensure flood safety. During the exploration phase of this dike reinforcement multiple design options were considered including a foreshore to reduce wave-overtopping. The preferred design for the dike reinforcement consists of a foreshore with a body of sand protected by a dam. The foreshore is designed in such a way that it offers additional benefits for nature and recreation.

THE CHALLENGE: AN INNOVATIVE AND SUSTAINABLE REINFORCEMENT OF THE IJSSELMEERDIJK

The IJsselmeerdijk protects the deep Flevopolder against flooding from the lake ‘IJsselmeer’. After new regulations, the dike no longer meets the flood risk management standards and needs to be reinforced. The client asked for an innovative and sustainable design.

THE SOLUTION: A FORESHORE AS PART OF THE DIKE REINFORCEMENT

The flood risk management task has been investigated in further detail and available design options for the dike reinforcement were listed. Stakeholders were involved to learn about their wishes. One of the promising design solutions to reduce wave-overtopping was the construction of a foreshore. Besides providing flood safety a foreshore can also contribute to biodiversity and recreation. Different designs for a foreshore were investigated (e.g., with/without dams and with/without additional sediment). The preferred design for the dike reinforcement consists of a foreshore with a body of sand protected by a dam.

THE OUTCOME: A DIKE DESIGN WITH BENEFITS FOR NATURE AND RECREATION

The design of the foreshore offers benefits for nature and recreation. The dam offers shelter from large waves. This gives opportunities for riparian vegetation to settle. Also, it leads to shelter, spawning and foraging opportunities for fish. The substrate of the dam provides additional habitat for shellfish such as mussels. Birds in turn benefit from the additional vegetation, fish, and shellfish. The proposed design also has additional recreational value with a boardwalk, observation tower and underwater viewing hut.

Impression of the foreshore design.

Odelinde Nieuwenhuis
Project manager coastal and river development
odeline.nieuwenhuis@rhdhv.com