Oesterdam Sand Nourishment Project Reefs
Oesterdam, Eastern Scheldt, the Netherlands After construction of the Eastern Scheldt storm surge barrier in 1986, the Eastern Scheldt tidal basin started to evidence a strong increase in the rate of intertidal flat erosion—at a rate of 45 hectares per year. This sharp increase affected the available feeding time for important migrating bird species; the lowered foreshore also resulted in a wave load increase on the dikes. To mitigate these impacts, the Ministry of Infrastructure and Water Management (Rijkswaterstaat) researched possible solutions and implemented the Oesterdam Sand Nourishment Project in 2013. The project consisted of dike foot nourishment and large-scale nourishment around the tidal flat, with a total volume of approximately 460,000 million cubic yards of sand. To prevent nourishment erosion, a number of man-made oyster reefs were placed along the edges of the nourishment. Monitoring conducted during the period of 2013-2017 revealed fast recovery of benthic species and biomass following the nourishment effort. The sand nourishment prevented the tidal flat from eroding further and created a sheltered habitat for benthic species on the tidal flat. The reefs develop over time into living solid structures, with only a small effect on nearby sand stabilization. The monitoring was executed by the partners of the Centre of Expertise Delta technology: HZ University of Applied Sciences, the Royal Netherlands Institute for Sea Research, Wageningen Marine Research, and Deltares.
116
