Creating and rehabilitating salt marshes through Building with Nature: more than just compensation. A contractors perspective

Salt marshes have a variety of functions including ecosystem support, flood protection, water quality improvement and habitat enhancement. Depending on the goal of the project, the design and construction focuses on one or more of these functions. By using the concept of Eco System Services (ESS), the added value for the entire project can be evaluated. In the past years, several pilots and projects have been carried out in which the natural function of the (salt) marsh / wetlands is combined with flood protection and ecosystem enhancement. The aim was to search for a design that integrated hydraulics, morphology and ecology from the start and could subsequently fulfill more goals at a lower cost. In addition, the design focused on the utilization of the strengths and materials present in the natural system thereby effectively integrating the final project into the local surroundings. Design and subsequent implementation were achieved following the principles of Building with Nature. The presentation provides a brief overview of the Building with Nature approach used, and then describes how it is implemented in practice using several case studies. In the case studies, it zooms in on which designs were considered and used, how they integrate the functions and importantly how the projects were constructed. Examples include: Sand engine project (the Netherlands): using the natural forces of the coastal system to ensure long term maintenance of the Dutch Coast at lower cost Houtribdijk pilot project (the Netherlands): investigating various foreshore designs and materials (including vegetation) to effectively protect existing of new dikes Cliff Pools bird sanctuary project: large scale pilot Wetland restoration/development using dredged material along the coast of the UK Markerwadden (the Netherlands) large scale wetlands creation using soft materials for nature and recreation development Pilot projects creating natural reefs and breakwaters using natural materials that are integrated into the (ecological) design (3D printed reefs, oysters, sand berms, etc) Wetland creation as an integral part of project design thus allows for beneficial re-use of dredged materials, hence contributes importantly to the sustainable development of marine infrastructure projects