Sand Motor
Large parts of the Dutch coast are eroding. To safeguard the hinterland, Rijkswaterstaat nourishes the coast frequently. Presently, a total of about 12 million m3 is nourished every year. It is expected that this volume will increase significantly in the coming decades due to sea level rise. To explore alternative solutions for depositing large amount of sand along the shore, a pilot project was developed called the Sand Motor.
Discover the Sand Motor in this interactive infographic.
New approach
A traditional design of a sandy nourishment has the primary objective of shoreline maintenance using a medium volume of sand (2-5 million m3). The lifespan of the nourishment is typically in the order of 5 years. This means that every 5 years the nourishment has to be redone, resulting in a frequent disturbance of the ecosystem. In the Sand Motor Pilot project, a concentrated mega-nourishment was constructed, rising up to 5 meters above mean sea level. By making use of natural processes to redistribute the sand, this innovative approach aims to limit the disturbance of local ecosystems, while also providing new areas for nature and more types of recreation.
Building with Nature
In 2011, Rijkswaterstaat and the Provincial Authority of South Holland agreed to construct a hook-shaped peninsula of about 21.5 million m3 of sand. It protrudes 1 km into the sea and covers 2 km alongshore. Trailing suction hopper dredgers picked up the sand ten kilometres off the coast and deposited it nearshore. The Sand Motor is a great example of Building with Nature.
By depositing a large amount of sand in a single operation, we can avoid repeated disruption of the vulnerable seabed. Natural forces, such as waves, wind and tide, will transport the sand to the right place for us. It is expected that sand replenishment at this part of the Delfland Coast will be unnecessary for the next 20 years.
Deltares’ contribution
Rijkswaterstaat assigned Deltares to conduct comprehensive field measurements for a period of at least five years. The field data has been analysed by Deltares together with Imares and Witteveen & Bos focusing on coastal and swimmer safety, dune formation and the ecological impact of the Sand Engine and its surroundings.
Deltares is also actively involved in the scientific research projects NEMO and NatureCoast at the TU Delft. Main focus is on the development of integral modelling tools on coastal morphology, aeolian transport and the fresh groundwater resources at the Sand Engine.
