Deltares takes part in Rhine Sediment Testing initiative

After dredging operations, a lot of sand and silt is lost from the Rhine-Meuse estuary into the sea or into depots.

In order to retain the dredged sand and silt in the natural system of the Rhine-Meuse estuary for as long as possible, a number of major players in this field have got together in the Rhine Estuary Sediment Testing Ground initiative.

A more efficient use of dredged sand or silt is good for the environment and the safety of the delta.

Sediment builds the delta area

Sediment, or sand and silt, is vital for delta regions. The Rhine-Meuse estuary is home to a complex interplay between the sea, river and sediment.

Every year, large quantities of sand and silt are dredged to keep the waterways and ports at the required depth. In the Rotterdam port area and the access channels alone, some 15-20 million cubic metres of sediment are dredged annually.

In addition, a lot of sediment is released during projects such as the construction of the Blankenburg Tunnel under the New Waterway. A large proportion of the clean sediment is transported to the sea or to depots elsewhere in the area.

At the same time, elsewhere in the Rhine-Meuse estuary, sediment is needed to fill scour holes in the riverbed, and for nature development and flood risk management.

In the long term, sediment is also needed to make the Rhine-Meuse estuary more climate-resilient and respond to sea level rise.

A testing ground for knowledge development and innovation

A testing ground, a pre-selected demarcated area, is used as a location for practical research to look at which solutions work well, which don’t, and potential improvements.

The goal of the Rhine Estuary Sediment Testing Ground is to deliver knowledge and new techniques for sustainable sediment management. In other words, management approaches that maximise added value for nature, river management, flood risk management and spatial quality so that, in the long term, the delta can rise in line with the sea level.

The new techniques will be tested and monitored by linking them to planned maintenance and development projects in three pilot areas that have still to be selected.

Those areas will serve as demonstration sites for new business cases for sustainable sediment management in the Rhine-Meuse estuary, and as test and monitoring sites for innovative solutions for sediment management.

Examples include the storage of sediment between dikes for protection purposes, the creation of salt marshes or mud flats for nature, or sand motor-like solutions for scour holes.

The Rhine Estuary Sediment Testing Ground initiative brings together the Port of Rotterdam Authority, Rijkswaterstaat, the World Wildlife Fund, Natuurmonumenten, the Hollandse Delta water authority, Wageningen Marine Research, the dredging company de Vries & van de Wiel and Deltares. Deltares is the lead partner in the consortium. The project will last four years (2021-2025).

It has been made possible by a subsidy for Public-Private Partnership Initiatives (PPS) from the Netherlands Enterprise Agency for Top Consortiums for Knowledge and Innovation (TKI).

Photo: DEME