System behaviour of coasts, estuaries and rivers

The banks of rivers, estuaries and coastlines are popular areas: a large proportion of the global population live there and the economic interests are considerable. Rivers, estuaries, deltas and coasts make up a chain system that transports water and sediments such as sand and clay. Climate change, sea-level rise and land subsidence affect this system, and this has implications for how these areas are used and managed. If you know how the water-sediment chain works, you can counter negative developments and encourage positive developments.

From problem to solution

Management agencies in these areas are often not aware of the impact of interventions and natural changes in the incoming and outgoing flows of water and sediment. Lower incoming flows lead to the erosion of banks and coastlines; higher flows result in the silting up of, for example, navigational channels but also land accretion. Controlling the flows of sediment, the sediment balance, can mitigate negative developments such as coastal erosion and encourage desirable developments like land accretion. The Dutch replenishment policy is an example of a sediment strategy: the structural erosion of the coast is countered by the annually replenishment of the sand that is lost to the sea. Government authorities are primarily interested in management strategies; businesses are interested in the development of sustainable solutions. Deltares is studying the water-sediment chain to further our understanding of how it works. We are also building models that will allow us to predict the impact of natural developments and human interventions. We advise both government authorities and businesses.