Delta Programme
Rhine Estuary-Drechtsteden
The Rhine Estuary, the Drechtsteden and the connected areas of Haringvliet, Hollands Diep and the waters linked to them (the Northern Delta Basins) form the transitional zone between the North Sea and the Rhine and Meuse rivers. A feature of this region is that the water levels, currents and sediment transport (the movement of sediment such as sand and gravel) is influenced by both the sea and the rivers. Sea and river processes meet up here, strengthening or weakening one another.
Consequences of climate change
The predicted climate change has various consequences for the region. The rising sea level means that dangerous situations can arise sooner and more frequently in case of storm surges. Barriers will therefore need to be closed more often. This increased closure frequency means that the chance of a closure coinciding with a high river discharge also increases. Climate change entails a greater chance that the required frequency of river discharges will increase, as will the quantities of water to be discharged. The combination of a higher sea level and high river discharges will mean that in the future, water levels will be higher than they are now. Consequently, the areas outside the dikes will be flooded more often and to greater depths.
In two of the four scenarios (Royal Netherlands Meteorological Society, 2006) climate change will also lead to more frequent low discharges from rivers in the summer. This will mean that salt intrusion from the sea will penetrate further inland along the riverbeds which will increase soil salination. As a result, it will be more difficult to use water for, among other things, agriculture and horticulture, ecology and maintaining the water level.
Study
With a view to this problem, the Delta Commission recommended in 2008 to study whether or not the area should be made ‘closable but open’. By using flexible barriers, the mouth of the Rhine area can be closed off at high water. In the Nationaal Waterplan [National Water Plan], the state announced that, together with other authorities, it would examine making the Rhine Estuary ‘closable but open’. Moreover, the benefits and disadvantages would be carefully set down. The study should also devote attention to other possible solutions.
The sub-programme Rhine Estuary-Drechtsteden is the responsibility of the Ministry of Transport, Public Works and Water Management, the Ministry of Housing, Spatial Planning and the Environment, the municipalities of Dordrecht and Rotterdam, the province of Zuid-Holland and the Hollandse Delta Water Board. The Programme Director is Huub van Zwam.
