The Rhine Estuary-Drechtsteden region is a densely populated area of immense economic significance to the Netherlands. It is an area of extremes: with port activities, urban areas, the Greenports (horticulture), and the Biesbosch nature reserve.
In this region – around Rotterdam and Dordrecht – water comes from two directions: the sea and the rivers. Economic and spatial development in the Rhine Estuary-Drechtsteden region is only possible if its flood protection and its freshwater supply are up to par, in the short and long term. The Rhine Estuary-Drechtsteden region has drawn up a preferential strategy to that effect. The region has been working on the implementation of this strategy since 2014, within the framework set out by the Delta Decisions.
A number of dyke sections in the Rhine Estuary-Drechtsteden area do not meet the current standards. In addition, a higher protection level has been agreed upon for most of the dykes, because of the increase in population and economic value behind the dykes. Furthermore, near dyke sections that are constructed on peat, subsidence causes additional tasking in terms of safety. In the Rhine-Estuary-Drechtsteden region, the flood risk management tasking is focused on the area around Rotterdam, the Krimpenerwaard, Alblasserwaard, Vijfheerenlanden, the Eiland van Dordrecht, and Voorne-Putten. Climate change will result in longer periods of drought, which will put additional pressure on the freshwater supply in the area. Finally, the region is faced with a spatial adaptation tasking, inter alia, in the areas outside the dykes.
Preferential strategy for flood risk management
As the elevation of the Rhine Estuary-Drechtsteden region is quite low, most areas will be submersed very quickly and to a substantial depth in the event of a flood. Flood prevention is therefore of great importance. This can be achieved by consistently choosing the best combination of three types of preventive measures: storm surge barriers, dykes, and river widening.
The Hollandsche IJssel remains an open river which can be closed off by a storm surge barrier. This provides the best opportunities for flood risk management, shipping, and the tidal ecology. A broad-based study will be conducted into the replacement of the Maeslant storm surge barrier in the Nieuwe Waterweg. One of the alternative solutions to be explored, along with replacing the storm surge barriers, involves the introduction of sea locks. This study is expected to commence around 2040. The Delta Programme monitors new insights in the fields of climate change, flood risk management, and freshwater supply; if need be, the study will be launched at an earlier date. In addition to limiting the flood risk, water-resilient spatial design adaptations are also being prepared. Additional attention is being paid to disaster management, in order, among other things, to protect the electricity grid and high-risk businesses from floods.
A special feature of the Rhine Estuary-Drechtsteden region is the long stretches of areas outside the dykes which are densely populated and offer many employment opportunities. These areas are not protected by the dykes. The region will devote additional attention to measures aimed at limiting loss as well as communication regarding the risks run by the residents.
Typical of the approach adopted in this region is that water issues and spatial development are considered in an inter-connected manner.
Preferential strategy for freshwater supply
For its freshwater supply, the western part of the Netherlands is dependent on a limited number of locations where freshwater from the rivers is let in (inlet points). The main inlet points are those near Gouda and Bernisse. In the future, these inlet points will become less reliable, because the water is increasingly salinising. At the same time, demand for fresh water is likely to increase. The freshwater supply to the western Netherlands will remain up to par by gradually expanding the emergency supply from the Waal and the Amsterdam-Rijn canal. The freshwater supply from the Brielse Meer lake will gradually become more resilient: its management will be optimised in the near future. In addition, an improved monitoring system will be introduced, and near Spijkenisse an additional water inlet will be put into operation. The water manager will implement “smart water management” to reduce salinisation in the Hollandsche IJssel, the Amsterdam-Rijn canal, the Noordzee canal, and near the Hagestein weir. In addition, consumers need to economise in their use of water by capitalising on innovations.
Various climate-proofing collaborations have been set up in the Rhine Estuary-Drechtsteden region, such as the Strategic Adaptation Agenda project for the areas outside the dykes, the Spatial Adaptation City Deal, and the Agniesebuurt/Zomerhofkwartier testing ground impact project (second phase).
In the Agniesebuurt/Zomerhofkwartier testing ground, the city of Rotterdam, the Schieland en de Krimpenerwaard District Water Control Board, residents and entrepreneurs are jointly working on innovative plans for urban water management. In the Agniesebuurt district, several innovations have already been implemented with the construction of the water plaza and various rain gardens.
In 2017, additional work will commence aimed at climate-proofing the entire Agniesebuurt area. Rainwater storage underneath the streets rather than discharging rainwater into the sewer system ensures that the neighbourhood is prepared for the future.
One of the components of the preferential strategy for flood risk management is an implementation agenda. Some of the measures scheduled for 2015/2016 are listed below.
- Alblasserwaard-Vijfheerenlanden study
The parties involved in this study are exploring smart ways of combining spatial and economic development with raising and improving the dykes. The focus is on the southern outskirts of the Alblasserwaard.
- Eiland van Dordrecht study
The Delta Decision on Flood Risk Management offers the option, in very special cases, of achieving flood protection by way of a “smart combination” of dykes, adaptation of the spatial design and additional attention to disaster management. The Eiland van Dordrecht is one of the locations for which such a smart combination might be attractive.
- Spatial Dyke Improvement Tools Pilot
The Spatial Dyke Improvement Tools pilot has investigated whether the existing spatial and financial tools enable spatial reservations for future-proof dyke improvements. The conclusion is that the spatial tools are up to par, yet especially effective if implemented on the basis of a collective regional vision.
- Strategic adaptation agenda for the area outside the dykes
In the Rhine Estuary-Drechtsteden region, four areas outside the dykes have been identified, faced with highly complex flood risk management, and costly solutions: Botlek, the Dordrecht historic port area, Noordereiland and Merwe-Vierhavens. In these areas, pilot projects have commenced aimed at developing a flood risk management plan or strategy. Based on the experience gained in these projects, a Strategic Adaptation Agenda will be drawn up for the area outside the dykes.
- Case study into disaster management
The Rotterdam-Rhine Estuary Security Region is working on a case study to open up new and existing knowledge, to be utilised for improving disaster management.
- Maeslant storm surge barrier
The Maeslant storm surge barrier plays a key role in protecting the area from flooding. The study explores how flood protection can be enhanced by improving the operation of the Maeslant storm surge barrier.
- Hollandsche IJssel integrated approach
With respect to the Hollandsche IJssel, the parties involved envisage an integrated approach, considering the aggregate system (flood defence, forelands and dykes). Linkage opportunities are also being reviewed, such as improving the accessibility of the Krimpenerwaard.
- River as a tidal park
The project focuses on softening and greening the – currently usually stony – embankments. Using natural processes is beneficial to nature development and recreation, and improves flood protection at a number of locations.
- Rhine-Meuse estuary study
At the request of the House of Representatives (Geurts motion), an additional study has been conducted into closing the Rhine-Meuse estuary on the seaward side, as a long-term option, involving locks in the Oude Maas and Nieuwe Maas, in combination with peak water storage in the Oosterschelde. The conclusion is that this is a fully-fledged alternative, to be explored in the context of the study into replacement of the Maeslant storm surge barrier (which is expected to commence in 2040). The Delta Programme monitors new insights relating to climate change, flood risk management, and freshwater supply; if need be, the study will commence at an earlier date.
An implementation agenda for 2017-2020 is currently being developed; it awaits endorsement by the Regional Consultative Body.
Delta Programme 2017
To view the progress made in this area, click here: Rhine Estuary-Drechtsteden in Delta Programme 2017.