The IJsselmeer region plays a pivotal role in Dutch water management. The region is of great value in terms of the natural environment and cultural history. The IJsselmeer Closure Dam (Afsluitdijk) has made the entire region safer and has enabled land to be reclaimed. A freshwater reservoir has been created which is of benefit to agriculture, industry and Nature in a large part of the Netherlands. Society uses the lakes and their banks in many different ways, including recreational activities, the extraction of drinking water, and shipping.
In order to continue to use all these functions to their full potential and to make improvements wherever possible, it is important to respond flexibly to new developments and insights. The preferential strategy for the IJsselmeer Region aims to keep flood protection and the freshwater supply in good order, and to expand flexibility. The focus in the years ahead will be on fleshing out the strategy. Pursuant to the IJsselmeer Region Pact and the Regional Agenda for 2050, the region is exploring opportunities regarding an integrated measures approach. The Delta Decisions constitute an important point of departure and framework in this regard.
The sea level is continuing to rise, possibly at a pace faster than was originally assumed. This has already made it more difficult to discharge water from the IJsselmeer into the Wadden Sea. At the same time, expectations are that climate change will necessitate an increase in the volume of river water to be discharged into the IJsselmeer in extreme weather conditions. Conversely, during prolonged drought the supply will decrease. The level management must be able to respond to these changes, especially as climate change and economic developments are expected to result in an increased demand for fresh water.
Flood risk management entails improvement of a number of primary flood defence systems (among which are the Afsluitdijk, Houtribdijk, and Markermeerdijk between Hoorn and Amsterdam). This will bring their safety levels up to standard again.
Preferential strategy for water discharge
If the sea level continues to rise, it will become more difficult to discharge water from the IJsselmeer into the Wadden Sea. Consequently, the water level of the IJsselmeer could rise. The point of departure in the Delta Decision on the IJsselmeer Region is that the average winter water levels of the IJsselmeer and Markermeer (NAP Normal Amsterdam Water Level -25 cm) will be maintained until at least 2050. The preferential strategy is based on a combination of discharging by gravity and pumping. The Afsluitdijk project involves the use of pumps to expand the discharge capacity to the Wadden Sea. The pumps in the sluices at Den Oever will become operational by 2022. If need be, the pumping capacity can then be increased step by step. After 2050, the IJsselmeer winter water level can be allowed to rise somewhat, but by no more than 10cm to 30cm, and only if this is cost-effective and necessary.
Preferential strategy regarding freshwater supply
The freshwater supply in the IJsselmeer Region can be maintained by implementing a cohesive set of measures in the main water system (the large lakes), regional water systems (smaller surface water supplies, drainage water, and canals) and among consumers. The availability of freshwater will increase by introducing flexible water level management in the IJsselmeer, Markermeer, and Zuidelijke Randmeren lakes. In the near future, this will make a 20cm “extra layer of water” available as a structural water reserve. The new water level ordinance required to this end will come into force in early 2018. This extra layer may need to be gradually increased in due course (probably only after 2050).
The authorities in charge of the regional water systems will restrict the use of freshwater from the IJsselmeer Region, for example by using adjustable sluices and more efficient flushing. The agricultural sector and industry will also be encouraged to save water, for example through underground freshwater storage and the re-use of process or cooling water. Agreements to this effect have been set down in the Administrative Agreement on freshwater supply measures in the IJsselmeer Region 2016-2021.
Amsterdam Region and IJssel-Vecht delta transitional areas
The water system in this area is connected to the North Sea, the IJsselmeer, and the major rivers. Due to its limited flexibility, interventions in these areas will impact the functioning of the water system. Furthermore, spatial developments and the water system are intertwined in this region. The Waterproof Westpoort adaptation strategy is expected to be ratified in the autumn of 2017. The Amsterdam Rainproof programme is embedded in the municipal organisation of the city, and is becoming increasingly manifest on streets, squares, rooftops, and in gardens. Amsterdam has conducted a stress test to identify locations vulnerable to extreme precipitation. Rainwater bottlenecks have been designated based on the outcomes of the test. The resolution of these bottlenecks will be incorporated into the municipal schedule of measures. This issue has given rise to a dynamic network of a wide range of urban parties, such as horticulturists, insurance companies, residents, and entrepreneurs. As a result, the efforts to rain-proof the city also extend to private properties. Rainproof development is the point of departure in new area developments. A case in point is the new IJburg Central Island.
IJssel-Vecht delta Region
At the end of 2015, the central government and the region adopted the results of the IJssel-Vecht delta MIRT Study. In 2016, the regional authorities incorporated the results in an implementation strategy. The measures can be divided into four issues: dynamic water level management, multi-layer flood risk management, climate-resilient development, and innovative collaboration (e.g., experimenting together with private parties on forms of financial collaboration and legal arrangements). The central government is supporting the efforts by exchanging knowledge and providing a platform for the project. The region is actively looking for projects in which multi-layer flood risk management or “smart combinations” appear promising.
Multi-layer flood risk management projects
On the island of Marken and in the IJssel-Vecht delta, options have been explored to partially achieve the desired flood risk management level by implementing spatial planning solutions. The MIRT Studies conducted have generated more insight into the feasibility of the multi-layer flood risk management concept. The IJssel-Vecht delta appeared to provide greater scope for spatial planning measures than the island of Marken.
IJsselmeer Region Pact
The regional parties involved have joined forces in the IJsselmeer Region Administrative Platform to monitor progress, to schedule measures and ensure a proper exchange of information. However, the ambitions of the platform extend beyond the Delta Programme. They also involve capitalising on linkage opportunities, synergy, and reinforcing spatial quality in combination with new (economic) developments. On 6 March 2015, government authorities and NGOs in the IJsselmeer Region set these ambitions down in an administrative agreement, the “IJsselmeer Region Pact”.
Delta Programme 2018
To view the progress made in this area, click here: IJsselmeer Region in Delta Programme 2018.