Preferential Strategy for the IJsselmeer Region
The Delta Decision on the IJsselmeer Region is aimed at preserving and wherever possible enhancing the functions of the IJsselmeer Region. In addition, the Delta Decisions on Flood Risk Management, Freshwater Supply, and Spatial Adaptation are also relevant to this area. The ambitions set out in these Decisions have been elaborated into the Preferential Strategy for the IJsselmeer Region.
The Preferential Strategy is being implemented in the form of specific measures for the IJsselmeer Region.
Flood Risk Management
By 2050, the primary flood defences (the flood defences protecting us against flooding from the sea, the major rivers, and the major lakes) must meet the standards that came into force on 1 January 2017. The IJsselmeer winter water level has a major impact on the flood defences. The level is regulated by sluices and pumps in the IJsselmeer Closure Dam. The flood risk management strategy is committed to “drainage by gravity if possible and pumping if need be”.
The point of departure of the strategy is that up to 2050, the average winter water level in the IJsselmeer Region will not keep pace with the sea level. After 2050, a limited rise along with the sea level would be an option; flexibility and adaptively keeping pace are key. Dyke improvements and the use of pumps in the IJsselmeer Closure Dam are the main solutions in the IJsselmeer Region to continue to meet the flood protection standards.
The freshwater supply strategy addresses two levels: the main water system and the regional water system. At the first level, the focus is on securing the freshwater supply, along with combating salinisation. At the second level, the aim is to retain water in the regional system, to cut back on water consumption, and to combat salinisation.
In the IJsselmeer Region, flexible water level management is pursued to create a maximum freshwater supply. If the probability of low river discharges should increase in the future, a solution could be to raise the River IJssel discharge volumes to Lake IJsselmeer through flexible management of the weir near Driel. Should river discharges drop even further, supplying water via the Amsterdam-Rijn Canal could be an option. This will be explored in the purview of the next review in 2026, via the Climate-proof Main Water System Freshwater Supply Strategy.
The regional parties around the IJsselmeer Region are committed to optimise water retention and to reduce water consumption through water saving and smart water management.
A prerequisite for a resilient freshwater supply is minimisation of the saltwater volumes entering Lake IJsselmeer via the sluices and locks in the IJsselmeer Closure Dam. Rijkswaterstaat is exploring several options to this end, including saltwater collection in deep pits behind the sluices (salt traps).
Spatial Adaptation as an integral element
There is no separate Preferential Strategy regarding spatial adaptation; however, this topic is an integral element of all the plans and measures pertaining to the IJsselmeer Region. Thus, measures are developed that serve multiple purposes. This fosters interconnection between system measures and climate-resilient planning in ongoing and future area developments.
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