|Networks||Regulatory context||Knowledge context||Realization framework|
Making use of Nature
The IJsseldelta South project goes beyond traditional integral planning in the significant role it assigns to nature development. When quantified, an area of 300 hectare of additional nature will be created. This will form an Ecological Main Structure (EHS) between the IJssel and the Veluwerandmeren. Additionally, an area of about 30 hectare will actually be added to the Natura-2000 area that borders the Veluwerandmeren. This addition of Natura-2000 reserve is a brand new approach that is as of yet rarely seen in integral development projects.
The project does not make use of sediment dynamics such as found at the Sand Engine pilots in both the North Sea and the Frysian IJsselmeer Coast. Yet other dynamics can be found within the latest iteration of the plans. The dominant dynamics in the region are related to water – both the river influx coming from the IJssel and the dynamics of the water in the IJsselmeer. Additional dynamics relate to wind and its influence on water levels and vegetation. Both of these are acknowledged and included in the plans for the systems, in particular when concerning the nature areas in the project.
The current system is rather low in dynamics. It is a polder area with agriculture, in between the IJssel river and the Veluwerandmeren. However, this polder forms the bottom of a former sea-arm of the river IJssel – the Reeve – connecting these. The bypass itself will closely follow this former estuary and reintroduce dynamics into the static system. In the project plans, the differences in height and sediment created by this former estuary are utilized and expanded upon. Subsequently, this project is not so much about utilizing dynamics as well as reintroducing them, while making use of the dynamics to foster greater biodiversity.
One of the causes for concern for flood safety relates to the tilting (opstuwing, scheefstand) of IJsselmeer water. During northwestern storms, the water of IJsselmeer is forced through a choke towards the IJsseldelta, leading to significantly higher water levels. This not only poses a threat to flood safety, but will be harnessed in the project to create a more diverse ecosystem. When the water is tilted, after the storm it will return to normal levels. By utilizing the natural height profile of the area, the system is designed so that water will be retained within small areas and more slowly flow back. This will create a marsh-like system which is presumed to create greater biodiversity than a more stable system.
Another important dynamics-related design feature concerns the heavy reeds that currently form the shore of the Vossemeer and Drontermeer. Due to two significant populations of heavily protected birds, these reeds must be protected. Heavy reeds only form when there is a significant amount of “long winds” striking the shores. By placement of these reedy areas in locations where these long winds can be expected to occur, the ecosystem is shaped by the dynamics of the dominant winds