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In theNetherlands, thebordering lakes (in Dutch:Randmeren) are a chain of lakes which separate theFlevopolder andNoordoostpolder from the ancient lands of the provinces ofGelderland,Utrecht,Overijssel andFriesland.[1]
Strictly speaking, these 'lakes' are not separated from each other, but are a continuous body of water between the old land and the newpolder lands, consisting of lakes divided by straits, dams,locks, or in some cases just a bridge over narrow water.
The purpose of these lakes is to isolate the water management of the polder land from that of the neighbouring old land. When a polder is created, the ground level within it is below that of the surrounding area. If the polder is connected directly to the old land, the groundwater level in the old land falls, which causes the soil to dry out.[2] This was observed in theNoordoostpolder,Overijssel andFriesland to the east and between theWieringermeerpolder andNorth Holland.
In addition, water flows to the new polder lands, creating a very wet area, especially at the edges of the polder. Drainage may be a solution, but this only increases the problem in the old land. If a large enough bordering lake is created between polder and old land, the water pressure and level remain the same. Water in the polder will be managed independently by a differentwater authority.
Historically, this technique was not applied to theNoordoostpolder or theWieringermeer. For theNoordoostpolder, the plan was abandoned because it was too expensive. TheWieringerrandmeer project between theWieringermeer andWieringen is still under discussion with the province ofNorth Holland.
The bordering lakes surrounding theFlevopolder offer opportunities forwater sports and the creation ofnature reserves.
From south-west to north:[1]
From south-west to north