Water management

Room for the River:
more safety in the Dutch Delta

Zomerbedverlaging tussen Zwolle en Kampen zorgt voor meer afvoercapaciteit van de IJssel

Traveling along rivers causes much more in our mind than just enjoying the recreational aspects. It makes us aware of the versatile importance of the flowing water.

Rivers are vital carriers of water and nutrients and components of the hydrological cycle, acting as drainage channels for surface water. Together all the rivers in the world drain about 75% of the land surface on earth. They provide habitat and nourishment, leave usable deposits of sediments, like sand and gravel, and the power of fast flowing rivers provides electrical energy.

                                               The river IJssel (photo: Room for the River)

But rivers can also wreak death and destruction when they flood. Human interventation often fails, but there are all kinds of methods to cope with floods. In the Netherlands people know how to live with water like almost nowhere else. Dutch history is marked by floods and the response to them. In the winter of 1953 the North Sea flooded, devastating the southwest of the country and killing more than 1.800 people in a single night. This disaster led to the prestigious Deltaworks, an ingenious network of dames, barriers and sluices.

Much of the Netherlands lies in a delta, which enables three major rivers: the Rhine, Meuse and Scheldt, to flow out to sea. Without dikes and coastal dunes, around two thirds of the Netherlands would be flooded. Flood protection is therefore
a high priority in water management for
 the Dutch Ministry of Infrastructure
and the Environment.                                                                                                           

Hoogwater Waal 1995 Veur-Lent - aanleiding RvdR!Hoogwater Waal jan 2011

Floods in the river Waal (photos: Room for the River)

Increasing risks of floods 

In 1993 and 1995, the Dutch rivers swelled to unprecedented levels. Large tracts of farmland were inundated and 250,000 people and one million head of livestock were evacuated. As a consequence, the Dutch government took measures to protect the
rivers region against flooding.

The project ‘Room for the River’, started in 2007, restores the river’s natural flood plain in places where it is least harmful in order to protect those areas that need to be defended. By 2015, through a series of more than 30 measures, they will have lowered and broadened the flood
plain and created river diversions and temporary water storage areas. The project will restore marshy riverine landscapes to serve once again as natural ‘water storage’ sponges and provide biodiversity and aesthetic and recreational values.         

Kribben Deventer uiterwaardvergravingingen Bolwerksplas, Worp en Ossenwaard

Groynes in the river IJssel (photo: Room for the River)

Sharing experience with countries all over the world

The Dutch Minister of Infrastructure and the Environment bears the overall responsibility for the Program. Also internationally Room for the River collaborates with its neighbour countries. The countries through which the Rhine, Meuse and Scheldt rivers flow, cooperate closely on flood protection. These countries are The Netherlands, Belgium, France and Germany. Room for the River also shares this experience with other countries all over the world, and highly values the experience obtained from these international exchanges.

Ontpoldering Overdiepsepolder, BiesboschOverdiepse Polder- 1 van de 30 plaatsen bescherming tegen overstroming. bestaande dijk Bergsche Maas verlaagd, dijk Oude Maas verhoogd, terpenplan bedacht door bewoners en ondernemers. Bij hoog water kan rivierwater daardoor door de polder stromen.

The Overdiepse Polder will become a spillway with a number of moulds where farmers are able to resettle. The moulds will be high enough to keep dry in times of high water. 

Nine different solutions

The project 'Room for the River' includes nine different solutions. 

Dike relocation  Relocating a dike land inwards increases the width of the floodplains and provides more room for the river. 

Lowering of floodplainsLowering (excavating) an area of the floodplain increases the room for the river during high water levels.

DepolderingThe dike on the river side of a polder is relocated land inwards and water can flow into the polder at high water levels.

Deepening summer bed The river bed is deepened by excavating the surface layer of the river bed. The deepened river bed provides more room for the river.

Lowering groynes 
Groynes stabilise the location of the river and ensure that the river remains at the correct depth. However, at high water levels groynes can form an obstruction to the flow of water in the river. Lowering groynes increases the flow rate of the water in the river.

Removing obstacles - Removing or modifying obstacles in
the river bed where possible, or modifying them, increases the flow rate of the water.

Water storage  The Volkerak­ Zoommeer lake provides for temporary water storage when exceptional conditions result in the combination of a closed storm surge barrier and high river discharges to the sea.    

High-water channel  A high­water channel is a diked area that branches off from the main river to discharge some of the water via
a separate route.

Strengthening dikesDikes are strengthened in areas in which creating more room for the river is not an option.

Source: www.ruimtevoorderivier.nl                                                                      Index

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