Flood

What do we see on the risk map?

Large parts of the Netherlands are protected from water by flood defences (dykes, dunes and engineering structures). A successive ring of flood defences which are more or less the same height is referred to as a dyke ring. Higher areas may also be part of a dyke ring. The land within the ring is referred to as a dyke ring area. The dyke ring area and the required protection level of every dyke ring are laid down by law in the Dutch Flood Defences Act [Wet op de Waterkering].

The risk map shows the dyke ring areas that could be flooded. The risk map also shows how high the water will rise in the worst case.

Dyke rings

dijkringen.gif

buitendijks gebied = river side of the dyke / rivier = river / dijk = dyke / dijkringgebied = dyke ring area / overstromingsgebied = flood area
 / overstromingsdiepte = flood depth


Flood depth
There are a great many factors that determine which parts of the land are flooded. Computer calculations have been developed for many areas to show how a flood could unfold. In the case of such calculations, assumptions are made about the location and size of a dyke breach and the water levels of the river or the sea. Calculations are then made as to which areas will be submerged and as to which flood depths will be reached at each location.
By combining the results of the calculations, a maximum flood depth can be determined for each location. In this way, the flood depth map indicates the areas that may be flooded and the water depths.

 

 

What is the risk?

A flood occurs if an unmanageable amount of water flows inland. Floods pose a real danger to the Netherlands, because:

  • large parts of our country are below sea level;
  • the Netherlands has a number of large rivers;
  • the climate is changing: sea level is rising and it is raining more often and more heavily.

The water may come from several sources: the sea or the large rivers and from inland waterways such as canals and lakes. A dyke may subside, a dune may be swept away, or the water may come over the dykes. An additional danger is that the power supply may fail, so that no communication by telephone, Internet and television is possible. Public health may also be at risk, which may be a reason for the government to advise evacuation.
 

 

What safety measures are there?

All public authorities – the state, provinces and municipalities – work together to avoid and to limit floods. Rijkswaterstaat – the Directorate General for Public Works and Water Management – and the water authorities are jointly responsible for maintaining and inspecting dykes, dams and dunes, and rivers are given more room. The municipalities inform and warn the population. Together with the emergency services (police, fire brigade and ambulance), the public authorities regularly rehearse the actions to be taken in the event or the risk of a flood. Water levels are monitored continuously, so there is, in principle, time to take action and to raise the alarm.
 

 

 

What can you do yourself?

The risk map contains information about the risk of floods in the Netherlands. It shows how high the water will be at your location and indicates safe, high ground.

You can prepare for a flood. What preparations must you make?

  • put together an emergency package;
  • list addresses where you can go to in an emergency;
  • draw up routes to get there.

If a flood is likely

You will be alerted via the local radio or TV, the siren, by SMS or via police or fire brigade sound trucks. You must then do the following:

  • listen to the disaster broadcasting station and visit – if possible – the website of your municipality or www.crisis.nl for the latest news;
  • follow the instructions of the authorities and the emergency services.

If you have to leave your house

  • shut off the gas, water and electricity at the mains;
  • take only vital articles with you (cash, medicine and copies of identity documents and insurance policies);
  • lock up your home;
  • place sandbags in front of doors and windows;
  • check whether your neighbours know that they have to leave;
  • wear sturdy shoes and warm clothing.
  • If you are leaving by car, place sandbags in front of doors and windows and take the following with you:
  • your emergency package;
  • your pets and food for them;
  • camping stove with extra fuel (gas, petrol), a set of pans and tableware;
  • a whistle (to call for help);
  • string and a plastic sheet to make a shelter;
  • extra fuel for your car.

If you cannot leave

  • go to the highest point in your house and take your emergency package with you;
  • hang a white sheet out of the window to let the emergency services know that there are still people in the house;
  • help others – if there is time – with their emergency measures and offer them a safe refuge if you have one.

During a flood

  • listen to the disaster broadcasting station;
  • follow all instructions;.
  • go to safe, high ground and stay there; wait until help arrives;
  • if you are safe, assist others close to you who need help;
  • do not wade or drive through the water. Fast-flowing water above your ankles can unbalance you and wash you away; see below for what you can do in the case of certain water levels.

Waterdepth

What can you do yourself?

0 - 20 cm

Store important items in a high and dry place.

Protect your possessions from damage (sandbags).

Cars are able to move at walking pace.

20 - 50 cm

Ensure that you, your family and important articles are safe.

People needing help can still be reached on foot; help others as far as possible.

50 - 80 cm

Military vehicles can still move; you can still be reached by the emergency services.

Ensure that you and your family are safe.

See where you can offer help in a safe place.

80 cm - 2 m

The first floor of your house is safe.

Ensure that you and your family are safe and take your emergency stocks and the battery-powered radio with you.

Listen to the disaster broadcasting station (local radio station) and follow the instructions of the emergency services.

2 - 5 m

The second floor of your house is safe.

Ensure that you and your family are safe and take your emergency stocks and the battery-powered radio with you.

Listen to the rampenzender [disaster broadcasting station] and follow the instructions of the emergency services.

more than  5 m

Go to the highest point in your house and take your emergency stocks with you.

Ensure that you are near an exit or on the roof so that you can be reached by the emergency services (boat or helicopter). Hang a white sheet out of the window to let the emergency services know that there are still people in the house;

Following a flood

You will be informed if your residential area is safe again. Do not try to investigate matters for yourself.
 

 

More information

  • Up-to-date water levels can be found at www.actuelewaterdata.nl.
  • Rijkswaterstaat’s storm tide warning service issues warnings for high water at www.svsd.nl.

 

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