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Dam failure

This risk file considers two types of dams: large dams - or reservoir dams - and river dams.  

River dams in Belgium are hydraulic structures built on rivers (Meuse, Sambre, Scheldt, etc.) and their tributaries, present in Wallonia, Flanders and Brussels. They are necessary for regulating the flow of rivers and essential for navigation.

As far as reservoir dams are concerned, Belgium has fifteen major structures included in the World Register of Dams established by the ICOLD (International Commission on Large Dams). The topographical configuration of Wallonia, combined with a "typically Belgian" rainfall, explains the location of the structures on the Walloon highlands which make up the roof of the Benelux.

The Province of Liège is concerned by 5 important sites:

  • Gileppe (Jalhay) [SPW]
  • Vesdre (Eupen) [SPW]
  • Bütgenbach [ENGIE]
  • Robertville [ENGIE]
  • Coo 3 basins (Trois-Ponts) [ENGIE]

The Province of Luxembourg is concerned by 2 sites:

  • Ourthe (Nisramont) [SPW]
  • Vierre (Chiny) [ENGIE]

The Provinces of Namur and Hainaut are concerned by 6 sites:

  • Ry de Rome (Couvin) [SPW]
  • Eau d'Heure (Eau d'Heure Lakes Complex) [SPW]
  • Pre-dam falemprise (Eau d'Heure Lakes Complex) [SPW]
  • Ry Jaune pre-dam (Complexe des Lacs de l'Eau d'Heure) [SPW]
  • Féronval pre-dam (Eau d'Heure Lakes Complex) [SPW]
  • Plate-Taille (Eau d'Heure Lakes Complex) [SPW]

[In the list above, the current manager of each dam is listed in square brackets].

The six structures (Bütgenbach - Roberville - Coo (3 basins) - Vierre) managed by the company Engie have as their primary purpose the production of hydroelectricity as well as flood control.
The nine other structures (Gileppe – Vesdre – Ourthe – Ry de Rome – Eau d'Heure – Falemprise – Ry Jaune – Féronval – Plate-Taille) managed by the SPW, are mainly intended for the supply of tap water and low-water support, as well as for flood control and electricity production in order of priority.

All these structures are equipped with monitoring devices and are subject to continuous safety monitoring. The major risk concerning a reservoir dam would be a sudden rupture of it. However, the risk is considered very low, but less serious incidents, such as uncontrolled releases, can occur without the structure being affected.

Causes

Consequences

BEFORE

In the event of an overflow or uncontrolled release of a dam, general recommendations related to flooding situations may apply to areas downstream:

  • Find out where flood-prone areas are.
  • Envisage waterproof materials for cellar hatches, inspection chambers, etc. 
  • Envisage materials for raising the living areas on the ground floor and basement, such as bricks or sandbags. 
  • Protect your important documents and valuables from the water.
  • Envisage boots, buckets and squeegees. 
  • Make sure you know where and how the gas and electricity can be switched off.
  • Keep gutters and ditches clean and unclogged.    

DURING

  • Do you need help from the fire service? 
    • Call for help via the digital counter 1722.be or the electronic form of your local fire service. 
    • Call 1722 if this number is active. 
    • Call 112 only for people in danger. 
  • Is someone potentially in mortal danger? Always call 112. 
  • Limit your movements and avoid dangerous areas. 
  • Use sandbags to block the doorways to basements, exterior doors, etc. 
  • Remove carpets and place furniture and valuables at a safe height. 
  • Switch off gas, electricity and water if necessary. 
  • Park your car in a safe place. Do not leave it in your garage. 
  • Make sure that unsecured objects in the garden cannot be washed away. 

Do you have to evacuate? 

AFTER

  • Clean your home and disinfect damaged areas. 
  • Ventilate rooms adequately, but also heat them so that humidity evaporates. 
  • Follow the recommendations of the authorities regarding the use of tap water.  

Have you suffered any damage? 

  • Do you need help from the fire service? 
    • Call for help via the digital counter 1722.be or the electronic form of your local fire service. 
    • Call 1722 if this number is active. 
    • Call 112 only for people in danger. 
  • Do you not need help from the fire service? Call in a qualified professional or carry out the repairs yourself (e.g. a tree that has fallen in the garden, a damaged garden shed, hail damage to your car). 
  • Take photos of the damage: these may prove useful for your insurance claim. 
  • Contact your insurance provider as soon as possible. They will answer all your questions and help you start the claims process. 
  • Check whether the Disaster Fund will intervene in your case. 

Impact and probability 

For this risk file, three scenarios were evaluated by the experts:

  • The considerable scenario: a dam overflows or releases in an uncontrolled manner. For a few hours or days, a higher than normal amount of water is released downstream.
  • The major scenario: a much larger overflow resulting in a downstream surge of large quantities of water.
  • The extreme scenario: a catastrophic and sudden rupture releasing a very large amount of water downstream and causing considerable damage in the valley.

The proposed results below relating to probability and impact describe a failure of a dam corresponding to the considerable scenario, evaluated by the experts involved as the most relevant scenario. 

The most relevant scenario evaluated by the experts involved therefore does not correspond to a scenario of sudden rupture. This situation would rather correspond to an extreme scenario whose probability is very low but where the downstream damage can be very significant, much greater than for the considerable scenario used here. 

How should you interpret these results? 

Within the BNRA, experts assessed three scenarios for each risk: considerable, major or extreme. On each page, you will find the results of the scenario with the highest score based on the combination of likelihood and impact. This does not mean that this scenario will occur or is the most likely. Read more here about how to correctly interpret the results. 

As pointed out in the previous point, the results presented here apply to the considerable scenario, assessed as the most relevant scenario.

 

Probability

Weak

Human impact

Very weak

Societal impact

Weak

Environmental impact

No impact

Financial impact

Weak

What do the authorities do? 

Maintaining dams is the responsibility of:  

The regional authorities also continually monitor the water situation. Based on observations, weather forecasts and thresholds, they attempt to predict the risk of flooding. When these thresholds are exceeded, they inform the local, provincial and national authorities. 

If rising waters cause flooding, the local and provincial authorities launch their special emergency and intervention plans for floods.

Risks other than rupture or flooding must be taken into consideration. To do this, Internal Emergency Plans must be drawn up for each dam with different crisis scenarios.

For the Walloon region, the Decree of 22 February 2024 specifically concerns the safety of reservoir dams.

Documents

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