Delta Decision on Flood Risk Management

The Delta Decision on Flood Risk Management revolves around new flood protection standards. These standards were developed on the basis of a risk-based approach: in addition to the probability of a flood, they also take account of the impact of flooding. The scope of such impact determines the the level of the standard.

Water Safety Delta Decision

The new standards provide everyone living behind a dyke or dunes with a minimum level of flood protection of 10-5: the risk of individual loss of life due to flooding must be less than 1 in 100,000 per year. A higher level of protection may apply for areas in which flooding could lead to large groups of casualties or significant losses. The presence of highly important so-called “vital functions” may also dictate a higher protection level. This is the case for the major gas production area in Groningen for which a higher level is proposed: the entire country would suffer if the supply were disrupted. Flood defences that already offer the required protection level will be properly maintained. Dyke improvement or river widening will ensure that all flood defences provide the proper level of flood protection. The sub-programmes have set down Preferential Strategies indicating the measures that will be necessary for both the short and long term. The Preferential Strategies constitute the basis for the implementation programme of the Delta Plan on Flood Risk Management. This programme seeks to employ smart combinations of several types of measures:

  • Layer 1: measures to prevent flooding (such as the improvement of dykes, dams, and dunes, and river widening);
  • Layer 2: containing the impact of flooding through spatial planning;
  • Layer 3: containing the impact of flooding through disaster management.