Delta Decision for Flood Risk Management

In the low-lying Netherlands, protection from flooding is vital. Climate change and sea level rise mean that extremely high water levels will become more frequent. The core of the Delta Decision for Flood Risk Management is that, by 2050 at the latest, the probability of mortality as a result of flooding for everyone behind the dikes will not exceed 1 in 100,000 per year (or 0.001%). This is the ‘basic protection level’. The protection level is higher in locations where the impact is very high, for example if there is a risk of large numbers of casualties, extensive economic damage and/or damage to vital infrastructure of national importance. 

Milestones 2015-2020

New standards

In the period 2015-2020, considerable progress was made on the implementation of the Delta Decision for Flood Risk Management. The protection objectives have been formulated as standards for the primary flood defences: the dikes, dunes, dams and storm surge barriers that protect our country against flooding from the sea, the large rivers and the large lakes. These standards have been set out in the Water Act which went into effect on 1 January 2017. 

Assessment of primary defences and dike upgrades

In addition, 2017 saw the start of the first National Assessment Round for these primary defences. A new set of statutory instruments is available for that purpose. This is a package of agreements and methods for the assessment of the primary defences. Progress can be followed in the Flood Risk Management Portal.

The Flood Protection Programme (HWBP) has also begun. The 21 water authorities and Rijkswaterstaat are working together in that programme on the largest dike upgrade operation since the Delta Works. The goal of the HWBP is for the primary defences (managed by the water authorities) to comply with the standards by 2050. It involves some 1,500 kilometres of dikes and nearly 500 locks and pumping stations. The completion of the dike upgrades is proceeding at a lower pace than required; the dikes to be tackled first often involve complex projects in densely built-up areas. From 2027 onwards, the annual number of kilometres of completed upgrades will increase markedly. 

Of the approximately 9 million people living behind a primary flood defence, about 78% already had the basic level of protection in 2020. In 2027, this percentage will increase to approximately 79%.

Smart spatial planning and crisis management

The Delta Programme does not focus exclusively on flood prevention. Limiting potential damage and the number of casualties if there is flooding after all is also a responsibility of the Delta Programme. The consequences can be mitigated by making smart choices in spatial planning and crisis management. The Working Group on Mitigating the Consequences of Floods issued an advisory document in this respect in 2018. Limiting the impact of floods with spatial planning measures is a component of the Delta Plan for Spatial Adaptation. 

The Steering Group for the Management of Water Crises and Floods (SMWO) improved water crisis management. An Evacuation Module for Large-Scale Floods is now available, including the app and website The National Water and Floods Information System (LIWO) provides up-to-date flood information.

‘The Safety Region Approach for Floods’ (WAVE2020) was a programme directed by the Steering Group for the Management of Water Crises and Floods (SMWO). The aim was to embed the management of water crises in the crisis plans of the safety regions. The safety regions worked in recent years on improving evacuation plans and collaboration between parties. The WAVE2020 Programme has now been completed but work is still continuing on the analyses. The lessons learned from the 2021 floods in Limburg will be included in those analyses. WAVE2020 has submitted a number of recommendations to the SMWO and they will be implemented in consultation with the Delta Programme.

Plans for 2021-2026

Projects, activities and milestones

In the coming years, there will be a range of projects and activities for the implementation of the Delta Decision for Flood Risk Management. The projects and activities are described in the Delta Plan for Flood Risk Management. During this period, there are several milestones:

  • The Minister of Infrastructure and Water Management (IenW) will report to the Senate and House of Representatives on the condition of the primary defences before the end of 2023. That report will be based on the first National Assessment Round. It is expected that all dike sections will have been assessed by mid-2022. The second National Assessment Round will run from 2023 to 2034. 
  • Before the end of 2024, the Minister will report on the effectiveness and impacts of Articles 2.2, 2.3, 2.12, 3.9, and 7.23 to 7.26 (inclusive) of the Water Act.
  • The SMWO will present a new joint vision for water crisis management in late 2022, looking ahead to 2030.

Knowledge and research

The knowledge questions about flood risk management are listed in the Knowledge Agenda of the Delta Programme. Important knowledge questions concern sea level rise. The final results of the Sea Level Rise Knowledge Programme will be available in 2026. The studies look at the rate of sea level rise from the second half of this century onwards. The research also shows how long the current strategies for flood risk management will be sustainable and describes the alternatives to keep the Netherlands safe and liveable into the distant future.

The Ministry of Infrastructure and Water Management is continuing to improve the tools for assessing and designing primary flood defences on the basis of new insights, in collaboration with the managers of the flood defences.

The SMWO is enhancing knowledge about crisis management by promoting knowledge exchanges between the organisations involved and conducting pilot projects. The crisis partners share knowledge in the Netherlands Water Management Centre. They also exchange knowledge and information with other countries.