Delta Decision for Flood Risk Management

In the 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 ‘base protection level’. 

The protection level is higher in locations where the potential 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 2015-2023

New standards

Between 2015 and 2023, 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

2017 saw the start of the first National Assessment Round for these primary defences. A set of statutory instruments is available for that purpose. This is a package of agreements and methods for the assessment of the primary defences. That assessment was completed in 2022. It is clear that a majority of primary flood defences do not yet comply with the standards for flood risk management.   

The Flood Protection Programme  (HWBP) was also launched in 2014: this is the largest operational project in the Delta Programme. The twenty-one water authorities and Rijkswaterstaat are working together in the programme on the largest dike upgrade operation since the Delta Works. The goal of the HWBP is for the primary defences to comply with the flood risk management standards by 2050. That work involves a total of approximately 1,500 kilometres of dikes and more than 400 engineering structures such as locks and pumping stations. A total of 196 kilometres of dike and 51 structures have now been upgraded or declared safe. Some 100 dike upgrade projects representing 814 kilometres of dike are planned for 2024-2035. The ambition to upgrade 50 kilometres of dike each year is expected to be fulfilled by 2026. 

Of the approximately 9 million people living behind a primary flood defence, about 78% already had the base level of protection in 2020. By 2028, this percentage will probably increase to approximately 81%. 

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 government authorities for which the Delta Programme works. 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.  

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 root 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 2024-2026

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:

  • By the end of 2024, the minister will report on the findings from the evaluation of the Water Act. 
  • The SMWO will present a new joint vision for water crisis management in late 2022, looking ahead to 2030. 
  • In 2022, development work continued on the system and the resources for the assessment and design of primary flood defences. The second National Assessment Round for the primary flood defences can therefore begin from 2023 onwards.  
  • On the basis of the first National Flood Probability Assessment Round, the Ministry of Infrastructure and Water Management, in close coordination with the water authorities and Rijkswaterstaat, will present the National Protection Overview to the House of Representatives in late 2023. 
  • The Second Flood Protection Programme (HWBP-2), the predecessor to the current HWBP, is in the completion phase. The Eemdijken-Zuidelijke Randmeren dike upgrade operation was completed in 2022. The latest project in this programme is now proceeding apace: the Markermeer dike (Hoorn-Edam-Amsterdam) upgrade. The first part of this operation was completed in early 2023. The entire project is expected to be completed by late 2027. 

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 tenable 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.