Adaptive delta management

The Delta Programme has looked at which short- and long-term solutions are needed to protect the Netherlands from high water, to safeguard adequate supplies of fresh water and to structure our country in climate-resilient and water-robust ways. It is difficult, and usually not desirable, to set out measures in every detail at present for the next 50 to 100 years. It must be possible to adapt solutions in line with new insights and circumstances. On the other hand, we must prepare; it should not be forgotten that it took decades to complete the Delta Works. We also want to make sure that, when the solutions are needed, they can also be put into place with minimum of expenditure. So what matters is to take the right steps at the right time: adaptive delta management. 

Key aspects of adaptive delta management

The key aspects of adaptive delta management are: 

• connecting decisions we make now with long-term agendas in the areas of flood risk management and fresh water; 
• ensuring that solutions are flexible; 
• having multiple strategies ready and ensuring we can switch track quickly if circumstances change (adaptation pathways); 
• connecting investments in flood risk management and fresh water with investments in areas such as spatial planning and nature, and making redevelopment water-robust and climate-resilient where possible. 

In this way, we ensure that sensible measures are implemented now and that, at the same time, there are enough options in the future for the measures that will be required then to protect the Netherlands from high water and supply it with enough fresh water. 

For example: the approach to the replacement of engineering structures (VONK) and the expansion of the Climate-Resilient Water Channel (KWA).

One example is the approach to replacing locks, dams and storm surge barriers. These engineering structures are ageing, not just because of wear and tear but also because they are no longer technically adequate. Rijkswaterstaat has now made an estimate for the next 50 to 100 years about which structures will need to be replaced, and when. Linking this replacement work to developments in the Delta Programme will prevent, for example, a lock being replaced because of its age when, ten years later, a pump will have to be installed at the same location because the water level is higher. 

Another example is the incremental and flexible expansion of the Climate-Resilient Water Channel (KWA) in the Central Netherlands. The additional supply of fresh water from the Lek river and the Amsterdam-Rhine Canal via the regional water system of the Hoogheemraadschap Stichtse Rijnlanden water authority is being used to cope with salinisation and water shortages. The Freshwater Delta Plan provides for a gradual expansion of the Climate-Resistant Water Supplies from approximately 7 to approximately 15 m3 a second. Nine of the ten subprojects have been completed. The Lopikerwaard subproject began in 2023 and it is the final measure. The work was completed in 2022 on the dredging of the canalised Hollandsche IJssel, widening the flow for the Enkele Wiericke Canal and widening the flow at the Polsbroek junction. In addition, subprojects for the Caspargauw storage location and Doorsluis Nieuwegein measures were completed in 2023. 

Monitoring, Knowledge, Action

Working adaptively means not waiting until we are overtaken by new insights or developments, but being constantly alert and taking cost-effective measures at the right time. The Delta Programme uses the ‘Monitoring, Knowledge, Action’ approach to visualise the current status of the Delta Programme. 

The approach provides answers to four questions: 

• Are we still on schedule: are operations proceeding according to schedule and are we achieving our objectives?  
• Are we still on track: are there any new developments that warrant changes to decisions made in the past? 
• Integrated approach: are we addressing the agendas in integrated ways? 
• Participation: is there broad participation from government authorities, business, stakeholder organisations and citizens where required? 

Signal Group

The Monitoring, Knowledge, Action methodology was introduced in 2017 for the 2018 Delta Programme. The Delta Programme conducts regular evaluations to determine whether a change of course is needed. The Signal Group was established for this purpose in 2017. The Signal Group is expected to identify and monitor changing circumstances that may be of Delta Programme-wide interest. The Signal Group consists of substantive experts from authoritative knowledge institutes that are relevant for the Delta Programme: KNMI, Netherlands Environmental Assessment Agency (PBL), Deltares, Wageningen University & Research (WUR), Rijkswaterstaat-Water, Traffic and Living Environment, and Statistics Netherlands (CBS). The Signal Group uses a methodology with eight indicators to pick up timely and reliable signals in order to guide the Delta Programme. Findings of the Signal Group and the possible impact of the signals on the preferred strategies are reported annually, set out in the annual Delta Programme and discussed with representatives of the areas and themes of the Delta Programme. An example is the signal that sea level rise may be accelerating. That led to the Minister of Infrastructure and Water Management’s initiative in 2019 to initiate a multi-year Sea Level Rise Knowledge Programme. 

Six-yearly periodical evaluation

On the basis of the results of Monitoring, Knowledge, Action, an annual assessment is made of whether the execution of the agreed projects is on schedule. The strategies can be adjusted annually. In addition, there is a systematic periodical evaluation of the Delta Decisions and preferred strategies every six years (see 2015 Delta Programme). The purpose of the six-yearly periodical evaluation is to check carefully whether there are developments that make it necessary to adjust the Delta Decisions and strategies and, where appropriate, to propose adjustments. The first periodical evaluation was in the period 2018-2020, allowing for reporting in the 2021 Delta Programme. The second periodical evaluation is expected in the 2027 Delta Programme. The periodical evaluations result in up-to-date Delta Decisions and preferred strategies: a new ‘picture’ after a careful review and a possible new adjustment in response to external and internal developments, incorporating adjustments made earlier (DP 2016 to DP 2020 inclusive).