Implementation agenda for Rhine Estuary-Drecht Towns

Milestones 2015-2025

Considerable progress has been made in the Rhine Estuary-Drecht Towns area in recent years. Milestones include:  

• A initial reconnaissance (Dutch) has been completed of alternative strategies for flood risk management in the Rhine Estuary-Drecht Towns area for the long term (>2 metres sea level rise). Six alternatives have been elaborated for this purpose. They differ in terms of keeping the connections to the sea open or closing them to a greater extent.  
• The ‘Dikes Development Framework’ (Dutch) was completed in the spring of 2025. It describes the basic principles and boundary conditions for flood risk management and spatial development in conjunction.  
• Rijkswaterstaat and the Directorate-General for Water and Soil (DGWB) have jointly completed a follow-up study looking at the lifespan of the Maeslant barrier that looks at the crucial elements of the barrier that may first limit its function. Those elements relate to both constructive and functional aspects, for example due to more frequent closures and the effect on shipping or the required management and maintenance. The conclusion is that, in the most unfavourable conditions (such as the upper limit of the rate of sea level rise), the barrier will have to be replaced in about 2065 at the earliest. The report will be added to this website as soon as possible.  
• A study of the costs for shipping and the port of closing the Maeslant barrier was completed in late 2024. These costs are estimated to be much lower than in previous studies because the closure time of the barrier is, in practice, shorter than previously assumed. This means that the costs of one or more closures per year are not currently limiting the functional lifespan of the barrier. Read more in the report (Dutch).
• A regional Impact Analysis (Dutch) was completed in early 2025 that examined the effects of continuing with the current strategy on spatial development in the area outside the dikes and the dike zones themselves. It was concluded that, assuming more than 1 metre of sea level rise, the effects in these areas on flood risk management will increase significantly if no additional measures are taken. In some areas outside the dikes, problems with excessive water that now occur once every 1,000 years will then occur once every 10 years. In the dike zones, the spatial impact will be significant if dike upgrade operations continue: 60% of the 590 kilometres of dikes in this area are intensively built-up. Strengthening the dikes also implies widening them, with potential effects on the buildings in place.  
• The scope of the periodical evaluation of the preferred strategy was determined in late 2023. The preferred strategy itself will be published in 2026. The focus of the evaluation is still on flood risk management but now more in conjunction with freshwater supplies and spatial adaptation and in the stronger connection with other major societal agendas in accordance with the position document of the Delta Programme’s Regional Consultation Platform. 
• As part of the Sea Level Rise Knowledge Programme, studies have been conducted to identify the dike upgrades needed in the future in the context of rising sea levels, extensive land subsidence and higher river discharges. The results of this system analysis from 2023 can be found here (Dutch). The Interim Report for the Sea Level Rise Knowledge Programme (Dutch) shows that, up to 1 metre of sea level rise, the effect of changing river discharges on water availability is larger than the effect of sea level rise. 
• The Schieland en de Krimpenerwaard water authority and Rijkswaterstaat are investing jointly in making the Hollandsche IJssel barrier more reliable. This investment means that less drastic dike upgrades will be needed on the river. An administrative agreement (Dutch) was signed for this purpose in 2023. In addition to a substantial net saving (of several tens of millions of euros), this also results in a significant reduction in the inconvenience for local residents.  
• The province of Zuid-Holland and the water authorities have drafted a joint Climate Cartography Set for Spatial Plans (Dutch): a set of maps about the suitability of spatial functions in relation to the characteristics of the water and soil system.  
• In 2022, the evacuation strategies established by the safety regions were elaborated on a supra-regional basis. The effects of possible or actual floods do not stop at the borders of a safety region.  
• During the past decade, a lot of new knowledge has been acquired about flood risk management in protected areas outside the dikes in the region and new policies have been developed. This knowledge was bundled in 2022 and the digital publication Ten years of work on flood risk management outside the dikes (Dutch) presents the main results, from strategy development to operational measures when high water levels are expected. These are the building blocks for living and working safely in the protected areas outside the dikes in our region. 
• The Hollandse Delta water authority developed a tool in 2021 to make a balanced assessment of new investments in a context of long-term climate risks.   
• In 2021, almost all the safety regions in the area produced impact analyses and evacuation strategies.   
• In 2020, the municipal authority of Dordrecht and the Zuid-Holland Zuid Safety Region published a report (Dutch) with suggestions relating to setting up flood shelter locations in existing or new buildings. 
• The municipal authority of Dordrecht and the Internationale Architectuur Biënnale Rotterdam (IABR) investigated the possibility of combining new housing on the Staart area, which is located outside the dikes, with a different layout of the area. The aim was to make it possible for the residents of Dordrecht to take shelter here in the event of floods, whether actual or impending.  
• The Port of Rotterdam Authority, working with government authorities and business, developed adaptation strategies for several parts of the port area that are located outside the dikes.  
• The Kinderdijk-Schoonhovenseveer dike upgrade was completed in 2018. The implementation of the upgrade took a range of synergy opportunities into consideration. An example is the Climate Dike in Streefkerk; this dike is so high and strong that housing construction is possible.   

Plans for 2025-2026 

A number of projects and measures are on the implementation agenda for the coming years. A few examples:  

• In the period until the end of 2025, the Delta Programme for the Rhine Estuary-Drecht Towns is working on the second update (“periodical evaluation”) of the preferred strategy. There are three tracks:  
  • research into the tenability and possible extension of the current strategy; 
  • the elaboration of multilayer safety on the basis of a number of area pilot projects (such as the Hoeksche Waard and Alexander Polder projects); 
  • the development of region-specific alternative strategies for flood risk management in relation to other spatial developments. These strategies are being formulated in terms of land use so that an estimate can be made of what we need to do, or refrain from doing, now to ensure that these strategies remain tenable in the long term.  
• The 'Strategic Adaptation Agenda for Unprotected Areas outside the Dikes' (Dutch) has been updated. Work is taking place on the development of actions for flood risk management outside the dikes. A project team is developing adaptation strategies for flood risk management in the urban areas in Rotterdam. Work has begun on the elaboration of the strategy for the Kop van Feijenoord area. A similar process will then be initiated for the Noordereiland.  
• The Rhine Estuary-Drecht Towns Delta Programme is actively involved in the national Sea Level Rise Knowledge Programme. 
• An updated knowledge agenda will also be handed over when the revised preferred strategy is published in 2026. 

Integration 

All the actors in the region are committed to coordinating work on the three agendas in the national Delta Programme – flood risk management, adequate fresh water, and climate-resilient and water-robust spatial planning – and, where possible, linking them to climate mitigation, the circular economy, housing construction, the energy transition, land subsidence and nature development. The Rhine Estuary-Drecht Towns Delta Programme is examining how this coordination effort can be further strengthened in the future.