Southwest Delta/Southwest Delta freshwater supply region

Implementation of flood risk management strategy

The preferential strategy for the Southwest Delta is aimed at a climate-proof, safe, ecologically resilient, and economically vital delta. With respect to the coast and the Oosterschelde, the refrain is “flexible where possible, rigid where needed”. The taskings are linked to environmental and other spatial ambitions wherever possible. In the Flemish-Dutch Scheldt Commission (VNSC), the Flemish Region and the Netherlands are working on a joint “Agenda for the Future” for the Scheldt estuary. The authorities in Zeeland are collaborating on disaster management and developing standards for inner dykes that can serve as buffers during a flood.

preferential strategy for the Southwest Delta

See DP2015, preferential strategy for the Southwest Delta.

On schedule

Virtually all the flood risk management projects in the Southwest Delta are on schedule. Some of these projects are highlighted below.

The dyke improvements under the Flood Protection Programme are proceeding as planned. Three dyke improvements on the island of Schouwen-Duiveland were completed in 2017: Burghsluis-Schelphoek, De Ruyter farm/Flaauwershaven, and Zierikzee-Bruinisse. 

The beach nourishment programme for the coast and the Westerschelde is aimed at keeping the sandy system in sustainable balance with the rising sea level. The programme is being carried out as planned. The Coastal Genesis 2.0 programme and the VNSC working group on coastal flood risk management in the Westerschelde estuary are exploring the long-term development in the sand budget. The results will be available in 2018 (VNSC) and 2020 (Coastal Genesis 2.0). In the Oosterschelde, sand replenishment is the most effective measure to combat sand deficit and preserve the intertidal area. Sand replenishment to the Roggenplaat shoal is scheduled for the winter of 2017/2018. 

The final report on the MIRT Study into integrated flood risk management in the Oosterschelde was completed in the spring of 2017. The report shows that according to the modelling, the Oosterschelde storm surge barrier can prevent storm surges until 2050, assuming a maximum rise in sea level of 85 cm until 2100. In that case, the only measures required up to 2050 will involve re-paving the locks platform (on account of overtopping water) and possibly reinforcing part of the stone cladding on the Tholen dykes and the Oesterdam (or adapting the forelands at these locations). The closing frequency of the Oosterschelde storm surge barrier will increase: from the current average of once a year to ten times a year in the event of a 60 cm rise in sea level, or 100 times a year in the event of a 125 cm rise in sea level. This may have serious consequences for the environment and land use. If the sea level rises by more than 50 cm, some components of the Oosterschelde storm surge barrier will probably need to be adapted. Delta Programme 2020 will report on such potential consequences and adaptations. 

Within the Flemish-Dutch Scheldt Commission (VNSC), the Flemish Region and the Netherlands are working on a perspective for the sustainable development of the Scheldt estuary (Agenda for the Future). The corresponding study is proceeding as planned. One of the questions is how smart(er) sediment management can enhance the balance between flood protection, port accessibility, and nature in the estuary. In 2018, the Commission will draw up the closing balance of the first research programme, together with the stakeholders.

The Security Region is using the latest insights to review the disaster management plans pertaining to floods in Zeeland, based on the guidelines provided by the national Water and Evacuation project. All the parties involved in the province (governments, businesses, stakeholders) are providing input. The plans will be ready in 2018.

On track

There is currently no reason to adjust the preferential strategy for the Southwest Delta. 

Integrated approach

The strategy for the Southwest Delta revolves around an integrated approach. Throughout the delta, the point of departure is: ecological resilience, economic vitality, and climate-proof security. In the Delta Plan on Flood Risk Management, the timely identification of linkage opportunities is already common practice. This has produced linkage opportunities in, e.g., Sint-Annaland (Tholen), Hansweert, and Yerseke (Zuid-Beveland). Within the framework of the Doing More With Dykes project, administrators have set down a top ten of projects enabling synergy between dyke improvement projects implemented by the district water board and spatial projects initiated by municipalities. A case in point is the restructuring of the Sint-Annaland port front, which is also pre-funded by the municipality. 

Another good example of an integrated approach to flood defence systems is the pilot involving five tidal turbines in a flood gate of the Oosterschelde storm surge barrier. The industrial partners of the plant consortium intend to further develop existing technology with the aim of garnering broad social acceptance, by factoring in vulnerable natural values and taking account of requirements in terms of flood risk management and water quality. The knowledge institutes Wageningen Marine Research, Deltares, Delft University of Technology, and Utrecht University have joined forces to map out how this project will impact tidal dynamics, ecology, and the sand budget. The Oosterschelde National Park and the nature organisations are monitoring the project closely. The plan is to install a second set of tidal turbines in another flood gate in 2018. The turbines will power some 1000 households in the province of Zeeland via the Delta grid.


The extent of participation is dictated by the nature of the project. In the Southwest Delta, participation ranges from joint studies to joint implementation and co-funding.

The participation process in the Southwest Delta commenced quite some time ago. The ambitions and goals for the area have been set down in collaboration with local stakeholders. A Delta Community is actively providing input and practical support. Every year, four newsletters are published. The annual working conference and network day support the joint approach. In the Southwest Delta Advisory Group, municipalities and NGOs in the fields of nature, the environment, shipping, recreation, and agriculture provide advice to the Regional Consultative Body for the Southwest Delta. The Advisory Group has, inter alia, drawn up an environmental vision for the Grevelingen and Volkerak-Zoommeer lakes, which has been incorporated into the draft National Framework Vision for these lakes. On the initiative of the Advisory Group, participation in several substantive themes has been intensified in 2017. 

The Flemish Region and the Dutch governments have set up the Scheldt Council to proactively involve relevant stakeholders in the development of forms of management and policy for the Scheldt estuary. This Council is composed of delegates from various bodies such as the Scheldt ports, regional and local governments, employers, agricultural associations, and nature organisations. In 2016, the focus was on sharing the interim results of the research programme, e.g., through the VNSC Scheldt symposium held in November 2016, digital newsletters, so-called Scheldt topics, and the annual Scheldt magazine (see http://www.vnsc.eu/publicaties).

Co-funding is another form of participation. A case in point is the sand replenishment at the Roggenplaat shoal: this project has been funded with contributions from local residents (through crowd funding), the Natuurmonumenten and Het Zeeuwse Landschap nature organisations, eight municipalities, the province of Zeeland, central government, and a European grant (INTERREG). 

Implementation of freshwater supply strategy (Southwest Delta freshwater supply region)

The preferential strategy for the freshwater supply in the Southwest Delta is aimed at securing a sufficient external supply of freshwater (including under changing climate conditions) and, if possible, making more efficient use of the water available. A key component is the preservation or improvement of the freshwater supply from the Biesbosch, the Hollandsch Diep, and the Haringvliet. The measures are founded on water availability agreements between water managers and consumers. The freshwater supply is closely related to the development perspective set out in the National Framework Vision for the Grevelingen and Volkerak-Zoommeer lakes.


preferential strategy for the freshwater supply in the Southwest Delta

See DP2015, preferential strategy for the Southwest Delta.

On schedule

The Administrative Agreement on freshwater in the Southwest Delta sets out the measures and pilots aimed at ensuring the resilience of the freshwater supply. Virtually all of them are proceeding as planned. The Roode Vaart project in Zevenbergen will be completed at the end of 2018. The Evides water company is engaged in preparations for improving the resilience of the reservoir system in the Biesbosch. Several pilots implemented under the Southwest Delta Freshwater Supply Testing Ground project have been completed. The results include a map of the freshwater-saltwater distribution in the Zeeland soil, insight into the potential of using brackish ambient water as process water, and expertise on the adaptation of various potato crops to saline conditions. An exploratory study into the application of a so-called Area Freshmaker (replacing saline groundwater by fresh groundwater) shows that this method is technically feasible. An Area Freshmaker of some 25 hectares can supply an area of some 200 hectares with freshwater. In this case, the cost price of the water will be some 20% less compared to the application of a small, farm-size Freshmaker. The report also outlines the organisational aspects and funding options involved in setting up an Area Freshmaker.

The decisions on a resilient water supply from the Biesbosch, Hollandsch Diep, and Haringvliet, and any alternative supply to areas around the Volkerak-Zoommeer lake are awaiting a decision on the National Framework Vision for the Grevelingen and Volkerak-Zoommeer lakes. Consequently, it is not certain whether phase 1 of the Roode Vaart transfer to West-Brabant, Tholen, and Sint Philipsland will be completed in 2021 as scheduled. For that reason, the four regional parties involved are reconsidering the process and the funding of the freshwater supply. 

The three provinces in the Southwest Delta have set down an action plan for the determination of water availability, and several pilots are under way. The plan elaboration for the restoration of freshwater-saltwater separation in the Krammer locks will be completed in 2017. 

On track

Currently, there is no reason for reconsidering the preferential strategy. The expectation is that the ongoing measures and the measures scheduled under the preferential strategy will enable attainment of the goals, properly and in good time. 

The course to be steered with respect to the Grevelingen and Volkerak-Zoommeer lakes depends on the final adoption of the National Framework Vision and the introduction of an associated alternative freshwater supply around the Volkerak-Zoommeer lake. The authorities have not yet managed to arrange the funding of the measures. Currently, this does not have any consequences for the integrated preferential strategy for the Southwest Delta. For the time being, the draft National Framework Vision and the Administrative Agreement between the region and the central government regarding the development of the Grevelingen and Volkerak-Zoommeer lakes will remain in force. Until further notice, the provinces, municipalities, and the central government have continued to budget their financial commitments. This ties in with the Declaration of Intent regarding the Delta Approach on Water Quality and Freshwater Supply (an element of the Major Waters strategy).

Integrated approach

The options for adopting an integrated approach differ considerably from one measure to the next, as do linkage opportunities. Improving the resilience of the Biesbosch basin system entails opportunities for linking up with nature. The realisation of the Roode Vaart transfer in Zevenbergen has become promising because the ambitions of the municipality of Moerdijk, the Brabantse Delta district water board, the provinces of Zeeland and Noord-Brabant, and the central government converged at the right time. 

The adapted flushing management in the Volkerak-Zoommeer and the innovative freshwater-saltwater separation at the Krammer locks, using an air bubble screen, are also integrated in nature. These measures entail the following linkage opportunities:

  1. improved fish migration options at the Krammer locks;
  2. shorter passage times for commercial shipping at the Krammer locks;
  3. reduced energy consumption for freshwater-saltwater separation at the Krammer locks;
  4. generation and storage of sustainable energy;
  5. more options for Smart Water Management in the Rhine-Meuse estuary.

The plan elaboration for the freshwater-saltwater separation will be completed in 2017.

Within the STRONG project and in the Policy Memorandum on Drinking Water, the provinces are identifying, in collaboration with the drinking water companies, Additional Strategic Supplies in order to ensure the resilience of the drinking water supply.


The freshwater supply measures set out in the preferential strategy are widely supported among entrepreneurs and NGOs in the Southwest Delta. These parties are represented in various bodies, including the Southwest Delta Advisory Group, that provides the Regional Consultative Body with solicited and unsolicited advice at the preferential strategy and Administrative Agreement on Freshwater Supply levels. 

Involvement of local stakeholders differs from one measure to the next, and also depends on the phase that a measure is going through. For example, local residents in the Zevenbergen port district are submitting their wishes for the Roode Vaart transfer, via workshops. The province of Zeeland and the Scheldestromen district water board are together substantiating the freshwater supply policy pursued in the province (freshwater supply testing ground) and the water availability process. Representatives of the recreational shipping sector are contributing expertise in the study into air bubble screens in the Krammer locks. Grid managers and power suppliers are weighing in on plans for the generation and storage of sustainable energy in this lock complex. 

A showcase for broad-based participation is the Waterpoort project. On the basis of a collective agenda, entrepreneurs, governments, and NGOs around the Volkerak-Zoommeer lake are exploring new developments in the fields of water, nature, and heritage that can enhance the region’s economic vitality.

Implementation of spatial adaptation strategy

Zeeland is one of the four pilots of the national Vital and Vulnerable programme. The province of Zeeland, Rijkswaterstaat, the district water board, municipalities, the Security Region, and Zeeland University of Applied Sciences are collaborating on the Zeeland Climate Adaptation programme aimed at reducing the impact of coastal flooding, waterlogging, drought, and heat stress. The province is focusing on the power supply and the chemical industry as important vital and vulnerable functions. The power supply is crucial to the continued performance of the other vital and vulnerable infrastructure during and after a flood. The chemical sector is represented relatively heavily in Zeeland. In the next two years, the parties will conduct various studies to substantiate the “Analysis” step. In 2019, the focus will be on the course of action (“Ambition” and “Action”). 

The Zeeland Security Region has embarked on the area elaboration regarding vital and vulnerable functions, in coordination with the Vital and Vulnerable pilot referred to above and the Climate Adaptation programme. This year, an impact analysis will be launched to provide insight into the effects of coastal flooding and serious waterlogging on the vital and vulnerable functions. In the Regional Flood Defence Systems Standards project, the province, district water board, Rijkswaterstaat, Security Region, municipalities, and stakeholders will subsequently explore which inner dykes can be used to reduce flood risks. In 2017, the experience gained in the Noord-Beveland pilot will be translated into a method to be used for all the dyke sections in Zeeland.

Municipalities in Zeeland are mapping out the risks of climate change by conducting climate stress tests. Such a test has already been completed in Noord-Beveland. In addition to the potential impact of a flood, the test also provides insight into the effects of extreme precipitation, drought, and heat. A climate stress test manual is available. The aim is that by 2020, all the municipalities in Zeeland will have a picture of their vulnerabilities during extreme weather and an overview of potential measures to reduce negative effects. They can factor in such measures when making choices in the spatial planning domain. 

The current heat stress calculation model is primarily focused on urban areas. In the impact project involving the development of a heat stress instrument for cities and villages in rural areas (third round of impact projects), Wageningen University and Research Centre and the Climate Adaptation Services Foundation have developed a calculation model in which region-specific conditions can also be factored in. The model is currently being tested in Zeeland. In early 2017, the municipalities of Vlissingen, Middelburg, and Borsele have installed measuring equipment. By the end of 2017, an analysis of the data will provide answers to the questions of whether rural areas in Zeeland are affected by heat stress, whether proximity to the sea will have a cooling effect during a heat wave, and where drought can be expected to cause damage to farmland. The final result of this impact project will be incorporated into the Climate Impact Atlas, in order to enable other rural regions to utilise the methodology and the tool. 

  1. Cover letter and Delta Programme Commissioner’s recommendations
  2. Introductory summary
    1. Continuing the work on a sustainable and safe delta
  3. Part I National level
  4. Progress of the Delta Programme
    1. Progress based on Monitoring, Analysing, Acting
    2. General picture of the progress
      1. On schedule
      2. On track
      3. Integrated approach
      4. Participation
      5. Effectiveness of the regions
    3. Progress in flood risk management
    4. Progress in spatial adaptation
    5. Progress in freshwater supply
    6. Embedding, knowledge and innovation, international collaboration
      1. Embedding
      2. Knowledge
      3. Innovation
      4. International efforts
  5. Delta Fund
    1. Developments in the Delta Fund
    2. Resources from other partners
    3. The financial taskings of the Delta Programme
    4. Financial security of the Delta Programme
  6. Part II Regions
  7. Progress per region
    1. IJsselmeer Region/freshwater supply region IJsselmeer Region
    2. Rhine Estuary-Drechtsteden/West-Netherlands freshwater supply region
    3. Rhine/ Area around the major rivers freshwater supply region
    4. Meuse
    5. Southwest Delta/Southwest Delta freshwater supply region
    6. The Coast
    7. Wadden Region
    8. Elevated Sandy Soils South and East
  8. Part III Delta Plans
  9. Delta Plan on Flood Risk Management
    1. Implementation programmes
      1. Flood Protection Programme
      2. Second Flood Protection Programme
      3. Room for the River
      4. Meuse Projects
      5. WaalWeelde
      6. IJsselmeer Closure Dam
      7. Repair of Oosterschelde and Westerschelde stone claddings - Zeeland foreland deposits
    2. River widening in interconnection with dyke improvement
    3. Studies ensuing from knowledge agenda and in regions
  10. Map Flood risk management measures
  11. Delta Plan on Freshwater Supply
    1. Measures to ensure the availability of freshwater in the Netherlands
  12. Map Freshwater supply measures
  13. Delta Plan on Spatial Adaptation
    1. Introduction
      1. Justification
      2. Aim and state of affairs of the Delta Plan
      3. Collective realisation
    2. Context
    3. “Analysis, Ambition, Action” – state of affairs
      1. Waterlogging
      2. Heat stress
      3. Drought
      4. Consequences of urban flooding
      5. Current approach
    4. Our intentions: expediting and intensifying
      1. Vision: from the present to 2050
      2. Ambition and strategy
      3. Interim goals
      4. Nationwide governance framework regarding spatial adaptation
      5. Funding
    5. Appendix 1. Action programme
    6. Appendix 2. Outcomes of regional meetings and round table discussions
  14. List of Background Documents
    1. Background documents
  15. Colophon
    1. Colophon content Delta Programme 2018
  16. How to use Delta Programme 2018