Pilot Project Mulit-Layer Safety Walcheren Zuid Beveland
The pilot focused on the question: how can we minimise flood risks by applying the concept of multi-layer flood risk management? Several meetings have been conducted to examine the infrastructure, vital and vulnerable objects, and linkage opportunities for different construction methods in concrete areas. The topic of crisis management has also been discussed. In the event of a disaster, how has evacuation been arranged? What bottlenecks are encountered in the infrastructure, and with respect to vital and vulnerable functions? Are there any leads for future improvements? In the pilot, a strategy has been developed for a safety-conscious approach to spatial developments and infrastructure in the decades ahead, in order to gain more control over the impact of a disaster.
Results
On the former island of Walcheren and the Zuid-Beveland peninsula, developments have been planned for the deepest polders. The challenge to be met in this pilot is to work out a strategy for the decades ahead focused on the adoption of a more risk-conscious approach when dealing with spatial developments and infrastructure. The main gain of the multi-layer flood risk management pilots is that participants from different layers hear one another’s accounts, expand their networks, and jointly work on a flood risk management vision.
Walcheren and Zuid-Beveland feature various types of areas, which call for different multi-layer flood risk management strategies:
- Elevated areas that largely remain dry during a flood and may serve as a refuge for people who need to evacuate. The Sloe area and the Goese Schans have been elaborated in the pilots as cases in point for elevated areas.
- Medium-high areas that are flooded slowly and to a relatively shallow depth. In such areas, it may be safe for some sections of the public to continue functioning in the event of a flood. A case in point for medium-high areas is Walcheren, west of the Kanaal door Walcheren canal. The pilot also examined whether water system taskings could be linked to flood risk management taskings in this area.
- Low-lying areas that are flooded quickly and deeply. Cases in point were the Middelburg “bathtub” south of the canal and Vlissingen east of the canal. Furthermore, this area is a particularly important resilience area in terms of facilities and employment opportunities.
In addition, the pilot explored what role infrastructure could play in multi-layer flood risk management, and whether multi-layer flood risk management measures could be linked to infrastructure developments.
Zooming in on a specific area in the pilots has produced the insight that differentiated multi-layer flood risk management strategies would be possible at the scale of Walcheren or Zuid Beveland. Walcheren offers opportunities for combining strategies. For example, restoring the inversion ridges during work on the water system would enable peak water storage in a limited part of Walcheren, linked to other functions (a “water collaborative” of water consumers and water producers). Closing off the inversion ridges will restore the church path system, which would be interesting from cultural-historical and recreational points of view. The church paths could also be used as escape routes for evacuations towards the northern dunes.
The Sloe area could serve as a temporary refuge from which people are evacuated in the event of a disaster. It should be noted, however, that the Sloe area is generally perceived as unsafe on account of its industry (hazardous substances) and the fact that it is located outside the dykes.
On account of its elevation, Goese Schans offers (long-term) safety and opportunities for multi-layer flood risk management: more houses at a safe spot. Based on a flood risk management risk analysis, this is a positive development that reduces the risk.
The towns of Middelburg and Vlissingen south-east of the canal are flooded quickly and deeply. This area accommodates 25,000 residents, a great many utilities and facilities, high-quality companies (employment opportunities, economic strength), a planned hospital, and vital infrastructure. The best strategy for this area is: keeping it dry! This location calls for the construction of a Delta Dyke, for example in combination with the navy premises development.
A second option involves an entirely different strategy, viz. preventive evacuation. A flood in this area will not impact the rest of Walcheren (water will be retained between the canal, the N57 motorway, and the dyke in line with this motorway). It is important for people in this area to know what they need to do, i.e., how and when they must leave the area.