Flood safety as leverage for sustainable urban development

09 October 2020 - Published by Elin Ljunggren
Rijkswaterstaat is working with international partners on an integrated approach to climate adaptation, which was tested in Dordrecht. Read on to learn how this vision was developed during two workshops last summer.
The challenges surrounding climate adaptation affect us all: from spatial development to flood safety and from accessibility to ecosystem restoration. But how do you tackle those challenges in an integrated way? This question is central to C5a (Cluster for Cloud to Coast Climate Change adaptation). Six European countries are working together on an integrated approach to adapting to climate change. The method is being developed in a number of case studies. In the Dordrecht case study, ‘De Staart’, Rijkswaterstaat works together with the municipality, the International Architecture Biennale Rotterdam and regional partners to test the approach. Experts from these organisations participated in a workshop series to develop a future vision for ‘De Staart’ together.

In the first workshop 'Flood safety as leverage for sustainable urban development', sketching a vision for the future for ‘De Staart’ in Dordrecht was the central topic. Together, the participants investigated what is needed to set up this location as a large-scale shelter for when the area is threatened by flooding. They approach this issue from four disciplines: spatial development, flood safety, accessibility and ecosystem restoration.

Living close to city, water and nature
Future developments on ‘De Staart’ must in any case be based on the quality of the area, because "Where can you live so close to the city, water and nature nowadays?" Accessibility is crucial for the development and quality of life of the area, but it is also important to investigate which infrastructure can remain available during a flood, so that residents can be evacuated to and from ‘De Staart’. Better opening up of the area also contributes to the experience of nature in the area and thus to its development. Finally, little will change for flood safety until 2050, but we must take advantage of the opportunity to include the role of ‘De Staart’ as a large-scale shelter location in the other tasks.

Mobility is crucial
Furthermore, the various disciplines investigated where there is synergy and where measures collide. In the future, there is space for living, working (industry), recreation and nature on ‘De Staart’. The limited available space raises the question, however, to what extent these functions can (continue to) exist independently from each other or, on the contrary, can or must be integrated. In the future of ‘De Staart’, mobility will therefore play a crucial role in designing the space, also with a potential evacuation in the event of a flood threat in mind.

Solve environmental problems first
After the workshop, the participants were enthusiastic to think together about integrated solutions on a larger scale. As a result of this, solutions come into view sooner than when each problem is tackled in isolation. However, the ubiquitous problem of polluted soil and associated environmental issues must first be resolved. That will be a precondition for all future developments, so is the general belief.

Confrontation with the future
During the second workshop, the participants confronted the established vision for ‘De Staart’ with the future. Emphasis was placed on the two most important future uncertainties: sea level rise and changes in mobility.

Four possible solutions
The report that Deltares (Dutch institute for applied research in the field of water and subsurface) produced for the Sea Level Rise Knowledge Program explores four possible solutions: ‘protect closed’, ‘protect open’, ‘seaward’ and ‘move along’. During the workshop we choose to focus on the scenarios ‘protect open’ and ‘protect closed’, both of which will have a major impact on Dordrecht. In addition to the sea level rise, mobility development is the other uncertainty in the future scenarios. Various trends and developments play a role in this, such as the development of shared mobility (from ownership to use), but also the e-bike and scooter as forms of individual mobility. In addition, due to corona, the major morning and evening traffic jams have disappeared due to the spread of traffic, although the number of movements on the road is already at the same level again as before the pandemic. The question is whether this will remain the case.

Scenario ‘protect closed’
In the ‘protect closed’ scenario, the participants immediately saw a major tipping point for nature in terms of ecosystem dynamics due to the disappearance of the tides. In the ‘protect open’ scenario, the changes are much more gradual. With a rise of one meter in sea level, nature is still quite robust, but the tipping point is at an increase of about two meters; then the grasslands flood and the banks disappear. In the ‘protect closed’ scenario, the participants stated that for flood risk management the evacuation problem is almost gone, because sea-dominated floods no longer occur.

Scenario ‘protect open’
In the 'protection open' scenario, ‘De Staart’ remains important as an evacuation area. With regard to spatial development, it applies to both scenarios that the sea level rise will remain limited, because these scenarios occur in the middle term (from 2030 onwards). In order to give way to new forms of mobility, the participants saw investing in a water-robust bicycle boulevard as crucial. A good connection with the train stations and high quality public transport is also necessary for ‘De Staart’. 

Mobility important in all scenarios
Mobility is important in all scenarios. Not only to keep ‘De Staart’ accessible in the event of a disaster, but also to achieve the desired higher density. Investments in public transport are necessary, because the car is expected to disappear from the cityscape in time. In the ‘protect closed’ scenario, mobility is the overriding factor, in the ‘protect open’ scenario, mobility follows urban development. The current natural values ​​will eventually disappear, which is why we already have to think about ecosystem values ​​that we want to preserve. From the point of view of both flood safety and the soil pollution problem, public areas can be raised by one meter.

Bringing insights into policy making and implementation
After this afternoon of working together, the participants felt that they were not yet ready, as became apparent during the workshop evaluation for the further development of the integrated approach of C5a. There was certainly enthusiasm for a third, closing workshop. This workshop should focus on the question of how the insights gained from these two workshops can be included into the practice of policy-making and implementation.

> Download pdf of Adaptation pathways map for De Staart