Climate adaptation in Dordrecht: Urban planning in the face of increasing flood risk
'Planning and Designing Cities for a Rising Sea Level’
Last August, the publication Planning and Designing Cities for a Rising Sea Level appeared, exploring ways in which residents of coastal areas can cope with climate change and rising sea levels. This poses important challenges for spatial planning. Lilian van Karnenbeek and Marleen van Rijswick – both affiliated with the Utrecht Centre for Water, Oceans and Sustainability Law – contributed a chapter about the case of Dordrecht. In this historic city, a monumental inner-city shopping street also serves as a dike protecting against river water. The city provides a striking example of what is at stake and what kind of policies are wise to pursue for the future. The relatively new Dutch policy concept of “multi-layer safety” (meerlaagsveiligheid) is explained through the example of Dordrecht’s water safety strategy for 2040.
More than any other municipality, the city of Dordrecht must take into account the threat of rising sea levels and the increasing likelihood of flooding. Yet this is not an entirely new concern: the St. Elizabeth’s Flood of 1421 already caused the city to become surrounded by water, leading to the formation of the so-called 'Island of Dordrecht', located between the branches of the Rhine and Meuse rivers (see box below).
The Saint Elizabeth’s Day Flood: disaster in slow motion
During the Saint Elizabeth's flood of 1421, a north-westerly storm coincided with very high river water levels, causing several dyke breaches. Because the holes in the dykes could not be repaired in time, the water had free rein. Where once lay the Grote Waard, a rich agricultural area, the tidal area of the Biesbosch developed over the years. Eighty years later, residents of the lost village of Wieldrecht had an altarpiece painted to commemorate this disaster. Wieldrecht is located at the top right of the painting near the dyke breach; Dordrecht is at the front left, with the still striking Grote Kerk. Two panels from that piece are now on display in the Rijksmuseum. It clearly shows how life in the Grote Waard seems to continue as normal; people are calmly bringing their possessions to safety, but there are no signs of drowning people or livestock. It was apparently only in the months and years after the dike breaches that the flooding grew into the “disaster” that ultimately destroyed the Waard.
River deltas such as those in the Netherlands have, since time immemorial, been attractive places to settle because of their fertile agricultural land – thanks to deposits of rich river clay – and their efficient opportunities for trade and transport by water. The downside of these advantages is their vulnerability to flooding. The historical concentration of people and economic activity in such areas is therefore easy to understand, but it now raises the question of how we can safeguard these assets and whether further urban development and investment are still responsible choices.
The Netherlands has a long tradition of flood prevention, through the construction of dikes, dams, and of course the Delta Works. Nevertheless, awareness has increasingly grown – especially since the river floods of 1993 and particularly 1995 – that a one-sided focus on preventing floods is not sustainable in the long term. In addition to protection, the approach must also focus on limiting damage and establishing effective crisis management. This combination of protection and control has, since 2009, been the official Dutch policy objective and is known as multilayered safety.
From Flood Prevention to Risk Management
The first layer, protection, still focuses on preventing floods through dikes and flood defences. In the Netherlands, most of the land is well protected by primary dikes and flood barriers maintained by the government agency Rijkswaterstaat and the regional water authorities. Under the Environment and Planning Act, which came into effect in 2024, it is assumed that land within the dike ring is adequately protected.
The second layer, spatial planning, can reduce the impact of a flood. In principle, Dutch municipalities determine independently how land within their borders—both inside and outside the dike system—may be used and developed. This is laid down in an Environmental Plan in accordance with the Act. However, the provincial and national governments may impose additional requirements, for example concerning construction in floodplains (to prevent a reduction in a river’s discharge capacity).
The third layer, disaster management, concerns preparation for flooding—through public information, crisis management, and evacuation plans. The Dutch Water Management Centre plays a role here, for instance by issuing timely warnings, alongside the national government and the water authorities (in consultation with the Veiligheidsregio's, the regional cooperation bodies for safety).
The concept of multi-layer safety aligns with the European Floods Directive of 2007 (Directive 2007/60/EC, on the assessment and management of flood risks) but, unlike the Directive, the Dutch approach is hierarchical—still giving top priority to the prevention of flooding.
A Dordrecht Shopping Street as a Flood Barrier
How is the Island of Dordrecht preparing for the future? Most of its territory lies within the dike system, yet there is also a considerable area outside the dikes—such as the freshwater tidal wetlands of the Biesbosch, a remnant of the St. Elizabeth’s Flood that still recalls the era before the Delta Works (see box above). A small portion of the urban area also lies outside the dikes, as shown on the map below (urban areas in red, the dike indicated in yellow).
The land within the dikes lies at the lowest elevation; it is generally very safe, but if the dikes were to fail, the higher-lying outer-dike areas would in fact be the safest—potentially serving as evacuation zones. According to the concept of multi-layer safety, the municipality must take the possibility of flooding into account in its spatial planning decisions.
The Voorstraat is a fine example of the challenges and limitations that densely built historic city centres face when trying to "go with the tide", adapting to rising sea levels on the one hand and higher peak river discharges on the other. This monumental shopping street also functions as a dike. However, because it is a very low dike and raising it would be far too complex, a temporary solution has been found: during periods of extremely high water, flood gates can be placed between the buildings. A municipal ordinance requires property owners to cooperate, and every year a Major Flood Barrier Test is held.
In its spatial strategy Eiland met kwaliteit (“Island with Quality”, up to 2040), the municipality of Dordrecht has outlined how spatial planning and water management must go hand in hand so that the negative consequences of flooding can be limited to some extent. The municipality can implement this ambition through regulations in its Environmental Plan. As an example, Van Rijswick en Van Karnenbeek mention the development of two higher-lying outer-dike areas, Maasterras and De Staart (see map above), where new housing will be combined with a role as evacuation zones for inner-city residents in case of flooding. In terms of crisis management, the municipality aims to become as self-sufficient as possible in responding to floods and to prepare residents for what actions they should take.
Limits to Municipal Autonomy?
As the Voorstraat illustrates, even improving the most basic level of flood safety can be problematic, despite the Netherlands’ centuries-long experience and ingenuity in building protective structures. This makes forward-looking spatial planning and effective management of flood risks all the more important. In such a context, planning evacuation routes and raising public awareness are not theoretical exercises but practical necessities. Homeowners themselves also share responsibility for flood safety—especially in areas located outside the dikes. According to the authors, awareness of flood risks among the Dutch population is still quite limited, partly because traditional flood protection has always emphasized dike-based prevention led by the government. A “climate label” for homes could help to raise this awareness.
Although Dordrecht’s plans for outer-dike development appear to be well thought out, the authors nevertheless question whether municipal decision-making power in spatial planning might be too extensive. After all, not every municipality will be able—or willing—to take sufficient responsibility and show the necessary foresight. For example, there appear to be few restrictions on inner-dike development, but in such cases the need to maintain adequate evacuation routes may easily be overlooked. This is not necessarily due to unwillingness or ignorance, but may also reflect a lack of municipal capacity to implement far-reaching measures in a densely built historic city centre—as the example of Dordrecht demonstrates.
NWO project Red & Blue and project Waterscape
Lilian van Karnenbeek is involved as a postdoctoral researcher in the research project Red & Blue – Real estate development & building in low urban environments, which maps out how low-lying cities (Red) can cope with rising water levels (Blue). Frank Groothuijse, professor of European and national environmental law, also participates in the project.
Marleen van Rijswick is professor of European and national water law and head of the Utrecht Centre for Water, Oceans and Sustainability Law. She works on a different study, NWO Project Waterscape, and is involved in the programme Future Flood Risk Management Startegies for Rivers and Coasts.
The article “Who protects the Netherlands against rising water? Implementing the multilayer safety strategy on the Island of Dordrecht” was published as part of the Red & Blue project and is included in the publication Planning and Designing Cities for a Rising Sea Level (Danish Architectural Press).