Culture and Climate Change – Architecture and Urbanism

The Amphibian Society

The classical situation in front of and behind the dikes and urban high water protection walls, in the conviction of absolute security, no longer exists. The increase in both the levels as well as the frequency of floods as a consequence of climate change, increases in the sealing of land, and the growing damage potential conditioned by continuing urbanisation all necessitate new forms of approaching the issue of flooding.

Map for Bad Kreuznach at the river Nahe – Water depth © Ministry of the Environment, Forestry and Consumer Protection Rhineland-Palatinate

The approach up until now of a continual heightening and expansion of safety systems produces – spatial conflicts aside – a maintenance requirement that is scarcely affordable and thus, in addition to the risk of the selected safety levels being surpassed, the risk of their failure as well. In addition to the obvious damage potential in offshore flooding areas, a failure or surpassing of statutory safety systems and their measurements set by statistical probabilities can also lead to flooding of onshore areas. This newly-defined risk also necessitates a new awareness of risk on the part of society.

The issue here is to differentiate between already existing settled areas in the flooding area and new urban planning developments, which as exceptions are at the same time pilot projects for high water-adapted construction – former port areas are a case in point. The former often require additional improvements to their existing safety systems in accordance with the expected water levels. Buildings can be protected by means of mobile elements, backpressure protection, high water-resistant materials and much more, albeit only to a limited extent. Statistically defined water levels provide no security guarantees that they will not be surpassed. The rule for new sites in flooding areas is that special-case authorisations be granted only for retention-neutral construction developments and plausible safety concepts, both on the individual buildings level as well as for the area as a whole, often as part of the city’s defensive line. Retention-neutral in this context means that the river’s drainage capacities are not further reduced in the course of the new construction.

Map for Bad Kreuznach at the river Nahe – Water depth © Ministry of the Environment, Forestry and Consumer Protection Rhineland-Palatinate

As the third potential flood hazard area, the onshore sites behind the safety systems are part and parcel of this new understanding of risk. Interestingly, they turn our customary concepts of security upside-down – however without their being completely abandoned. We are optimally prepared only with the combination of the most effective defence system possible together with the necessary preventive measures being in place in the event of its failure. Communicating this is difficult.

The more we prepare ourselves for future extreme weather events, the more important is operational high water protection. Who is responsible? And how can responsibilities be communicated between collective and individual tasks? When dealing with potential high water events – especially with extreme events – operational measures can no longer be implemented exclusively “from above.” Particularly in the urban context, they demand a civil society that is aware of its risk situation and at the same time is in possession of absolutely practical knowledge of what to do if such an event occurs.

Human error remains the greatest risk factor in the case of high water – often in the most banal of ways. The factor of time is therefore the greatest enemy of risk awareness. Not only does our belief in the probability of an extreme event dwindle the longer the last high water event lies in the past; we also often no longer know what to do and who is to do it. Responsibilities are unclear, maintenance is forgotten, emergency procedures are not tested.

The German insurance industry developed the zoning system for flooding, backwater and heavy rain (ZÜRS) to evaluate a building site in terms of its flooding risk. Here, there are four classes of hazard. A statistical flooding probability of less than once in 200 years applies to about 86 % of buildings in Germany. Only about 3 % of Germany’s buildings stand in the GK3 and GK4 zones, with a statistical flooding risk of ten to 50 years, i.e. more frequently than ten years. However, not all buildings are insurable against high water. If the probability of regular flooding is present, as in the case of the classical flooding areas, insurance protection will either not be available at all, or only with high deductibles. At the same time, insurance protection can be refused if adequate safety measures have not been taken for the building in question. Here, too, individual action is required.

In addition to all preventive and operational measures of catastrophe management for an extreme event – from prepared evacuation to someone to drive the cars away who can still tell where the passable street ends and the river begins (which in a high water-event is often no longer possible on account of the high degree of water turbidity) – we still need more. In addition to mediation between public and private actors, we not only need a regularity in high water events to create consciousness of the issue, but also a spatial readability: by means of the integration of the architectural potential of varying high water levels in construction developments in flood-hazard areas, new urban typologies can be developed that allow for more frequent flooding, therefore not only minimising damage potential, but also counteracting the typical forgetting of the hazard. Only in this way can an awareness and thus an amphibian society emerge, one that is able to protect itself and at the same time has the knowledge necessary for the event that it cannot protect itself.
Cornelia Redeker
works as an architect and city planner in Munich

Translation: Ani Jinpa Lhamo
Copyright: Goethe-Institut e. V. 2010

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