Is the flood risk getting out of hand?
After each flood, there is a lot of discussion about better prevention, but rarely any action. An article by Woflgang Kron for the "Süddeutsche Zeitung".
April 2006: It was flood disaster time again: First the River Elbe overflowed its banks in Germany, and then the Danube's waters flooded the southeast of Europe. And we heard the same demands we had heard many times before: "We must give rivers more space" and "We need better flood control." Haven't we learned anything? We always expect the "state" to act, help, and pay. But who or what is the state? We all are: local authorities seeking to allocate new land for development, homeowners on rivers wishing to convert their basements into beautiful living areas. Yet we expect the state, above all, to ward off the risk. Quite obviously, taking precautions pays off. Every euro spent on flood control measures can save many times this amount in damage. However, what is the right prevention strategy, and what is practicable?
Where there is no space, we cannot relocate dykes or create retention areas. After all, no homeowner wants a high dyke right in front of the window. And public funds spent on flood control must be diverted from other purposes. Usually, it takes much longer to discuss the appropriate measures to be taken than for a flood to fade from public memory. A fundamental problem is that flood prevention needs to be done on a large scale and include big, small and very small rivers if everybody is to benefit from it in equal measure. Flood damage, however, usually affects a small portion of the overall river system only, and is thus more or less a "local" problem. This is why people often argue that it would be cheaper to simply pay for the damage caused than put a lot of money into large-scale flood mitigation. Moreover, from a political viewpoint, it is much easier — and more popular with the public in times of crisis — to finance relief efforts than to allocate funds to flood control projects which often pay off only in the long run. That flood control structures prove their effectiveness by preventing major damage soon after being built — as happened in the Bavaria flood in 2005 — is a rare and lucky exception.
Selective application of different measures of flood control
However, as convincing as this argument may seem, it is flawed. On closer scrutiny, it becomes evident that the cost of prevention exceeds the cost of damage only in the case of spectacular floods, i.e. rare and extreme events. If left uncontrolled, frequent minor floods also cause damage — and they are an everyday occurrence. It is therefore essential to apply different measures of flood control selectively rather than using a "one-fits-all" approach. The removal of impervious surfaces, the restoration of rivers and the relocation of dykes are very effective ways of controlling frequent flood events occurring every twenty years or less, especially on small rivers. To protect ourselves against major flood peaks which occur every hundred years or so, however, we need protective structures such as dykes, large, controlled retention areas and floodways, because the measures mentioned above will be of very limited effect in such an event. They have proved to be almost completely ineffective in case of extreme floods occurring on average once in several hundred years. When dealing with such an event, the most important thing is to have efficient organisational structures in place for taking appropriate ad-hoc measures, saving people from being harmed and containing the damage caused.
In such a situation, it must be conceivable to give up an area where losses would be relatively minor in order to protect, say, a city. Such an option should be discussed well in advance, and not when disaster is already on its way. It must even be possible to explore the option of sacrificing a whole village for flood control purposes. In this case, there would have to be generous and contractually established compensation payments by far exceeding the cost of the damage to property in order to serve as an "incentive" to the village people concerned. This is cheaper than having to pay for flood damage to a city. It is important to look at each river basin as a whole, and minimise the overall risk, i.e. the overall expected damage.
Maintaining public awareness is prerequisite
How can large-scale precautionary measures be implemented? And can we afford them? For basic protection, the answer is yes. For protection against extreme events, it is no. That does not mean that we need to endure such events helplessly. We just have to protect ourselves in other ways. This can only be achieved if the general public is sufficiently aware of the risk. Maintaining this public awareness is no easy feat and causes costs, but it is still comparatively cheap. The most effective way of preventing damage is to keep out of the flood's way by setting buildings back from the water's edge. Homeowners, too, have to be aware of the risk and act accordingly. They should ask themselves if it makes sense to install a heating system or oil tank in the basement, and if they really need a carpeted party room down there.
At communal level, authorities should not permit development of flood-prone areas. The new German flood protection law, while making it more difficult for communities to build up such areas, cannot completely prevent them from doing so. It is simply not acceptable that an individual or a community should benefit from building in high-risk areas, while the general public has to foot the bill if a disaster occurs. When the government provides aid to flood victims after a catastrophe, private precautions must also be taken into account. Quite obviously, there are cases when the state must help, but the willingness to take precautionary measures will be undermined if those who spent money on protecting themselves get the same amount as those who conveniently relied on the government.
Last year's flood in southern Bavaria and the current floods on the Elbe and Danube rivers have clearly shown the importance of building adequate flood control structures. Apart from that, however, everybody should know what to do in an emergency. From the public debate, it sometimes seems as if flood control technology could eliminate the risk. This is wrong. We will never be completely safe. There will always be floods and inundations, and they will cause damage. This is something we all have to realise. There will always be a residual risk that we have to live with. Experts have been warning for years that this risk is increasing with the changing climate.
The German original of this article was published in the Süddeutsche Zeitung, Munich, on April 20, 2006
Wolfgang Kron is Head of Hydrological Risks at Munich Re.