After the weather-loopholes of the Aude, who have made at least eleven died in the night from Sunday 14 to Monday 15 October, voices were raised to denounce the massive urbanization of the territories, which has been accused of exacerbating the risk of flooding. Frédéric de Lanouvelle, a spokesperson for the ministry of the interior, has referred in an interview to LCI this need to rethink the policies of redevelopment of the territory : “It will be necessary to rebuild thinking about adaptation our planning to these climatic phenomena. “In the only region of Provence-Alpes-Côte d’azur, a million people live in flood-prone areas.

Geographer and master of conference at the Ecole normale supérieure, Magali Reghezza-Zitt points out that” one French person in four lives in a flood zone “. If there is ” no miracle solution “, the geographer believes that an “urban renewal” is necessary and should respond to the ecological challenges posed by the multiplication of these episodes of severe weather.

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In what way planning policies of the territory taken in recent years have an impact on the damage caused by the floods ?

Magali Reghezza-Zitt. Over the past fifty years, we have witnessed a high level of urbanisation of flood-prone areas. These land uses can be explained by a combination of factors. First, people have tended to forget the dangers, because there has been no disastrous floods for many years. Then, many parts of the south, such as the Aude, have seen the populations of retirees or young families wanting to access the property who were not aware of the dangers of the mediterranean environment.

The progressive urbanization is made on plain land that, until then, were agricultural, while, historically, the villages settled in height in order not to be flooded. Urbanisation and sub-urbanisation have led to a waterproofing of surfaces (the ” bétonisation “), which is criticized today, because it prevents the infiltration of water into the soil. But it must also be remembered that, sometimes, the violence of weather events is that the soil is not able to absorb the volumes of water that are so important in so little time.

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in the past, there was less damage because there were fewer people and valuable assets exposed in high risk areas. Since then, the vulnerability has increased dramatically. In the 1980s and 1990s, has seen an increase in the one-storeyed houses, particularly to meet the demand of a population that was thought at the time of retirement, when the mobility is less, and that the stairs are a problem. Except that this architecture is not adapted to the risks of flood flash flood : people find themselves trapped in their house while the water rises. Urbanisation therefore plays a role undeniable in the aggravation of the risk related to flooding, as it increases runoff and the exposure of vulnerable populations.

How can we contain these risks related to urbanization ?

One cannot generalise. It is necessary, on the contrary, an approach that is very fine territories, which each have their own specificities. The risk is simply arguing about the role of local elected officials, who also pay the legacies of what has been done in the past, with buildings that escaped the norms, sometimes legally. We need these elected officials to work on the development of the territory. We must ask ourselves : what is the one fact of this urbanization inherited ? How you arrange what remains to develop ? How can we accompany the elected officials of small communes ? On which are already huge burdens, for they manage these matters in the face of pressures from administered and sponsors ?

today, a common half of its territory, which is all or part located in a flood zone. One French person in four lives in a flood zone. Nothing on the paris region, this is about 850 000 people. Of the municipalities are sometimes to 100 % in a flood-prone area. We can’t all move.

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there is no miracle solution, but a range of possible actions that are going in the right direction. Some cities, like Marseille or Paris, are trying to désimperméabiliser the soil, for example in végétalisant roofs, débétonnant the courses of the school. Some jurisdictions are investing in levees to protect the existing, when other are inventing a new urbanism by raising the homes or building levels additional shelters.

anyway, the development solutions are in a very long time. A land-use planning policy, which must necessarily be in connection with the transition to ecological, this is think and is spread over a period of thirty to fifty years. In the medium term, many actions of urban renewal will take place in the next ten years. In the short term, the important challenge is the preparation of the inhabitants, the mayors, of all the actors of the territory, to cope with the crises that will inevitably occur.

What are the impulses given by the public authorities on the subject ?

There is a lack, at national level, a strong political will, including national representatives, to register once for all the issue on the political agenda in order to drive forward a policy on risk reduction related to floods, which does not limit itself to legal instruments that are piling up and a national strategy that the State departments are wearing as they can, but not necessarily all the support they would need. The subject does not appear in the democratic debate, particularly at election time, then it involves a lot of world.

so there is also a responsibility of citizens, as long as they have not been affected, refuse to take the necessary measures, which are often costly, sometimes making a pressure on their elected representatives, who find themselves caught between the hammer and the anvil. The land issues are very important and elected officials must too often choose between the security and development of the territory. This permanent arbitration between different risks demand a democratic choice and political fort, in which each one takes his share.