Restricted area of the flood risk prevention plan (PPRI) of the Clain Valley in Vienna

For natural PPRs, the environmental code defines two categories of zones (L562-1): areas exposed to risk and areas that are not directly exposed to risks but where measures may be planned to avoid aggravating the risk. Depending on the hazard level, each area is subject to an enforceable settlement. The PPRI de la Vallée du Clain has 4 regulatory zones: — red zone: zone of flood expansion fields, in which it is possible, from time to time, to encounter isolated constructions. The risk is strong, inconstructibility is the general rule. — violet area: urbanised sectors located on the outskirts of urban centres and subject to a strong to very strong hazard. The risk is high, the development of urbanisation is severely limited. — orange zone: historic urban centres subjected to a strong to very strong hazard. These areas are a particular interest combining remarkable architecture and mixed occupation (habitat, shops...). Urban renewal is permitted, despite a high risk. — blue zone: urbanised areas located in low or medium hazard. This area is constructible, under conditions.