Economic development and increasing urban development pressure have resulted in the frequent use of river flood plains as residential areas.
The protective effect of technical flood defences such as walls, dykes and flood retention facilities works only up to the respective basis flood. Floods above this overrun the protected areas and damage is caused. Absolute flood protection can therefore never be guaranteed.
Because of the potential risk of an extreme flood in excess of the protective devices, preventive flood protection is of great relevance. This is divided into the following components:
In addition to natural hydrological influencing variables such as precipitation quantity of snowmelt, there are other factors that affect a flood wave and moreover represent an interface to environmental protection.
The retention of water in the catchment area slows the flow of precipitation into the outlet channels and thus reduces the maximum magnitude of a flood event. Rapid rising of streams/rivers with smaller catchment areas can therefore be slowed down and the risk of overlapping flood waves can be reduced, particularly in larger rivers.
On the following pages, you can find out about the retention potential of:
People who live and work within the immediate vicinity of a river should be aware of the risk of flooding. As soon as the terrible images of a flood event have disappeared from people’s heads, awareness of the danger decreases rapidly. Constantly maintaining this awareness also contributes to the behaviour of the citizens being adapted so they are able do the right thing in an emergency situation.
Information, education and preparation are necessary so every person affected knows the options for action and can contribute effectively to reducing the damage.
Effective preventive flood protection is characterised by effective land use provisions, which determine both the nature and the extent of use for building development on flood plains. To reduce the risk of flooding in densely populated areas, the river must first be given as much expansion area as possible in order to be able to level out the maximum of the flood wave. Deliberately keeping relevant areas clear is therefore an important element of damage reduction.
The objective of risk provision is to limit the extent of the damage and damage loss in the case of very rare events. Hazard defence, disaster prevention and – in the absence of state aid – insurance companies serve this purpose.
In the event that flood damage occurs despite appropriate precaution and defence measures, private reserves or taking out insurance will help to lessen the economic consequences.
With so-called “extended elemental damage insurance”, it is possible to insure oneself against flooding and other risks. Such insurances are voluntary and may be taken out by a citizen if required. A similar consideration applies for the insurer, who is at liberty to refuse insurance cover for a customer because of the exposed risk situation.