Flood is the periodical inundation of an area of land by water. The flood suspends sediment and deposits fine bedload on the floodplain (overbank sedimentation).
Floods in Switzerland
In the event of a dynamic flooding, the strong currents are responsible for the damage caused. Quite often erosion is a side effect of this. The damage of static flooding, on the other hand, is caused by the depth of water in the flooded area. Often walls are damaged due to the long time they stand in the water. Flooding can damage cellars and ground floors in buildings as well as arable land, because of the water and the deposited gravel, sand and mud. Scouring is noticeable near piers and corners of buildings.
Floods, in some cases extensive, arose in Switzerland in the context of the storm events of 1987, 1999, 2005 and 2007. The floods caused billions of Swiss francs in damage, a fact that highlighted the limits of technical flood protection measures.
Based on the strategy of integrative risk management more measures will be taken in future to limit the damage caused by natural hazard events. For example, damage potential is reduced through spatial planning measures in that areas at risk from such damage are not subject to development and space is conserved or created for watercourses and water bodies. Hazard maps provide the basis for the assessment of risk in particular areas. If these risk management measures are insufficient, modern technical measures that reduce the hazard potential are taken (e.g. channel improvement, retention measures or the drainage and redirection of flood peaks).