Flood — district flooding as a result of water level lifting in the rivers, lakes, the seas because of rains, rough thawing of snow, a wind setup of water on the coast and other reasons which causes a loss to human health and even leads to their death, and also causes a material damage.
Floods quite often are caused by water level increase in the river owing to course blocking up by ice at an ice drift (jam) or owing to a course blockage under a motionless ice cover congestions of intra water ice and formation of an ice stopper (zazhor). Quite often floods arise under the influence of the winds making up for water from the sea and causing increase of level at the expense of a delay in the mouth by the brought river of water. Floods of this kind were observed in Leningrad (1824, 1924), the Netherlands (1953). On sea coasts and islands of flood flooding of a coastal strip by a wave which is forming at earthquakes or eruptions of volcanoes at the ocean (can result see. Tsunami). Similar floods are frequent on coast of Japan and on other islands of the Pacific Ocean. Floods can be caused by breaks of dams, protective dams.
Floods happen on many rivers of Western Europe — Danube, Seine, Rhone, On and others, and also on Yangzi's rivers and Huang He in China, Mississippi and Ohio in the USA. In the USSR big floods were observed on the Dnepr Rivers (1931) and Volga (1908 and 1926).