Floods accompanied mankind since its inception. It is a natural phenomenon and not a threat to the environment, but is often connected with considerable victims among both humans and animals as well as any material damage.
The first information about the flood in Genesis we find the Bible, when after 40 days and nights of rainfall experienced flooding vast areas of water. Deluge, so named because this could be possible flooding especially in the semi-arid areas, which include, inter alia, Mesopotamia.
As the story further floods are becoming better documented.
Getting information about the floods in Poland, according to Jan Dlugosz Chronicle, took place between 998 and 1118th The best documented flood was in Krakow in 1813. Posts and flood boards to date show the water level at the monastery of SS Norbertine.
In the following years was a big flood in 1934 in the Dunajec basin, in the coming years, in 1997, mainly in the Oder in 2001 in Gdansk.
Particularly disastrous was the flood in 1997, found in the area south and west of Polish, which is due to an injury, was an unprecedented phenomenon for over 200 years. It is the result of the exceptional rainfall intensity, mainly in the upper basin of the Oder and the Vistula.
Precipitation occurred in three waves, the first of which resulted in high water on the Oder, the second wave of a renewed spate and caused a surge of water from tributaries of the Oder, and the third wave took over the Vistula river basin. The largest amount of rainfall was recorded between 6 and 8 July 1997. Precipitation greater than 100 mm / day occurred in the triangle Jelenia Gora - Nowy Sacz - Warsaw. Higher rainfall exceeding 200 mm / day, occurred in the Sudeten and Carpathian Mountains, the Giant Mountains and the Dunajec White Tarnowska. By contrast, precipitation higher than 250 mm / day occurred in the upper river Neisse Kłodzka Little Vistula, Sola, Raba and Dunajec and the Moravian Gate. Maximum flow of water on the Oder River was 3600 m3 / s.
Flooding its range covered 652 communes in 26 provinces in the basins of the Oder and the Vistula. The town was flooded in 2592, of which 1,362 totally and partially in 1230. Underwater tyś.ha there were 665 land, 480 bridges were destroyed and about 1370 km of roads. The estimated material losses amounted to 12 billion zł. 33 were flooded and damaged sewage treatment plants has around 300 km of dikes in the river basin of the Vistula River and about 800 km in the Oder.
The areas covered by the floods were evacuated ok.162, five thousand. people and 54 people were killed. In addition, drowned about 1900 pieces of cattle, about 5,900 pieces of pigs, 260 sheep units and about 1 million pieces of poultry. Killed a lot of wild game. Apart from the risks to life and health of people flooding caused significant damage to the environment and the inhabitants belongings. Flooding has revealed all the failures and niedomogi and misconduct in the programming, organization and coordination of rescue operations and for cleaning protective.
Experience resulting from the floods were the basis for many decisions taken to prevent its effects.
It should be noted about the three major floods in the world.
In 1931, floods occurred in China, when it killed 3.7 million people, then in 1979 a flood in India and floods in 1993 in the Mississippi River.
Floods can be the result of normal natural phenomena to which man can not prevent, either as a result of human activity through the disruption of normal natural phenomena, and as a result of technical failure of equipment.
The main cause of flooding is greater drop of water in relation to the possible infiltration of the soil in unit time.
Natural Causes of floods are as follows:
· Flood nawalne - from the violent rains (30 - 40 mm) in a short period of time, not foreseeable,
· Flood prolix - mainly from the rain in the summer months when rainfall lasting 3 - 5 days foreseeable
· Ice jam flooding - resulting from blockage of the river called the profile. Pancake ice and ice bottom, it is in the spring after a cold winter (Pancake ice - ice crystals are compressed in a spongy mass forming in the water at a temperature of
