Flood disaster has always been one of the severe natural disasters
in Northeast China, and it is juxtaposed with drought disaster
as two main natural disasters. Flood disaster is caused
by the excessive amount of water and the movement or
the form of existence which can do harm to human's society
under some environmental conditions. The flood disasters include rainstorms,
snow-melting flooding, mudslides, storm surges, soil salinization,
and snow disasters, etc, among which the rainstorm disaster
is the most frequent and most loss. In the historical document,
people had used "rain", "heavy rain" and "lao" "liao"
to describe flood disasters.By 20th century, meteorological
and hydrological observation had developed, and people started
to use "rain condition", "water condition"
and "disaster condition" these 3 quantitative indicators
to describe flood disaster.
The flood disaster records
in Northeast China can be divided into two sections,
the two periods: before and after the founding of the
People's Republic of China. Generally speaking,
the data record in the previous period is simple,
the temporal and spatial distribution characteristics
of the disaster are not prominent, the disaster situation
is not complete, and all types of flood disasters
are simply called floods. The rainfall, flood and disaster data
in the latter period are relatively sufficient,
and it has the basis for compiling flood classification.
According to the causes, floods can be divided into five kinds.
(1) Storm flood: flood caused by heavy rain and rainstorm.
(2) Snowmelt flood: the temperature or rainfall
causes the snow on moutains to melt, forming a flood.
(3) Glacier flood: a flood caused by melting glaciers
as a result of rising temperatures.
(4) Ice flood: the ice in the riverway breaks the dam,
forming a flood
(5) Dam-break flood