China has a vast territory and about 2/3 of the land area has floods
with different types and different degree of hazards, except deserts,
Gobi and extreme drought regions and high mountain areas. If a slash
is drawn from northeast to southwest along the 400mm rainfall isoline,
our countries can be divided into two parts, in which the eastern region
is the key area for flood control.
In 1870, the Yangtze River suffered from the largest
flood in history. According to the investigation,
the peak flow rate in Yichang station is 105 000 steres
per second; Hongfeng flow in Zhicheng station is 11000 steres
per second. The flood mainly came from Jialing river basin.
In the early July, there was a long-continued and heavy rain
between Jiangsuo jiang river basin and the Three Gorges and then,
the heavy rain zone move eastwards slowly. The flood was
the biggest flood since 1153. According to statistics, more than
30 counties in Hubei province and 20 counties in Hunan province
suffered from severe flood. In addition, the north of Henan,
the Chengde city of Hebei province and the lower reaches of
the Huai River and the middle and lower reaches of the Liao River
also suffered from the flood.
During the flood season in 1998, there were 8 flood peaks in the upstream of
the Yangtze River, which encountered the flood in the middle and lower
reaches of the Yangtze River, forming great flood in the whole basin.
The flood flowed down vigorously and the water overflowed all over the basin.
Coupled with the overflow of Songhua River in the northeast and Nenjiang,
our whole country, including the most seriously affected areas, which is Jiangxi,
Hunan, Hubei, Heilongjiang, a total of 29 provinces and some other municipalities
and autonomous regions have suffered the unexpected calamities. The disaster
affected 223 million people and more than 3000 people died. In addition,
6.85 million houses collapsed, more than 2000 hectares of land were submerged
and caused economic loss of more than 255.1 billion yuan.