4 types of the causes of natural disasters

Natural disasters are the destruction on human society caused by some human activities, the imbalance in the natural evolution and the variation of natural phenomenon, such as climatic, geological and biological phenomenon.

The causes of natural disasters can be classified into four types:

(1)Meteorological disasters

Storms: Tropical cyclone, typhoon, southwester, and snowstorms.

Flooding and droughts disasters: Rainstorms, snow-melting flooding, mudslides, storm surges, soil salinization, and snow disasters.

Climate disasters: Frost damage, snow storms, high-temperature damage, and thunderstorms.

(2)Geological disasters

Earthquakes and landslides

(3)Biological disasters

Pests, epidemics, forest fire and red tides.

(4)Disasters caused by human activities

The soil denudation, the water and soil loss and the desertification caused by the vagetation deterioration, and the pollution caused by the industrialization (especially water pollution).

The spacial and temporal distribution of floods and droughts

Due to its special geology and climate, a large amount of natural disasters have taken place in northeast of China, among which the flooding and droughts are the most serious issues.

According to the statistics of Heilongjiang Province, natural disasters(the flooding and droughts take up 68.6%, and other disasters take up 31.4%) damage area sums up to 93,730,000 hectares.

According to the statistics of Jilin Province, the proportion of flood and drought disasters of the total natural disasters is 73%, and other natural disasters account for 27%. These data indicate that flood and drought disasters are the main natural disasters in Northeast China, and are also the main subjects of this book.

Table.1 The various natural disasters in Heilongjiang Province