The main causes of flood and drought disasters are climate, temperature and rainfall specifically. Hence, the change of temperature and rainfall should be taken primary for study about the laws and cycles of flood and drought disasters. According to the collection and analysis of historical documents about the different drought and waterlogging grades in Songhua River, Liao River and some other regions in Northeast of China, combine with temperature and rainfall statistics more than 100 years history of Shenyang city, Changchun city and Haerbin city, which can separately stand for the south part, middle part and north part of this area.
There is a uniform trend in the temperature of Northeast China.
The latitude in Northeast area between north and south is 15 degrees so that the temperature in south and north is quite different. In accordance with statistical information from 1910 to 1990, annual average temperature in Shenyang station was always 7.8 degrees,and it was 23.4 degrees in June to August. Annual average temperature in Changchun station was always 5.0 degrees,and it was 21.7 degrees in June to August. Annual average temperature in Haerbin station was always 3.6 degrees, and it was 21.5 degrees in June to August. The temperature difference between north and south is 4,2 degrees.
In spite of the great temperature difference between north and south parts in Northeast area, there is an unified changing trend. The annual air temperature residual mass curve as well as sliding average curve among the ten years of the three stations which representative the south part, the middle part and the north part of Northeast have the same changing direction: the time from 1910 to 1930 was the cooling period, 1970 to 1990 was heating up period, from 1930 to 1970, the temperature just moved up and down according to annual average data. The temperature in 1980s reached the peak for one hundred years, 1.4 degrees to 1.8 degrees higher than the beginning of this century. There is a bigger increase in south part than north part. Shenyang station has increased by 1.8 degrees in recent one hundred years, and Changchun is 1.5 degrees and Haerbin is 1.4 degrees. Temperature moved upward mostly from 1919 to 1936 and from 1975 to 1990.
The information is provided by Disaster Risk Reduction Knowledge Service.
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