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Distribution of arid areas(Chapter Ⅱ)

2019-12-11  |   Editor : houxue2018  

Thirdly, drought in China is persistent. In the history of our country, drought occurred frequently in successive years, for example, 170 droughts occurred in Beijing from 1470 to 1949, of which 115 occurred in successive years. The drought in 1637 -1643 and 1939-1945 lasted for seven consecutive years. After 1949, drought still occurred in successive years, such as the middle and lower reaches of the Yangtze river from 1958 to 1961 for four consecutive years of drought, resulting in agricultural production. Three successive years of drought from 1966 to 1968. The persistence of drought often aggravates the drought and makes the disaster serious.

Drought can occur all over China, but with different frequency and degree. Statistical data from the past 50 years show that there are five distinct drought centers in China (Fig. 6-4):

(1) Northeast arid area

Drought mainly occurred in the spring and summer from April to August in this region, with a 66% probability of spring drought and a 50% of summer drought.

(2) Arid Region of Huang-Huai-Hai (East Northwest and North China).

It is the largest arid area in China with less precipitation and higher variability, and the frequency of drought is also the highest in the country. Drought may occur from March to October during crop growth, and even in spring, summer and autumn in some local areas in a few years, but mainly in spring, almost every year, spring drought occurs in varying degrees.

(3) Yangtze River Basin.

Drought may occur from March to November, but mainly in summer and autumn, drought is most likely to occur from July to September, summer drought is the most harmful.

Figure 6-4 Distribution of Drought Disasters and Seasonal Drought Areas in China

(4) South China.

Drought may occur in this area all the year round, but typhoon precipitation often occurs in summer and autumn due to the early rainy season in South China, therefore, drought mainly occurs in late autumn, winter and early spring. In most years, drought lasted for 3 to 4 months, up to 7 to 8 months.

(5) Southwest China.

The scope of drought in this area is relatively small, drought usually begins in October or November of the previous year and ends in April or May of the next year, local areas in individual years lasted until June, but drought mainly occurred in winter and spring.

Figure 6-4 Distribution of Drought Disasters and Seasonal Drought Areas in China

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