Causes of Spring Drought in Yunnan-Guizhou Plateau

First of all, it shows that Yunnan-Guizhou Plateau belongs to subtropical monsoon climate. Because it is located on the east coast of subtropical continent with 25 ~ 35 north latitude in winter, it is warm in winter, and the average temperature in Leng Yue is above 0℃. Summer is hot, the average temperature in the hottest month is above 22℃, and the temperature changes obviously in seasons with four distinct seasons. The annual precipitation is generally 1, 000 ~ 1, 500mm, which is more in summer, but there is no obvious dry season. Compared with the temperate monsoon climate, the seasonal changes are basically similar, except that the winter temperature is higher and the annual precipitation increases. So, why is there a spring drought? This is my analysis.

First of all, it should be related to precipitation. Details are as follows:

According to the daily precipitation data of 88 stations from March to May in 54 years from1951to 2004, the spring drought intensity index in Yunnan-Guizhou karst area is calculated, and the time series of the spring drought intensity index in this area is analyzed by wavelet, revealing the complex structure of the spring drought intensity index in Yunnan-Guizhou karst area with multiple time scales. The results show that the series changes of the spring drought intensity index in the whole region have obvious periods and abrupt points, and the spring drought intensity index has the periodic characteristics of about 22 years. The period of 13 ~ 15 years in overweight and serious areas is also very significant, with a main period of 2 ~ 3 years; There is also a period of 9 ~ 1 1 year in the middle arid area and the light arid area, and there is a main period of 3 ~ 4 years. According to the main cycle forecast, the drought degree in overweight and serious areas will be aggravated; The degree of drought in mild and moderate drought areas will be alleviated. At the same time, the distribution characteristics, circulation field and physical factors of spring drought are analyzed. )

Secondly, because we are in the temperate monsoon climate zone,

Properties: 1. In spring, the temperature rises rapidly and evaporates vigorously.

2. Strong wind accelerates water evaporation.

3. Mainly influenced by the northwest wind, the southeast wind brings less water vapor and less precipitation.

This river has just passed the dry season, and the runoff is very small.

Society: 1. When crops enter the growing period, the water demand is large, and the agricultural water consumption increases.

2. The increase of industrial production and domestic water consumption has caused the shortage of water resources.

Finally, it is also the biggest difference from the cause of spring drought in North China, that is, it is located in Kaster landform area, with good water permeability and strong dissolution. It leads to the rapid infiltration of surface water, the decrease of surface water and the drought of the surface, which is also an important reason for the spring drought.

I choose geography, I hope it will help you. . . O(∩_∩)O~ This is also a test of my usual study! ~)