The natural environment of Ganzhou

Ganzhou City is located in the upper reaches of Ganjiang River, and rainstorm and flood are the main natural disasters. April to September is the flood season, May to June is the flood season, and floods in spring and autumn also occur from time to time. The average annual precipitation in Ganzhou in 20 12 years 1967mm is 25% more than the average in the same period of many years. The annual measured runoff is 4.310.33 billion cubic meters, and Ganzhou runoff is unevenly distributed during the year. The measured runoff in flood season (April-September) is 27.594 billion cubic meters, accounting for 64% of the annual runoff, and the runoff in non-flood season is 65.438+53.9 billion cubic meters, accounting for 36.0% of the annual runoff. Runoff recharge of rivers is mainly precipitation, which belongs to rainwater recharge type.

According to the investigation of 17 important large and medium-sized rivers and Ganjiang, Gongshui, Zhangshui, Shangyou, Taojiang, Mei Chuan, Guiba, Mianjiang, Pingjiang, Lianjiang, Xiangshui, Qinjiang, Chongyi, Jiuqu, Xunwu and other counties 18, through the investigation of metal compounds, non-metal compounds, and so on in river water. The qualified Grade III water in the whole year is 22.2%, 14.2% in wet season and 310.4% in dry season; Grade iv lightly polluted water quality is 7.9% in the whole year, 10.6% in wet season and 5.6% in dry season; ⅴ-class heavily polluted water quality is 0.8% in the whole year, 0. 1% in wet season and 8.1%in dry season; The seriously polluted super-V water quality is 5.0% in the whole year, 3. 1% in the wet season and 5.8% in the dry season. Ganzhou city is located in the southern edge of the middle subtropical zone and belongs to the subtropical monsoon climate zone. It has the climatic characteristics of prevailing winter and summer monsoon, concentrated precipitation in spring and summer, distinct four seasons, mild climate, abundant heat, abundant rainfall, short hot summer and cold winter time and long frost-free period. The average total precipitation in Ganzhou is 13 18.9 mm, which is10.8% less than the same period of previous years, and it is a partial year (including normal years in Shangyou, Dayu and Xingguo, special years in South China, and juvenile years in other counties and cities). Dayu 1554.9 mm is the most, and Longnan 1 152.2 mm is the least. The annual average temperature in the city is 19.8℃, which is 0.9℃ higher than the same period of last year. The average annual temperature in each county and city is between 19. 1~20.8℃. The annual average temperature in Du Yu is 20.8℃, and the lowest is Shicheng 19. 1℃. 20.2℃ in zhanggong district.

spring

It has been raining. From March to May, cold and warm air flows frequently meet in southern Jiangxi, and the weather is changeable, sometimes cold and sometimes hot, with continuous rain. Once the cold and warm air currents are violently opposed, there may be severe weather such as thunderstorms, strong winds, hail and heavy precipitation.

summer

Flood first, then drought, less heat. In early summer, Ganzhou city is in the southwest airflow on the edge of subtropical high, with sufficient water vapor. Encounter cold air, heavy rainfall, easy to concentrate. In June, the average rainfall in Ganzhou was 254.3 mm, and the highest monthly rainfall 1968 reached 534.2 mm, the highest in the whole year. The average rainstorm this month 17 stations is the main flood season in Ganzhou City. From July to August in midsummer, the highest temperature in the central basin during the day is generally above 36℃, but the temperature in the morning and evening is generally below 30℃. Although it is hot during the day, it is not so hot.

autumn

The sun is shining and the weather is cool. 10-165438+1about a week in the middle of October, it is often controlled by high pressure from north to south, with stable atmospheric stratification and fine weather. The monthly average rainy days are only 6-8 days, the monthly average temperature is 14-2 1℃, and the monthly average relative humidity is 70-80%, which is the least rainy season in the whole year.

winter

Cold but not cold, less rain and snow. The latitude in southern Jiangxi is low, and there are mountains in the north to stop cold air from driving directly south. It is late in winter and has little freezing damage. Often controlled by the dry and cold air mass in the north, few clouds and rain form. During the day, the sun is shining and the temperature is high; Radiation cooling at night, the temperature can drop below zero, forming frost and ice. When attacked by a strong cold wave, it can produce solid precipitation or freezing weather, but the probability is very small, and the average annual snowfall days are only 1-2 days.