Xiushan is located in the middle of Wuling Mountains, outside the southeast edge of Sichuan Basin, and is the gateway to southeast Sichuan. It is located between 28 9 ′ 43 ″-28 53 ′ 5 ″ north latitude and108 43 ′ 6 ″-10918 ′ 58 ″ east longitude. It borders Huayuan, Longshan and Baojing counties in Hunan Province in the east and northeast, Songtao Miao Autonomous County in Guizhou Province in the south, southeast and west, and Youyang Tujia and Miao Autonomous County in the north and northwest. The northeast corner is only 20km away from laifeng county. It is 604 kilometers from Changsha, 656 miles from Wuhan, 556 kilometers from Guiyang and 650 kilometers from Chongqing. It is one of the most remote counties in Chongqing. The county covers an area of 2,462 square kilometers, and the border line is 320 kilometers long.
topography
Xiushan is located in the southeast Sichuan fold belt, which is the south of the secondary uplift belt of Wuling Mountain. The ground span is between 28 9 ′ ~ 28 53 ′ north latitude and108 43 ′ ~10918 ′ east longitude ... It is adjacent to Dalou Mountain in the west. It overlooks Qiyao Mountain in the north and belongs to Wushan and Dalou Mountain. Pingba, hills, low mountains and Zhongshan are intertwined. The southwest is high and the northeast is low. In the middle is a triangular basin. Most parts of the county are between 500 and 800 meters above sea level. The elevation of sedan chair in the southwest is 163 1.4m, which is the highest peak in the county. The lowest elevation is Lanniwan in Gao Qiao Village, Shidi Township, with an elevation of 245.7 meters. There are many rivers and streams in the territory, the rivers are strongly cut, the surface fluctuates greatly, and the mountains and rivers are mostly distributed northeast along the structural line. Xiushan landform can be roughly divided into three types: flat dam area, low mountain hilly area and low mountain area. The west and south are low-middle mountainous areas, accounting for 30.24% of the total area; The eastern and northern parts are low hills, accounting for 38.8 1% of the total area, and the middle part is the flat dam area of the river basin, accounting for 30.94% of the total area.
geology
Xiushan geological structure belongs to the Neocathaysian and Cathaysian systems, and is located in the southern margin of Chuanxiang sag on the Yangtze platform. The main structural lines are NNE-NE, and the skirt folds are NNE-NE, with gentle syncline dip angle and large anticline dip angle, which is partially affected by faults and has inversion phenomenon. Faults are well developed in the county, especially in the southern Proterozoic, the lower Paleozoic and the northern Xiushan anticline. The strike of the main fault is basically consistent with the fold axis, which is NNE and NW.
climate
Xiushan is a subtropical humid monsoon climate with four distinct seasons, normal temperature, abundant precipitation and less sunshine. The annual average temperature 16℃ is basically normal. Among them, 1 month is the coldest, with a monthly average temperature of 5℃. July is the hottest, with an average monthly temperature of 27.5℃. The ground temperature is the same as the air temperature, with the highest in July and the lowest in 1. Rongxi, Hong 'an and Shidigu have the best heat conditions, and the average annual temperature is above 65438 07℃. The average temperature of flat dams and shallow hills is between 65438 06℃ and 65438 07℃. The annual average temperature of Sangai and Jiaoziding in the west, Jiaozishan in the south and Bamian Mountain in the northeast is between 10℃ and 14℃. The average annual temperature in other areas is between 65438 04℃ and 65438 06℃.
The annual precipitation1341.1mm. More than 80% of the annual precipitation is in1/kloc-0 ~ l700 mm. May and July are the most, and both are close to 200 mm. 1 month is the least and insufficient. From the distribution of ten-day season, there are obvious precipitation peaks in three months throughout the year, that is, early May, late June or early July and mid-September, and the average rainfall in ten-day is 765, 438+0.2, 76.4 and 60 mm respectively. From the distribution of precipitation in the four seasons, the summer precipitation is the most, followed by spring, autumn and winter, accounting for 37%, 365, 438+0%, 24% and 8% of the total annual precipitation respectively. 1June, 979, the rainstorm was as high as 155.5mm, which was the largest rainstorm on record.
The annual sunshine hours in China are 12 13.7 hours, accounting for 28% of the available sunshine hours, which is one of the low sunshine areas in China. The sunshine hours in 80% years are less than 1300 hours. The sunshine is the most in July, which is 20 1.8 hours, and slightly more in August, which is 199.4 hours. The sunshine hours in July and August account for one third of the total sunshine hours in the whole year. 1 month is less, 48.8 hours, and February is the least, only 44.7 hours. 1 and the total sunshine hours in February only account for 8% of the whole year.