A geographical investigation report on rivers, landforms and vegetation in Sinan

Sinan County is a county under the jurisdiction of tongren city. Located in the northeast of Guizhou Province, the middle and lower reaches of Wujiang River, it is under the jurisdiction of Tongren District. Its geographical coordinates are 107 52'- 108 28' east longitude and 27 32'-28 10' north latitude. The county is 57.6 kilometers long from east to west and 69.3 kilometers wide from north to south, with an administrative area of 2,230.5 square kilometers. Yinjiang County in the east, Shiqian County in the south, Fenggang County in the west and Dejiang County in the north. The four main county-level highway networks in Sinan County are Sinan-Shiqian, Sinan-Dabachang, Sinan-Fenggang, Shagou-Hepengxi and so on. [ 1]

As of 20 1 1, Sinan County has a registered population of 677,053, with a total area of 2,230.5 square kilometers.

geology

The exposed strata in Sinan County are Cambrian, Ordovician, Silurian, Permian and Triassic in turn from old to new. In Triassic and Permian

Wuling mountain range

Series strata are most widely exposed, followed by Silurian and Ordovician, and Quaternary is rare. The missing strata are Devonian, Carboniferous, Jurassic and Cretaceous.

Sinan county is located in the west edge of Xuefeng ancient land stable platform in geological structure, and in the northeast structural deformation zone of Fenggang with the Zunyi fault arch in Tailong, northern Guizhou. Therefore, the development of faults and folds has created a unique geological and geomorphological environment in Sinan County.

Sinan county is mainly characterized by Sinan compression-torsion fault and Tangtou compression-torsion fault, both of which are large-scale regional faults. According to the internal and external dynamics and surface morphology of landform formation, the landform in this area can be divided into four types: structural erosion, dissolution, low mountain valley, dissolution, erosion and accumulation.

Sinan lies between Wuling Mountain and Dalou Mountain. Controlled by structure, lithology and Wujiang river system, it presents many landforms such as peak cluster mountains, gentle hilly valleys, river valleys and stone forests.

topography

Sinan County is located in the northern edge of the Guizhou Plateau to the hilly slope of Xiangxi, and is located in the Wuling Mountains and

Between the Daloushan Mountains. Rivers and mountains develop along these tectonic lines. The main stream of Wujiang River enters the county from the southwest corner, flows to Tangtou estuary along the northeast, and divides the county into two parts. Due to the strong mainstream of Wujiang River and its tributaries,

Cutting, Sinan County forms a V-shaped basic contour with high southeast and northwest edges and low Wujiang River Valley in the middle. The highest altitude in the eastern edge is 148 1m, the highest altitude in the northwest is 1302m, and the altitude of Wujiang Exit-Entry Administration Office in the middle.

388m, exit elevation 340m, relative height difference1141m. Geomorphologically, Sinan County is dominated by mountains, 108 1.7 1 km2, accounting for 48.5%. Qiulingji

887.35 square kilometers, accounting for 39.78%; There are few dams, 26 1.44 square kilometers, accounting for 1 1.72%.

climate

Sinan county is located in the humid climate zone of mid-subtropical monsoon, with long spring and summer, short winter and autumn, hot summer and warm winter.

Point. The annual average temperature 17.3℃, 1 month is the coldest and July is the hottest. On August 27th, 0972, the extreme maximum temperature was 65438+40.7℃, and on October 30th,/kloc-0, the extreme minimum temperature was 65438+65438+ minus 5.5℃.

The temperature in Wujiang river basin is high, and the temperature in northwest, southeast and marginal areas is low. The temperature in winter and spring is lower than that in summer and autumn.

Southeast wind and south wind are the most common in Sinan County. The wind power is generally 2 ~ 4, and the maximum wind speed can reach 8, and the maximum wind speed is 18m/ s. The annual evaporation of water surface is between 510.8 ~ 935.3mm.

Sinan county is a county with more disastrous weather, and the main disasters are drought (spring drought and summer drought), hail, strong wind, late spring cold, freezing and heavy rain. Severe droughts include spring drought and summer drought.

hydrology

Besides the main stream of Wujiang River, there are 6,065,438+0 streams in Sinan County, all of which are distributed in a network with Wujiang River as the datum of water system, belonging to Wujiang River system in the Yangtze River basin. Among them, there are 28 rivers with a basin area of more than 20km2, with a total length of 535.3km, and the sinan section of Wujiang River is 613.4km. There are 7 tributaries in Wujiang River.