Geographical environment of Yanggao County

The Yanshan movement formed the Six Ridges Mountain, Yunmen Mountain Mountain and Cailiang Mountain Uplifts in China, which obviously passed through the Himalayan mountains and formed very steep mountains. There is a big fault caused by uplift in front of the mountain and an obvious fault triangle. At this time, the mountain is the vast "Datong Lake". Due to the inherited activities of Yanshan movement, the whole crust uplifted, the closed mountain pass split from the fault, and the lake retreated, forming a Cenozoic faulted basin in Sangganhe anticline of Shanxi platform, with NNSE as the main component line. The north-central part became an inland lake subsidence basin under the Yanshan movement, and the pre-Yunmen Mountain fault was clearly visible. The margin of the basin is a vast alluvial fan, which reflects the characteristics of the boundary between the ascending area and the descending area. About the late Middle Ages, under the action of Yanshan Movement, the whole arch of Shanxi rose, which made the old fault move again. Moreover, the tensile stress is derived at the crankshaft of the big arch, resulting in a series of normal faults, which make the big fault valley underground, and the land sandwiched between them is squeezed and relatively uplifted, becoming a dome, which is today's hills. Under the strong pressure, magma overflowed from the fault cracks in the south and became a volcanic remnant hill. During the Mesozoic Jurassic, the pre-Yunmen Mountain fault and the Cailiangshan fault in the northwest squeezed each other, which caused the mountain covered with virgin forests to sink, then flooded and gradually became inland lake deposits. Today, the basin in Great Wall Township is produced here, just like Datong Basin and Coal Sea Cluster in the west. Therefore, there are coal-bearing strata under the rock stratum, and there are 2 ~ 3 layers of minable coal seams, mainly black carbonaceous shale with thin layers of black limestone. Due to the continuous ascending and descending movements of the NE-trending and NW-trending faults, the basement is uneven and the thickness of loose sediments is unequal. Yunmen Mountain, Cailiangshan, and Liu Ling mountain areas have relatively large rises, relatively large basin subsidence, and deep and large faults are formed in front of the mountains, with a height difference of1.560m..

The main strata in Yanggao County are: Sanggan Group, which is mainly distributed in Yunmen Mountain, Cailiang Mountain, Heilongdong Mountain and the central hilly area, and there are also outcrops in Liu Ling Mountain area; The Great Wall System (commonly known as Sinian System) is distributed in Liuling Mountain in the south and Gedun Mountain in the middle, and it is also exposed in Jiayao area. Cambrian, distributed in Yujiayao area and central hilly area in Liuji mountain area; Ordovician, mainly distributed in Liujishan area; Jurassic, distributed in Changcheng Township, northwest of China; Tertiary, composed of upper middle series. Miocene outcropped in the central hills and gullies. It is uniformly distributed in the central hilly area. Yanggao County has a W-shaped fold. The undulating landform can be divided into three units: denudation structure, erosion structure and accumulation structure. Landforms include mountains, hills, plains, basins and valleys. Traditionally, it can be roughly divided into three categories: mountains, rivers and hills.

In terms of agricultural regionalization, the total area of Yanggao County is 1 0,704.6 square kilometers (256,000 mu), of which the mountainous area (rocky mountainous area+Bianshan Yukou) is 539.8 square kilometers (8 1 0,000 mu), accounting for 31.7%; Sichuan area (Pingchuan+Beach) covers an area of 622.6 square kilometers (93,000 mu), accounting for 36.5%; The hilly area is 542.2 square kilometers (8 1 10,000 mu), accounting for 3 1.8%. Close to three points of the world.

Yunmen Mountain is a mountainous area with exposed fault-block metamorphic rocks, covering an area of 365,438 0.6 square kilometers. The main peak is located at the back of Bai Liu ditch in Tanzao Town, with an altitude of 265,438+065,438+08 meters, so it is named because there are often clouds floating in the mountains.

Cailiangshan is a mountainous area where metamorphic rocks in fault blocks are denuded, belonging to Yinshan residual vein, with an area of 149+0 square kilometers. This area is in the west of the county seat 10, bounded by Kaishankou in the north, Jule in datong county in the south and Yuhe in the west, stretching for dozens of miles. The main peak is 2 144.6 meters above sea level, turning to the southwest of the sewer, which is a watershed with Datong city.

Liu Lingshan is a bare mountain area. The top of the mountain retains the planation plane of Beitai period, and the valley in the mountain is wider in Tangxian period. It covers an area of 60.5 square kilometers and runs east-west. It seems that there are six straight ridges, which are very spectacular and famous. Huangyangjian, the main peak, is 2420.5 meters above sea level, which belongs to Hengshan Mountain System and is the highest peak in Beiyue. To the north of the mountain watershed is the Yanggao boundary, with good vegetation on the back slope, many birch trees and once inhabited by beasts and snakes. Iron ore, marble and limestone are buried in the mountains. There are more than a dozen hill villas in the valley, such as Loess Slope and Wang Guan Palm.

Bianshan Yukou District includes three Bianshan Yukou Districts in the south, north and west, covering an area of 298 square kilometers, accounting for 17.5% of the total area of Yanggao County. North Shanyukou area 130.6 square kilometers; Xishan Gukou covers an area of 90.2 square kilometers; The southern Shanyukou covers an area of 7 1.5 square kilometers. The hilly area is 542.2 square kilometers, which is nearly one third of the area of Yanggao County. The landform is very typical, the gullies develop rapidly, mostly in the shape of "V", and there are many valleys in the valley, which are fragmented. The altitude is between 1 100 ~ 1400 meters, and the relative height difference is not large. It can be divided into two types: Qiu Nan and Qiubei, and the watershed between them is the bare low mountainous area. Qiu Nan covers an area of 243.5 square kilometers; Qiubei covers an area of 298.7 square kilometers; The exposed low mountain area of Fengmen Mountain is the watershed of Qiubei in Qiu Nan.

Heilongdong Mountain is located in the north of Laniangcheng Village, with an altitude of1335.6m, the highest point. There are Daquan Mountain and Fenghuang Mountain in the north of the middle of the mountain, with an altitude of 1266 meters. Pingchuan District consists of south and north, covering an area of 238 square kilometers, accounting for 14% of the total area of Yanggao County. Including Beipingchuan, also known as Yanggao Basin. It covers an area of 55.9 square kilometers and is 1050 ~ 1 100 meters above sea level. It is a grain-producing area with good water and fertilizer conditions. Nanchuan Valley is a part of Datong Basin, which is the Sichuan Valley on both sides of Sanggan River. It is the lowest elevation in Yanggao County, between 850-920m, with an area of 182. 1 km2.

Due to the large area of water accumulated in the center of Yanggao Basin in the beach area, the potential in Tianzhen County is high to the east, and the drainage is not smooth, so the groundwater has to be stored statically in the basin, and there is a clayey water-resisting layer underground, forming a salinized beach. The area is divided into two parts: basin and basin edge, covering an area of 384.6 square kilometers. It accounts for 22.5% of the total area of Yanggao County. The lowest elevation in the center of the basin 1008m (south of Xutun) is about 1030m around Yao Sibari Terrace and Shahetai Terrace. It belongs to saline-alkali land with an area of 2 14.9 square kilometers. The edge of the basin is a part of the village beside the beach with an altitude of1050m to1100m. Area 169.7 km2. Different degrees of saline-alkali damage also belong to the beach area.

Yanggao County 13 townships, except beixutun township, have more than two types of landforms. Yanggao County has a continental monsoon climate. The four seasons are distinct, the temperature difference between day and night is obvious, and the regional differences are obvious. It is windy and rainy in spring, and the temperature rises rapidly; Summer is hot and rainy; The temperature drops rapidly in autumn, and the air is crisp in autumn; There is little rain and snow in winter, and it is cold and dry.

The annual average temperature is 7.65438 0℃, the extreme maximum temperature is 38.65438 0℃, and the extreme minimum temperature is-365438 0.8℃. The annual average precipitation is 411.3mm; The annual average sunshine hours are 269 1.4 hours; The annual average wind speed is 2.3m/s; The maximum pressure is 920.0 hectopascals, the minimum pressure is 872.5 hectopascals, and the maximum wind speed is 27. 1 m/s; The maximum snow depth is 25 cm; The annual frost-free period is 19 from April to September 25th, with an average of 135 days. The maximum depth of frozen soil is143 cm; Crops are harvested once a year, and the main meteorological disasters are drought, sandstorm, frost, flood and hail.

March-May in spring is a transitional period from winter circulation to summer circulation, and it is a season of alternating cold and warm air. Less precipitation is called "nine droughts in ten years". The temperature rises rapidly, but the cold air activity is frequent and the temperature is changeable, which often causes "late spring cold" and late frost, strong wind and dusty weather. The seasonal average temperature is 8.3℃, and the precipitation is 57.2 mm, accounting for 14% of the annual precipitation. The number of windy days accounts for 58% of the whole year.

The summer from June to August is mainly controlled by the continental depression. When the Pacific subtropical high extends to the northwest and affects the local area, the southeast monsoon appears, and the tropical maritime air mass brings abundant rain, the precipitation days increase, the precipitation increases, the sunshine time is long, and the radiation intensity is high. The seasonal average temperature is 20.6℃, and the precipitation is relatively concentrated. The precipitation is 265.4 mm, accounting for 65% of the annual precipitation. The precipitation in July is the largest month in the whole year, accounting for 42% of the seasonal precipitation. The temperature in July is also the highest month in a year, that is, the same period of water and heat, so local floods or periodic droughts often occur. At the same time, strong convective weather such as thunderstorms, strong winds and hail often causes losses to industrial and agricultural production.

From September to June, autumn165438+1October, the Mongolian high began to develop and gradually invaded southward, controlling the county territory, and the precipitation decreased significantly, the temperature dropped rapidly, the weather was stable, the autumn air was crisp, the sunshine time was shortened, the radiation intensity was weakened, and the temperature dropped obviously, sometimes resulting in early frost disasters. The seasonal average temperature is 7. 1℃, and the precipitation is 76.5mm, accounting for 19% of the annual precipitation.

From winter 12 to February, the Mongolian high pressure is strong and stable, covering the whole country. Levin is close to the high-pressure center, which is more obviously controlled by it. Polar cold air frequently invades south, forming a northerly wind with strong wind, cold and dry, and abundant sunshine. The seasonal average temperature is -8.0℃, and the precipitation is 8.0mm, accounting for 1.9% of the total annual precipitation. The main climatic factors in China are as follows: The temperature trend in Yanggao County is warmer. Yanggao is rich in water resources except for the lack of water at the top of the mountain. There are streams, springs and seasonal rivers in mountainous areas, confined springs in piedmont, hills and depressions, rivers in basins and abundant groundwater.

1The Detailed Investigation Report of Groundwater Resources in Yanggao County submitted in May, 989 estimated that the total water resources in Yanggao County was 283.089 million cubic meters per year. Surface water159.374 million cubic meters/year; Groundwater123710.5 million cubic meters/year. In the total water resources, Laibin's water resources are 449 1 10,000 m3/year, accounting for 15.9% of the total.

The situation of water resources in Yanggao County is: surface water. The surface water resources in Yanggao County are supplied by runoff and spring water generated by natural rainfall. The total surface runoff is 87.384 million cubic meters/year, which comes from domestic and foreign river basins, with an area of 2 184.6 square kilometers (48 1 square kilometers overseas), and the annual recharge of spring water is 36.78 million cubic meters/year.

There are five rivers in China, 12 1 mountain spring. These five rivers are: Sanggan River, Dengbai River, Wuqi River, Heishui River and Huang Shuihe. Dengbaihe River is a secondary tributary of Yongding County, which originated in the hilly area in the middle of Yanggao County. Huang Shuihe, which originated in the mountainous area of Cai Liang, Yanggao County and Fengzhen, Inner Mongolia, flows into Heishui River in Yanggao, and Wuqi River, which originated in Tianzhen, flows into the river, and belongs to Yanghe River in the east. The total length of the Dengbai River is 34 kilometers, with a drainage area of 390 square kilometers. The fresh water flow is 0.26 cubic meters per second, the wet season is 0.39 cubic meters per second and the maximum flood is 2 17 cubic meters per second. The territory of Heishui River is 23 kilometers long, with a drainage area of 363.4 square kilometers and a clear water flow of 0.4 cubic meters per second. The maximum flood in a hundred years is 822 cubic meters per second; Huang Shuihe is 27 kilometers long, with a drainage area of 1.86 square kilometers and clean water of 0. 1.5 cubic meters per second. Maximum once-in-a-century flood150m3/s; Wuqi River is 24 kilometers long, with a drainage area of 177. 1 square kilometer and a clear water flow of 0.02 cubic meters per second. Sanggan River, a first-class tributary of Yongding River, flows out of Ce Tian Reservoir into Yanggao and flows eastward 16 km into Hebei, with a drainage area of 557.5 square kilometers. The annual runoff is 0.06 ~ 557 million cubic meters, and the general fresh water flow is 0.4 cubic meters per second, 5.57 cubic meters per second in wet season and 0.27 cubic meters per second in dry season.

The density of river network in Yanggao County is 0.077 kilometers per square kilometer, and the total runoff is 62.8 million cubic meters. The total groundwater recharge in Yanggao County is 13 1 10.7 million cubic meters/year. Among them, Yanggao Basin is 94.2010.5 million m3/year, and Datong Basin is 36.9057 million m3/year. The recoverable reserves are 77.4095 million cubic meters/year. Among them, Yanggao Basin is 54,507,200 m3/ year and Datong Basin is 22,902,200 m3/ year. Adding surface water resources, the available water resources in Yanggao County are148,849,500 m3/year, only 70,37810,000 m3/year, accounting for 47.3%, with a potential of 52.7%.

Most of the water levels in Yanggao River Basin have declined, with an annual decline of 0.05-0.86 meters, and some of them can reach 2.35 meters. Youzai, the piedmont of Aoshi Mountain and the lower reaches of Deng Bai are stable areas, and the water levels from Qianjiabao and Heertun to Shijiazhuang and Xiajiachang are on the rise.