Second, formation rocks
The county is outcropped in the middle of Late Paleozoic Devonian to Cenozoic Quaternary. There was no Cretaceous in Mesozoic. Except for Tertiary and Jurassic, which belong to continental piedmont facies and inland lake facies respectively, other strata belong to coastal and shallow sea facies, and the metamorphic degree is shallow. The strata before Jurassic are all shallow metamorphic slate, sandstone and limestone. There are contact metamorphic biotite schist, sericite, phyllite and amphibole, as well as dynamically metamorphic mylonite, breccia and phosphorite. Only at the edge of the submerged body and on both sides of the fault zone. Some strata before Jurassic were damaged by intrusive rocks and fault structures to varying degrees. Tertiary strata are distributed in the northeast of the fault. Triassic strata are only exposed in the southwest of the fault. The county seat is divided into two parts: rock and rock.
Thirdly, there are 10 kinds and more than 50 points of minerals found in Min County.
(1) metal minerals
Iron ore: distributed in Shana, Naizigou and Haza areas of Chabu town. The reserves are relatively concentrated, with a grade of 25-35%. Others, such as grassland in Lv Jing town, lion in Mawu town, Shi Gan ditch in Shen Du town, Xiaozhaigou, Honghualin in Hetao town, Xuanwo in Mazichuan town and Eryanggou in Chabu town, are distributed. But the reserves are small and the grade is low.
Copper mines: located in Gaojiashan and Shanghetuo in Hetuo Township, Tunba in Lv Jing Town, Bangou and Tongyugou in Chabu Town. The highest grade is 7.5%.
Gold deposits: mainly distributed in Jinchanggou of Lv Jing Town, Bachagou (Xuanwo) of Mazichuan Township, Suolongkou of Suolong Township and Luerba of Xu Qin Township.
Aluminium-zinc ore: distributed in Bangou, Tongyugou, san huang Zui in Xiaozhai Township, Gaojiashan, Zhashang in Hetao Township, Shangqi Street in Tunba, Lv Jing Town and Damogou in Puma Town. The highest grade is 15%.
Mercury mine: Cuogou, Minshan Township. The reserve is 2 17.5 tons.
Antimony ore: distributed in Hetuo village, Jieshi Mountain in Lujing town, Luerba in Xu Qin township, Dagouzhai in Shili town, Ganzhai, Kanfeng in Xizhai town and Li Zhan.
Vanadium ore: It is distributed near Shanghetuo Village in Hetuo Township, with little reserves.
(2) nonmetallic minerals
Limestone: The Shimen in Hetuo Township has a large reserve, which has been developed and utilized at present. Minshan, Longwangtai, Taohe, Diezang and Erlanggou in Chabu Town are also distributed near the county seat.
Gypsum: produced in Hongshuigou, Wendu Township, with unknown reserves.
Coal: mainly distributed in Eryanggou of Chabu Town, Desert Gully of Minshan Township, Laoyashan of Sigou Township, Watershed of Mazichuan Township, Langdutan of Lv Jing Town and other places. Eryanggou has a reserve of about 500,000 tons, which is long-flame coal, black powder, high volatile matter, high ash and high sulfur, and is being developed and utilized. Mazichuan Valley, Lvjinglang Doutan and other places are peatlands with a reserve of about 5 million tons. At present, there is no deep development, and farmers make their own heating or use it as flower cultivation soil.
Silicon ore: distributed in Xuehuashan, Banggushan and Xizhai Town. The reserve is about 135300 tons, which is under development. 1. The landform of Minxian County is characterized by plateau landform and belongs to the fold belt of the northern branch of the West Qinling Mountains. The mountainous area of the county accounts for 88.8%. In the south, there are Min 'e Mountain and Dalaliang where the Yangtze River and the Yellow River divide water. In the north, there are Muzhailing and Lingluoshan where Taohe River and Weihe River divide water. The mountains and rivers in the whole territory are undulating and magnificent.
2. Type 1, erosion cutting mountainous area: mainly distributed in Taohe River basin, Puma River, Bashan River and the upper reaches of Lujing River, with high altitude, steep mountains, deep valleys, shallow cutting and moderate erosion. The relative height difference is between 400-1000 m. The hillside is covered with sedimentary, eluvial and Quaternary thin-layer aeolian loess, with serious soil erosion, exposed ridge rock mass, few terraces in the ditch, low temperature and obvious vertical wetting zone. Vegetation is dominated by mixed wells of alpine meadows and conifers and broad leaves. Forest and animal husbandry resources are abundant.
2. High prototype mountainous area: It is mainly distributed in the vast area of Ma Wu, east of Banha Mountain and upstream of Diezang River, with an altitude of about 2,800, gentle terrain, low and round mountains and a relative height difference of about 400 meters. There are basins, beaches and complete vegetation in mountainous areas, mainly swamps, meadow swamps, meadow grasslands and mountain meadows. The temperature is low and humid, and the prospect of developing animal husbandry is good.
3. River valley and terrace area: mainly distributed in Taohe River and Diezang River basins, with flat and open terrain, terraces II-III, and Sichuan land and terrace in the middle. Xichuan, Nanchuan and Mei Chuan, as well as Langdutan and Houzhitan in the east, are all large-scale Sichuan-Taiwan areas. The Sichuan-Taiwan region in the middle reaches of Taohe River has a long frost-free period and is the main agricultural intensive cultivation area. Minxian County is located on the edge of Qinghai-Tibet Plateau, which is the transition zone from Gannan Plateau to Loess Plateau and Longnan Mountain. The sea level rise in most parts of China is affected by the alternating action of continental air mass and subtropical warm and humid air mass and the influence of topography on atmospheric rise, forming a cold and humid climate feature. Natural disasters such as heavy rainfall, low temperature, short frost-free period and hail. Meteorology is specifically:
The annual average sunshine hours are 22 14.9 hours;
The maximum sunshine hours are 2456.6 hours.
The annual average temperature is 5.7℃;
Extreme minimum temperature-26.3℃;
The extreme maximum humidity is 365438 0.8℃;
The average monthly temperature in the hottest month (July) is 65438 06℃;
The lowest month, the monthly average temperature is (1 month)-6.9℃;
The annual rainfall is 45 1.4-8 17.8mm, and the rainy season is mostly concentrated in May-September, accounting for 79.4% of the annual rainfall.
The annual average evaporation is1188.2 mm;
The annual average relative humidity is 68%;
The annual average frost-free period is 90- 120 days;
The maximum frozen soil depth is 40-60 cm;
The maximum snow thickness is 40 cm;
The dominant wind direction throughout the year is northwest wind, with an average wind speed of 1.3— 1.5 m/s and a maximum wind speed of 24 m/s;
The basic earthquake intensity is 7 degrees. First, water resources.
Min county is rich in water resources, with atmospheric precipitation, with an average annual precipitation of 596.5 mm, which is close to the national average of 630 mm. There are 22 rivers in China, with an average annual runoff of 4.209 billion cubic meters. The per capita fresh water runoff is more than four times that of the whole country. Rivers have the characteristics of high altitude, large longitudinal slope and long flow. Rich in hydropower resources, with a reserve of 325,600 kilowatts and an annual power generation of 2.85 billion kWh.
The second is the water system and major rivers.
The whole water system is divided into two major river basins, the Yangtze River and the Yellow River, and three major water systems. Taohe River system, which belongs to the Yellow River basin, has 16 tributaries, and Weihe River system has 5 tributaries. The Qiushan River system belonging to the Yangtze River basin is only 1. There are 22 rivers with self-produced water, 2 rivers with annual runoff of more than 65.438+billion cubic meters, 654.38+ 00 rivers with annual runoff of 654.38+00-60 million cubic meters, and 654.38+00 rivers with annual runoff of less than 654.38+00 cubic meters.
1, Taohe River: a first-class tributary of the Yellow River. From Lengdikou, Xizhai Town, this county to the east, it passes through Xizhai, Qingshui, Shili, Minshan, Suburb, Chabu, North Zhejiang, Mei Chuan, Xijiang, Xiaozhai, Zhongzhai, Baozi, Weixin, etc. 12 townships, occupying the flag in Baozi Township and entering Lintan, which is horseshoe-shaped, with a drainage area of 2 177.
2. Stacked Tibetan River: a first-class tributary of Taohe River, originating from the north side of Daliang in the basin. The flow length is 42. 1km, and the drainage area is 827. 1km2. The main tributaries are Xuqin River, Lvye River, Nangou River and Caozi River. The process is Mazichuan and Sigou in Xu Qin, and the suburbs enter Tao Tao. The average annual runoff is 226 million cubic meters. The average flow rate is 7. 16m3/s, and the slope is 25.4%.
3. Lvjing River (Bangshahe) is the second largest river in China, belonging to the first-class tributary of Weihe River, which originates from the north side of zhilaliang in West Qinling, with a drainage area of 7 13.7 square kilometers and a domestic flow of 54.8 kilometers. The main tributaries are Shendu River, Diaogou River, Ketaigou River, Xiahe River and Lihe River, with an annual average flow of 654.38 0.28 billion cubic meters and an average flow of 4.05 cubic meters per second, with a slope of 654.38 0.4%.
4. Nana River: the third largest river produced by itself and the second tributary of Taohe River. Originated in the west side of Banha Mountain, with a total length of 28.8 kilometers and a drainage area of 279.8 square kilometers. Runner, grain route, tea ceremony; The main tributaries are ditch water of Eryanggou, Sangou, Sigou, Yiren Gully and Hali, with an average flow of 56 million cubic meters for many years, with an average flow of 1.77 cubic meters per second. The proportion decreased by 20.8%. I. Soil characteristics and types The soil in Minxian county includes 13 soil types, 19 subcategories, 45 soil genera and 59 soil species.
(1) Soil characteristics: The whole soil includes zonal soil, tundra soil, desert soil and non-zonal soil. The Taohe River basin in the northwest belongs to the southern part of the Loess Plateau in central Gansu, and there are black soil, ridged soil and loessial soil. Most of the southwest and central areas belong to the edge of Gannan Plateau, with subalpine meadow soil, mountain dark brown soil and black soil. Black soil, gray cinnamon soil, chernozem and mountain meadow soil are distributed in the eastern part of Qinling Mountains. It has the characteristics of the crossing transition zone of various soil divisions in China.
1. Black soil: distributed at an altitude of 2,500-3,000m, involving 22 towns. Covering an area of 2,537,800 mu, accounting for 47.3% of the county's total land area, it is the main soil in the county. The soil color is dark gray, with loose soil and good structure.
2. Black loessial soil: mainly distributed in mountains, rivers, plateaus and river valleys along the Taohe River at an altitude of about 2100-2,700 meters, with an area of 896,000 mu, accounting for 16.7% of the total area of the county. The soil is fine but not sticky, loose but not scattered.
3. Chernozem: It is mainly distributed on sunny slopes and dry ditch terraces in Lujing, Shen Du, Hetao and Sigou at an altitude of 2,400-2,700 meters, with an area of/kloc-0.849 million mu, accounting for 3.52% of the county's total area. The soil layer is 50-65,438+000 cm thick, mostly loam.
4. Mountain warm brown soil: It is mainly distributed in the shady slopes of Xu Qin, Suolong, Mawu and Puma at an altitude of 2600-3200m, with a total area of 206,400 mu, accounting for 3.85% of the county's total area. The soil is moist and the leaching effect is obvious.
5. Grey cinnamon soil: mainly distributed in Ma Wu and Suolong areas with an altitude of 2100-2,600 meters in the east, with an area of 357,600 mu, accounting for 6.66% of the total area of the county. The soil is moist and loose, with high humus content and gravel in the surface layer.
6. Alpine meadow soil: distributed in the southwest of the county at an altitude of 3,000-3,700 meters, with an area of 33,700 mu, accounting for 0.63% of the total area of the county. It belongs to sandy loam.
7. Subalpine meadow soil: It is distributed in the east, south and southwest of the whole territory at an altitude of 3200-3500m, with an area of 674,500 mu, accounting for 12.57% of the total area of the county. Vegetation is dominated by alpine shrubs and weeds.
8. Mountain meadow soil: It is mainly distributed in the gentle mountainous areas or Saiya skirt areas with an altitude of 2,500-2,900 meters, such as Puma, Lv Jing, Suolong and Mazichuan in the southeast. Area 136900 mu, accounting for 2.54% of the county's total area. Suitable crops are mainly wheat, highland barley, broad bean, potato and rape.
9. loessial soil: loessial soil, also known as Dabai soil and Huangbai soil. It covers an area of 23,900 mu, accounting for 0.45% of the county's total area. The soil layer is deep, the soil is loose and the color is yellow.
10, red soil: mainly distributed in the western part of Banha Mountain at an altitude of 2260-2800 meters, with an area of 107800 mu, accounting for 2.0 1% of the total area of the county. Thick grass roots, many plant roots, dark red humus layer, medium light color, sticky structure, slightly tight and porous.
1 1. Marsh soil: it is a peat layer with low terrain, poor drainage, heavy parent material and high groundwater level, and it is often in seasonal or long-term water accumulation state. Above the peat layer is the grass root layer. The bottom layer is a hidden layer, which is grayish blue or bluish gray. It is distributed in Du Lang Beach, Hou Zhi Beach, Lvjing Jingqing Beach, Suolong Douzi Beach and Mazichuan Cross Ditch, covering an area of 35,000 mu, accounting for 0.65% of the county's total area.
12, Neogene soil type: distributed in Taohe River, Diezang River and other river valleys. It covers an area of 45,900 mu, accounting for 0.85% of the county's total area. It is the soil formed by recent river alluvial cultivation and maturation.
13, coarse soil: except Shen Du, Minshan and Weixin, the rest 19 townships have it. Distribution area10.210,000 mu, accounting for 1.9% of the county's total area. Generally, the terrain is steep and the erosion is serious.
Second, biology.
(1) plants
1. Woody plants: There are 139 species of trees and shrubs in the county, belonging to 32 families and 62 genera. There are 64 kinds of trees, among which spruce, fir, larch, Pinus tabulaeformis, Pinus armandii, Tamarix chinensis and Robinia pseudoacacia are the main timber trees.
Economic trees include pepper, apricot, peach, plum, apple, pear and walnut. Fruit trees are mostly distributed in Taohe Platform, Puma and Ma Wu Valley areas, as well as the semi-mountainous areas and dam areas below 2500 meters above sea level.
2. Herbs: 646 species, belonging to 87 families and 324 genera. Among them, there are 520 kinds of forage grass, mainly Polygonum viviparum, Festuca arundinacea, Bromus Bromus, Hairy Grass, Alfalfa, Astragalus membranaceus, Carex densiflora and so on. The conditions for developing animal husbandry are good.
3. Medicinal plants: Min County is known as the "Millennium Medicine Town" and is rich in more than 200 kinds of Chinese herbal medicines. Among them, Angelica sinensis is famous at home and abroad for its high yield and high quality. Fritillaria, Radix Hedysari, Radix Astragali, Radix et Rhizoma Rhei, Radix Gentianae Macrophyllae, Notopterygii Rhizoma, Ginseng Radix, Bupleuri Radix, Cimicifuga Rhizoma, Radix Saposhnikoviae, Scutellariae Radix, Radix Codonopsis, etc. They are all precious medicinal materials.
4. Grain and oil crops: Grain crops include winter wheat, spring wheat, potatoes, broad beans, peas, lentils, highland barley, oats, oats and buckwheat. Wheat is mainly produced in Sichuan-Taiwan area and Mawu-Puma Valley area on both sides of Taohe River. Cool-loving crops, such as highland barley, oats, broad beans and potatoes, are widely planted in mountainous areas below 2800 meters above sea level in this county. Among them, broad bean has become a fist product and has begun to enter the international market.
5. Vegetables: Zhou Min has more than 30 kinds of vegetables, which will be introduced continuously in the future and promoted in plastic greenhouses. Up to now, there have been hundreds. There are more than 20 kinds of edible vegetables such as bracken, pepper, spicy vegetables, hippopotamus chef, wolf belly vegetables, silkworm moss, Grifola frondosa, Lycium barbarum and Sophora alopecuroides.
(2) Animals
1. Wild animals: The precious animals protected by the state include blue pheasant, musk deer, pangolin, Sumen antelope, crested deer, clouded leopard, wild goat, lynx and otter. In addition, there are bears, wild boar, leopards, weasels, rabbits, foxes, wolves and thorns. Wild birds include harrier, eagle, pigeon, magpie, golden rooster, pheasant, owl, cuckoo, woodpecker, goose and duck. Scales include bigmouth fish, whitebait, grouper, toothfish (Lujing), Yangtze fish, snake, scorpion and so on.
2. Livestock and poultry
Livestock: cattle, cows, yaks, horses, donkeys, mules, pigs, sheep, rabbits, dogs and cats.
Poultry: chickens, ducks, geese, pigeons and bees. 1. Hail: Min County has high terrain and complex terrain. Due to the influence of atmospheric circulation, water vapor forms hail at high altitude and low temperature. Topographically, hail has more windward slopes, less leeward slopes, more northern slopes than southern slopes, and more mountains than Sichuan. From the time point of view, severe thunderstorms accompanied by hail appear at any time in summer. This kind of rain is one of the biggest natural disasters in this county because of its high density and fierce force. According to statistics, from 1970 to 1980, the average annual hail disaster area reached more than 654.38+10,000 mu. There are seven hailstorms every year in Chengguan District, with the maximum 15 (1959) and the minimum 1. May-September is the peak of hail every year, especially in June and July, when crops are ripe. Once hail disaster occurs, there is often no grass harvest. Sometimes it will lead to flash floods, which will destroy farmland, roads and houses and cause serious losses to people's lives and property. 1On August 25th, 984, a hail caused more than 300,000 mu of disaster, which was terrible.
Hail has obvious regional characteristics. According to disaster statistics, Hetao, Lv Jing and Huang Jinshan are hail-prone areas, with an average annual disaster area of about 20,000 mu. Shili, Wendu and Zhongzhai are secondary hail disaster areas, with an average annual disaster area of about 654.38 0.110,000 mu. In other areas with light disasters and less disasters, the average annual affected area is less than 0.5 million mu. Hail and rain have formed three fixed routes in China. The first one enters from the northwest, passes through Baozi, Weixin, Zhongzhai, Xijiang and Mei Chuan, and is blocked by Dongdashan (365,438+000 meters). It is divided into two tributaries, one is Tuo Dou, Hetao and Shijiatai, and the other is extended to the suburbs and Sigou south through Chagang. Article 2 Starting from Bawang Mountain and passing through Puma and Hongya to Shen Du, Huang Jinshan and Lv Jing. Article 3 Entry from Lintan, passing through Qingshui, Shili, Minshan and Xu Qin, leaving the county.
Second, the flood.
There are two types of flood disasters:
One is heavy rain. Strong and concentrated rainfall, flash floods and mudslides have destroyed farmland, villages, highways and bridges, endangering people's lives and property.
The other is caused by a wide range of long-term continuous rain. Generally, it occurs in May-10, and it rains for about half a month, with precipitation of 88.5-123.4 mm. The river rises, scouring the river banks and fields.
Third, the freezing disaster.
Affected by the cold air pressure in southeastern Siberia and the southward movement of polar cold air, it caused disasters such as cold wave weather, frost and soil freezing.
Frost: commonly known as "black bully", the ground temperature is below 0℃, which mostly occurs in spring crop germination and seedling growth period. Especially the late frost on April 8 and the early frost in summer and autumn when the ears are full. The frost period is longer, about 240 days, the frost-free period in suburbs is about 123 days, the frost-free period in Dongshan District is about 90 days, and the frost-free period in mountainous areas is about 70 days.
Frozen soil: The soil in Minxian County is frozen for a long time with a large thickness, which generally occurs from the end of June 165438+ to March of the following year. The ground temperature below 0℃ sometimes affects the harvest of late autumn root crops and delays the spring sowing date. Dongshan district is more obvious, with the frozen soil thickness below 79 cm and the freezing time above 100 days. The frozen soil layers of Zhongzhai and Baozi in the lower reaches of Taohe River were less than 75 cm thick and frozen for 54 days. Every time the altitude rises 100 meters, the temperature drops by 0.65℃, and the frozen soil thickens accordingly. Generally, shady slopes are thicker than sunny slopes, and the freezing time is earlier than sunny slopes.
Fourth, drought.
Drought is more common in Chuanba area along Taohe River, including Chabu, Mei Chuan, Xijiang, Zhongzhai, Baozi and Weixin. Mountain areas are generally not afraid of drought. Judging from the farming season, there are three kinds of drought phenomena that harm crops in a year.
Drought in late spring: refers to the "Kong Yu period" in early and middle April.
Early summer drought: that is, from long summer to the first half of the solstice.
Drought in late summer: it only harms vegetables and angelica, which is beneficial to crops.
Fifth, pests and diseases
There are mainly 2 1 species of crop diseases, among which there are 7 kinds of wheat diseases, including three rust, white stem disease, red and yellow dwarf disease, scab, take-all disease and nematode disease. Potato diseases include late blight and ring rot. There are three kinds of diseases of Angelica sinensis: mouth disease, water rot and dry rot. Rape diseases include mosaic disease, powdery mildew and root rot.
Pests 12 species, including 4 wheat pests, such as armyworm, water fly, aphid, thin-bellied fly, etc. There are four kinds of potato pests: grubs, needle worms, cutworms and mole rats. Broad bean pests have two litters of horses; There are three kinds of pests in Angelica sinensis: golden needle worm, grub and cutworm. Rape pests include fleas, aphids and cabbage worms.
In addition, there are more than 20 kinds of grass famine disasters caused by wild grass seeds flying, such as moles, mice, foxes, rabbits, pheasants and so on.
Sixth, the earthquake
Minxian County is located in the northern zone (Lanzhou-Tianshui zone) of China North-South seismic belt. It is one of the 1 1 counties listed by the Ministry of Urban and Rural Construction and Environmental Protection 1987 (Pixian, Suqian and Xinyi in Jiangsu, Tancheng in Shandong, Minxian and Tanchang in Gansu, Mianning, Ganzi and Kangding in Sichuan, Eryuan and Xundian in Yunnan).