Geographical location and scope
The administrative area includes 2 1 county (city) of Jiamusi City, hegang City, Shuangyashan City, qitaihe city City and Jixi City, and yilan county City of Harbin City. There are 52 state-owned farms and eight forest industry bureaus in the Territory. The total area is about 108900 square kilometers, the total population is 8.625 million, and the population density is about 79 people/square kilometers.
It is between 45 01′ ~ 48 27 ′ 56 ″ north latitude and13013 ′ ~135 05 ′ 26 ″ east longitude. Located in the northeast corner of China, it starts from the southeast end of Xiaoxing 'anling in the west, reaches Wusuli River in the east, reaches Xingkai Lake in the north and reaches Xingkai Lake in the south, with a total area of 5 1300 square kilometers. North-south part
Wanda Mountain divides Sanjiang Plain into two parts: the northern part of the mountain is a swamp low plain formed by the confluence of Songhua River, Heilongjiang River and Wusuli River, with an area of 42,500 square kilometers, which is a narrow Sanjiang Plain; Shannan is an alluvial-lake swamp low plain formed by Wusuli River and its tributaries and Xingkai Lake, covering an area of 8,800 square kilometers, also known as Muling-Xingkai Lake Plain.
The narrow Sanjiang Plain is a part of the intermountain basin in the middle reaches of Heilongjiang, surrounded by mountains on three sides, with Qingheishan, a branch of Xiaoxing 'an Mountains, Nadanha Daling, a branch of Wandashan Mountains, in the south, and Nadanha Daling, a main branch of Wandashan Mountains, in the east, which belongs to the Mesozoic-Cenozoic inland fault depression. Mesozoic and Cenozoic sedimentary caprocks are accumulated on the composite fold basement, and the thickness of Quaternary system is generally120 ~ 200m, and the maximum thickness can reach 280m. Except for the cohesive soil layer with a surface thickness of 3 ~17m in the east, it is mainly alluvial sand pebbles, which become a porous aquifer rich in groundwater. The altitude is 45-60 meters, and the lowest in Fuyuan Delta is only 34 meters. It slopes slowly from southwest to northeast, with a total slope of about 0. 10‰. The river winds through the vast floodplain. The main landform types are terraces and floodplains, and the western and southern edges are skirt-shaped alluvial-diluvial inclined plains, with slow transition between different types. The same type of ground undulation is generally only 0.5 ~ 2 meters, and only a few isolated hills are seen on the plain. Disc-shaped and linear shallow depressions are widely distributed and the cutting is weak. Except Heilongjiang, Songhua River and Wusuli River, all small and medium-sized rivers are plain swamp rivers, and most of them are covered by swamp vegetation.
Muling-Xingkai Plain borders the south foot of Wanda Mountain in the north and Kent Aling in the west. The Quaternary sediments in this area are mainly alluvial, lacustrine sand and gravel with a thickness of 10 ~ 150m, and the surface is covered with cohesive soil with a thickness of 1 ~ 4m. 55-95m above sea level, east-west height difference 10-20m. Generally, the terrain is inclined from west to east with a slope of 0.6-0. 1 ‰. Muling floodplain and lakeside floodplain are wide, and the ground is generally swampy.
climate
Sanjiang Plain belongs to temperate humid and semi-humid continental monsoon climate, with annual sunshine hours of 2400 ~ 2500 hours, monthly average temperature of 1 ~- 18℃, July average temperature of 2 1 ~ 22℃ and frost-free period of 120 ~ 65438. The freezing period is as long as 7 ~ 8 months, and the maximum freezing depth is 1.5 ~ 2. 1 m. The annual precipitation is 500 ~ 650 mm, and 75 ~ 85% is concentrated in 6 ~ 10.
topography
The vast and flat landform of Sanjiang Plain, the cold and wet climate with concentrated precipitation in summer and autumn, slow runoff, rivers with sudden flood peaks and seasonal frozen-thawed cohesive soil make the surface too wet for a long time and accumulate too much water, forming a large area of swamp water and swampy vegetation and soil, which constitutes a unique swamp landscape. Swamp and swampy land covers an area of about 2.4 million hectares, which is the largest swamp distribution area in China. Aquatic plants and swamp plants mainly include narrow leaves and thick shells, swamp willows, Carex and reeds. Carex bog is the most widely distributed, accounting for about 85% of the total swamp area, followed by reed swamp. Soil types mainly include black soil, albic soil, meadow soil and swamp soil, among which meadow soil and swamp soil are the most widely distributed. Sanjiang Plain is known as the "Great Northern Wilderness". Before the large-scale reclamation in 1950s, meadows and swamps were endless, and there were patches of forests and many wild animals. After reclamation, many large state-owned farms have been built, and the "Great Northern Wilderness" has become the "Great Northern Warehouse" and an important commodity grain base in China.
environmental aspect
At present, the environmental conditions in the Sanjiang Plain remain good, and the air quality in the vast forest areas, rural areas and most farms is clean. The natural water quality is good except for some river sections. The natural swamp wetland covers an area of 6.5438+0.347 million hectares, which is an important habitat and breeding ground for rare waterfowl. Six national wetland nature reserves have been built, of which three are listed in the list of internationally important wetlands, and the endangered waterfowl under protection are red-crowned cranes and swans.
harvest
The harvest season in Sanjiang Plain is the most desirable. In the vast fields, rivers crisscross, agricultural machinery roars, rice flowers are fragrant, and wheat waves roll. Modern farms that lead the level of mechanization in the country are full of vitality and are busy and prosperous. Sanjiang Plain in winter is quiet and leisurely. The off-season is as long as the winter. In this land where countless educated youths have devoted their youth and sweat, 10 counties and cities along the Yangtze River have been opened to Northeast Asia as a first-class port, and ordinary people who live comfortably and peacefully have begun to look forward to a better future. ...
One of the top ten "New Tianfu"
Sanjiang Plain was selected by chinese national geography magazine as one of the top ten "new and rich" in China.
The top ten "New Tianfu" are ranked as follows: Chengdu Plain, Jianan Plain of Taiwan Province Province, Ili River Basin, Shandong Peninsula, Southern Fujian Hilly Plain, Sanjiang Plain, Yarlung Zangbo River Dawan Area, Hulunbeier, Northern Jiangsu Plain and Ningxia Plain. The annual grain output in Sanjiang Plain is150,000 tons, and the per capita cultivated land area and per capita grain output are more than four times the national average. The scale of agricultural production here is huge, and the degree of agricultural mechanization ranks first in China. At the same time, the regional environment is beautiful and the pollution is very small. The shrinking trend of wetland area in Sanjiang Plain has been obviously curbed. There are 10 wetland nature reserves above the municipal level, which have received the attention and support of international eco-environmental organizations.
North China Plain
China's second largest plain. Located in the lower reaches of the Yellow River. It starts from Taihang Mountain and Western Henan Mountain in the west, reaches the Yellow Sea, Bohai Sea and Shandong Hill in the east, starts from Yanshan Mountain in the north, reaches Tongbai Mountain and Dabie Mountain in the southwest, reaches northern Jiangsu and Anhui in the southeast, and is connected with the plain in the middle and lower reaches of the Yangtze River. It extends to seven provinces and cities including Beijing, Tianjin, Hebei, Shandong, Henan, Anhui and Jiangsu. It covers an area of about 300,000 square kilometers. Mainly from the Yellow River, Huaihe River, Haihe River, Luanhe River alluvial, so it is also called Huanghuaihai Plain. The lower reaches of the Yellow River naturally cross the middle and are divided into two parts: the Huanghuai Plain in the south and the Haihe Plain in the north. Over the past century, the Yellow River has reclaimed 2300 square kilometers of land here. The plain continues to extend to the ocean, the fastest being the Yellow River Delta, with an average of 2-3 kilometers per year. The terrain is low and flat, mostly below 50 meters above sea level, and the eastern coastal plain is below 10 meters above sea level. Slightly inclined from west to east. It mainly belongs to Cenozoic giant depression with a sedimentary thickness of about1500 ~ 5000m. There are many low-lying areas and lakes and swamps on the plain. Concentrated in the northern part of the Yellow River alluvial fan between Baoding and Dagu, Tianjin. The contact area between the eastern edge of alluvial fan and Shandong hills has poor drainage and high groundwater level, which is easily threatened by floods and forms saline-alkali land. 1949, it was reformed and managed. It has a warm temperate monsoon climate with obvious changes in four seasons. The Huaihe river basin in the south is in a transitional area to the subtropical zone, and the temperature and precipitation are higher than those in the north. The average annual temperature in the plain is 8 ~ 15℃, and it is cold and dry in winter. The average temperature in Leng Yue (65438+1October) is 0 ~-6℃, the average temperature in the hottest month in summer (July) is 28℃, and the average annual precipitation is 600 ~ 800 mm; The frost-free period is 6 ~ 8 months; There is plenty of sunshine, and the average sunshine hours in most years are 2300 ~ 2800 hours. Most crops are planted three times a year, and two times a year in the south. The soil is deep and fertile. The main food crops are wheat, rice, corn, sorghum, millet and sweet potato, and the cash crops are mainly cotton, peanuts, sesame seeds, soybeans and tobacco. Rich in mineral resources, such as coal, oil and iron ore, China's famous Dagang Oilfield and Shengli Oilfield. The eastern coasts of Bohai Sea and Yellow Sea are flat and suitable for drying sea salt. There are famous Luchang salt area and Subei salt area, and there are also important saline-alkali industrial bases. North China Plain is the cradle of ancient culture in China, with many ancient cities, such as Beijing (Hebei), Handan, Kaifeng, Shangqiu and Huaiyang.
Plains of the Middle and Lower Reaches of the Yangtze River
The banded plain in the middle and lower reaches east of the Three Gorges of the Yangtze River in China. It is bounded by Huaiyang Mountain in the north and Jiangnan hills in the south. The terrain is low and flat, and the ground height is mostly below 50 meters. The middle reaches include Jianghan Plain in Hubei, Dongting Lake Plain in Hunan and Poyang Lake Plain in Jiangxi. The downstream plain includes the Yangtze River Delta along the Yangtze River in Anhui, Chaohu Plain and between Jiangsu, Zhejiang and Shanghai, in which the ground height of the Yangtze River Delta is below 10 meter. Rivers, branches and lakes are criss-crossed on the plain. Dongting Lake, Poyang Lake, Taihu Lake, gaoyou lake, Chaohu Lake, Hongze Lake and other famous freshwater lakes are all distributed in this narrow strip. Xiangxiang is known as the "Water Town and Zeguo", which is rich in fish, shrimp, crab, water chestnut, lotus and reed. Mild climate, frost-free period 240? In 280 days, double-cropping rice can be planted in the south of the Yangtze River, and grain, cotton and aquatic products occupy an important position in the country, which is known as the "land of plenty". The middle and lower reaches of the Yangtze River are economically developed, including big cities such as Shanghai, Nanjing and Wuhan and medium-sized cities such as Suzhou, Wuxi, Changzhou, Zhenjiang, Yangzhou, Taizhou, Nantong, Wuhu, Nanchang and Changsha.
The banded plain in the middle and lower reaches east of the Three Gorges of the Yangtze River in China. Huaiyang Mountain and Huanghuai Plain are in the north, and Jiangnan hills and Zhejiang and Fujian hills are in the south. It is alluvial from the Yangtze River and its tributaries. It covers an area of about 200,000 square kilometers. The terrain is low and flat, and the altitude is mostly about 50 meters. The middle reaches include Jianghan Plain in Hubei, Dongting Lake Plain in Hunan and Poyang Lake Plain in Jiangxi. The downstream plains include the plain along the Yangtze River and Chaohu Lake in Anhui Province (the central plain of Anhui Province), and the Yangtze River Delta between Jiangsu, Zhejiang and Shanghai.
Most of the climate belongs to the north subtropical zone, and a small part belongs to the northern edge of the middle subtropical zone. The annual average temperature is 14 ~ 18℃, the most Leng Yue average temperature is 0 ~ 5.5℃, the absolute minimum temperature is-10 ~-20℃, the hottest month average temperature is 27 ~ 28℃, and the frost-free period is 2 10 ~ 270 days. For agricultural crops, the annual precipitation is 1000 ~ 1400 mm, which is concentrated in spring and summer. Zonal soil is only found in low hills and gentle hills, mainly yellow brown soil or yellow cinnamon soil. The southern margin is red soil, and most of the plains are paddy soil. With developed agriculture and high land reclamation index (62. 1% in Shanghai and 45.6% in Jiangsu), it is an important grain, cotton and oil production base. Rich in rice, wheat, cotton, rape, silkworm, ramie, jute and so on.
Rivers and branches crisscross, and lakes are dotted. The lake covers an area of 20,000 square kilometers, equivalent to 10% of the plain area. There are more than 1300 large lakes, including small lakes, on the two-lake plain, totaling more than 10000, with an area of 12000 square kilometers, accounting for more than 20% of the area of the two-lake plain, which is the place with the largest number of lakes in China. There are fresh water lakes such as Poyang Lake, Dongting Lake, Taihu Lake, Hongze Lake and Chaohu Lake, which are connected with the Yangtze River and have the functions of regulating water volume and reducing flood peak. They produce fish, shrimp, crab, lotus, water chestnut and reed, as well as world treasures such as Chinese sturgeon, Chinese alligator and baiji. Aquatic products occupy an important position in China, known as the land of plenty. It is one of the most economically developed regions, including Shanghai, Nanjing, Wuhan, Nanchang, Suzhou, Wuxi, Changzhou, Zhenjiang, Yangzhou, Taizhou, Nantong, Wuhu and Changsha.
The main industries are steel, machinery, electricity, textiles and chemistry, and it is an important industrial base. The plain is located in the hub of China's north-south and east-west transportation networks, with developed land and water transportation. The Yangtze River runs through the middle and becomes an east-west waterway artery, and its many tributaries form a huge waterway network.
The plain in the middle and lower reaches of the Yangtze River is alluvial by the Yangtze River and its tributaries, east of the Three Gorges, south of Huaiyang Mountain and Huanghuai Plain, and north of Jiangnan Hill and Fujian-Zhejiang Hill. It spans six provinces of Jiangxi, Hubei, Hunan, Anhui, Jiangsu and Zhejiang, and is one of the three major plains in China. It includes four parts: the two lakes plain, the Poyang Lake plain, the central Anhui plain and the Yangtze River Delta. The middle reaches of the plain are relatively vast. The plain in the lower reaches of the Yangtze River is long and narrow. The terrain here is flat, the rivers are curved and the lakes are densely covered. Known as the "Water Town Zeguo", it is the main agricultural area in China. Poyang Lake, Dongting Lake, Taihu Lake, Hongze Lake and Chaohu Lake are the five largest freshwater lakes in China.
form
The plain in the middle and lower reaches of the Yangtze River is one of the three major plains in China. Located along the middle and lower reaches of the Yangtze River east of Yichang, Hubei, it consists of two lakes (Jianghan Plain in Hubei and Dongting Lake Plain in Hunan), Poyang Lake Plain, Jiangsu-Anhui Plain along the Yangtze River, He Lixia Plain (Central Plain in Anhui) and Yangtze River Delta Plain, covering an area of about 200,000 square kilometers.
(1) The two lakes plain includes northern Hunan and southern Hubei. In ancient times, it used to be a misty dream, and later it was filled with sediment washed down by the Yangtze River and its tributaries. It covers an area of 50,000 square kilometers and is divided into Jianghan Plain and Dongting Lake Plain. The plain is densely covered with water networks and is known as the "land of fish and rice".
(2) Poyang Lake Plain is located in the northwest of Jiangxi to the southwest of Anhui, covering an area of 20,000 square kilometers. The terrain is low and flat, and the altitude is below 50 meters.
(3) Central Anhui Plain is located along the Yangtze River in central Anhui, near Chaohu Lake, with a small area.
(4) The Yangtze River Delta is located in the east of Zhenjiang, south of the Canal and north of Hangzhou Bay, covering an area of 50,000 square kilometers. It is alluvial by the Yangtze River and Qiantang River, and the altitude here is only about 10 meter. On the delta, rivers crisscross and lakes are dotted, which is known as the "land and water country". Here is rich in rice, fish and shrimp, and the grain output occupies an important position in the country. There is a saying in history that "Suzhou and Shanghai are familiar, and the world is enough."
The middle and lower reaches of the Yangtze River are located on both sides of the Yangtze River and its tributaries east of Wushan, and are divided into four parts by the surrounding low hills (see Jiangnan hills): the two lakes plain, the Poyang Lake plain, the central Anhui plain and the Yangtze River Delta, with an area of 300,000 square kilometers and an altitude of less than 50 meters. The Yangtze River Delta is located in the east of Zhenjiang, Jiangsu Province, north of Hangzhou Bay and south of Toarey Yang Canal, with an area of about 50,000 square kilometers, and the elevation is mostly below 10. Known as "Water Town Zeguo", it is one of the most densely populated areas in China.
The two lakes plain is bounded by Jingjiang River, which is called Jianghan Plain in the north and Dongting Lake Plain in the south. Jianghan Plain is mainly formed by alluvial deposits of the Yangtze River and the Han River. Since the entrance of Jingjiang North dike into Jianghan Plain was completely blocked around 1300, the sediment carried by Hanjiang River has played a major role in the development of Jianghan Plain, and its delta has become an important part of Jianghan Plain. The terrain of the Hanjiang River Delta is also slightly inclined from northwest to southeast, and there are many lakes in the southeast front. Dongting Lake Plain is mainly formed by the Yangtze River sediment flowing southward through Taiping, Ouchi, Songzi and Tiao County (blocked at 1958) on the south bank of Jingjiang River. The area is about 1 1,000 square kilometers. Most of them are below 50 meters above sea level, high in the north and low in the south, with dense water networks and fertile soil. The flood plain in the middle of Poyang Lake Plain, except the red mounds at the edge, is mainly formed by the scouring and silting of rivers such as Jiangxi, Fuzhou, Xinjiang, Poyang Lake and Xiushan, among which Ganjiang is the main one. It covers an area of about 20,000 square kilometers. The terrain is low and flat, most of which are below 50 meters above sea level. The water network is dense, and the surface is covered with red soil and river alluvium. The plain along the Yangtze River in Jiangsu and Anhui mainly refers to the long and narrow alluvial plain distributed along the banks of the Yangtze River between Hukou and Zhenjiang, including Wuhu Plain and Chaohu Plain. The width and width of the plain alternate, the river flows in and out, and the velocity is gentle; Since Datong, every time supported by the tide, the flow velocity has slowed down and the sediment deposition has been strengthened. Especially when the river passes through the rock head forced by the rock mound, river branches and sandbars appear between the branches. There are many lakes on both sides of this river.
The Yangtze River Delta is developed from the estuary below Zhenjiang. To the north of the delta is the He Lixia Plain. The plain is a dish-shaped depression with high, middle and low levels in the Zhou Dynasty. The northern edge of the depression is the old course of the Yellow River; The southern margin is the delta on the north bank of the Yangtze River; The west edge is Hongze Lake and Yunxi levee; The eastern edge is the coastal plain of northern Jiangsu.
topography
The two lakes and plains are bounded by Jianghan Plain in the north and Dongting Lake Plain in the south. Jianghan Plain is mainly formed by Yangtze River and alluvial sediments. Since the entrance of Jingjiang North dike into Jianghan Plain was completely blocked around 1300, the sediment carried by Hanjiang River has played a major role in the development of Jianghan Plain, and its delta has become an important part of Jianghan Plain. The terrain of the Hanjiang River Delta is also slightly inclined from northwest to southeast, and there are many lakes in the southeast front. Dongting Lake Plain is mainly formed by the Yangtze River sediment flowing southward through Taiping, Ouchi, Songzi and Tiao County (blocked at 1958) on the south bank of Jingjiang River. The area is about 1 1,000 square kilometers. Most of them are below 50 meters above sea level, high in the north and low in the south, with dense water networks and fertile soil.
The flood plain in the middle of Poyang Lake Plain is mainly formed by the scouring and silting of rivers such as Jiangxi, Fuzhou, Xinjiang, Poyang Lake and Xiushan, with Jiangxi as the main one. It covers an area of about 20,000 square kilometers. The terrain is low and flat, most of which are below 50 meters above sea level. The water network is dense, and the surface is covered with red soil and river alluvium.
The plain along the Yangtze River in Jiangsu and Anhui mainly refers to the long and narrow alluvial plain distributed along the banks of the Yangtze River between Hukou and Zhenjiang, including Wuhu Plain and Chaohu Plain. The width and width of the plain alternate, the river flows in and out, and the velocity is gentle; Since Datong, every time supported by the tide, the flow velocity has slowed down and the sediment deposition has been strengthened. Especially when the river passes through the rock head forced by the rock mound, river branches and sandbars appear between the branches. There are many lakes along the Yangtze River. According to the causes, there are tectonic lakes and river relic lakes.
The Yangtze River Delta is developed from the estuary below Zhenjiang. To the north of the delta is the He Lixia Plain. The plain is a dish-shaped depression with high, middle and low levels in the Zhou Dynasty. The northern edge of the depression is the old course of the Yellow River; The southern margin is the delta on the north bank of the Yangtze River; The west edge is the west dike of He Yun; The eastern edge is the coastal plain of northern Jiangsu.
zone
The plain in the middle and lower reaches of the Yangtze River is mainly formed by alluvial sediment carried by the Yangtze River and its tributaries, with a total area of more than 200,000 square kilometers, most of which are below 50 meters above sea level. There are many ports and lakes in the territory, and it is known as "Water Town and Zeguo". About 20 million to 30 million years ago, the Yangtze River estuary below Zhenjiang was like a trumpet-shaped triangular harbor with a vast water surface and strong tides. Supported by the tide, most of the sediment brought by the Yangtze River is deposited. At first, it piled up into a huge sand embankment on the north and south banks.
One on the north shore extends eastward from Yangzhou to Nantong. To the north of this sandbar is the He Lixia Plain, which is mainly formed by alluvial sediments of ancient Huaihe River and Yellow River. A sandbar on the south bank of the Yangtze River extends from Jiangyin to Jinshan Caojing in the southeast, and connects with a sandbar on the north bank of Hangzhou Bay to form an encirclement, which encloses the triangle harbor as a lagoon basically isolated from the sea, but there are still some gaps connected with the sea. This is the ancient Taihu Lake. Later, due to the continuous siltation of the tide flowing backward along the gap of the sand dike and the sediment brought by the rivers in the upper reaches of the ancient Taihu Lake, the land continued to expand, and the ancient Taihu Lake continued to shrink and was divided into many small lakes such as Dianshan Lake and Yangcheng Lake. At the same time, the sediment of the Yangtze River continues to accumulate along the coast, forming a new delta.
Now in the west of Shanghai, starting from Jiading Waigang in the north, crossing Maqiao in Shanghai County to Jinshan Caojing, you can also see an intermittent ancient shell sand belt, which was the ancient coastline five or six thousand years ago. The land east of this line is a part of the new delta formed by sediment deposition since 5000 years. Today, the land in Nanhuizui in the east of Shanghai and the eastern end of Chongming Island is still growing.
The annual average temperature in the middle and lower reaches of the Yangtze River14 ~18℃; 1 Monthly average temperature 0 ~ 5.5℃; The average temperature in July is 27 ~ 28℃, and the absolute maximum temperature can reach above 38℃. The annual precipitation 1000 ~ 1500mm is evenly distributed in seasons, but there is a "summer drought". The frost-free period is 2 10 ~ 270 days, and the active accumulated temperature above 10℃ reaches 4500 ~ 5000℃. Crops can be harvested twice a year, and the triple cropping system of double cropping rice can be developed in Jiangnan area. The plain in the middle and lower reaches of the Yangtze River is an important production base of grain, oil and cotton in China, and it is also the region with the richest water resources in China. The natural water system of the Yangtze River and criss-crossing artificial canals make this area the densest river network area in China. This area is the most concentrated area of freshwater lakes in China. The famous freshwater lakes are Poyang Lake, Dongting Lake and Chaohu Lake. The lake and marsh area is rich in aquatic biological resources, which is the area with the widest distribution and the highest yield of aquatic plants in China. Freshwater aquatic animals are also the highest in China, except still water, bream, bream, silver carp, carp, crucian carp, green grass, and various migratory fish in the estuary, mainly silver carp, bream, fragrant fish and whitebait (including whitebait and whitebait), as for Chinese sturgeon and alligator sinensis.
Distribution of traditional Chinese medicine resources
The plains in the middle and lower reaches of the Yangtze River are mainly composed of low hills, basins, lake depressions and coastal beaches, including Jianghan Plain, Dongting Lake Plain, Poyang Lake Plain, Jiangsu-Anhui Plain along the Yangtze River, Yangtze River Delta and He Lixia Plain. There are many lakes on the plain, and rivers and lakes are connected in series. The vast alluvial plains and basins with deep and fertile soil provide good growth conditions for domestic and wild medicinal organisms. In terms of climatic conditions, there are some differences between Jiangnan and Jiangbei: the temperature in Jiangnan is slightly higher than that in Jiangbei in winter, Jiangnan has obvious subtropical characteristics, and Jiangbei has the climatic characteristics of transition to warm temperate zone.
(1) Types of Common Medicinal Materials
There are some important commonly used medicinal materials distributed here, which can be supplied to the whole country and exported. Among them, wild medicinal materials with high yield and high quality include Smilax glabra, motherwort, Radix Codonopsis, Radix Puerariae, Polygonum Cuspidatum, Prunella vulgaris, Peucedanum praeruptorum, Linderae, Flos Chrysanthemi Indici, Sanguisorba officinalis, Herba Artemisiae Scopariae, Polygonum Multiflori Radix, Fructus Ligustri Lucidi, Radix Adenophorae, Stemonae Radix, Fructus Trichosanthis, Radix Platycodi, Radix Salviae Miltiorrhizae, Fructus Arctii, Herba Epimedii, Cynanchum Cynanchi, and Hedyot The cultivated medicinal materials include Eucommia ulmoides, Magnolia Officinalis, Cornus officinalis, Pinellia ternata, Radix Isatidis, Carthami Flos, Fructus Psoraleae, Radix Platycodi, etc.
(2) Aquatic medicinal plants
The middle and lower reaches of the Yangtze River have the eastern plain of China, which is also the area with the highest lake density in China. Five famous freshwater lakes in China-Dongting Lake, Poyang Lake, Taihu Lake, Hongze Lake and Chaohu Lake are all located here. This area is close to the ocean, located in the southeast Asian monsoon belt, with warm and humid climate, abundant precipitation, large area and many kinds of aquatic vegetation in the lake area. Aquatic medicinal plants in the lake are distributed in a regular ring from shallow coastal water to deep central water, followed by emergent plants, floating plants and submerged plants. Emergent plants refer to species whose roots are rooted in bottom mud and whose upper parts or Ye Ting are born on the water surface. Most of them are distributed in shallow water, shallow ponds, gullies and paddy fields in inner lakes. The main medicinal plants are reed, water candle, cattail, lotus flower, water chestnut, arrowhead, Alisma orientalis, Sparganum, Acorus calamus, Acorus gramineus, scallion and Curcuma tuber. Most of them are distributed in still waters such as lakes, ponds and gullies. The main medicinal species are Euryale ferox, water chestnut, wild water chestnut, duckweed, Manjianghong, Manjianghong, Yeping, Eichhornia crassipes, Alternanthera philoxeroides, water shield, water lily, Eupatorium adenophorum, water fern and Polypodiaceae. The main medicinal species are POTAMOGETON POTAMOGETON, POTAMOGETON POTAMOGETON, Ceratophyllum, Sargassum and Sophora alopecuroides. In addition, there are aquatic medicinal plants, such as rush, Pennisetum, arrowhead, Cynanchum stauntonii, amaranth and cress. The important cultivated medicinal materials in the lake area are Euryale ferox, Alisma orientalis, and water chestnut, water chestnut, lotus, water spinach and so on.
(3) Animal medicinal materials
Animal medicinal materials in this area include pearl, mother-of-pearl, toad venom, earthworm, hedgehog skin, Eupolyphaga Seu Steleophaga, turtle shell, stiff silkworm, cicada slough, leech, endothelium corneum Gigeriae Galli, centipede, oyster, water lily, tabanus, grubs, dung beetles and dung beetles. There are Agkistrodon halys, Zaocys, Agkistrodon, Pangolin, Otter, Leopard, Monkey, Deer, Bear, Civet, etc.
(4) Mineral medicinal materials
There are not many kinds of mineral drugs, mainly fluorite, magnetite, talc, violet, Qiu Shi, Anonymous, Halloysitum rubrum, chlorite, Daiheyi, mirabilite, native copper, actinolite, mica, Halloysitum rubrum, Yuliang stone, amber, Eguanshi and gypsum.
Present situation of water environment
(1) Water environment characteristics in the Yangtze River Delta
The geographical range of the Yangtze River Delta is between 28 45' and 33 25' north latitude and 65 438+065 438+08 20'-65 438+023 25' east longitude. Administrative regions include Shanghai, Nanjing, Hangzhou, Zhenjiang, Yangzhou, Taizhou, Nantong, Suzhou, Wuxi, Changzhou and Jiaxing. The total land area of the Yangtze River Delta is 99600 km^2, accounting for about 1% of the national land area. The total population of the whole region is about 74047 1 10,000, accounting for 6.05% of the total population in China. The Yangtze River Delta faces the ocean in the east, with low terrain, vertical and horizontal river networks and numerous lakes. Its water system includes the Yangtze River Estuary, Taihu Lake, Canal, Qiantang River and Yongjiang River, which constitutes the unique delta water system of Zeguo, a water town.
The main lake in the Yangtze River Delta is Taihu Lake, which is the third largest freshwater lake in China. There are more than 220 rivers around the lake, including more than 70 human lakes and more than 50 lakes/kloc-0, with a storage capacity of 4.67 billion m 3.
In the Yangtze River Delta, rivers intersect, rivers are connected, and the water system is developed. Because of the small water level difference and low flow rate in plain area, the direction of water flow is uncertain due to the height control of water conservancy projects and the influence of gate opening and closing and drainage. Rivers and lakes not only bear the local surface water runoff, but also bear about 2 million km^2 of incoming water in the upstream provinces and regions of 15. In flood years, the Yangtze River Delta is the flood corridor of the upstream water system. Because facing the ocean, it is vulnerable to typhoons, rainstorms and storm surges, and floods caused by waterlogging or waterlogging often occur. In the dry season, the lack of upstream water often leads to serious drought and aggravates the deterioration of water quality in rivers and lakes. In addition, some rivers have high sediment concentration, siltation and slow river bed gradient. Reservoir sediment deposition makes sediment adsorb pollutants, which intensifies water pollution and increases the difficulty of water resources development and utilization.
(2) The present situation of water pollution in the Yangtze River Delta.
The Yangtze River Delta is a famous water town. Water resource is a big advantage and should not be short of water. However, with the rapid economic development, the quality of water, soil and atmospheric environment in the Yangtze River Delta region has generally declined a lot compared with 20 years ago. Taihu Lake Basin is the heart of the Yangtze River Delta and the "heart" of the region. The water quality of Taihu Lake was Grade I-II in 1960s, Grade II in 1970s, Grade II-III in early 1980s, Grade III in late 1980s, Grade IV-V in some areas, Grade IV in mid-1990s, Grade V or worse in 1/3 lake area, frequent cyanobacteria and Alternanthera philoxeroides, serious eutrophication of the lake, and difficult to guarantee the safety of drinking water.