Natural topography, climate, rivers, humanities, urban population and folk customs in the middle and lower reaches of the Yangtze River are 500 words

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. Plant crops two or three times a year? Annual precipitation 1000 ~ 1400? Millimeter? Focus on 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. Agriculture is developed, and the agricultural reclamation index is high (Shanghai 62. 1%, Jiangsu 45.6%? ), is an important grain, cotton and oil production base. Rich in rice, wheat, cotton, rape, sericulture and ramie? Jute and so on. Rivers crisscross? Dots on the lake? This lake covers an area of 20,000 square kilometers? , equivalent to the plain area? 10%? . On the two lakes plain? There are more than 300 large lakes 1.000, including small lakes1.000, with an area of1.20 thousand square kilometers, accounting for more than 20% of the plain area of the two lakes, making it the place with the largest number of lakes in China? . There are many freshwater 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 natural reservoirs to regulate water volume and reduce flood peaks, and produce fish? Shrimp, crab, lotus, water chestnut, reed, Chinese sturgeon, alligator, baiji and other world treasures. Aquatic products occupy an important position in China and are known as the land of plenty. It is one of the most economically developed areas, including Shanghai, Nanjing, Wuhan, Changsha, Nanchang, Suzhou, Wuxi, Changzhou, Yangzhou, Nantong, Wuhu, Jiujiang, Yueyang and Yichang. ?

zone

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 from the south bank of Jingjiang River passing through Taiping, Ouchi, Songzi and Tiao County (blocked at 1958). 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. 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. ?

climate

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℃. This area belongs to subtropical monsoon climate, with mild winter and little rain, and high temperature and rainy summer. There is more precipitation in spring and summer. From June to July every year, affected by the summer monsoon and the cold air in the north, "Meiyu" is formed, which lasts for a long time. The length of rainy season is greatly influenced by "quasi-static stop before Jianghuai". After the rainy season, due to the influence of the western Pacific subtropical high, typhoon activity decreased, forming a "summer drought". ?

river

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. Famous freshwater lakes include Poyang Lake, Dongting Lake, Taihu Lake and Chaohu Lake. ? Poyang Lake: The largest freshwater lake in China and the second largest lake in China, located on the south bank of the Yangtze River. ? Dongting Lake: Located in the north of Hunan Province and south of Jingjiang reach of the Yangtze River, it is the second largest freshwater lake in China. ? Taihu Lake: Located at the junction of Jiangsu Province and Zhejiang Province, it is the third largest freshwater lake in China. ?

mankind

Crops can be harvested twice a year, and paddy field is the main type of cultivated land. 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 middle and lower reaches of the Yangtze River have convenient shipping and dense towns. Five urban agglomerations centered on Wuhan, Changsha, Nanchang, Nanjing and Shanghai have been formed. Together with the upstream Chongqing urban agglomeration, it is the economic and cultural center and transportation center of the region, which has a strong radiation and driving effect on regional economic development. ?

city

The main cities in the middle and lower reaches of the Yangtze River are Shanghai, Nanjing, Wuhan, Changsha, Nanchang, Yueyang, Jiujiang and Yichang.

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