Compare the similarities and differences of geographical environment between the Yellow River Delta and the Yangtze River Delta.

The Yangtze River Delta starts from Toarey Yang Canal in the north, Hangzhou Bay in the south, Zhenjiang in the west and the seaside in the east, including Shanghai, southern Jiangsu Province, northern Zhejiang Province and its adjacent waters. It covers an area of about 99,600 square kilometers and has a population of about 75 million. This is a vast plain. The coastline here is straight and the sea is yellow and muddy. There are shoals in the intertidal zone with a width of several kilometers to several tens of kilometers. This urban agglomeration has gathered great strengths in industry, finance, trade, education, science and technology, culture and so on, and plays an important role in promoting the economic development of the Yangtze River Basin, connecting domestic and foreign markets, attracting overseas investment, promoting industrial and technological transfer, participating in international competition and regional structural adjustment.

The Yangtze River Delta is the largest estuary delta in China, which generally refers to the alluvial plain of the Yangtze River sediment east of Zhenjiang and Yangzhou, and is located in the southeast of Jiangsu Province, Shanghai and Hangjiahu areas of Zhejiang Province. The apex of the Yangtze River Delta is near Zhou Zhen Town, Yizheng City, with Yangzhou, Jiangdu, Taizhou, Hai 'an and Bencha as the northern boundary, and Zhenjiang, Ningzhen Mountain Range, the eastern foot of Maoshan Mountain and the northern foot of Tianmu Mountain to the north bank of Hangzhou Bay as the western and southern boundaries.

form

The delta basement is a part of the Yangtze paraplatform, and the Himalayan tectonic movement interrupted the subsidence. During the Quaternary neotectonic movement, the crust and sea level frequently rose and fell. After the last transgression, the sediment carried by the Yangtze River continued to deposit, and the estuary began to develop deltas.

Due to the Coriolis force, the main channel continuously flows to the right, so that the sand groups in the estuary merge into the sandbars and sandbars formed in Hongqiao period, Huangqiao period, Jinsha period, Haimen period and Beisha period in turn, forming Hanjiang, Taixing, Jingjiang, Rugao, Nantong, Haimen and Qidong counties on the north bank of the Yangtze River today. Now the sand islands near the estuary are Chongming, Changxing and Hengsha.

The sand mouth on the north bank extends all the way to the northern boundary of the delta, and the ground elevation is 6-8 meters.

The sand mouth on the south bank extends eastward through Jiangyin, Taicang, Waigang and Maqiao, with a ground elevation of about 4.5 ~ 6 meters, and reaches Hangzhou Bay after connecting with the north bank of Qiantang River. The repulse bay in Shazui silted up and became the predecessor of the ancient Taihu Lake. Since then, Repulse Bay has silted up and gradually evolved into a low plain criss-crossing lakes and rivers. The coastal area outside the sand mouth on the south bank has been silted up into a coastal plain.

There are a series of residual hills scattered in the delta, with an altitude of 100 ~ 300 meters. Most of them are composed of Devonian sandstone and Carboniferous and Permian limestone, and a few are composed of Yanshanian granite and trachyte.

history

In the early days of the delta, humans engaged in fishing, hunting and farming here.

After two great migrations of the Eastern Jin Dynasty, the Southern and Northern Dynasties and the Southern Song Dynasty in the 4th-6th century A.D., and the construction of the river network since13rd century, the Delta has gradually developed into a famous land of plenty and silk in China.

Modern industry rose earlier, inland river shipping was developed, Shanghai-Nanjing and Shanghai-Hangzhou railways were built one after another, and Shanghai, Suzhou, Wuxi, Changzhou, Zhenjiang, Nantong and Yangzhou in Jiangsu, Hangzhou and Jiaxing in Zhejiang developed into industrial towns one after another.

In order to promote and strengthen the economic union and cooperation in the Yangtze River Delta region and promote the sustainable economic development in the Yangtze River Delta region, the 14th municipal economic commissions (offices) were initiated and organized by Shanghai, Wuxi, Ningbo, Zhoushan, Suzhou, Yangzhou, Hangzhou, Shaoxing, Nanjing, Nantong, Changzhou, Huzhou, Jiaxing and Zhenjiang 1992, 14.

1997, the municipal government of the above-mentioned 14 city and the municipal government of the newly established 15 city in Taizhou voluntarily formed a new economic coordination organization-Yangtze River Delta Urban Economic Coordination Committee through equal consultation. The Coordination Committee has an executive chairman and an executive chairman, with Shanghai as the executive chairman. The executive chairman is rotated by other member cities except Shanghai. The coordination meeting is held every two years. The Coordination Committee has a liaison office next to the Executive Chairman as a permanent office, which is responsible for daily work. The member city cooperation office (committee) is the specific liaison and handling department of the coordination meeting.

A part of the plain in the middle and lower reaches of the Yangtze River. It is located in the east of Zhenjiang City, Jiangsu Province, north of Hangzhou Bay and south of Toarey Yang Canal. It covers an area of about 50,000 square kilometers. The terrain here is low and flat, and the altitude is below 10 meter. However, there are also some isolated hills, such as Huishan in Wuxi, Tianping Mountain in Suzhou, Yushan in Changshu, Sheshan in Songjiang and tianmashan. They either stand on the plain or in Taihu Lake. Some have become a mountain of flowers and fruits. The apex of the Yangtze River Delta is near Zhenjiang, a triangular harbor about six or seven thousand years ago. The mouth of the Yangtze River is like a trumpet opening eastward. The water surface is vast and the tidal effect is remarkable. With the support of seawater, most of the 470 million tons of sediment brought by the Yangtze River are deposited into sandbars on the north and south banks. The sandbars on the north bank extend eastward from Yangzhou to Rudong, and the sandbars are mainly composed of the Yellow River and the sandbars to its north. The sandbars on the south bank extend from Jiangyin to Caojing, Jinshan County, Shanghai, and connect with the sandbars on the north bank of Qiantang River, forming the Taihu Plain. He Lixia Plain is located on the north bank of the Yangtze River, covering an area of about 6.5438+0.4 million square kilometers, and it is a dish-shaped depression. The central lake of the depression swings continuously, mainly including Sheyang Lake and Dazong Lake. Due to the low terrain, floods are extremely serious in history. In order to change this situation, the Huaihe River is blocked in the west and the tide is blocked in the east. Digging canals and enhancing irrigation and drainage capacity will make this disaster-stricken area become an important grain production base in the Jianghuai Basin. Taihu Plain is located in the south of the Yangtze River and is the main body of the Yangtze River Delta. The plain is centered on Taihu Lake and looks like a big plate. The terrain is high, medium and low for a week. This topographic feature makes the upper reaches of the Yangtze River and Taihu Lake flood, and the lower reaches flood. Typhoons and rainstorms often hit here in summer and autumn. Flood disasters occur frequently. In order to resist natural disasters, the local people made great efforts to dig rivers and open canals, remove stagnant water, repair dikes and build gates, and gradually formed a dense water network connected by ditches. This is the area with the highest river network density in China, with an average length of 4.8-6.7 kilometers per square kilometer. There are more than 200 lakes on the plain. The Yangtze River Delta is criss-crossed, dotted with lakes and developed agriculture.

■ Yangtze River Delta

The delta formed by the Yangtze River and Qiantang River in China, including Jiangsu Province, the southeast of Shanghai and the northeast of Zhejiang Province, is a part of the plain in the middle and lower reaches of the Yangtze River, covering an area of about 50,000 square kilometers. The apex of the delta is in Zhenjiang and Yangzhou, reaching Xiaoyangkou in the north and Hangzhou Bay in the south. The altitude is mostly below 10 meter, and the hills are low (such as Huishan, Tianpingshan, Yushan and Langshan). 200 ~ 300 meters above sea level. The annual sediment discharge of the Yangtze River is 400-900 million tons. In general, 28% of the sediment is deposited in the Yangtze River, and in some years it is as high as 78%. The delta continues to extend to the sea. The ancient shazui in Changzhou, Changshu, Taicang, Jinshan and other counties south of the Yangtze River is mostly 4 ~ 6m above sea level. The ancient sand mouth in Yangzhou, Taizhou, Taixing and Rugao, north of the Yangtze River, is 7-8 meters above sea level. The ancient sand mouths in Jiangnan and Jiangbei developed gradually after the highest sea level stabilized in the late glacial period. About 2000 years ago, the north bank sand mouth extended to Liaojiaozui, and the south bank sand mouth extended to the southeast with the mainstream of the Yangtze River and connected with the mouth sand mouth of Qiantang River, and the sediment continued to accumulate. From 1958 to 1973, it moves forward by148m on average every year. It belongs to the northern subtropical monsoon climate, with abundant rainfall, vertical and horizontal waterways and dotted lakes, and is known as the water town and country. Fertile land, agricultural production of rice, cotton, wheat, rape, peanuts, silk, fish and shrimp. It is one of the most densely populated areas in China. Such as Shanghai, Suzhou, Changzhou, Wuxi, Zhenjiang, Yangzhou, Taizhou and Nantong. Among them, Shanghai is the largest industrial and commercial city in China and a world-famous foreign trade port, while Suzhou and Wuxi are scenic spots and emerging industrial cities.

There is a tidal flat wetland of 153000 hectares where the ancient Yellow River enters the sea in northern Shandong Province. The raging river rushes through here and flows into the sea. This is the Yellow River Delta Nature Reserve, established by 1987 to protect wetland ecosystems and rare and endangered birds.

The Yellow River Delta, with Ninghai in Kenli County as the axis, starts from the mouth of Taoer River in the north, reaches the mouth of Zimai River in the south, and spreads eastward, showing a fan-shaped terrain. The elevation is below 15m, with an area of 5,450km2, which is the youngest land in China. Modern Yellow River Delta is an alluvial fan formed by Yellow River alluvial action since 1855.

The Yellow River Delta Nature Reserve is only 60 kilometers away from Dongying City, with a temperate monsoon continental climate, four distinct seasons, abundant sunshine and the same period of rain and heat, with an average annual precipitation of 5565438 0.6 mm. This delta is a marine sedimentary plain filled with a large amount of sediment carried by the Yellow River. The landforms of the modern Yellow River Delta include floodplain highlands, sloping fields and large depressions. The new land belt formed by the swinging of the Yellow River is wide and low-lying. The area is expanding year by year, and the ecological type is unique. A large area of shallow sea beaches and wetlands has been formed at the intersection of Haihe River, which has become an important "transit station" and wintering breeding ground in the inland of Northeast Asia and bird migration around the western Pacific Ocean. According to the preliminary investigation, there are more than 800 kinds of aquatic organisms in this area, including amphioxus, finless porpoise and Songjiang perch. There are hundreds of wild plants here, and wild soybeans are endangered plants protected by the state and widely distributed. There are about 187 species of birds, of which 108 species are listed in the Sino-Japanese Migratory Birds Protection Agreement, including 32 species of national key protected wild animals such as red-crowned crane, white stork, golden eagle, great bustard, swan, cygnet, grey crane and bee eagle, and various water animals such as heron, goose and duck.

The modern Yellow River Delta has a unique landscape, vast and young land, novel natural landscapes such as trees, grasslands and wild animals, and strong wild interest. The exotic "Tao Jin" pierced the blue sea, forming a rare spectacle in the world. It is rich in oil and natural gas resources. There are many derricks in Shengli Oilfield, including Dongying Bridge, dampproof dike and other magnificent modern projects, as well as Dongying, a new oil industrial city rich in natural resources. It is a treasure house of the motherland and has broad development prospects.

The Yellow River is a river that is good at siltation, decision and migration. It carries about 65.438+0.6 billion tons of sediment downward every year, and the sediment in the estuary delta and coastal areas is about 65.438+0.2 billion tons. On average, 654.38+0.5-3 kilometers are pushed to the Bohai Sea every year, and 23-28 square kilometers of land are newly built every year, so that 30,000-40,000 mu of sea area is silted up into new land resources. Today's mulberry garden can be realized here. This advantage has injected new vitality into conservation. Whether it is used as a resting place and wintering habitat for rare birds or as a unique estuary ecosystem, it has great scientific value and ecological significance.