According to the study of geological evolution history, the Yellow River is a relatively young river. In the late Early Pleistocene, 1 15000 years ago, there were only some unconnected lake basins in the basin, each of which formed an independent internal water system. Since then, with the uplift of the western plateau, rivers have been eroded and eroded. After the Middle Pleistocene of 654.38+0.05 million years, lakes and basins have been gradually connected, forming the embryonic form of the Yellow River system. It was not until the Late Pleistocene (654.38+ 10,000 years ago) that the Yellow River gradually evolved into a big river running up and down from the source to the estuary.
Because the flood of the Yellow River carries a lot of sediment, it quickly silts up after entering the downstream plain, and the mainstream wanders in the overflow area, people begin to build dikes for flood control, and the flood channel keeps silting up and rising, becoming an "overground river" higher than the two banks. Under certain conditions, it will overflow the flood and take a new road. The severity of river migration in the lower Yellow River is unique in the world. According to written records, the Yellow River has been diverted many times. The river changes from Zhengzhou in the west, Tianjin in the north and Jianghuai in the south, covering an area of 250,000 square kilometers. During the period from the 5th year of Zhouding (602 BC) to the 2nd year of Jianyan in the Southern Song Dynasty (1 128) 1700, the migration of the Yellow River was mostly in the area north of the present river, invading the Haihe River system and flowing into the Bohai Sea. During the 700 years from 1 128 to 1855, the Yellow River oscillated in the south of the current channel, invaded the Huaihe River system and flowed into the Yellow Sea. 1855, the Yellow River burst at Dongbatou, Lankao, Henan Province, and later diverted to capture the Daqing River in Shandong Province and enter the Bohai Sea. Due to the constant change and diversion of the lower reaches of the Yellow River, as well as the influence of transgression and regression, the length and basin area of the lower reaches of the Yellow River are also constantly changing, which is one of the outstanding characteristics that distinguish the Yellow River from other rivers. The middle and lower reaches of the ancient Yellow River had mild climate and abundant rainfall, which was suitable for primitive human survival. The loess plateau and the alluvial plain of the Yellow River have loose soil and are easy to cultivate, which is suitable for developing primitive agriculture and animal husbandry. The characteristics of loess are beneficial for our ancestors to dig holes and live together. The special natural geographical environment provided good conditions for the development of ancient civilization in China. As early as 165438+ million years ago, "Lantian people" lived in the Yellow River basin. There are also "Dali people", "Dingcun people" and "Hetao people" living in the basin. Yangshao culture, Majiayao culture, Dawenkou culture, Longshan culture and many other ancient cultural sites are spread all over the country. These ancient cultural relics are not only numerous and complete in variety, but also developing from far to near, systematically demonstrating the development process of ancient civilization in China.
As early as 6000 years ago, agricultural activities began to appear in the basin. About 4000 years ago, some blood tribes were formed in the basin, among which Yan Di and Huangdi were the most powerful tribes. Later, the Yellow Emperor gained the position of leader and merged with other tribes to form the "Huaxia nationality". Later generations regard the Yellow Emperor as the ancestor of the Chinese nation. There is the Huangdi Palace in xinzheng city, Henan Province, and the Huangdi Mausoleum in huangling county, Shaanxi Province. Chinese people all over the world regard the Yellow River Basin as the cradle of the Chinese nation, calling it "Mother River" and "Four Shames", and regard the yellow land as their "root".
From the Xia Dynasty in the 2nd/kloc-0th century BC, in the historical period of more than 4,000 years, the dynasties established their capital in the Yellow River basin for more than 3,000 years. Among the "seven ancient capitals" in the history of China, Anyang, Xi, Luoyang and Kaifeng are located in the Yellow River Basin and its adjacent areas. A large number of Oracle Bone Inscriptions remains in Yindu (which belonged to the Yellow River valley at that time), creating a precedent for written records in China. Xi 'an (including Xianyang), from the Western Zhou Dynasty, Qin Dynasty and Han Dynasty to Sui Dynasty and Tang Dynasty, has 13 dynasties as its capital, and has a history of thousands of years. It is a famous "Eight Rivers Imperial Capital". After the Eastern Zhou Dynasty moved its capital to Luoyang, the Eastern Han Dynasty, the Wei Dynasty, the Sui Dynasty, the Tang Dynasty, Hou Liang and the Hou Zhou all established their capitals in Luoyang, which lasted for more than 900 years and was known as the "ancient capital of nine dynasties". Kaifeng, located on the south bank of the Yellow River, was called Bianliang in ancient times. During the Spring and Autumn Period, Wei Huiwang moved its capital to Daliang, and the capital was established here in the Northern Song Dynasty, which lasted about 200 years. For a long time, the political, economic and cultural center of China has been in the Yellow River Basin. The middle and lower reaches of the Yellow River are the earliest areas for the development of science, technology, literature and art in China. Around 2000 BC, bronzes appeared in the basin, and the bronze smelting technology of Shang Dynasty reached a fairly high level, and iron smelting began to appear at the same time, marking the development of productive forces to a new stage. The shovel and iron axe unearthed in Luoyang after a series of treatments show that China developed the softening technology of cast iron more than 2000 years earlier than European countries. China's ancient "four great inventions"-papermaking, movable type printing, compass and gunpowder-all originated in the Yellow River basin. A large number of literary classics, from the Book of Songs to Tang poetry and Song poetry, and a large number of cultural classics are also produced here. After the Northern Song Dynasty, the national economic center of gravity gradually shifted to the south, but in the process of China's political, economic and cultural development, the Yellow River basin and the plain area in the lower reaches of the Yellow River are still in an important position. The long history of the Yellow River Basin has left a very precious legacy to the Chinese nation, leaving countless places of interest, which is the pride of our nation.
The Yellow River is the second longest river in China, second only to the Yangtze River, with a total length of 5,464 kilometers. It zigzagged through Qinghai, Sichuan, Gansu, Ningxia, Suiyuan, Shaanxi, Shanxi, Henan and Shandong provinces, and flowed eastward into the Bohai Sea, where more than 30 major tributaries and countless streams gathered along the way, with a drainage area of more than 750,000 square kilometers. The middle reaches flow through the vast loess plateau, and many tributaries carry a lot of sediment into it, which is the river with the largest sediment concentration in the world. This river is yellow, hence its name.
The Yellow River originates from the Zhanzonglie Canal at the northern foot of Bayan Kara, Qinghai, with an altitude of more than 5,400 meters, and the surrounding mountains are covered with snow all year round. There is a sea of stars at the source of the Yellow River, which is a swamp of countless small lakes. After leaving Xinghai, enter Eling Lake and Zhaling Lake to Maduo, bypass Jishishan and Xiqingshan, and cross Longyangxia to Guide, Qinghai, with a total length of 1900 kilometers. The upstream section is from Guide to Hekou Town, Suiyuan Province, with a total length of 1500 kilometers. The Yellow River is in Gansu, passing through many grand canyons and gathering many tributaries. The middle reaches from Hekou Town to Yujin, with a total length of 1 100 kilometers. The river flows south through the Loess Plateau, carrying a lot of sediment, rushing down to Hukou, where the terrain is steep, forming Hukou Waterfall, and then passing through Longmen Gorge to Tongguan, the river channel becomes wider, and the water volume increases greatly because of the confluence of Qin Fen, Luohe and Xiaoshui tributaries. When the river reaches Tongguan, it is blocked by Huashan Mountain, turns east, crosses Sanmenxia to Luo Yu, and then enters the plain area. The downstream section flows into the Bohai Sea from Jinmeng to Lijin County, Shandong Province, with a total length of more than 870 kilometers. Due to sediment deposition and slow water flow, dikes were built on both sides of the river, which became a "river above the ground".
The headwaters and upper reaches of the Yellow River are the most tortuous, followed by the middle reaches, and the lower reaches are straight. From Lanzhou to Tongguan, the river bypasses a rectangle on three sides, which is the famous Hetao, about 2000 kilometers long. In ancient times, rivers drifted downstream. This river sometimes flows into the Bohai Sea in the northern part of Shandong hills, and sometimes takes the Huaihe River in the southern part of Shandong hills and flows into the Yellow Sea, with a distance of 500 kilometers.
Harnessing the Yellow River and building water conservancy have a long history.
The earliest irrigation project in China was the pond in the Yellow River Basin (now southwest of Xianyang, Shaanxi Province), and it was recorded in The Book of Songs that "the pond flows northward and wets the paddy fields". In the early Warring States period, large-scale water diversion and irrigation projects began to appear in the Yellow River basin. In 422 BC, Ximen Bao built twelve canals by imperial edict, leading to Zhanghe River, a tributary of the Yellow River at that time, to irrigate farmland. In 246 BC, Qin built the Zheng Guoqu in Shaanxi and irrigated more than 40,000 hectares of land with Jinghe River. "So the guanzhong fertile soil, no fierce years. Qin Fuqiang died as a vassal. " It played an important role in the process of Qin's unification of China.
The Han Dynasty paid more attention to farmland water conservancy, built six auxiliary canals and white canals, and expanded the irrigation area of Zheng Guoqu. At the same time, Guo Cheng Canal and Lingbi Canal were built on the Weihe River, and Guanzhong area became the earliest economic zone in China. In order to consolidate the frontier, the policy of reclaiming farmland and guarding the frontier was implemented from Qin and Han Dynasties, and canals were opened to irrigate fields in Huangshui River Basin and Ningmeng Hetao Plain along the Yellow River, which turned a large desert into a green state and won the reputation of "being on the south of the Yangtze River". In order to ensure the supply of Kyoto such as Chang 'an, Luoyang and Kaifeng, the water transport development in the middle and lower reaches of the Yellow River has a long history. Dayu's achievements in harnessing water also include harnessing the Yellow River, and his "magic power" is found almost everywhere. After the Spring and Autumn Period and the Warring States Period, the documentary records of river regulation gradually increased, and a large number of precious historical materials were preserved.
As early as the Spring and Autumn Period and the Warring States Period, dikes were generally built in the lower reaches of the Yellow River. In 65 1 year BC, Qi Huangong, one of the five tyrants in the Spring and Autumn Period, put forward an "irresistible" ban to solve the dispute of embankment construction among vassal states. In the long historical period since then, with the frequent flooding and diversion of the Yellow River, defending against the Yellow River floods has become a major event of successive dynasties, and a lot of manpower and financial resources have been invested to continuously block the mouth and repair the defense. In the Western Han Dynasty, there were official positions such as "River Embankment Builder" and "River Embankment Man", and all county governors along the river had the responsibility of guarding the river embankment, with thousands of full-time personnel guarding the river embankment. "Ten counties near the river, heavily treating the river embankment", the river defense project has been quite large. According to Hanshu? According to Gou's records, the Yellow River has become a "river on the ground" up and down the Qishuikou (now southwest of hua county), and its embankment is "four or five feet high" (about 9~ 1 1 m), and its embankment is also very high. Historical records? It is recorded in Hequ Book that in 109 BC, Emperor Wu of the Han Dynasty ordered "Renji and Guo Chang to send tens of thousands of people to stop floods" and personally led his ministers to the scene to participate in flood control. It can be seen that flood control of the Yellow River is already a quite huge project. The earliest large-scale river regulation project recorded in Historical Records was "Wang Jing River Regulation" in 69 AD, "Yongping 12 years, and it was planned to build a branch canal", "sending hundreds of thousands of soldiers to build a dike with Wu Wang, and building a dike from Xingyang to Haikou thousands of miles east". "In the summer and April of the 13th year of Yongping, a branch canal was built ... Zhao Yue said:' ... Now, the embankment has been built, the canal has been rectified, the water has been cut off, the gate has been set up, the rivers and tributaries have been diverted, and its old traces have been restored'". Although the scene saves the service fee, it is still tens of billions. The invasion of the Yellow River south was curbed, and the water transport in the side canal was resumed, which achieved good results.
Kaifeng, the capital of the Northern Song Dynasty, was seriously flooded by the Yellow River. The Song Dynasty attached great importance to river management, and set up a water superintendent with greater authority to be responsible for river management. Local officials along the river attach importance to river affairs, and set up river bank judges in each state to be responsible for river affairs. The imperial court was very important and participated in the debate on river regulation strategy. During this period, the problem of river regulation has aroused many people's discussion, deepened their understanding of the situation and water situation of the Yellow River, and made great progress in river engineering technology. In particular, Wang Anshi presided over the mechanical dredging of rivers, diverting water from the Yellow River and developing silt irrigation, and made many innovations in river management technology.
After the Ming Dynasty, with the development of social economy and the aggravation of the flood disaster of the Yellow River, the imperial court paid more attention to river management, and the river management institutions were gradually improved. In the Ming Dynasty, the Ministry of Industry was in charge of river management, and the prime minister was directly responsible for the river. Later, the Prime Minister added the title of military affairs to the river channel, so that he could directly command the army. Local officials below the governor of the provinces along the river also had the responsibility of river channel management, which strengthened the unified management of downstream river channel affairs. In the Qing dynasty, the governor of the river channel had greater authority and was directly ordered by the court. In the late Ming and early Qing Dynasties, the river regulation made great progress, and the technology of dike maintenance and management made great progress. A group of effective river regulation experts, represented by Pan Jixun and Jin Fu, emerged. During the late Qing Dynasty and the Republic of China, wars continued, the national government declined, and river management was at a standstill. In modern times, water conservancy experts, represented by Zhang and Zhang, strongly advocated the introduction of western advanced technology and studied the comprehensive management strategy of the Yellow River, but it was always difficult to make achievements due to the constraints of social and economic cooperation.
Throughout the history of harnessing the Yellow River, before the founding of the People's Republic of China, the so-called river harnessing was actually limited to the lower reaches of the Yellow River, and it was mainly passive flood prevention. However, the long history of river management has left many documents and classics, which are rare for other rivers in the world. This is a valuable legacy, which deserves our further study and reference. Yangtze River: The Yangtze River is the largest river in China, with a total length of 6,397 kilometers (from Tuotuo), which is generally called 6,300 kilometers. The total area of the river basin is1800,000 square kilometers, and the annual water inflow into the sea is about 960 billion cubic meters. In terms of the length of the main stream and the amount of water entering the sea, the Yangtze River ranks third in the world.
Tuotuo River, the upstream source of the Yangtze River, originated from the Gladin Winter Snow Mountain in Tanggula Mountain on the southwest border of Qinghai Province, and was called Tongtian River after meeting with the south source of the Yangtze River. From Batang estuary in Yushu county to Yibin city in Sichuan province, it is called Jinsha River. Yibin is called the Yangtze River and Yangzhou is called the Yangtze River. The Yangtze River flows through Tibet, Sichuan, Chongqing, Yunnan, Hubei, Hunan, Jiangxi, Anhui, Jiangsu and other provinces and cities and joins the East China Sea in Shanghai. There are tributaries such as Yalong River, Minjiang River, Tuojiang River, Jialing River, Wujiang River, Xiangjiang River, Hanjiang River, Ganjiang River, Qingyi River and Huangpu River. It intersects with the Beijing-Hangzhou Grand Canal in Zhenjiang City, Jiangsu Province.
The upper reaches of the Yangtze River are above Yichang City, Hubei Province, with many rapids. Yichang to Hukou in Jiangxi is the middle reaches, with meandering development and numerous lakes (Poyang Lake and Dongting Lake are the largest). Below the mouth of the lake is the downstream, the river is wide, and Chongming Island is alluvial at the mouth of the river. The Yangtze River is rich in water resources. During the flood season, 10,000-ton ships can reach Wuhan, and boats can trace back to Yichang.
The Yangtze River valley is a densely populated and prosperous area in China, and Chongqing, Wuhan, Nanjing and Shanghai are important cities along the Yangtze River.
The Yangtze River is the most abundant river in China, with a total hydropower capacity of 200 million kilowatts. The main stream of the Yangtze River has a navigable mileage of more than 2,800 kilometers and is known as the "golden waterway".
The Yangtze River is a steep Three Gorges (Qutang Gorge, Wuxia Gorge and Xiling Gorge) in Duan Xiongwei from Fengjie in Chongqing to Yichang in Hubei. The Three Gorges Project, the largest water conservancy project in the world, is located in Sandouping in the middle of Xiling Gorge.
The Yangtze River is the largest river in China and one of the largest rivers in the world, with a total length of more than 6,300 kilometers. It originated in the southwest of the main peak of Tanggula in Qinghai-Tibet Plateau-Geladan Winter Snow Mountain (33 28 ′ north latitude, 965 438+0 08 ′ east longitude). The main stream flows through Qinghai, Tibet, Sichuan, Yunnan, Hubei, Hunan, Jiangxi, Anhui, Jiangsu, Shanghai and other provinces, municipalities and autonomous regions 10 and flows into the East China Sea. The total length is about 6,300 kilometers (if Dangqu is the source, the total length of the Yangtze River should be 6,403 kilometers), ranking third in the world. The basin is located between 24 30 ′ and 35 45 ′ north latitude and 90 33 ′ and 65 438+065 438+02 25 ′ east longitude, with an area of 65 438+800,000 square kilometers (excluding Huaihe River Basin), accounting for about 65 438+0 of the total land area of China. The average annual water inflow into the sea reaches 1 trillion cubic meters, ranking third in the world. In ancient times, it was called Jiang for short, and it was called Dajiang and Changjiang only after the Six Dynasties.
General situation of the main stream The name of the main stream of the Yangtze River is different: the source to Dangqukou (called "Qu" River in Tibetan) is Tuotuo, which is the main source of the Yangtze River, with a total length of 358 kilometers; From Dangqukou to Batang Estuary in Yushu County, Qinghai Province, it is called Tongtianhe, with a length of 8 13 km; Batangkou to Minjiang Estuary in Yibin, Sichuan, known as Jinsha River in ancient times, is 2308 kilometers long; Yibin's Minjiang River estuary is about 2800 kilometers away from the Yangtze River estuary, commonly known as the Yangtze River. Yibin and Yichang in Hubei Province are called "Chuanjiang" (the Three Gorges section from Fengjie to Yichang is also called "Xiajiang"), Zhicheng in Hubei Province is called Jingjiang, and Yangzhou and Zhenjiang in Jiangsu Province are also called Yangtze River below. Plateau and mountainous areas account for 65.6% of the basin area; Hills account for 24%; Plains and lowlands account for 10.4%.
There are 48 tributaries of the Yangtze River, covering an area of 6.5438+0 million square kilometers; More than 50,000 square kilometers are Yalong River and Minjiang River and their tributaries, including Dadu River, Jialing River, Wujiang River, Yuanjiang River, Xiangjiang River, Hanjiang River and Ganjiang River. Among them, the Yalong River, Minjiang River, Jialing River and Hanjiang River are more than 65,438+10,000 square kilometers, and the Jialing River basin has the largest area, about160,000 square kilometers.
Most of the freshwater lakes in China are distributed in the middle and lower reaches of the Yangtze River, with Poyang Lake, Dongting Lake, Taihu Lake and Chaohu Lake in larger areas.
The Yangtze River originates from the Qinghai-Tibet Plateau between Bayan Kara and Tanggula Mountain, on the southwest side of Gladin, the main peak of Tanggula Mountain. Glaciers are widely distributed here, and meltwater from snow and ice is the source of the Yangtze River. From Jiangyuan to Haikou, it can be divided into three sections. Above Yibin, Sichuan, it is upstream; Yibin, Hubei to Yichang is the middle reaches; Below Yichang is the downstream. The upper reaches are about 3,500 kilometers long, and the Chumar River is the northern source of the Yangtze River. Muluwusu River is the southern source of the Yangtze River, with long water flow and large water volume. According to the principle that the source of the Yangtze River is only far away, Tuotuo River, its longest tributary, should be the positive source of the Yangtze River. The section from the mouth of Dangqu River to Yushu in Qinghai is called Tongtianhe, which is 8 13 kilometers long. The river is wide and the water is slow. From Yushu to Yibin, it is called Jinsha River, which was called Lishui in ancient times. From north to south, it crosses the Hengduan Mountains, turns northeast near Shigu in Yunnan, enters the Sichuan Basin, and joins the Minjiang River in Yibin, with a total length of 2,300 kilometers. Known as the Yangtze River after Yibin. The middle reaches are about 1000 km long. Because they flow through the Sichuan Basin, they are often called Chuanjiang. From Yibin to Chongqing, the river is quite tortuous. This river runs from Baiti Mountain in Fengjie to Nanjinguan in Yichang, passing through the Grand Canyon in the mountainous area at the junction of Sichuan and Hubei. From west to east, there are Qutang Gorge, Wuxia Gorge and Xiling Gorge, collectively known as the Three Gorges, with a total length of 204 kilometers. There are rapids everywhere on the beach, and the river gap is very large. It has been called the natural barrier of the Yangtze River since ancient times. The downstream section is about1850km long, with small river drop, slow water flow and wide river surface, generally more than 2km, and the narrowest part is 650m. The river course is very tortuous, especially the section from Zhijiang, Hubei Province to Chenglingji, Hunan Province, which was called Jingjiang in ancient times and is known as the "nine-bend ileum". Due to the slow flow rate and excessive sediment deposition, whenever the flood season comes, it is easy to cause flood disasters. Since ancient times, there has been a saying that "a long river travels a thousand miles, and the danger lies in Jingjiang". From Yichang to Wuhu, there are many lakes on both sides of the strait, among which Dongting Lake and Poyang Lake are the largest. Dongting Lake is the natural reservoir of the Yangtze River. After the river entered Jiangsu, it bypassed Ningzhen Mountain to the northeast because of mountain resistance. Turn from Zhenjiang below to southern Sichuan and enter the delta region. The terrain is flat, the lakes are dotted, and the waterways are intertwined like a net, which is a scene of water towns and villages. The mouth of the river is 80 kilometers wide, showing a spectacular view of the river and the sea. There are many famous osawa on both sides of the Yangtze River, with beautiful scenery and many tourist attractions. Because of the long process, wide river basin, fertile land and convenient irrigation, there is a "land of abundance" in the middle reaches and a "land of plenty" in the lower reaches, which is rich in products. Although the cradle of the Chinese nation is in the Yellow River Basin, according to historical records, after the Yin Dynasty was destroyed, the territory reached the Yangtze River Basin in the south, and then the Yellow River and the Yangtze River Basin became the focus of China's historical and cultural development. There are many famous cities along the river, such as Chongqing, Yichang, Wuchang, Nanjing and Shanghai. Shanghai is the largest industrial and commercial city in China. There are many places of interest on both sides of the Taiwan Strait, which are valuable materials for understanding the history of China, and there are also many myths and legends, which are valuable heritages of China literature. Since ancient times, the trunk and tributaries of the Yangtze River have been the main artery of water traffic in southern China, crossing east and west, running through north and south, with a total length of more than 80 thousand kilometers. Ten thousand-ton ships can reach Nanjing, 3000-ton ships can reach Hankou, 1000-ton ships can reach Chongqing, and 500-ton ships can reach Yibin.
■ Plain in 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. 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. Large lakes, including small lakes, have an area of10.3 million square kilometers, accounting for more than 20% of the plain area of the two lakes, which is 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 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 and are known as the land of plenty. It is one of the most economically developed areas, including Shanghai, Nanjing, Wuhan, Nanchang, Suzhou, Wuxi, Changzhou, 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.