"A bridge flies north and south, and Tianzhu becomes a thoroughfare."

Looking at Tianmen Mountain by Li Bai

"Tianmen broken Chu River, Higashi Shimizu flow at this point. The green hills on both sides of the strait are opposite, and the sails are alone. "

-dangtu county, Anhui Province on both sides of the Yangtze River, and Liangshan and Xiliangshan in Hexian County.

Linjiangxian

The third paragraph of "Twenty-one History Tanci" said the prologue of Qin and Han Dynasties (2)

short for Shenyang/a surname

Rolling the Yangtze River eastward,

The waves washed away the hero.

Right or wrong, success or failure,

Castle peak is still there,

A touch of sunset red.

White-haired fishing fires in Zhu Jiang,

I am used to watching the autumn moon and the spring breeze.

A pot of turbid wine likes to meet,

How many things have happened since ancient times,

This is all a joke.

Du Fu

Endless forests shed leaves one after another; The endless river rolls its waves all the time.

Clear sky Ren Shang's "Looking at the Great River in Beigushan"

The lonely city is surrounded by mountains, and the top of the mountain is located in high autumn. Seeing the Yangtze River rushing into the sea, the sky seemed to fly to the west.

The surging river flows eastward, and those heroes of the past are gone forever. Su Shi's Niannujiao Chibi Nostalgia.

The stars leaned down from the clearing, and the moon came running from the river.

Leaves fall like a waterfall, and I watch the long river always roll on Du Fu and climb up the mountain.

The lonely sail is far away, but I can send Meng Haoran to Guangling in the sky of the Yangtze River.

Tianmen breaks the Chu River, and Higashi Shimizu flows back to Li Baiwang Tianmen Mountain.

The mountain is flat and primitive, and the river flows into the river (Li Bai's "Seeing Friends Off at Jingmen Ferry")

The largest river in the country. Originated in the southwest of Gladang East, the main peak of Tanggula in Qinghai-Tibet Plateau. The mainstream winds eastward from the Qinghai-Tibet Plateau, passes through Qinghai, Xizang Autonomous Region, Sichuan, Yunnan, Hubei, Hunan, Jiangxi, Anhui, Jiangsu and Shanghai, and flows into the East China Sea in Shanghai. The total length is 6300 kilometers. The basin area is 1.8 million square kilometers, accounting for 1/5 of the national area.

river source

There are different opinions about the source of the Yangtze River since ancient times. There are two opinions about the source of the Yangtze River in some modern geographical works: one is that "all rivers are of the same origin", both the Yangtze River and the Yellow River originate in Bayan Kara, the Yangtze River originates in the southern foothills and the Yellow River originates in the northern foothills. The other is that the Yangtze River originates from Mount Kekexili. There are two sources: Murusu River in the south and Chumar River in the north. In the summer of 1976 and 1978, the Yangtze River Basin Planning Office organized Jiangyuan investigation teams twice, went deep into the Jiangyuan area, conducted detailed field visits, and found out the Jiangyuan water system and its source. The upper reaches of the Yangtze River are located between Kunlun Mountain and Tanggula Mountain, and there are many rivers, among which the largest are Chuma River, Tuotuo River and Dangqu River. Among them, both the basin area and the water quantity are the largest in Dangqu. According to the principle that "the source of the river is only far away", Tuotuo River is determined as the positive source. There is Dangqu in the south and Chumar River in the north. In Jiangyuan area, there are more than 40 snow-capped mountains above 6000 meters above sea level. The temperature is low and the four seasons are like winter. The annual precipitation is 200 ~ 400 mm, mainly snowfall. The average temperature in July is lower than 0℃. Only under the strong radiation of the sun during the day can the temperature reach above 0℃, and the trickle formed by the melting of ice and snow becomes the original water source of the Yangtze River.

main stream

From the source of the Yangtze River to the estuary, it crosses three huge steps in China's topography, passes through different geological structures and strata, and receives tributaries along the way, which has different influences on the valley shape and flow characteristics of the Yangtze River. According to the hydrological and geomorphological characteristics, the main stream is divided into three sections: the upper reaches from Heyuan to Yichang, the middle reaches from Yichang to Hukou, and the lower reaches below Hukou.

① Upstream part. The upper reaches of the river span two topographical steps. The total length is 4529 kilometers, accounting for 72.0% of the length of the Yangtze River. The basin area is 6.5438+0.006 million square kilometers, accounting for 55.6% of the basin area. Tuotuo River and the upper reaches of Tongtian River (from Nangji Balong to Batang Estuary) are the hot spots in the hinterland of Qinghai-Tibet Plateau, the first step. Because at the top of the plateau, the river valley is wide and shallow, generally the river width is 300 ~ 1700 meters, the river is winding, the water is slow and scattered, and there are many tributaries. From Batang estuary to Yibin, it is called Jinsha River, which is the transition section from the first step to the second step. The terrain here is steep, with high mountains and deep valleys. Except for the wide river valley in some areas, the river runs through the canyon with a large slope and the river is swift. Below the stone drum in Yunnan, it suddenly turns to the northeast, and the famous Tiger Leaping Gorge is 35 kilometers below the stone drum. The canyon is 16 km long, and the narrowest part is only 30 meters. Leave the Tiger Leaping Gorge, cross the northern Yunnan-Guizhou Plateau, enter the second step below the new town of Sichuan Province, and gather the Minjiang River near Yibin, which is called the Yangtze River. Yibin to Yichang is 1030 km long, which is customarily called Chuanjiang. The river twists and turns in Sichuan Basin, and the riverbed is gentle. Along the way, many tributaries, such as Tuojiang River, Jialing River and Wujiang River, were accepted, and the water volume increased greatly and the river surface widened. The Yangtze River flows through Baidicheng in Fengjie, East Sichuan, passes through the transition section from the second step to the third step, and passes through three anticlines and two synclines in July, Wushan and Huangling, forming the world-famous Three Gorges of the Yangtze River (Qutang Gorge, Wuxia Gorge and Xiling Gorge), with a total length of about 200 kilometers, and canyons and wide valleys are arranged alternately.

② Middle reaches. The Yangtze River leaves the Three Gorges below Yichang and enters the middle and lower reaches of the Yangtze River at the third level. The river widens, the water flows slowly and the river bends. It is 927 kilometers long, accounting for 14.7% of the length of the Yangtze River. The basin covers an area of 679,000 square kilometers, accounting for 37.6% of the basin area. Among them, the section from Zhicheng in Hubei to Chenglingji in Hunan is about 420 kilometers long. Because it was Jingzhou area in ancient times, it was named Jingjiang. Jingjiang River is divided into Upper Jingjiang River (from Zhicheng to Ouchikou) and Lower Jingjiang River (from Ouchikou to Chenglingji). The bend of the lower Jingjiang River is developed, and it is known as the "nine-bend ileum". There are many lakes on both sides of the middle reaches, which are connected by rivers and lakes, forming two huge water systems, Dongting Lake and Poyang Lake. After the Yangtze River accepted the water directly from two major river systems and tributaries, the water volume more than doubled. Enter the downstream section below hukou.

③ downstream section. The water depth is wide, from the mouth of the lake to the mouth of the sea, 844 kilometers long, accounting for 13.3% of the length of the Yangtze River. The basin area is 6.5438+0.23 million square kilometers, accounting for 6.8% of the basin area. The main stream of the Yangtze River is also called the Yangtze River in Yangzhou and Zhenjiang, Jiangsu Province. In ancient times, it was named after Yangtze Tianjin and Yangzi County. Now foreigners often use the name Yangtze River to refer to the whole Yangtze River. Affected by the tides below Datong, the average tidal current entering the Yangtze River estuary reaches 266,000 cubic meters per second, which is 8.8 times of the annual flow into the sea of the Yangtze River. Under normal circumstances, the total amount of water coming from a tidal wave is about 3.25 billion cubic meters, and it can reach 4.5 billion cubic meters during the spring tide. Due to the backward flow of seawater, the flow speed of the river slows down, and the sediment carried by it is deposited in the downstream reach, especially near the estuary. So dozens of sandbars of different sizes have been formed in the middle of the river, the largest of which is Chongming Island.

Runoff resources and hydraulic resources

The basin is located at 24 27 ′ ~ 35 54 ′ north latitude and 90 33 ′ ~12219 ′ east longitude. Located in the East Asian monsoon region, most areas belong to subtropical monsoon climate, except for a few areas with plateau cold climate. There is abundant precipitation, with an average precipitation of 1057mm. Rainfall is the main source of recharge for most rivers except for the heavy snowfall in the Jiangyuan area of the Qinghai-Tibet Plateau. Runoff mainly comes from upstream and middle reaches, accounting for 47. 1% and 47.2% respectively, while the downstream only accounts for 5.7%. The average annual runoff for many years is 975.5 billion cubic meters. The installed capacity of exploitable hydropower resources is about 65.438+0.97 billion kilowatts, and the annual power generation is about 654.38+0 trillion kilowatts, accounting for 53.4% of the national exploitable hydropower resources. Hydraulic resources are mainly concentrated in the upper reaches above Yichang, accounting for 8 1.5% of the basin.

The main stream of the Yangtze River has a long history, with numerous tributaries and abundant water. It doesn't freeze all year round. The navigation mileage of the main stream is 70,000 kilometers, and the navigation channel available for motor boats is about 30,000 kilometers. The main stream of 3,000 kilometers below Yichang can be used by ships, and the 10,000-ton seagoing vessel can reach Nanjing directly. At the same time, the main stream is connected with the ocean, which not only facilitates the connection between the basin and the coastal areas, but also carries out economic and trade exchanges with foreign countries, so it is called the golden waterway.