The Yellow River, also known as Huang he, is the second-longest river in China and the sixth-longest in the world, with an estimated length of and a drainage basin of . Beginning in the Bayan Har Mountains, the river flows generally eastwards before entering the long Ordos Loop, which runs northeast at Gansu through the Ordos Plateau and turns east in Inner Mongolia. The river then turns sharply southwards to form the border between Shanxi and Shaanxi, turns eastwards at its confluence with the Wei River, and flows across the North China Plain before emptying into the Bohai Sea. The river is named for the yellow color of its water, which comes from the large amount of sediment discharged into the water as the river flows through the Loess Plateau.

The Yellow River basin was the birthplace of ancient Chinese civilization. According to traditional Chinese historiography, the Xia dynasty originated on its banks around 2100 BC; Sima Qian's Shiji () record that the Xia were founded after the tribes around the Yellow River united to combat the frequent floods in the area. The river has provided fertile soil for agriculture, but since then has flooded and changed course frequently, with one estimate counting 1,593 floods in the 2,540 years between 595 BC and 1946 AD. As such, the Yellow River has been considered a blessing and a curse throughout history, and has been nicknamed both "China's Pride" and "China's Sorrow".Cheng, Linsun and Brown, Kerry (2009) Berkshire encyclopedia of China, Berkshire, p. 1125

The Yellow River's basin presently has a population of 120 million people, while over 420 million people live in the immediate provinces which rely on it as a water source. The basin comprises 13 percent of China's cultivated land area. The area receives uneven rainfall, only 2 percent of China's water runoff—water and sediment flow has decreased five-fold since the 1970s, and until recently, the river frequently did not reach the sea. Since 2003, China has been working on the South–North Water Transfer Project to alleviate the strain on the river's water supply.

Etymology When the Yellow River was still somewhat clear, it was simply referred to as 'the river' (, Old Chinese: ). Observations made at the Yumenkou gorge, where the river leaves the modern Loess Plateau, indicated the river changed to muddy sometime between 367 BC and 165 AD, according to chronicles' records. The alternative names 'murky river' (, ) and '(muddy) yellow river' (, ) were attested in 145 BC. As cited in Sima Qian (author), Burton Watson (translator). (1971). Records Of The Grand Historian Of China: Translated from the Shih-chi of Ssu-ma Ch'ien, "Vol. I". New York: Columbia University Press. p. 109. quote: "But the lands of Ch'i too has its rich fields in Lang-ya and Chi-mo in the east, the fastnesses of Mount T'ai in the south, in the west the banks of the muddy Yellow River, and in the north the resources of the Gulf of Pohai." and in 429 AD respectively. The name Yellow River fully replaced Murky River by the end of Tang dynasty, for unclear reasons.

In the Shaanxi loess plateau, it is referred to as 'river, my lord' (, ) in the Jin language. In Mongolian, it is called ( 'yellow river') or Khatan gol ( 'queen river'). The river is mentioned in the Kul Tigin stele as the 'green river' (Old Turkic: yašïl ügüz, 𐰖𐱁𐰞𐰽𐰺𐰍).the Kultegin stele (side I), line 17 The Tibetan name is "River of the Peacock" (; ).

History

Dynamics

The river has long been critical to the development of northern China, and is regarded by scholars as a cradle of civilization. Flooding of the river has also caused much destruction, including multiple floods that have resulted in the deaths of over one million people. Among the deadliest were the 1344 Yellow River Flood, during the Yuan dynasty, the 1887 flood during the Qing dynasty which killed anywhere from 900,000 to 2 million people, and a Republic of China era 1931 flood (part of a massive number of floods that year that killed 1–4 million people).

The cause of the floods is the large amount of fine-grained loess carried by the river from the Loess Plateau, which is continuously deposited along the bottom of its channel. The sedimentation causes natural dams to slowly accumulate. These subaqueous dams are unpredictable and generally undetectable. Eventually, the enormous amount of water needs to find a new way to the sea, forcing it to take the path of least resistance. When this happens, it bursts out across the flat North China Plain, sometimes taking a new channel and inundating most farmland, cities or towns in its path.

The traditional Chinese response of building higher and higher levees along the banks sometimes also contributed to the severity of the floods: When flood water did break through the levees, it could no longer drain back into the river bed as it would after a normal flood, as the river bed was sometimes now higher than the surrounding countryside. These changes could cause the river's mouth to shift as much as , sometimes reaching the ocean to the north of the Shandong Peninsula and sometimes to the south.Gascoigne, Bamber and Gascoigne, Christina (2003) The Dynasties of China, Perseus Books Group,

Another historical source of devastating floods is the collapse of upstream ice dams in Inner Mongolia with an accompanying sudden release of vast quantities of impounded water. There have been 11 such major floods in the past century, each causing tremendous loss of life and property. Nowadays, explosives dropped from aircraft are used to break the ice dams before they become dangerous.The Ice Bombers Move Against Mongolia. strategypage.com (29 March 2011)

Before modern dams appeared in China, the Yellow River used to be extremely prone to flooding. In the 2,540 years from 595 BC to 1946 AD, the Yellow River has been reckoned to have flooded 1,593 times, shifting its course 26 times noticeably and nine times severely.Tregear, T. R. (1965) A Geography of China, pp. 218–219. These floods include some of the deadliest natural disasters ever recorded. Before modern disaster management, when floods occurred, some of the population might initially die from drowning and many more would suffer later from the ensuing famine and spread of diseases.

Cradle of civilization

In Chinese mythology, the giant Kua Fu drained the Yellow River and the Wei River to quench his burning thirst as he pursued the Sun.Summary of the story given in the definition of : Historical documents from the Spring and Autumn periodGernet, Jacques. Le monde chinois, p. 59. Map "4. Major states of the Chunqiu period (Spring and Autumn)". English version: and Qin dynasty"Qin Dynasty Map ". indicate that the Yellow River at that time flowed considerably north of its present course. These accounts show that after the river passed Luoyang, it flowed along the border between Shanxi and Henan Provinces, then continued along the border between Hebei and Shandong before emptying into Bohai Bay near present-day Tianjin. Another outlet followed essentially the present course.

During the era of the Three Sovereigns and Five Emperors (around the early 21st century BC), the Yellow River flooded repeatedly, and Yu the Great was ordered to control the waters. The Yu Gong records: "Guiding the River from Jishi, it reached Longmen; southward to Huayin; eastward to Dizhu; then further east to Mengjin; passing east of Luorui, it reached Dapei; crossing north of Jiang River, it reached the Great Plain; then spreading northward into nine channels, they merged into the Inverse River and entered the sea." The "Jishi" mentioned here refers to the Amne Machin Mountains near present-day Xunhua Salar Autonomous County in Qinghai Province. This passage describes how, below Longmen, the Yellow River flowed southward to Huayin, then turned east, passing through Sanmen and Mengjin where it joined the Luo River. Continuing downstream, it passed north of Dapei Mountain, crossed through the Zhang River, and flowed northward east of present-day Quzhou County in Hebei, before splitting into several branches that each emptied into the sea. The northernmost branch served as the main channel, turning south at present-day Shen County before heading east, following the Zhang River to the southwest of Qing County, and then flowing northeast through the southeast of Tianjin into the Bohai Sea. Because this course is recorded in the Yu Gong, it is known as the "Yu River."

Shift of the Yu River In the fifth year of the reign of King Ding of Zhou (602 BC), the river left these paths and shifted several hundred kilometers to the east. The Yellow River burst its banks and changed course at Suxu Mouth in Liyang (southwest of present-day Xun County, Henan), deviating from the original course of the Yu River. It then flowed into the sea at Zhangwu (northeast of present-day Cang County, Hebei), marking the first major course change of the Yellow River recorded in history since Yu the Great tamed the floods. After the diversion at Suxu Mouth, the new channel ran roughly eastward from near Hua County, then northwest of Puyang in Henan, before turning northward; it bent east again north of Guan County in Shandong, then north again through Chiping, gradually shifting northward through Cangzhou in Hebei, and finally entering the Bohai Sea north of present-day Huanghua County in Hebei. Meanwhile, the original Yu River channel continued to carry water intermittently until it dried up completely in the middle of the Warring States period. Sabotage of dikes, canals, and reservoirs and deliberate flooding of rival states became a standard military tactic during the Warring States period.Allaby, Michael & Garrat, Richard. Facts on File Dangerous Weather Series: Floods, p. 142. Infobase Pub., 2003. . Accessed 15 October 2011. As the Yellow River valley was the major entryway to the Guanzhong area and the state of Qin from the North China Plain, Qin heavily fortified the Hangu Pass; it saw multiple battles and was also an important chokepoint protecting the Han capitals of Chang'an and Luoyang. Major flooding in AD 11 is credited with the downfall of the short-lived Xin dynasty, and another flood in AD 70 returned the river north of Shandong on essentially its present course.

Imperial times

From around the beginning of the 3rd century, the importance of the Hangu Pass was reduced, with the major fortifications and military bases moved upriver to Tongguan. In AD 923, the desperate Later Liang general Duan Ning again broke the dikes, flooding in a failed attempt to protect his realm's capital from the Later Tang. A similar proposal from the Song engineer Li Chun concerning flooding the lower reaches of the river to protect the central plains from the Khitai was overruled in 1020: the Chanyuan Treaty between the two states had explicitly forbidden the Song from establishing new moats or changing river courses.Elvin, Mark & Liu Cuirong (eds.) Studies in Environment and History: Sediments of Time: Environment and Society in Chinese History, pp. 554 ff. Cambridge Uni. Press, 1998. .

Breaches occurred regardless: one at Henglong in 1034 divided the course into three and repeatedly flooded the northern regions of Dezhou and Bozhou. The Song worked for five years futilely attempting to restore the previous courseusing over 35,000 employees, 100,000 conscripts, and 220,000 tons of wood and bamboo in a single yearbefore abandoning the project in 1041. The more sluggish river then occasioned a breach at Shanghu that sent the main outlet north towards Tianjin in 1048.

Southern course period