Yellow River
The Yellow River, also known as Huanghe, is the second-longest river in China and the sixth-longest river system on Earth, 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".
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 very 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'. 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 ' yellow river' were attested in 145 BC and in 429 AD respectively. The name Yellow River fully replaces 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 or Khatan gol. The river is mentioned in the Kul Tigin stele as the 'green river'. The Tibetan name is "River of the Peacock".
Geology
The Yellow River first formed sometime during the Late Miocene, Pliocene or Pleistocene, as a result of the Tibetan Plateau being uplifted.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 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.
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.
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. 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.
Ancient times
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. Historical documents from the Spring and Autumn period and Qin dynasty 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.The river left these paths in 602 BC and shifted several hundred kilometers to the east. Sabotage of dikes, canals, and reservoirs and deliberate flooding of rival states became a standard military tactic during the Warring States period. 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 numerous 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.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.
In 1128, Song troops under the Kaifeng governor Du Chong Dù Chōng, d.1141) breached the southern dikes of the Yellow River in an effort to stop the advancing Jin army. The resulting major river avulsion allowed the Yellow to capture the Si and other tributaries of the Huai River. For the first time in recorded history, the Yellow River shifted completely south of Shandong Peninsula and flowed into the Yellow Sea. By 1194, the mouth of the Huai had been blocked. The buildup of silt deposits was such that even after the Yellow River later shifted its course, the Huai could no longer flow along its historic course, but instead, its water pools into Hongze Lake and then runs southward toward the Yangtze River.
A flood in 1344 returned the Yellow River south of Shandong. The Yuan dynasty was waning, and the emperor forced enormous teams to build new embankments for the river. The terrible conditions helped to fuel rebellions that led to the founding of the Ming dynasty. The course changed again in 1391 when the river flooded from Kaifeng to Fengyang in Anhui. It was finally stabilized by the eunuch Li Xing during the public works projects following the 1494 flood. The river flooded many times in the 16th century, including in 1526, 1534, 1558, and 1587. Each flood affected the river's lower course.File:Ma Yuan - Water Album - The Yellow River Breaches its Course.jpg|thumb|The Yellow River Breaches its Course by Ma Yuan. Flooding of the river has been the cause of millions of deaths. The 1642 flood was man-made, caused by the attempt of the Ming governor of Kaifeng to use the river to destroy the peasant rebels under Li Zicheng who had been besieging the city for the past six months. He directed his men to break the dikes in an attempt to flood the rebels, but destroyed his own city instead: the flood and the ensuing famine and plague are estimated to have killed 300,000 of the city's previous population of 378,000. The once-prosperous city was nearly abandoned until its rebuilding under the Kangxi Emperor in the Qing dynasty.
The question of how aggressively flooding should be controlled, and whether it should be steered back to its original channels when it migrated, was a topic of controversy in the imperial court. Rival cliques made arguments based on budgetary, technical and strategic criteria. Geographer Charles Greer identifies two competing schools of thought on how to control the Yellow River. One, which he identifies as Confucian, advocated containing the river between higher levees, thus maximizing the amount of river basin land that could be cultivated. The other, which he associates with Taoism, favored lower levees separated by as much as 5–10 kilometers. In one particular long-running debate during the 11th century reigns of the Renzong and Shenzong emperors, when the river repeatedly broke its levees and migrated north and west, officials battled over whether expensive measures should be taken to return the river to its former channels. The Shenzong emperor ultimately decreed that the river be allowed to remain in its new course.
Traditional flood control techniques made use of levees, revetments to absorb the energy of the water, overflow basins, drainage canals and polders. Treatises on traditional flood control techniques were written by officials such as Pan Jixun, who argued that joining branches of the river increased the water's power and this in turn increased its ability to flush sediment. The difficult situation around the confluence of the Yellow River, the Huai, and the Grand Canal, however, still led to a major flood of the regional center Sizhou and Pan's dismissal from court. Subsequently, the river's 1680 flood entirely submerged Sizhou and the nearby Mausoleum to Ming Ancestors beneath Hongze Lake for centuries until modern irrigation and flood control lowered the water level enough to permit their excavation and the tombs' restoration starting from the 1970s.