Yellow River clearing investigation: Where does the sediment go? The annual sediment reduction is 700 million tons.

Original title: Yellow River Change Survey

Big river "clear stream"

Since 2000, the Yellow River, the largest river in the world with the largest amount of sediment and the largest sediment concentration, has experienced a sharp decline in sediment content, and it has quietly changed its posture.

According to the measured data of the Yellow River Shaoguan Hydrological Station, from 2000 to 2015, the annual average amount of yellow sediment was only 264 million tons, which was 83.6% lower than the average value of natural incoming sand of 1.592 billion tons. Although the runoff of the Yellow River decreased by 46% compared with the annual average in the natural period, the sediment concentration of the Yellow River decreased by 71% to 10.8 kg/m3.

The history of the "Yellow River Clear" can be found 43 times, the longest one is 1727, the Yellow River clarified more than 2,000 miles, lasting more than 20 days. The "Yellow River Clear" since the new century has a long history and is far from being recorded. It is rare in history.

Since the people's governance in 1946, the ancient Yellow River was systematically treated for the first time, completely reversing the sinister situation of "three years and two breaches, one hundred years and one diversion", and achieved 70 years of peace. The important reason is that the ecological management of the Loess Plateau has achieved remarkable results in the past 20 years. It is undergoing a historical change from “local improvement, overall deterioration” to “total improvement and local good development”, with an average annual reduction of 435 million into yellow sediment. Ton.

The reporter of the "Weiwang" News Weekly learned that the new change of the Yellow River to the sand not only affects the development trend of the downstream "hanging river" river channel, but also relates to the formulation of the future yellowing strategy and the implementation of the major planning for the treatment of yellow . In recent years, the relevant state departments have organized a number of research groups to analyze the causes and predict the situation of the Yellow River, but did not form a unified understanding, and failed to make a judgment on whether this change is trend or periodic.

At present, after the sedimentation of the Yellow River has been sharply reduced, an optimistic theory has risen, and the Yellow River sediment problem has been basically solved. The Yellow River has become the world's highest safety factor river. However, during the interview, the Yellow River Conservancy Commission and some experts in the treatment of yellow believed that under the hard conditions of the “suspended river” situation in the lower Yellow River and the unrestricted supply of sediment on the Loess Plateau, the Yellow River flood “suspension sword” remained high in yellow. The top of the Huaihai Plain. The sediment that is stopped by soil and water conservation measures is only sleeping. Once it is awakened by super rain, it will enter the river in an alarming magnitude, and a high-sand flood will hit.

On July 26th, the Wuding River, a tributary of the Yellow River in northern Shaanxi, experienced an ultra-historical flood. The amount of sand at 4,500 cubic meters per second was as high as 980 kilograms per cubic meter. When the flood that was poured into the county town of Suide was receded, it was found that the silt in some sections was as thick as 1 meter. Immediately after the tributary floods are superimposed, the Yellow River forms No. 1 flood... At 10:00 on July 28, when the flood peaks evolved to the Heyang section of the Xiaobeigan River, the high-sand floods drastically washed the riverbed, and the large chunks of the river bottom were picked up. The rare phenomenon of "covering the bottom of the river"...

In the opinion of the experts in the Yellow River, the "big test" of the Yellow River is not in a short period.

Yellow River clearing investigation

According to the measured data in May, the sediment concentration of the Yellow River does not exceed 0.8 kg per cubic meter.

In the non-flood period, more than 80% of the Yellow River is clear

Ecological construction projects, climate change, water conservancy projects, economic and social development are important reasons for the sharp decline of sediments in the Yellow River.

The recent sharp decline in yellow sediments is not indicative of future trends, and it is not appropriate to be too optimistic about the future amount of sand:

The role of soil and water conservation measures is limited. If excessive rainfall occurs, soil erosion will increase.

The chance of a big flood increases, and once it is broken, it may lead to a diversion.

"Small water and small sand" has many hidden dangers, and clearing the water to the future will create a new danger

The Yellow River governance should maintain strategic strength to prevent strategic misjudgment caused by local and short-term changes.

In the middle and late May, the reporters of "Weiwang" News Weekly started from Baotou, Inner Mongolia, and interviewed the Yellow River to the Lijin in Shandong, and saw a Yellow River that was completely different from the past. From Hekou Town in Tokto County to Taohua Temple in Zhengzhou, the middle reaches of the Yellow River, more than 1,200 kilometers, is already clear in the river; until the Kaifeng, the Yellow River is pale yellow.

This means that, together with the upstream of the clear water, in the non-flood period, more than 80% of the Yellow River is clear. Shaoguan Hydrological Station controlled 91% of the Yellow River basin area, 90% of runoff and almost all sediment content data. According to the measured data in May, the sediment concentration of the Yellow River does not exceed 0.8 kg per cubic meter.

The Yellow River has turned southward from Hekou Town, and the Loess Plateau has been divided into two halves and rushed to Sanmenxia, ​​Henan. The sediments received all the way accounted for 89% of the total amount of yellow sediment. Our reporter interviewed the “main production area” of this Yellow River sediment, but the past “one turbid yellow” has changed into a clear stream.

“The Yellow River has been clear for more than ten years. Sometimes, the water is even green.” Jia Changzhi, a farmer from Yonghe County, Shanxi Province, lived on the bank of the Yellow River from a young age. Facing the Yellow River, the 54-year-old said with regret: “Now The Yellow River is not powerful. In the past, the waves were more than two meters high, and the people coming outside could not sleep at night."

The reporter of "Looking" stood by the Hukou Waterfall, but saw the waves falling from the mouth of the pot like snow, and some were white and green. The mouth of the Huanghe River in Hancheng, Shaanxi Province, the river is clear and sturdy. In the gentle rivers of the river, the reflections of the mountains on both sides are visible.

On May 23, the splash of water from the Hukou Waterfall of the Yellow River formed a beautiful rainbow in the sun.

From Kaifeng to the mouth of the sea, the Yellow River turned yellow; but compared with more than 10 years ago, the color was shallow. Experts explained that in the non-flood period, Xiaolangdi Reservoir discharged water, and in the evolution, it rushed to the bottom of the river to reproduce the "natural color" of the Yellow River. It is understood that in 1999, after the Xiaolangdi Reservoir was filled with water, it entered the sand-blocking operation. From 2000 to 2015, the average annual sediment transport in the lower reaches of the Yellow River was only 64 million tons, which was 1.139 billion tons less than the average value of 1950-1999.

Xiaolangdi Reservoir is a “trump card” for regulating the water and sediment of the Yellow River. The capacity of the sand storage tank is 7.55 billion cubic meters. According to the original design, after 14 years of use, the capacity of the sand storage tank is basically full, but only 3.2 billion cubic meters are currently deposited.

According to Li Erong, a geological history expert, there are 43 records of “Yellow River Clearance” recorded in history. The longest one was 1727, and the Yellow River clarified more than 2,000 miles for more than 20 days. The “Yellow River Clear” since the new century, the duration The length is rare in history.

Where did the Yellow River sediment go?

Since the Yellow River has a hydrological record in 1919, the Yellow River has measured a maximum sediment concentration of 911 kg per cubic meter, and the annual maximum sediment transport volume reached 3.91 billion tons. Where is the sediment on the Loess Plateau going? Inner Mongolia Erdos 600295, shares it, Yan'an, Yulin, Shaanxi, is the most important sand source of the Yellow River. The reporter of "Weiwang" News Weekly visited more than ten counties along the river to explore the mystery of the sedimentation of the Yellow River.

In the past, Ordos transported 160 million tons of sand to the Yellow River each year, of which 100 million tons of coarse sand was easily deposited in the river, accounting for 25% of the total coarse sand. After more than 30 years of governance, the comprehensive management of soil erosion in Ordos reached 50%. On August 17, 2016, the historical extreme rainfall occurred in Ordos. Due to the effectiveness of soil and water conservation measures, the local sluice and sedimentation of the first ten tributaries of the Yellow River changed little; the Xiliugou levitation runoff of the storm center reached 7176 cubic meters per second, which can be practical. Only formed a flow of 3000 cubic meters per second.

In the past 20 years, the ecological management of the Loess Plateau has achieved remarkable results, and a historic shift from “local improvement, overall deterioration” to “total improvement and partial good development” is taking place. From 1999 to 2015, Yan'an accumulated a total of 10.7 million mu of farmland and forestry, covering 19.4% of the country's land area, with a vegetation coverage of 67.7%. According to the test, when the slope is ecologically treated, the runoff and the sediment are reduced by 58% and 78%, respectively. A survey in Yulin City showed that only one-third of soil erosion was reduced due to the construction of silt dams.

According to the data provided by the Yellow River Conservancy Commission of the Ministry of Water Resources (hereinafter referred to as the Yellow Council), in the past 20 years, 435 million tons of yellow sediment has been intercepted every year through soil and water conservation measures.

Experts pointed out that in addition to ecological construction projects, climate change, water conservancy projects, and economic and social development are also important reasons for the sharp decline of the Yellow River sediment.

There are 26 large reservoirs and 170 medium-sized reservoirs in the Yellow River Basin above Shaoguan, but most of them are distributed in areas with slight soil erosion. The research group of the Yellow Committee and other organizations visited 90% of the large and medium-sized reservoirs in the field. The analysis and calculation showed that the recent reservoirs intercepted 173.4 million tons of sand, of which the Yellow River mainstream reservoir blocked 81 million tons. In addition, due to the large amount of water stored in the upstream reservoir, the sedimentation of the Inner Mongolia section of the Yellow River is severe. At present, the Bayan Gol to the Sanhu estuary has formed a 268-kilometer-long “suspended river” on the ground, with a total of 52 million tons of sediment deposited each year.

In the investigation of the Yellow River Middle Travel Tour with the research team of the Yellow River Survey and Design Company, the reporter of the "Weiwang" News Weekly discovered the Jinshan Gorge River section, and the sand mining field was dotted. It is understood that in the past ten years, the urbanization of the middle reaches of the Yellow River has accelerated, and under the infrastructure and real estate, there has been a “harvesting heat”.

Starting from Baode County, Shanxi Province, there are 40 kilometers along the Yellow Highway and 32 beaches along the banks of the river. Fengjiachuan Township Fengjiachuan Village is home to four sand fields. The sand field worker Feng Zailian said: "The Yellow River sand is the best washed sand. It is the best building sand. The sand field can dig more than 20 trucks a day, and one car can hold 30 tons of sand." The reporter went to Shunde County along the Yellow Highway for 30 kilometers, and saw 31 fields on the side of Jude, and 27 on the other side of Liulin County in Shanxi. In the Xingxian, Jixian, and Hejin sections of Shanxi, there are also sand fields of the same magnitude. The experts of the Yellow River Survey Planning and Design Company in the same industry estimate that about 100 million tons of sediment will be dug away every year.

Sand mining field on the bank of the river in Baode County, Shanxi Province

According to preliminary estimates, the above sand reduction factors are reduced to more than 760 million tons of yellow sediment per year. As for the impact of recent climate change on the increase and decrease of yellow sediment, the controversy is huge and there is no clear result.

In an interview with this reporter, it was found that a large number of peasants who went out to work or moved to towns in the sand-producing areas of the Loess Plateau caused a large number of sloping farmland to be abandoned or abandoned, which led to the natural restoration of vegetation. However, this factor is used to measure the effect of intercepting sand from ecological construction. When not fully considered. Shaanxi Yudeqiaogou is a small natural watershed completely restored, and has achieved “zero cultivation”.

Twenty years ago, 20 mm of rain per hour produced sand, and today no rain is produced below 70 mm per hour. There are more than 2,000 mu of cultivated land in the former Beihui Village of Watai Township, Xing County, Shanxi Province. Now it only grows more than 600 mu. Fengjiachuan Village, Fengjiachuan Township, Baode County, Shanxi Province has 5,000 mu of cultivated land, less than 1,000 mu of cultivated land, and some terraced fields are also abandoned.

How much sand will the Yellow River come in in the future?

The annual average annual rainfall of the Yellow River is 1.592 billion tons. Calculated from the measured data from 1919 to 2015, the actual annual average of the Yellow River has reached 1.158 billion tons since the hydrological record. In recent years, relevant departments have carried out a lot of research on the future trend of the Yellow River to come to the sand, but the conclusions are very different.

The “Twelfth Five-Year” National Science and Technology Support Project – “Research and Application of Water and Sediment Control Technology of the Yellow River” research group believes that the main underlying surface factors of the middle and upper reaches of the Yellow River are actually reducing sand per year from the study of the water and sediment conditions of the Yellow River from 2007 to 2014. 1.56 billion to 1.73 billion tons, including forest and grass terraces and other factors reduce the annual average of 1.254 billion to 1.411 billion tons, and the reservoir silt dam and irrigation diversion will increase the sediment by 320 million tons.

After studying the annual average rainfall and rainfall intensity of the main sediment-producing areas of the Yellow River since 1956, the research team found that the average value of the study period was basically the same, even partial, not only did not reduce sand, but also played a role in increasing sand for most of the time. The research team estimates that under the conditions of years of average rainfall, the future of the Yellow River Shaoguan Station will be between 450 million and 500 million tons.

The main research period of the research on the change of water and sediment in the Yellow River is from 2000 to 2012. The contribution rate of rainfall to sediment reduction is 20%, and the contribution rate of ecological and hydraulic engineering to sediment reduction is 80%. Both were 1.106 billion tons.

According to the "Yellow River Basin Comprehensive Planning", the current water conservancy and water conservation measures reduce the annual average of 400 million tons of sand. After the initial treatment of the soil erosion zone in 2030, the annual reduction of yellow sediment into 600 million to 650 million tons. By then, the amount of yellow sediment can be reduced to 950 million to 1 billion tons, and the long-term can be reduced to 800 million tons.

Zhang Jinliang, chairman of the Yellow River Survey and Planning Company, published a paper stating that human limited short-term manual intervention will not have a long-term impact on natural events such as coming to the river. The annual Yellow River annual rainfall is roughly 800 million to 1.75 billion tons. The average amount of sand coming is not less than 1 billion tons.

Has there been a similar change in the history of the Yellow River? Some research results show that land use and vegetation changes on the Loess Plateau have a decisive impact on the Yellow River sediment transport. In the history of better vegetation, the amount of yellow sediment entering the year is between 600 million and 1.1 billion tons. Some experts believe that the impact of human activities before the Northern Song Dynasty was small, and the annual sediment load of the Yellow River was 200 million tons.

It is worth noting that an important indicator for observing river sediment, the incoming sand coefficient, is in the opposite direction of the inconsistency. The incoming sand coefficient is the ratio of sediment concentration to flow rate and is a quantitative representation of the relationship between water and sediment. Comparing the period from 1919 to 1959, 1960 to 1986, and 1987 to 2015, the length of the series was more than 20 years. The sedimentation coefficients of Shaoguan hydrological station were 0.028, 0.024, and 0.027, respectively, showing the characteristics of decreasing first and then increasing.

On April 30th, tourists visited the Hukou Waterfall Scenic Spot in the Yellow River? Rao Beicheng photo

Some experts pointed out that the recent sharp decline in yellow sediments can only reflect the effects of rainfall and water and soil conservation measures in a specific period of time, and cannot be used to represent the trend of yellow sediment in a long period of time in the future. Not too optimistic.

"Green change" hidden risk

From 1922 to 1932, the Yellow River experienced a period of dry and dry sand. In 1928, the runoff was only 19.9 billion cubic meters, and the sediment transport was only 438 million tons. After the drought, there will be a big flood. In 1933, the Yellow River experienced a torrential rain and flood, with a sediment load of 3.9 billion tons, causing more than 50 breaches in the lower reaches of the Yellow River. The floods swept through 67 counties in the four provinces of Shandong, Shandong, and Jiangsu, resulting in more than 3 million people. Affected.

The reporters of "Weiwang" News Weekly interviewed in northern Shaanxi, but they saw the hills of the yellow scorpion that was steamed in the past, and were covered with pieces of pine, hedgehog and forest fruit. "High soil and high slope" The impression has been subverted by green. While marveling at this great change, experts reminded that ecological water conservation measures are not omnipotent for reducing the Yellow River to the sand, and should be alert to the risk of being hidden by green.

The Weichuan River flowing through Nanniwan has a vegetation coverage rate of 85%. In July 2013, the Xiachuan River experienced high-intensity rainfall with a mean value of 3.9 times over the years. The runoff and sediment transport were 17 times and 15.5 times respectively of the multi-year average. The basin was built in 1958 in the Shengli Reservoir. In the previous 55 years, more than 3 million cubic meters of sediment was deposited. After the storm, the silt increased by more than 2 million cubic meters. It is understood that there were 6 rains in the Luanchuan River Basin at that time. Due to good vegetation conditions, the first 4 times did not produce flow, most of the rain was infiltrated; the 5th rainfall produced a small flood peak, which proved that the underlying surface was saturated; to the sixth time Rainfall, the ecological “green net” was torn open, and there was a large production stream and a large sand production situation.

Zhang Jinliang said that the “2013.7” flood of the Luanchuan River has a very important warning significance. The amount of sediment transported by the river is directly proportional to the higher order of the flow. When the rain reaches a certain level and exceeds the vegetation tolerance range, the runoff will suddenly increase exponentially and take away a lot of sediment. This also proves that soil and water conservation measures only work under a certain amount of rainfall. In the event of excessive rainfall, soil erosion will increase.

At present, 58,400 silt dams have been built on the Loess Plateau, controlling 16% of the total area of ​​soil erosion, which has become an important line of defense for the Yellow River sediment. The sedimentation period of the backbone dam is generally 10 to 20 years, and the small and medium-sized silt dam is generally 5 to 10 years. Many silt dams are built earlier, some of the dams are full of reservoirs, and the sand-blocking function is lost. Once the over-designed storms and floods occur, the silt dams may collapse and the sediments will be silted. Re-into the river.

The Jialu River flowing through Jia County, Shaanxi Province, is the first-level tributary of the Yellow River. The Liugou silt dam in the basin was built in the 1970s. After 40 years of siltation, it was basically full. In July 2012, the torrential rains washed the silt dam, and in just three days, the silt was washed away. The Kangya kiln silt dam in the basin was also destroyed. In just 20 hours, all the silt was taken away.

Zhang Jinliang believes that the sediment-producing capacity of the main sediment-producing areas of the Yellow River will not change for a long period of time, and the supply of sediment can be said to be unlimited. For a specific sediment-producing area, there is a certain rainfall threshold. When the rainfall condition is less than the threshold, the amount of sand generated by erosion is continuously stagnant in the slope or local channel, and the amount of incoming yellow sand is small; when the rainfall condition satisfies the threshold At the time, the long-term “zero deposit” of sand will be “completed” into the yellow. The silt dams, terraces and other sand-blocking projects also have the risk of “zero deposits and acquisitions”.

After long-term dry and dry sand, in July 1998, the Xiliugou River Basin in Ordos, Inner Mongolia, ushered in heavy rain. On July 12, after the flood with a sediment concentration of 1,350 kg per cubic meter entered the Yellow River, the sediment carried intercepted the Yellow River. A giant sand bar with a length of 10 kilometers, a width of 1.5 kilometers, a thickness of 6.27 meters and a sedimentation capacity of nearly 100 million cubic meters was formed, causing huge disasters.

The staff carried out the vertical measurement of sediment in the section of the model of the Xiaolangdi reservoir in the Yellow River. Zhu Xiangshe

Increased chance of flood

Since the flood of 15,300 cubic meters per second in the lower reaches of the Yellow River in 1982, the Yellow River has not experienced floods of more than 10,000 cubic meters per second for 34 consecutive years, but there are hidden dangers in the calm.

In July 2016, it was a Haihe River Basin, but there was heavy rain in the northern part of the Yellow River. If the rainfall drifted to the Yellow River Basin, the peak flow of the Huayuankou Hydrological Station would reach 18,900 cubic meters per second. Experts pointed out that the occurrence of a major flood has periodic characteristics. The same magnitude flood, the longer the time interval, the higher the probability of occurrence. In 1958, a flood of 22,300 cubic meters per second occurred in the lower reaches of the Yellow River, which was a 60-year flood, which was 59 years ago. In 1982, a flood of 15,300 cubic meters per second occurred in the lower reaches of the Yellow River, which was a 30-year flood. It has been 35 years.

The middle reaches of the Yellow River are characterized by frequent rainstorms and high intensity. In 1977, Wushenqi, Inner Mongolia, experienced heavy rains, with a rainfall of 1400 mm in 9 hours. Heavy rains in the Huanghuaihai area in the lower reaches of the Yellow River are also quite rampant. In 1975, the Huaihe River Basin experienced heavy rains. The 24-hour rainfall in the rainstorm center reached 1,060 mm. The floods caused dozens of reservoir dams including two large reservoirs. If the rain zone was slightly northerly, the lower reaches of the Yellow River would face a huge test.

The Yellow Commission has estimated that there may be a flood of 55,000 cubic meters per second in the lower reaches of the Yellow River. Experts pointed out that although soil and water conservation has obvious effects on water reduction and sediment reduction in the lower Yellow River, from the historical process of formation of extraordinarily large floods, the role played by rainfall is dominant.

Combined with the current analysis of topographic features, once the downstream levees are breached, the flood-sand-sand disasters affect 110 counties (cities) in the five provinces of Yunnan, Shandong, Henan, Anhui and Jiangsu, with a total land area of ​​about 120,000 square kilometers and a population of over 1 Billion, the area of ​​cultivated land is 112 million mu. Moreover, after the collapse of the Yellow River Embankment in history, there has never been a precedent for immediate closure.

The Lan Khao Dong dam head is called the "last bend" of the Yellow River, and the calm and calm Yellow River flows soothingly, without a trace of sorrow and violent. In 1855, the Yellow River was diverted here to form the current flow path. For more than 600 years, the Yellow River has long invaded the Huaihe River Road and entered the Yellow Sea from Jiangsu Dafeng. From 602 BC to 1855 BC, the Yellow River was rerouted five times, and a fan-shaped swing from north to south with a range of 250,000 square kilometers was completed on the Huang-Huai-Hai Plain. Experts pointed out that according to the characteristics of the current flow path of the Yellow River, once the breach is made, it may lead to a diversion, and its disaster is unbearable.

The Yellow River Flood Control Team of Zouping County, Shandong Province visited the Yellow River Bank (photo taken on July 7, 2014) Photo by Dong Naide

"Small water and small sand" has many hidden dangers

In the past decade or so, due to the sharpening of the Yellow Sediment and the use of the Xiaolangdi Reservoir for sand interception, the lower reaches of the Yellow River have been in the process of “small water and small sand” for most of the time. However, the Yellow River has not been safe, and the rivers in some river sections have changed greatly. New problems have emerged in flood control, and new hidden dangers have been added.

The reporter of "Weiwang" News Weekly saw that the traffic in Qingzhuang County, Shuyang County, Henan Province, although there was only 700 cubic meters per second of flow, the Yellow River still formed a sloping river, and the water head was dangerous. The Qingzhuang dangerous work originally had 15 picking shoals. Before 2013, it was all by the river. After the formation of the deformed river, it fell sharply. The No. 8 dam did not depend on the river. It had to repair three dams downstream.

Chen Baoguo, director of the Flood Control Office of the Yellow River Bureau of Fuyang City, said: "In recent years, there have been three deformed rivers in the Xiangyang section. If it is not timely rescued, it will trigger a series of changes in the downstream rivers. Once the Henghe River and the inclined river hit the levee, there will be a breach. risk."

The anti-mite experts of the Yellow River pointed out that in the past, the dangerous work and control projects in the lower reaches of the Yellow River were laid out according to the situation of the Zhongshui River channel with a flow rate of 4000 cubic meters per second. Now the water is less and the conditions are changed. The new situation that emerged was: the old project did not rely on water, the new project had not been repaired; the place where it should not be washed, the silt was not silted; the wandering section of the river was intensified, and the river was almost one year old. change.

In the Su Yanzhuang project in Lucheng County, Shandong Province, the reporter of the "Weiwang" News Weekly saw that due to the small energy of the clear water, there was a "sitting bend" in the straight river. After the river was lifted, the main slashing force cut the beach surface without protective measures, causing the 700-meter-long and 300-meter-wide arable land to fall into the river. Fu Jianqin, chief engineer of the Yellow River Bureau of Heze City, said: "The danger of continuing development may lead to a sneak peek into the back road of the Su Shizhuang project, flooding the 16,000 mu of cultivated land in the beach area and directly rushing into the Yellow River embankment."

There are more than 50 spur dikes in the control project of Laojuntang in Dongming County, Shandong Province. In recent years, the river has been steadily falling. The previous dams No. 1 to No. 6 did not rely on water, and the No. 8 to No. 15 dams were mainly slipped. At present, the main slip has fallen to 26 to 29 Dam. It caused more than 1,500 acres of beach land to fall into the river. The river department has repaired three dams and the slopes have been partially controlled.

Flowing through the Yellow River in Kaifeng City, Henan Province

Experts pointed out that after the sediment is sharply reduced, clearing the water to the future will create a new danger. In the past, the high-sand flood flooded the left bank and smashed the right bank, smashing one side and forming a relatively stable river channel; the clear water washed away on both sides, causing river channel changes; when the flood came, it was very likely to go through the clear water flow road; 70 years of painstaking construction A considerable part of the various projects will not work, and some river sections will be affected.

In view of the current river regime, some experts suggest to abandon the downstream “wide river embankment” policy, and build two new embankments along the Yellow River channel to transform the Yellow River into a “narrow river” of 3 to 5 kilometers. On the one hand, on the one hand, there is a large number of projects that do not rely on water and sun. Experts also pointed out that after the construction of the "narrow river", the lower reaches of the Yellow River will be liberated, and 1.9 million people will not need to relocate, killing two birds with one stone.

Experts who disagree with it believe that although the lower reaches of the Yellow River are not silting up, the sediment storage capacity of the Xiaolangdi Reservoir will be back to the silt state. Although the “narrow river” has high efficiency of sediment transport, the river siltation rises quickly, and it is difficult to get out of the dilemma of “hanging river in the hanging river”; and the current downstream flood control system has changed too much, and it should not be implemented lightly.

Some experts pointed out that the Yellow River with more water and less sand is the most complicated and refractory river in the world. The management of the Yellow River should maintain a strategic force to prevent strategic misjudgment caused by local and short-term changes. If we can firmly promote the "Yellow River Basin Comprehensive Plan" approved by the State Council in 2013, and further improve the water and sediment control system of the Yellow River, we can basically achieve the goal of the current river course continuing for more than 150 years. LW

When does the Yellow River "human sand race" stop?

Although the sedimentation into the Yellow River has been sharply reduced, the construction of the Yellow River water and sediment control system has achieved initial results, but the law of sediment transport on the Loess Plateau has not changed, and the “human sand race” that lasted for thousands of years in the lower Yellow River is far from the field.

The uncoordinated relationship between the water and sediment of the Yellow River is basin-type. It is not a certain point or a certain river section. It is necessary to adjust it to coordination. If a single project cannot complete the task, it needs a water and sand regulation system to complete it.

The Hukou Waterfall of the Yellow River ushered in the biggest flood peak of this year, Zhang Yunqiang, on July 27.

On July 26th, the Wuding River, a tributary of the Yellow River in northern Shaanxi, experienced an ultra-historical flood. The amount of sand at 4,500 cubic meters per second was as high as 980 kilograms per cubic meter. After the flood that was poured into the county town of Suide was retreated, the silt in some sections was as thick as 1 meter. The next day, the tributaries flooded and the Yellow River formed the No. 1 flood peak.

At 10 o'clock on July 28, when the flood peak evolved to the Heyang section of the Xiaobei main stream, the high-sand floods drastically washed the riverbed, and the large chunks of the river bottom were picked up, forming a rare phenomenon of “covering the bottom of the river”. On the afternoon of July 28, after the flood entered the Xiaolangdi Reservoir, the high-sand water flow sneaked into the clear water to form a “hetero-heavy flow” spectacle.

In the interview, the reporter of "Weiwang" News Weekly learned that since the Xiaolangdi Reservoir was put into use in 2000, through the sand interception and water regulation and sand adjustment, the rivers in the lower reaches of the Yellow River have washed more than 2.8 billion tons of sediment, and the "hanging river" has not grown taller. The lower reaches of the Yellow River enter a rare period of balance of erosion and siltation. However, this year's "water and sand variation" played by the Yellow River No. 1 flood has issued a warning: although the sedimentation of the Yellow River has been reduced, the sedimentary system of the Yellow River has achieved initial results, but the law of sediment transport on the Loess Plateau has not changed, and the lower reaches of the Yellow River continue. Thousands of years of "human sand racing" is far from the time of the game.

How about the Yellow River going up?

"The river is full of ocean and the north is alive." Before the Spring and Autumn Period, the Yellow River was in the middle of the road along the Dagu Road. During the Spring and Autumn Period, the various vassal states began to build water to block the water, so that the Yellow River evolved from the underground river to the ground. At the beginning of the Western Han Dynasty, there was a record of "the river was higher than the house."

In the 7th year of AD, Jia Ran Ying gave a letter to the Western Han Dynasty, and proposed a policy of governance for the frequently-resolved Yellow River. This is the famous "Jiarang Three Strategies", which first comprehensively expounded the Yellow River governance thought and had a great impact on later generations. The upper policy is to manually divert the road, not to compete with the water, so that the Yellow River is “smooth and unforced”; the middle policy is to divert the channel, kill the water and anger, and divert the yellow irrigation; the lower policy is to passively increase the thickening of the embankment, but “the labor costs are not Already, the numbers are all right, and the afterlife is endless."

Limited by various conditions such as productivity and population growth, most of the rivers in the past have adopted the strategy of building embankments and waters, thus making the "human sand race" lasting. Due to sedimentation, the riverbed in the lower reaches of the Yellow River rises by about 10 centimeters per year. When the riverbed is silted to a certain extent, the river water will flow out of the river channel and find another way out, and then the breach and diversion will occur, so that the cycle will reciprocate. "Goods" has become a major feature of the Yellow River. According to statistics, during the more than 2,500 years before the founding of New China, there were 26 major diversions in the lower reaches of the Yellow River, with 1,594 breaches.

In 1952, when Chairman Mao Zedong inspected the Yellow River, he once asked this question: "How about the Yellow River going up?" In order to ensure the downstream security, after the founding of New China, the Yellow River embankment was raised four times. The current average height of the levee is 10 meters. The earthwork used can be used to build 13 Great Walls. However, in the age of Anzhen, the danger of "hanging the river" has not been lifted. At present, the riverbed in the lower Yellow River is generally 4 to 6 meters above the ground on both sides of the river, which is 20 meters higher than the ground in Xinxiang City and 13 meters higher than the ground in Kaifeng City.

In the past 30 years, with the increase of water use along the Yellow River, the amount of sand entering the lower reaches of the Yellow River has decreased, and the sedimentation of the main channel of the Yellow River has increased, and a suspended river has emerged in the hanging river. At present, the “secondary suspended river” appears in most of the lower reaches of the Yellow River, and its form is: “slot height, beach low, and bank of the embankment”:

The outside of the river trough is 2~3 meters above the beach surface, and the inside is "shallow dish", and the beach surface is 4~6 meters higher than the back river surface. Even if small and medium floods occur, the main trough is difficult to accommodate, and the lateral ratio is greater than the vertical. Under the unfavorable river conditions of several times or even ten times, it will inevitably lead to major river changes, and the emergence of Henghe River and the inclined river will increase the risk of the dyke "rushing" and "breaking out".

Shaping a harmonious relationship between water and sand

On July 4, 2002, with the opening of the three sand-discharging gates of Xiaolangdi Reservoir, the turbid yellow water rushed out like a dragon, and fell into the river after a beautiful arc in the air. It is the largest in the history of world water conservancy. The longest-running water and sand adjustment has since opened. By 2015, after 19 water and sediment adjustments, 966 million tons of silt in the downstream rivers will be sent to the sea. At the same time, the Yellow River channel is also cut deeper and cut more than 2 meters, and the minimum overcurrent capacity is increased from 1,800 cubic meters per second to 4,200 cubic meters per second.

The Yellow River is difficult to treat, and it is heavy in sediment. The roots are in the water and sand, and the relationship between water and sand is not coordinated. According to estimates, 56% of the Yellow River's water comes from Lanzhou and above, while 90% of the sediment comes from the middle reaches of Hekou Town to Sanmenxia. 60% of the annual water volume and 80% of the sand amount comes from the flood season. The flood season is mainly concentrated from several storms and floods. . Can we use artificial means to break the time difference and space difference, recombine the water and sand, and become unbalanced to adapt to the downstream river channel?

The Huangzhi expert told the reporter of "Weiwang" News Weekly to transfer water and adjust sand. It is to manually arrange reservoir water storage, create flood peaks, adjust natural water and sediment processes, change unbalanced water and sand relations, wash and clean downstream rivers, and reduce river siltation. . With the completion and construction of the Xiaolangdi Reservoir, this was born in the 1940s and was formed in the 1980s. The use of natural laws to change the distribution of the Yellow River sediment distribution finally has practical conditions.

Overlooking the Yellow River from a high altitude, at the exit of the Shanxi-Shaanxi Gorge, a blue wave emerges like a huge sapphire. This is the Xiaolangdi Reservoir. The “super reservoir” with a total storage capacity of 12.65 billion cubic meters is like a young and strong heart, bringing a new balance and vitality to the ancient Yellow River. In the 19 times of water and sediment adjustment, the "Ace" of water and sand regulation was used abnormally to form a number of classic battles.

From August 26 to September 8, 2003, in just 14 days, nine floods occurred in the main tributaries of the middle reaches of the Yellow River, namely, the Weihe River, the Weihe River, the Luohe River and the Yihe River. The Weihe River and the Weihe River in the upper reaches of Xiaolangdi have a large amount of sediment, while the Luohe and Yihe Rivers that enter the Yellow River at the bottom of Xiaolang are basically clear water. "The time and space are poor, so that the water is backed by sandbags." Through the use of Xiaolangdi Reservoir, the high-sand floods of the Weihe River and the Weihe River will be stopped first. When the Yihe River and the Luohe River are turned into yellow, the high-sand floods will be released, and the turbidity will be artificially adjusted to reduce the silt.

In the following several water adjustment and sediment adjustment, the Yellow River Conservancy Commission carried out joint dispatching of the three reservoirs of Wanjiazhai, Sanmenxia and Xiaolangdi, and performed a large-scale drama of the man-made flood peak “big relay” on the river section of more than 1,000 kilometers. The downstream river channel was washed away, and some of the silt in the Xiaolangdi Reservoir was cleaned up by artificially shaping the heterogeneous flow.

After a period of founding the country, the force of sand control was mainly on the word "block". In 1960, the Sanmenxia Reservoir, the first dam of the Wanli Yellow River, was put into operation. Due to the unclear understanding of the laws and regulations of the Yellow River water and sediment, the application mode of “water storage and sand interception” was adopted. In just one and a half years, the reservoir has deposited 1.5 billion tons of sediment, and it has formed a “blocking sand” in the Yellow River into the Yellow River.

From 1962 to 1973, the Sanmenxia Reservoir was in an open state for most of the time, but the exploration of the core operation of the Yellow River, the reservoir, did not stop, and finally found the way to use the “storage and drainage”. The silt problem of sediment-laden river reservoirs has been opened, and the technical foundation has been laid for water and sand adjustment.

Standing on the Xiaolangdi Dam, the blue waters are all in sight. In the area of ​​silt reduction, the Xiaolangdi Reservoir has a storage capacity of 12.65 billion cubic meters, of which 7.5 billion cubic meters are used for sand interception, which can ensure that the lower reaches of the Yellow River are not silted up for at least 20 years; Under the storage capacity, in the non-flood period, the water is stored, and the water is drained during the flood season. The long-term use is maintained through the balance of scouring and silting, and the water and sand adjustment is maintained.

Tourists watched the Yellow River Xiaolangdi water and sediment adjustment in Jiyuan City, Henan Province (photo taken on July 5, 2015)

Improve water and sediment control system

From the Mengjin River in Henan Province to the more than 460 kilometers of the Yellow River in the Gaoyang Village, it is called the “tofu waist”. Historically, two-thirds of the Yellow River’s breaches and diversions took place here. When the reporters of "Weiwang" News Weekly searched along the river, they found that the place named "mouth" has many special names, such as Huayuankou, Liuyuankou and Zhaokou. Every "mouth" has memories of history and pain. .

On such a short track, facing the opponents of the Jinshan Gorge that recharge their batteries and accumulate huge potential energy, they simply block and have no chance of winning. In order to change this disadvantage, we must build a perfect water and sand control system on the Yellow River, change the passive sprint for the relay long-distance running, and finally win the game.

Although there are currently 28 reservoirs on the main stream of the Yellow River, most of them are concentrated in the upper reaches, with power generation as the main function; in the middle and lower reaches of the Yellow River, only the Xiaolangdi Reservoir can be used for the comprehensive regulation of water and sediment. According to the current design of water and sand conditions, after the silt is full, the Xiaolangdi will become a river-type reservoir. In the long-term storage capacity of 5.1 billion cubic meters, only 1 billion cubic meters of storage capacity can be used for water and sediment adjustment. At that time, the river channel in the lower reaches of the Yellow River will return to the silt state. The "human sand race" will continue to open after the intermission, and the better river channel shape obtained by sand interception and water adjustment and sand adjustment will gradually deteriorate.

Since the new century, the ecological construction of the Loess Plateau has made great achievements, and the sedimentation into the Yellow River has been sharply reduced. However, Liu Changming, an academician of the Chinese Academy of Sciences, pointed out that the hydrothermal conditions in the Yellow River Basin determine that the restoration of vegetation on the Loess Plateau will not unrestricted development. At present, the vegetation conditions and water and sediment conditions in the middle reaches of the Yellow River have basically reached a relative balance, the vegetation restoration effect tends to be stable, and the sand-blocking effect is not far from the “ceiling”.还有一些专家指出，黄土高原强烈的水土流失发生在距今25万年至30万年前，进一步加剧在距今5万年前，远远早于人类频繁活动时期，仅靠水土保持，无法根本解决黄河泥沙问题。

专家向《瞭望》新闻周刊记者指出，黄河水沙关系不协调是流域性的，并非某一点、某一河段，要将其调节到协调，单一工程完不成任务，需要水沙调控体系来完成。

在国务院通过的《黄河流域综合规划》中，黄河水沙调控体系中主体除了干流已建成的龙羊峡、刘家峡、三门峡、小浪底水库，还规划在上中游修建黑山峡、碛口、古贤三座调节性水库，再与干流、支流其他控制性水库互为补充，才能共同构建完善的黄河水沙调控体系。

专家指出，在小浪底水库拦沙库容淤满前，应在黄河干流再兴建一座控制性水库，与小浪底联合进行水沙调控，以便在有限的库容和水量条件下发挥最大的减淤效果。经多方论证，适时启动古贤水库建设已成为共识。

古贤水库位于山西吉县和陕西宜川县交界处，总库容可达134.6亿立方米，其中拦沙库容可达93.6亿立方米，可控制主要淤积在下游河道中的直径大于0.05毫米粗沙的80%。在设计水沙条件下，与小浪底水库联合运用60年，可减少下游河道淤积量79亿吨。

本世纪初，治黄专家在黄河中游禹门口至潼关河段，找到了一个可淤积泥沙100亿吨的“大泥盆”。禹门口至潼关河段俗称黄河小北干流，河道总面积1100平方公里，其中滩地面积为682平方公里，多为人烟稀少、荆棘丛生的盐碱地，是一个“天然泥盆”。从2004年起，黄河水利委员会连续三年在小北干流河段进行“放淤”试验，成功地将400多万吨粗泥沙淤积在黄河沿岸的盐碱滩里。

专家最后向本刊记者表示，如果这一河段没有大型控制工程，仅靠无坝放淤，吃掉100亿吨泥沙目标根本无法实现。而古贤水库建成后，可人工塑造适合放淤的水沙过程，从而开辟出一个为下游河道减淤的全新战场。LW

饥渴的黄河

缺水已是黄河面临的最大挑战，宜适时启动南水北调西线工程，以解黄河之渴

内蒙古磴口县刘拐沙头，黄河在乌兰布和沙漠边缘平静缓流（2011 年3 月摄）任军川

黄河是我国北方唯一横贯东西的巨川大河，是西北、华北的“生命之泉”。其天然径流量排在长江、珠江、松花江、淮河之后居第五位，仅为长江的6%，却以占全国河川径流量2%的有限水资源，灌溉了全国13%的粮食产量，保障了全国14%的GDP产值，养育了占全国12%人口的60多个大中城市、340个县。

也因此，黄河日渐“消瘦”，维持流域社会经济发展的功能已近极限。近日，《瞭望》新闻周刊记者调研了解到，按最新统计，黄河流域地表水开发利用率和消耗率已达86%和71%，远超黄河水资源承载能力。缺水，已是黄河面临的最大挑战。宜适时启动南水北调西线工程，以解黄河之渴。

水资源量持续减少

黄河是中国大江大河中第一个进行流域初始水权分配的河流。

早在1987年，国务院就批准了《黄河可供水量分配方案》。该方案分配基数采用的黄河天然径流量为580亿立方米。然而，最新的水资源调查显示，黄河天然径流量已不足500亿立方米。据预测，到2030年，黄河天然径流量还将减少20亿立方米。

《瞭望》新闻周刊记者采访获悉，据对气候变化趋势研究，多年来黄河流域降水量变化不大，但有三个人为因素成为黄河径流量减少的重要变量：

一是生态改善植被大面积恢复。对比20世纪70年代和2012年黄河主要产沙区林草梯田覆盖变化遥感图会发现，黄河中游广大地区，已被大片的绿色覆盖。目前黄河中游地区林草梯田覆盖率已由上个世纪70年代的20%，提高到54%，林草梯田综合覆盖率不到30%的面积已由上个世纪70年代的81%减少到3.5%。

中国科学院院士刘昌明等专家指出，植被恢复是黄河流域径流减少的重要原因。对黄河中游11个子流域研究发现，随着植被增加，蒸腾散发上升，大量可利用的呈液态、固态的水资源——蓝水被转化成以气态或分子态存在于大气和土壤中的绿水。与1980年至1999年相比，2000年至2013年蒸腾散发的绿水增加8.6%，径流减少幅度近20%。

二是水利工程增多加剧了水面蒸发。目前，黄河流域共修建蓄水工程1.9万座，其中干流已建、在建水库就达28座。水库蓄水后水面扩大，蒸发量相应增加，导致径流量减少。本刊记者在采访中还发现，在水资源紧缺的华北、西北一些城市，近年来出现大造城市景观水之风。有的城市“拦河筑坝”，把河水“圈”在城内；有的城市耗巨资“挖地造湖”引水造景。专家指出，目前这些北方城市年均蒸发量超过降雨量一倍，一些西北城市甚至超十倍。“水面大了，蒸发量必然要大，造成宝贵水资源的巨大浪费。”

三是黄河流域地下水开采量增加，部分地区严重超采。从1980年到目前，黄河流域地下水开采量由93亿立方米上升到137亿立方米，增幅达47%。地下水超采面积达1.59万平方公里，其中山西就达1.05万平方公里。严重超采面积占总面积78%，形成十个巨大漏斗。超采地下水，使产汇流关系发生变化。在同等降水条件下，径流量减少。

在黄河水资源减少的同时，黄河流域用水却呈刚性增长。1950年黄河流域供水量为120亿立方米，目前已达510亿立方米，黄河支持流域社会经济发展的功能已到极限。

专家预测，到2030年，仅黄河流域需水量就达550亿立方米，而黄河每年还要向流域外地区供水100亿立方米。届时，即使来水正常年份，每年也有100亿立方米以上的用水缺口。黄河是一条多泥沙河流，每年必须要保证一定的冲沙水量和生态基流。据1987年国务院分水方案，黄河每年应有210亿立方米的入海水量。如果计算生态水量，从2000年起，黄河已出现每年50亿立方米的用水缺口，有限的黄河水资源已无法在农业、工业、生态用水中达到平衡。

一位水利专家这样向《瞭望》新闻周刊记者比喻：在河流的开发利用上，我们总觉得河流这把“水壶”用之不尽，把“兴河流之利”简单理解为添置更多的茶杯、茶碗，但有可能这些东西还没备齐，壶里就没水了。

左图：黄河支流洛河岸边河南省伊川县城关镇古城村的农民在抢种水稻（2009年6月4日摄）王颂摄右图：游客在山西平陆黄河湿地自然保护区观赏大天鹅（2016年10月30日摄）刘文礼摄

流域节水空间有限

《瞭望》新闻周刊记者调研获悉，黄河目前总用水量中农业用水占74%，工业及三产用水占18%，生活用水占7%，生态用水占1%（主要为黄河入海口生态用水）。

近20多年来，黄河流域节水水平大大提高。与1980年相比，每万元工业增加值用水量由877立方米减少到46立方米，农业实际灌溉定额由542立方米减少到385立方米。《黄河流域水资源综合规划》认为，理论上，黄河流域总体节水潜力为83.6亿立方米，其中农业节水潜力为59.3亿立方米，工业为22.3亿立方米，生活节水为2亿立方米。

农业是黄河上的用水大户，目前黄河上中游地区占全流域农业用水量85%，节水潜力最大。《黄河流域水资源综合规划》认为，中上游农业节水潜力在51.6亿立方米。但近期的一些研究成果表明，黄河中上游农业节水空间并没有这么大。

黄河宁蒙河套灌区目前已发展成为灌溉规模达1400万亩的大型自流灌区，成为国家重要的农产品000061 ,股吧主产区，但这里长期采用大水漫灌，农业实际灌溉定额分别高达885立方米和508立方米。

据黄河勘测规划设计公司课题组研究发现，河套灌区周边沙漠环绕，土壤中风沙土占半数以上，农业灌溉具有明显的生态用水功能；不仅保证农作物生长需要，还可以补足地下水，满足周边植被与湖泊湿地用水需要。灌区一些水利工作者也向本刊记者表示：“如果没有几千年的大水漫灌，河套地区早变成沙漠了。”

内蒙古河套灌区处于库布其沙漠和乌兰布和沙漠夹击之下，多年平均地下水总补给量为30.7亿立方米，其中渠系与土壤补给占95%，如此才得以维持灌区平均地下水埋深为1.5至2米的绿洲存在条件。如果将农田渠系利用系数由目前的接近0.5提高到0.58，地下水埋深将接近2.5米红线，可能引发生态系统性变化。

黄河勘测规划设计公司课题组认为，黄河上中游六省区农业灌溉工程毛节水潜力为34.5亿立方米，而且每节约一立方米单方水投资高达25.5元。一些专家指出，黄河目前没有发生供水危机，主要是靠大量挤占河道生态用水支撑的，但日积月累后，会产生量变到质变的河流生态危机；仅靠节水，已难以弥补巨大的用水缺口，需要跨流域调水解黄河之渴。

适时启动南水北调西线工程

“南方水多，北方水少，如果可能，借一点来也是可以的”。1952年毛泽东主席视察黄河时，听到当时的黄委会主任王化云介绍已派勘探队到通天河查勘，希望把通天河水引到黄河里来时，风趣地说：“通天河是猪八戒去过的那个地方。”随后，便阐发了南北水调的伟大构想。

根据2002年国务院批复的《南水北调工程总体规划》，南水北调西线工程通过在长江上游通天河、支流雅砻江和大渡河上游筑坝建库，开凿输水隧洞，穿越黄河长江分水岭巴颜喀拉山，分三路（三期）每年共调170亿立方米的水进入黄河上游。2006年，水利部要求将第一二期工程（第一第二条线路）水源合并，作为南水北调西线一期工程。根据项目建议书，一期工程将从雅砻江上游、大渡河

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