The lower reaches of the Yellow River are aboveground rivers. Where exactly did it start?

"Hanging River" is the unique title of the Yellow River, the second largest river in China.

The Yellow River is the cradle of the Chinese nation, and it is also a famous Hunhe River at home and abroad. It lies like a golden dragon on the vast land in the north of the motherland. The so-called "hanging river" refers to the lower reaches of the Yellow River, which is also called "Tianhe" locally.

The annual runoff of the Yellow River is more than 56 billion cubic meters, which is only one twentieth of the annual runoff of the Yangtze River, while the annual sediment transport is as high as 65.438+0.6 billion tons, nearly four times that of the Yangtze River, so it has become the river with the largest sediment concentration in the world. If 1 .600 million tons of sediment is piled into an embankment with a height of 1 m and a width of1m, it can circle the equator of the earth 27 times.

The Yellow River runs down from the Qinghai-Tibet Plateau, merging into a sword, splitting peaks and valleys, and running through deep valleys. At the narrowest part of the canyon, looking up at the sky from the bottom, the sky is a line; Overlooking the valley, Malik is surging with rapids. The middle reaches of the Yellow River flow through the largest loess plateau in the world. Soil erosion is serious in hilly and gully region of Loess Plateau, which is the main source of sediment. After crossing the middle reaches, the river leaves the canyon and enters the downstream alluvial plain, with a river course of more than 870 kilometers, which traverses Henan and Shandong provinces. Because the downstream river channel is flat, the water flow slows down and a lot of sediment is deposited, which makes the riverbed rise year by year. Every year, about a quarter of the sediment brought by the lower reaches of the Yellow River is accumulated in the lower reaches. Because the riverbed is raised year by year, year after year, the riverbed in the lower reaches of the Yellow River is generally 3 ~ 5 meters higher than the ground outside the levee, and some of them are as high as 9 ~ 10 meters, hence the name "hanging river".

The hanging river on the earth's surface

Yellow River-a suspended river on the ground [channel characteristics]

The loess plateau is a basin-type landform, with sediment discharge and rapid water collection in the rainstorm and flood zone. The downstream inflow peak is high, the waves are high and the flow is urgent, but the water quantity is small. In order to adapt to the flood characteristics, the flood control strategy of wide river is implemented in the downstream, so that the flood stays in the vast beach area and the flood sediment is mainly transported into the sea by the main channel. The whole downstream river course is characterized by wide upper part and narrow lower part, steep upper part and slow lower part, and small lower part is for flood control. The narrow part of the river in the mountainous area below Ai Shan is 400-500m wide, and the narrowest part is only 287m, which has always been the bottleneck of flood control in the lower Yellow River.

The flood threat in the lower reaches of the Yellow River is serious, which is mainly caused by the fact that the flood can't transport all the sediment into the sea and the river silts up and rises. From 1920 to 198363, the sediment deposited in Tiexie-Lijin River is1650 million t; During the 33 years from 1950 to 1983, 7 billion t was precipitated.

Yellow River-Suspended River on the Surface [Erosion and Deposition Characteristics]

Under the condition of natural river course, the flood silted the beach and brushed the trough, which increased the height difference between the beach and the trough and improved the flood discharge conditions. Small and medium-sized floods and small water in non-flood season are deposited in the main channel, which raises the main channel and reduces the flat flow and flood control capacity.

In a long period of time, large floods and medium and small floods appear alternately, thus maintaining the shape of high beaches and deep troughs in the lower reaches of the river and having certain flood control ability.

Yellow River-a suspended river on the ground [flood control]

In the upper reaches of the Yellow River, flood and sediment are mainly transported into the sea in the river course, and dikes, dangerous works and beaches constitute the downstream defense system.

Historically, the Yellow River burst its banks, mostly in the tail water of a big flood or subsequent floods. Due to the high sediment concentration of the Yellow River levee, it is easy to liquefy when it meets water, and its corrosion resistance decreases rapidly.

The main stream swings, crosses the river, bends the river, rolls the river, leans against the embankment and floods along the embankment, which is a serious danger for flood control of the Yellow River, because the flood runs out of danger after going straight into the levee or liquefaction. This is the biggest difference between flood control in the upper reaches of the Yellow River and other clear water rivers (underground rivers).

Moreover, the Yellow River levee burst, and floods and sediment poured down, which not only caused floods, but also caused serious sediment deposition. Rivers, lakes, pits, villages and cultivated land were razed to the ground, forming sand dunes for a long time.

At the same time, the liquefaction dams and riverbeds with high sediment concentration were rapidly deepened and widened by floods. The huge height difference between the riverbed and the ground behind also makes the breach extremely difficult to plug.

Yellow River-A River Hanging on the Ground ["96.8" Flood]

Since the operation of Sanmenxia Reservoir, the downstream channel has changed from high beach and deep trough to secondary suspended river, which fundamentally changed the basic conditions of the main channel for water and sediment transport, resulting in difficulties in flood control and flood fighting, and posing a serious flood threat to the downstream.

Since the people put the Yellow River under control, 1958 has successfully defended against the 22,300m3/s flood at Huayuankou. On August 5th 1996, a medium-sized flood of 7600 m3/s at Huayuankou was flooded. The "96.8" medium-sized flood of the Yellow River was seriously abnormal, and the downstream flood threatened seriously.

1, the flood peak evolution speed is particularly slow.

A week later, the second flood occurred, and the peak of Huayuankou reached 5,520m3/s on August 13, catching up with the first flood in Sunkou on August 15. The two peaks are combined into one peak, and the flow rate is only 5540m3/s. ..

The flood lasted 369.3 hours from Huayuankou to Lijin, which was twice as long as the normal flood time 187 hours. The length from Jiahe Beach to Gaocun River is 120km, and the flood time is120h, which is 6 times of the normal flood time.

2. The flood level is abnormally high.

Huayuankou, Sunkou and Luokou are all the highest flood levels in history. The water level of dangerous projects and pilot projects above Gaocun generally exceeds the historical highest water level of 0.16-1.29 m ... The highest flood level at Huayuankou Station is 94.73m, which is 0.9 1m higher than the flood level 1958, and the peak flow is 2300 m3/s. Before the diversion of 1855, the medium-sized flood overflowed the high beaches such as Yuanyang, Fengqiu and Kaifeng. The severity of the flood threat in the lower Yellow River indicates that it has surpassed the disaster situation before the diversion.

Yellow River —— Above-ground suspended river [secondary suspended river]

The average flow of the main channel of the wide river channel is 3000 m3/s, which has the characteristics of slow floodplain velocity, long water retention time, deep water accumulation and difficult drainage. However, in the 1950s before Sanmenxia Reservoir was put into operation, the horizontal flow of natural rivers was 7,000-8,000m3/s ... The cross section of the river was characterized by high troughs, low beaches and depressed dike roots.

The plane shape of the river channel is that the production dike, beach lip and control project are connected together, and the river channel and the main channel are divided into several closed beach areas. When the flood flow reaches 3000 m3/s, it will flood the beach and turn into a series of interconnected flood detention and sediment detention plain reservoirs, basically losing the functions of flood discharge and sediment transport channels. "96.8" flood, the flood detention in the floodplain of wide channel was 654.38+0 billion m3.

According to the calculation, the flood detention capacity of wide channel beach can reach 2 billion m3. It has become a large plain reservoir and is divided into several irregular small reservoirs connected end to end. When the flood flows in such a river channel, it is inevitable that the horizontal river, the oblique river, the rolling river, the embankment and the embankment will be generally flooded.

Yellow River-Suspended River on the Ground [Evolution of Secondary Suspended River]

When 1958 succeeded in flood control, the river channel was a high beach and deep trough, and it was already a second-class suspended river when 1982 was aerial surveyed. The evolution from high beach deep trough to high beach lip secondary suspended river in low beach root depression with high trough is mainly caused by the regulation of Sanmenxia in muddy water reach.

During the period from 1950 to 1960, there were 2,578.6 million tons of siltation in Tiexie-Lijin * *, including 76.77% in the beach and 23.23% in the main channel. In the main channel siltation, the wide channel accounts for 98.79%, and the narrow channel accounts for 1.438+0%. In the beach siltation, the wide channel accounts for 84.23% and the narrow channel accounts for 15.77%. It can be seen that the distribution of siltation in the lower reaches of the river is reasonable, which is in line with the narrow width of the upper part of the river, with the main channel area accounting for 1/3 and the beach surface accounting for 2/3. Basically, it is parallel siltation and uplift, and the flood control ability is maintained.

During the operation period from Sanmenxia 1960 to19910, the total siltation of Tiexie-Lijin was 2,382.7 million m3, including 20. 1 100 billion m3 on the beach, accounting for 844. The siltation in the main tank is 21.81.600 million m3, accounting for 9 1.56%. In the main channel siltation, the wide channel accounts for 78.55%, and the narrow channel accounts for 2 1.45%. In beach siltation, the wide channel accounts for 13. 13%, and the narrow channel accounts for 82.87%. The siltation of wide channel beach only accounts for 1. 1% of the total siltation. It can be seen that the main and tributary reservoirs, such as Sanmenxia, store floods, and the downstream rivers scour and deposit. The consequence is that there is no siltation in the wide river beach, but the siltation in the main channel and narrow river channel is aggravated.

Another major change is the reduction of major floods. The lower reaches of the Yellow River are "great rivers and good rivers". Such as 1958 flood, beach siltation1050,000 t, main channel scouring 865 million t, beach-trough height difference increasing, advection increasing and river channel improving. In 1950s, there were nine floods above 10000m3/s, but only two floods after 1960. The loss of scouring action of warping beach leads to the main channel siltation, which changes the main channel from siltation to siltation height, and then forms the evolution of secondary suspended river.

Yellow River-Suspended River on the ground [Causes of Secondary Suspended River]

According to the research results of the Yellow River, the flood sediment transport capacity of the downstream channel is directly proportional to the higher flood discharge power. The basic function of flood control in the middle and upper reaches of the reservoir is to store flood and cut off peaks, so as to reduce the flood control burden in the lower reaches. Qingshui River, an effective flood control measure, has caused serious siltation in the main channel, weakened the ability of flood to carry and transport sediment, and lost the flood control ability of the channel. The flood control function of Sanmenxia reservoir is at the expense of silting the main channel and sacrificing the downstream flood control ability. From the completion of the second reconstruction, sediment discharge, to the sedimentation of the downstream main channel in the 1970 s, the river entered a downward stage. In 1982 aerial survey, the area from Tiexie to Lijin inner beach (between beach lip and production dike) is 969km2, the area of Bund (between production dike and levee) is 18 18 km2, and the area of middle channel (including tender beach, side beach and heart beach) is/kloc-0. After 1980s, the development of secondary suspended river was accelerated. The "96.8" medium-sized flood plain proved that the existing river channel had lost its function of flood discharge and sediment transport.

Yellow River-A River Hanging on the Ground ["96.8" Flood]

During the "96.8" flood, the dikes in the lower reaches of the Yellow River were in danger of water seepage and slope collapse 170. There are 1500 dam piles at 140 of the pilot control project. There are 2,960 dams and 5,280 dam times in the dangerous industrial control project. Among them, there are 76 rivers in Henan, 52/kloc-0 dams and 2263 accidents; Shandong River has 255 dams, 2448 dams and 30 17 dams.

There are 40 counties, 173 townships and 1345 villages in Henan and Shandong provinces, with the affected population of/kloc-0.07 million people and 230,000 hectares of flooded farmland. The affected population in the beach area accounts for 63% of the permanent population of 6.5438+0.688 million.

Yellow River-A River Hanging on the Ground [Serious Threat of Flood]

The "96.8" flood is only equivalent to once every three years. In the event of a flood with a once-in-60-year fortification standard, the water level in the wide reach will generally be higher than 1.2-3.3m, and the water level in the reach below Sunkou will generally be higher than 2.5m, and the height of Luokou Station will exceed 3.25m, which will greatly increase the danger of the dike.

According to the current river regime, Huang Lin levee 1.400km will all be near the water, and the superelevation is less than 240km (excluding 390km with the superelevation less than 0.5m), and the embankment body 686km cannot meet the requirements of the saturation line.

At present, there are more than 400 execution ports in the history of dikes, with a total length of 95.438+0 km. When blocking the mouth, a large number of straw, wooden stakes, hemp strips, masonry, etc. Buried under the dam, forming a solid permeable layer. There are potholes in Koumenbei River, which is easy to form a water passage when the water level is high in flood season, threatening the safety of dikes.

The foundation of the Yellow River levee is mostly multi-layered, with 7- 18m underground being interbedded with fine sand, sandy loam, loam and clay, and sandy soil below. The foundation has some problems such as seepage deformation, liquefaction, settlement and uneven settlement.

The Yellow River-a suspended river on the ground [hyperconcentrated flood]

The flood with high sediment concentration is a serious water and sediment that causes siltation in the downstream channel. According to the data analysis of 1 1 hyperconcentrated flood 1950 ~ 1983, the flood discharge time is 102 days, the water volume accounts for 2% of the total inflow in the past 34 years, and the incoming sediment volume accounts for 14% of the total inflow.

Yellow River-Hanging River on the Ground [1933 Flood]

1984, Huangwei Institute of Water Sciences proposed that if the flood of 1933 occurred again, the sediment concentration in the lower reaches of the flood season would be very high, and the water level along the way would be generally high. After the flood, the river siltation is serious and the flood discharge capacity is greatly reduced, which should be the key countermeasure for flood control of the Yellow River.

In 15 years after its study, the riverbed silted, the water-blocking objects in the river increased, the main channel and beach lip continued to rise, and the secondary suspended river intensified its development.

1933 flood is a flood with high sediment concentration. The maximum peak discharge of Huayuankou is 22,000m3/s, which comes once every 60 years. The sediment transport capacity was 4.2 billion t, and the downstream channel silted 2 billion t. Only Yuanyang River burst 107 times, and it was executed for 33 times.

The flood of 1933 has occurred for 67 years. At present, the river type is secondary suspended river, but the medium-sized flood with 7600 m3/s will flood the beach and stay away from the high beach and deep trough of 1933.

Yellow River-a suspended river on the ground [1933 flood]

According to the flood of type 1933 calculated in the initial report of Xiaolangdi Reservoir, the data of incoming water and sediment are as follows:

The once-in-a-millennium flood volume is 29.98 billion m3, the sediment volume is 6.709 billion t, and the average sediment concentration is 223.8kg/m3. After the regulation of Longyangxia and Liujiaxia Reservoirs, the flood volume became 22.4 billion m3, the sediment volume remained unchanged, and the average sediment concentration increased to 299.5kg/m3.

The annual flood volume is 35.3 billion m3, the sediment volume is 8.383 billion t and the average sediment concentration is 237.5kg/m3. After the operation of Longyangxia and Liujiaxia Reservoirs, the flood volume became 27.63 billion m3, the sediment volume remained unchanged, and the average sediment concentration increased to 303.4 kg/m3.

The construction of Xiaolangdi Reservoir is mainly for flood control of the Yellow River. Moreover, the flood control of the Yellow River should not only deal with floods, but also deal with sediment. What is more difficult is sediment. However, the initial report of Xiaolangdi project did not carry out flood dispatching and flood control planning, and did not analyze and estimate the siltation consequences of reservoirs or downstream rivers.

General plan of yellow river regulation

The Yellow River-A General Plan for Governing the Yellow River [Governing the Yellow River by Blocking]

1955 Yellow River Regulation Plan has arranged 46 main stream steps below Longyangxia, and 1988 revised plan has been adjusted to 29 levels. The total cascade storage capacity of the main stream is 96.5 billion m3, which is 3.3 billion m3 less than the original plan. The total storage capacity is 49 billion m3, accounting for 87.5% of the natural runoff of 56 billion m3 in Huayuankou, which has exceeded the exploitable water volume. Coupled with the water consumption of tributary projects, water diversion projects, utilization and ecological control, it is not accidental that the downstream inflow decreases, or even becomes a problem of seasonal rivers and inland rivers.

Yellow River —— General Program for Harnessing the Yellow River [Estuary Erosion]

Academician Lin Bingnan put forward the suggestion of introducing seawater into the lower reaches of the Yellow River. Academician Ren Meihua published an article in the second issue of Science and Technology Herald (1999), which pointed out: to build a plain reservoir with a storage capacity of 5000- 1000000 m3, introduce seawater into the reservoir at a speed of 5000 m3/s, and discharge water into the Lijin River. After about 7 years of regulation, the flood level in Lijin can be reduced by 3m, which is enough to cause Lijin.

The Yellow River-A General Plan for Harnessing the Yellow River [Originated from Zhengzhou]

Wang Wei, a water conservancy survey and design institute of Huangwei, wrote in the Contemporary Yellow River Governance Forum that the water transferred from the North to the North flows into the Yellow River, and it is better to transfer water from Zhengzhou than from Dongping Lake: clear water carries sand, the scouring route is long and the scouring effect is good. In the whole year, the water increased by 654.38+00 billion m3 and the siltation decreased by 200 million t; The newly-increased water volume is 20 billion m3, and the downstream channel is basically silted.

Yellow River-Master Plan for Harnessing the Yellow River [Diversion Plan]

According to the planning of the Yellow River Committee, the new downstream water diversion line starts from Yuanyang, Henan, passes through Fanxian, chiping, Yucheng and Linyi, and enters the sea in Wudi, Shandong. The total length of the line is 500km, and the river width is 10km. The south bank of the upper section uses the existing Beijin levee, and the river surface is high in the south and low in the north. The flood will mainly flow along the new dike on the north bank, which is a great threat to the dike, and it will take twenty or thirty years for the new dike to be stable. The service life of Xinhe River is only 60 years.

The new channel covers an area of about 5000 square kilometers. Except for the breach disaster before the initial operation of the new channel, the original channel will be a waterless desert, and all the existing water diversion projects and corresponding projects will be abandoned. The low-lying area between the existing river course and the original river course will become the hardest hit area of waterlogging and saline-alkali land. Water transfer will not only cost a lot of money and immigrants, but also have a great adverse impact on the economic and social development and stability in the lower reaches of the Yellow River, as well as on the economic development and modernization in the Central Plains and even the whole country.

water resource

Yellow River-Water Resources [Water Shortage in the Future]

According to the research results of "Main Problems and Countermeasures of the Yellow River" organized by experts from the Ministry of Water Resources and the Yellow River Committee, the natural runoff of the Yellow River is 56 billion m3 (Huayuankou), the water consumption of the whole basin is about 50 billion m3, the actual water consumption is about 40 billion m3, and the river runoff consumption is about 30 billion m3. In normal years, the water shortage is 4 billion m3 in 20 10, in 2030 it is 1 10 billion m3, and in 2050 it is16 billion m3, and the water shortage will increase in dry years.