The role of Yellow River reservoir construction in sand prevention and control

1, the important role of reservoir optimal operation in maintaining the health of the Yellow River

On the main stream of the Yellow River, Longyangxia, Liujiaxia, Wanjiazhai, Sanmenxia and Xiaolangdi reservoirs have been built. In recent years, through the rational operation of reservoirs or reservoir groups, water and sediment regulation, flood control and ice prevention, and beneficial operation have played an important role in optimizing the allocation of water resources, protecting the ecological environment, maintaining the health of rivers, and promoting the healthy development of social economy, with remarkable social, economic and ecological benefits.

1. 1 Water and sediment regulation continuously improve the flow capacity of rivers and gradually restore their basic functions.

Since the 1990s, due to the drought along the Yellow River, the decrease of incoming water and the over-utilization of water resources, the water used for sediment transport in the Yellow River has been squeezed in large quantities, and the amount of water entering the lower reaches of the Yellow River has dropped sharply. The contradiction between supply and demand of water resources has become increasingly prominent, which has aggravated the downstream siltation and greatly reduced the flow capacity, resulting in increasing flood control pressure, and the horizontal flow has dropped from 6000 cubic meters per second to about 2000 cubic meters per second. In 2002, a flood with a flow rate of 1.800 cubic meters per second occurred in the lower reaches of the Yellow River, resulting in flooding. In 2003, the flood flow of Lankao section of the Yellow River in Henan Province was 2400 cubic meters per second, which caused a serious flood disaster, and nearly1.20 thousand people in the beach area were trapped by the flood. Therefore, since 2002, the Yellow River Commission has carried out water and sediment regulation five times in a row, and washed the downstream channel with "artificial flood peak", which improved the sediment deposition in the downstream, gradually improved the flow capacity of the channel, and comprehensively washed the downstream channel. The minimum flow capacity is increased from 1800 m3/s before implementation to 3,500 m3/s, and the basic functions of the river are gradually restored.

1.2 Water and sediment regulation has improved the river ecosystem and effectively curbed the siltation and elevation of the river bed.

Due to the lack of water and sediment in the Yellow River and the disharmony between water and sediment, the Yellow River is constantly silting up and rising, the main channel is shrinking, and the secondary suspended river is formed in the lower reaches of the Yellow River, and the wetland ecosystem of the Yellow River is deteriorating. In order to change this situation, from 2002 to 2005, the Yellow River Commission has carried out four consecutive water and sediment adjustments, which have washed more than 300 million tons of sediment into the sea, and the main channel in the lower reaches of the Yellow River has been completely washed away, and the average elevation of the channel bottom has decreased by 1 m. The fifth water and sediment regulation this year has washed 6,065,438+10,000 tons of sediment into the sea, effectively improving the river pattern, reducing the sediment deposition in the river channel and being contained.

The five water and sediment transfers of the Yellow River since 2002 have also provided favorable water conditions for wetland ecological restoration. This year, the Yellow River injected more than 20 million cubic meters of river water into the Yellow River estuary wetland for the fifth time, which made the Yellow River estuary area full of pits and ponds, dotted with blue waves of reservoirs, forming a large area of water surface and wetlands, effectively alleviating the phenomenon of wetland reduction caused by seawater erosion. The Yellow River Estuary wetland grows at an average annual rate of 50,000 mu, becoming the fastest growing nature reserve in the world, with the total wetland area increasing to 200,000 hectares. The area of wetland reed has increased to 50,000 hectares, Tamarix forest10.3 million mu, and 393 species of wild plants in nature reserves. Endangered and rare aquatic animals such as the Yellow River saury, and many national rare birds such as black-billed gull, oriental white stork and red-crowned crane appear in the Yellow River estuary, and the number of birds in the delta has increased to 283, with increasingly rich biodiversity resources and stable ecology.

1.3 water and sediment regulation is beneficial to adjust and straighten out the river regime, shape and maintain the reclaimed water channel.

Most of the Yellow River is formed by the accumulation of wandering rivers, with serious siltation, shrinking form, wide and shallow channels, scattered water flow, no fixed channel, wandering and swaying mainstream, dense sandbanks and numerous tributaries, and the phenomena of oblique rivers, cross rivers and rolling rivers occur from time to time, especially in dry season, when the water flows with the Gulf, it often forms a battery-like river regime, which in turn leads to small water disasters or small water disasters. According to the evolution law of the Yellow River when the small water enters the bay and the flood tends to the middle, the reservoirs are used to jointly dispatch water and sediment to shape artificial normal flood, give full play to the bed-building function of flood, adjust the river regime, shape a relatively stable middle waterway, and improve the flood discharge and sediment discharge capacity of the river. In March this year, the Yellow River Committee conducted an experiment to reduce the elevation of Tongguan by flood scouring in the peach flood season of the Yellow River, which made the river regime adjustment in Tongguan reach smooth and formed a single regular main channel.

1.4 Water and sediment regulation is beneficial to the health of the reservoir and can reduce the adverse effects after the completion of the reservoir.

By regulating water and sediment, a large amount of sediment is discharged from the reservoir by using the density current of the reservoir, so as to adjust the siltation form of the reservoir, reduce the siltation of the reservoir, improve the benefit of the reservoir, enhance the health of the reservoir and prolong the service life of the reservoir. This year, the Yellow River diverted water and sediment for the fifth time. Through the joint operation of Sanmenxia and Xiaolangdi Reservoir, on June 25th, Xiaolangdi Reservoir successfully created density current again, and the Xiaolangdi Reservoir discharged 8,465,438+100000 tons of sand.

The Yellow River flood in the peach flood season has a certain effect on lowering Tongguan elevation. From 1987 to 1998, the average erosion of Tongguan elevation in peach flood season decreased by about 0. 19m. However, since Wanjiazhai Reservoir was put into operation in peach flood season, the flood peak and flood volume entering Tongguan Station have decreased, and the elevation of Tongguan has changed from Wanjiazhai to Wanjiazhai in peach flood season. In order to reduce the influence of Wanjiazhai Reservoir on Tongguan elevation, the Yellow River Committee conducted an experiment to reduce Tongguan elevation by using Taoshui flood of the Yellow River from March 23rd to 29th this year. Through the operation of Wanjiazhai Reservoir, the Taoshui flood process was optimized, and the siltation patterns of Wanjiazhai and Sanmenxia Reservoirs were improved, so that the whole reach of Xiaobei main stream of the Yellow River was washed away by 765.438 million tons and the elevation of Tongguan was reduced by 0.2 meters.

1.5 Water and sediment regulation can effectively play the social and economic functions of the reservoir.

Water and sediment regulation can not only improve the natural function of the river, but also give full play to the social and economic functions of the reservoir, rationally allocate water resources, solve the contradiction between supply and demand of water resources as a whole, improve the comprehensive benefits of power generation, irrigation, ecological landscape tourism and water supply of the reservoir, promote the sustainable development of the economic and social environment in the basin, and realize the harmony between man and nature. Since 2002, the Yellow River Commission has used Wanjiazhai, Sanmenxia, Xiaolangdi and other reservoirs to adjust water and sediment, which has ensured the domestic water and industrial and agricultural production water for urban and rural people along the Yellow River on the premise of ensuring flood control safety. In the rare autumn flood of the Yellow River in 2003, through the "joint operation of four reservoirs", the peak flow was reduced, the disaster loss was reduced, and good social and economic benefits were achieved.

The reasonable operation of 1.6 reservoir effectively solved the crisis of cut-off and ensured the continuous smooth flow of the river.

Since 1970s, the lower reaches of the Yellow River have been frequently cut off due to unfavorable water and sediment conditions and over-exploitation of water resources. The Yellow River was cut off for the first time in 1972, and in the following 26 years, it was cut off for 2 1 year. From 1990 to 1998, the Yellow River was cut off every year, especially in 1997, which lasted for 226 days and the cut-off reach was 704 kilometers. Since 1998, the state authorized the Yellow River Water Conservancy Commission to implement unified water regulation and management of the Yellow River, and through measures such as rational reservoir regulation and utilization, the crisis of water cut-off has been effectively solved, and the Yellow River has been continuously flowing for seven years. For example, on July 22nd, 2002, the flow of 0.95m3/s appeared in Tongguan section of the middle reaches of the Yellow River. At the critical moment of the cut-off crisis, Wanjiazhai Reservoir timely dispatched water to ensure the continuous smooth flow of the river.

1.7 scientifically adjust the water quantity by using the reservoir, realize the utilization of rain and flood, and reduce the loss of flood and drought disasters.

Because of the uneven distribution of rainfall in time and space, drought and flood often alternate in the Yellow River basin. Through the rational operation of reservoirs, flood storage and drought relief, abundant storage and dry use, timely storage and water conservation, reduction of flood peaks and rational utilization of rain and flood resources, efforts are made to grasp the initiative of flood control and drought relief and reduce losses caused by flood and drought disasters. In 2005, Shaanxi Provincial Defense General made full use of Heihe, Shitou and Fengjiashan reservoirs to strengthen flood dispatching and staggered Weihe floods twice. The flood peak of Weihe River decreased by 970 cubic meters per second in the first flood, and decreased by 500 cubic meters per second in the second flood. In addition, Sanmenxia reservoir has been used free of charge during the flood, reducing the pressure of flood control and ensuring the flood.

1.8 reservoir rationally regulates water quantity, effectively solving the pollution of river water environment.

Using the self-purification function of water, the water quantity can be reasonably adjusted through the reservoir to dilute the polluted water body and increase the water environmental capacity, so as to improve the water quality and effectively resolve the river water environmental pollution. On the afternoon of June 5438+1October 5, 2006, a diesel oil spill occurred in gongyi city, Henan Province, which caused oil pollution in the lower reaches of the tributary Luohe River and threatened the water quality of the main stream of the Yellow River. The Yellow River Committee promptly increased the discharge of Xiaolangdi Reservoir, closed the discharge gates of Guxian and Luhun Reservoirs, and relayed the monitoring of important sections such as downstream water supply sources to resolve river water pollution incidents in time.

2. Countermeasures and measures to strengthen reservoir optimal operation.

2. 1 Strengthen unified dispatching management of reservoirs

At present, most of the reservoirs built on the main stream of the Yellow River are managed by different units and departments. For example, there are 18 reservoirs in the upper reaches of the Yellow River (2 have been built and 6 are under construction), belonging to 9 management units. The pattern of departmental division, compartmentalization and multi-head water control has not changed. If these reservoirs still adopt the original dispatching management mode and only operate according to their respective tasks, it will not only affect the overall comprehensive utilization efficiency of cascade reservoirs in the basin, but also cause a series of ecological and environmental problems. In addition, in recent years, with the development of the western region and the reform of the power system, there has been a hydropower development boom in the upper reaches of the Yellow River. All parties concerned scramble to seize the right of hydropower development, and some projects even start construction under the condition of incomplete examination and approval procedures, which makes hydropower development blind and disorderly and lacks unified planning and management. Therefore, it is an irresistible trend to implement unified reservoir dispatching and unified management of hydropower development. Establish an efficient and authoritative unified management organization for hydropower development of reservoirs in the middle and upper reaches of the Yellow River as soon as possible, clarify the responsibilities of relevant units, improve the consultation and communication mechanism, strengthen supervision, inspection and management, unite and cooperate, strengthen unified joint dispatching of reservoirs, strictly manage hydropower development planning, maintain a good hydropower development order, give full play to the comprehensive benefits of reservoirs, and protect the ecological environment.

2.2 Strengthen scientific scheduling, and vigorously improve the level of scheduling management.

Reservoir comprehensive operation is a huge systematic project, involving many complex technical problems. Traditional operation means alone can no longer meet the requirements of timeliness and modernization of water resources dispatching. It is necessary to speed up the construction of "digital water diversion". Establish and improve a modern water resources dispatching management system integrating information collection automation system, computer network system, decision support system, reservoir dispatching information platform, hydrological information platform in the middle and upper reaches of the Yellow River, remote video consultation system and dispatching command center, hydrological station network system for reservoir operation monitoring, fully digital water quality automatic monitoring station, remote automatic monitoring and monitoring of water intake and other systems to realize the exchange and sharing of reservoir dispatching information. Build a water resources regulation system to maintain river health, seriously carry out research on reservoir ecological regulation based on reservoir water and sediment combined regulation mode and basin scale, further improve the index system of reservoir scientific regulation, strengthen the research on river ecological health evaluation and regulation measures, scientifically identify and evaluate the degree of river ecological health, fully understand and understand the problems faced by river ecology, and analyze and master the natural laws of its development and change. According to the water demand of organisms themselves and the environmental water demand on which organisms depend, the river ecological water demand, the river ecological basic flow and the critical flow without scouring and silting are determined, and how to use the minimum water volume of reservoirs and the shortest discharge time to form an effective dispatching method with the best silting reduction effect on the downstream rivers is carefully studied, and the theoretical and technical system of water transfer and the ecological environment response mechanism are established. Earnestly study the interest changes and compensation mechanism of related objects before and after the implementation of reservoir ecological regulation, further explore the laws of river water and sediment movement and erosion and deposition changes, shape a harmonious relationship between water and sediment, formulate a scientific and feasible comprehensive reservoir regulation plan, further improve the implementation plan of water and sediment regulation, conscientiously do a good job in water and sediment regulation plans with different regulation methods and combinations of discharge and sediment concentration, and build a water and sediment regulation team with quick response, excellent technology and excellent work style. Using weather radar, global positioning system, satellite remote sensing, geographic information system, underwater radar, remote monitoring, real-time transmission of image data network and other technologies, we will strengthen water quantity and quality monitoring and weather, water regime and rain forecast, improve the early warning system, realize remote automatic monitoring, monitoring, surveillance and early warning of reservoirs, major hydrological stations, water quality monitoring stations, important water intakes and control nodes, and provide various forms of information services for scientific analysis and decision-making of water transfer, which will be greatly improved.

2.3 Improve the laws and regulations on reservoir dispatching management, and strengthen management and dispatching according to law.

Effective laws and regulations and strict law enforcement are important guarantees for reservoir regulation and water resources management. Therefore, it is necessary to further strengthen economic and legal means, establish water resources dispatching management system, ecological compensation mechanism and water quantity dispatching compensation mechanism, constantly improve water laws, regulations and law enforcement system, build a water management system and a new water resources regulation and control mechanism adapted to modern development, further revise and improve existing laws, regulations and policies related to reservoir dispatching and comprehensive water resources management, strengthen the connection and coordination between laws and regulations, and improve operability. Conscientiously implement the Regulations on Water Dispatching of the Yellow River and other laws and regulations, strengthen macro-control of water resources and reservoir dispatching management according to law, regulate human water use behavior with laws and regulations, ensure that laws are followed, law enforcement is strict, violators are prosecuted, and maintain a good water resources management order, so that all kinds of hydropower development projects are carried out in strict accordance with relevant laws and regulations in terms of project establishment, investment, construction, project quality standards, water distribution, benign operation management mechanism of projects and benefit play after completion. At the same time, a unified water resources management system combining development and protection, water quantity and quality, urban and rural areas, surface water and groundwater, water intake and use, water supply and drainage will be established, so that the reservoir dispatching management will gradually move towards normalization, standardization, legalization and modernization, and promote the sustainable utilization of water resources, the virtuous circle of ecological environment and the sustainable development of social economy.

2.4 Establish and improve the water and sediment regulation engineering system.

The main problems of the Yellow River are less water and more sediment, and the water and sediment are unbalanced. Therefore, water and sediment regulation by reservoir is a powerful measure to improve water and sediment conditions, prevent floods and reduce siltation. It is necessary to co-ordinate the water and sediment resources in the main branches of the Yellow River basin, strengthen the construction of water and sediment regulation engineering system, and conscientiously do a good job in the overall planning of water and sediment regulation engineering system. Establish and improve the water and sediment regulation engineering system of the Yellow River as soon as possible, with Longyangxia, Liujiaxia, Heishanxia, Daliushu, Qikou, Guxian, Sanmenxia and Xiaolangdi as the main water conservancy hubs, implement joint and unified regulation of the whole river, effectively regulate flood and sediment, ensure the basic flow of the river during the drought period, reduce the flood flow in time, realize cross-time regulation of the whole river and sediment, and shape a coordinated and balanced relationship between water and sediment, so as to make the Yellow River as much as possible.

2.5 Improve and optimize the reservoir operation mode.

With the continuous improvement of the level of water resources development and utilization, the contradiction between supply and demand of water resources intensifies, and the role of optimal allocation of water resources is strengthened, thus enhancing the role of reservoirs in the regulation of water resources in river basins. However, the original reservoir design and operation mode did not consider its impact on the downstream ecology and water environment of the reservoir area, so that the long-term accumulated ecological and environmental responses became increasingly apparent in various ways. Therefore, we should completely change our ideas, stand at the height of the whole basin, set out from ensuring the sustainable development of the basin and maintaining the health of the river, and establish and improve the comprehensive operation mode of the reservoir. Reservoir operation is no longer the pursuit of self-interest, but is brought into the unified allocation of the whole basin, which has become an important means to unify the allocation of water resources in the basin, rationally adjust the interests of all parties and coordinate the relationship between social economy and ecological environment. Using advanced dispatching technology and means, on the basis of meeting the requirements of ecological protection in the downstream of the reservoir and water environment protection in the reservoir area, the functions of flood control, power generation, irrigation, water supply, shipping and tourism of the reservoir are fully exerted, and the negative impact of the reservoir on the ecology in the downstream of the dam and the water environment in the reservoir area is controlled within an acceptable range. And gradually repair the ecological and environmental systems, improve the social, economic and environmental benefits of the reservoir, and restore and maintain the health of the river.