What are the disadvantages and advantages of Dujiangyan water conservancy project without dam construction?

Dujiangyan, a world cultural heritage, located in Chengdu, Sichuan Province, is a grand water conservancy project characterized by water diversion without dams.

Specific pros and cons:

Advantages:

First, flood control. Damming upstream can regulate water flow and reduce the impact of flood on the middle and lower reaches. Water conservancy facilities such as flood dikes can also prevent tidal sand and river water from scouring the other side, conserve water and soil, have flood control effects on low-lying cities and prevent floods from damaging agriculture.

Second, use water. Solve local water use and rationally allocate water resources. For example, the South-to-North Water Transfer Project has solved the problem of water shortage in the north. It also increases the carrying capacity of water resources and improves the allocation efficiency of resources.

Third, shipping. After the impoundment of the dam, the upstream channel is widened and deepened, which improves the upstream shipping conditions and reduces the influence of seasons on shipping.

Fourth, power supply. Hydroelectric power generation is the sustainable development of light machine energy, which can reduce the environmental pollution caused by the use of fuel and coal. For example, the Three Gorges Hydropower Station effectively solved the energy crisis in southern China and promoted the rapid economic growth.

Verb (short for verb) Tourism. Tourism has increased the air humidity in the surrounding areas, improved the growth of surrounding vegetation and promoted the development of tourism.

Sixth, irrigation. Dujiangyan, for example, is responsible for the irrigation of farmland in Sichuan basin and the water supply of enterprises and cities in Chengdu. As well as comprehensive services such as flood control, power generation, bleaching, aquatic products, aquaculture, fruit, tourism and environmental protection, its irrigation area ranks first in the country.

Disadvantages:

Impact on fish: The construction of reservoirs and dams will change information such as flow velocity, water temperature and water level, which will inevitably affect the spawning and growth of fish. The construction of some dams cut off their migration routes, making some fish unable to lay eggs, and the number decreased obviously, which affected the population reproduction.

Sediment problem: Damming the river blocks the natural river, which leads to the change of river flow pattern, and then leads to the change of hydrological characteristics of the whole river upstream and downstream and estuary. This is the biggest ecological problem brought by dam construction, which will lead to the gradual precipitation of part of suspended load and bed load sediment, resulting in reservoir siltation and corrosion of discharge buildings, further leading to frequent natural disasters, land salinization, soil fertility decline, and long-term salinization and swamping of large areas of soil.

Causing geological disasters, including earthquakes, landslides, falling rocks and mudslides. The accumulation of water bodies in reservoirs built in fault zones and geological disaster areas leads to changes in crustal structure, which may become the conditions for inducing earthquakes. For example, the northeast fault of Qiyueshan, the biggest drawback of the Three Gorges Project, is likely to cause an earthquake.

Impact on terrestrial ecological environment:

(1) destroys a large number of woodlands, grasslands, farmland and other vegetation, affecting the habitat of terrestrial animals. At the same time, the industrial wastewater and domestic sewage produced in the construction process are directly discharged into the river without treatment, which changes the physical and chemical properties of the river, worsens the living environment of reptiles along the river bank and causes the imbalance of regional ecosystem.

(two) the construction of water conservancy projects need to relocate the land and residents in the flooded area and within the scope of the project, dismantle and rebuild the infrastructure such as industrial and mining transportation, and protect cultural relics and historic sites.

What are the characteristics of Dujiangyan?

Dujiangyan has the characteristics of "dividing into four or six and being poor".

Dujiangyan canal head hub is mainly composed of three main projects: fish mouth, flying sand weir and treasure bottle mouth. The three factors cooperate organically, restrict each other, operate cooperatively, divert water for irrigation, divert flood and reduce disasters, thus having the characteristics of "four points and six points, and relieve drought".

Dujiangyan is a world cultural heritage (listed in the "World Cultural Heritage" list by UNESCO in 2000), a world natural heritage (giant panda habitat in Sichuan), a national key cultural relics protection unit, a national scenic spot and a national AAAAA-level tourist attraction.

Dujiangyan is located in the west of Dujiangyan City, Sichuan Province, on the Minjiang River in the west of Chengdu Plain. Dujiangyan water conservancy project, which was built in 256 BC, is the oldest and only grand water conservancy project in the world. Its characteristic is that no dam is built to divert water. It is a national key cultural relics protection unit. Dujiangyan has beautiful scenery and many cultural relics, including Fulongguan, Erwang Temple, Anlan Suoqiao, Yuleiguan, Lidui Park, Yuleishan Park and Lingyan Temple.

I hope the above content can help you. If in doubt, please consult a professional lawyer.

Legal basis:

Article 12 of the Building Law of People's Republic of China (PRC)

Construction enterprises, survey units, design units and engineering supervision units engaged in construction activities shall meet the following conditions:

(1) It has a registered capital that meets the requirements of the state;

(2) Having professional and technical personnel with legal practice qualifications suitable for the construction activities they are engaged in;

(3) Having the necessary technical equipment to engage in relevant construction activities;

(4) Other conditions stipulated by laws and administrative regulations.

Article 13

Construction enterprises, survey units, design units and engineering supervision units engaged in construction activities are divided into different qualification grades according to their registered capital, professional and technical personnel, technical equipment and completed construction performance, and can engage in construction activities within the scope permitted by their qualification grades only after passing the qualification examination and obtaining the qualification certificates of corresponding grades.

Article 20

Where public bidding is carried out for construction projects, the contracting unit shall issue a tender announcement in accordance with legal procedures and methods, and provide the tender documents containing the main technical requirements, main contract terms, bid evaluation standards and methods, and the procedures for bid opening, bid evaluation and bid selection.

The bid opening shall be conducted in public at the time and place specified in the tender documents. After the bid opening, the bids shall be evaluated and compared according to the bid evaluation standards and procedures stipulated in the tender documents, and the winning bidder shall be determined among the bidders with corresponding qualifications.