What is the function of the reservoir?

Reservoir is one of the engineering measures widely used in flood control in China. A comprehensive reservoir with flood storage capacity should be built at an appropriate position in the upstream of the flood control area, and the flood storage capacity of the reservoir should be used to reduce the flood peak flow into the downstream river, so as to achieve the purpose of reducing flood disasters. There are two different ways for reservoir to regulate flood, one is flood detention and the other is flood storage.

1. Flood detention

Flood detention is to let the flood temporarily stay in the reservoir. When there is no gate control on the spillway of the reservoir and the water level of the reservoir is flush with the elevation of the spillway crest, the reservoir can only play the role of temporary flood interception.

2. Flood storage function

In the case of spillway without sluice gate, in the stage of reservoir management and operation, if the reservoir water level can be reduced to the reservoir flood limit level before flood season, and the reservoir flood limit level is lower than the spillway crest elevation, the storage capacity between the flood limit level and the spillway crest elevation can play a role in flood storage. Part of the flood stored in the reservoir can play a planned role in the dry season.

When the spillway is equipped with gates, the reservoir can play a greater role in flood storage, and the reservoir can adjust the flow by changing the opening of the gates. Because of the gate control, the flood control limit water level of this kind of reservoir can be higher than the spillway crest, and the gate opening can be adjusted at any time to control the flow during flood discharge, which has dual functions of flood detention and storage.

2 the beneficial role of the reservoir

The precipitation that falls on the ground (partially seeps into the ground) in the basin is called river runoff after it is discharged into the river in different ways from the ground and underground. Due to the variability and non-repetition of river runoff, the incoming water is different from year to year, from season to season, and from region to region. Most water conservancy departments (such as irrigation, power generation, water supply, shipping, etc. ) need a relatively fixed water consumption and water consumption time, and their requirements are often not fully adapted to natural water supply. In order to solve the problem of redistribution of runoff in time and space and fully develop and utilize water resources to meet the requirements of water conservancy departments, people often build some reservoir projects on rivers. The beneficial function of the reservoir is to regulate runoff, store flood and make up for drought, so that natural water can meet the requirements of the water conservancy department in time and space.

[Edit this paragraph] Disadvantages of building reservoirs

1. Increase the frequency of geological disasters in the reservoir area

The construction of reservoirs may induce earthquakes and increase the frequency of earthquakes in the reservoir area and nearby areas. Because the lower parts of the mountains on both sides will be submerged for a long time in the future, the frequency of landslides, landslides and mudslides will increase.

2. Lead to sediment deposition in the reservoir area.

Due to the interception of the dam and the backwater effect caused by the change of water potential in the reservoir tail area, sediment will inevitably accumulate in the reservoir, especially in the dam and reservoir tail (backwater effect).

3. Soil salinization of downstream land

Continuous irrigation makes the groundwater level rise and brings the salt in deep soil to the surface. The high content of salt and various chemical residues in irrigation water leads to soil salinization.

4. The water quality in the reservoir area and downstream has deteriorated.

The water surface area of the reservoir area is large, a large amount of water evaporates, and soil salinization increases the salt and chemical residues in the soil, thus polluting the groundwater and increasing the salt content of the downstream river.

5. Changes of river water quality

Due to the deterioration of water quality, the speed of water flow slows down, and aquatic plants and algae spread everywhere, which not only evaporated a lot of river water, but also blocked the river irrigation channels and so on. These aquatic plants not only spread all over irrigation channels, but also invaded major rivers. They hinder the effective operation of irrigation channels and need to be cleaned by mechanical or chemical methods frequently. This increases the maintenance cost of the irrigation system.

6. Impact on downstream rivers

Due to the change of water potential and sediment concentration, it may also change the river direction and the alluvial degree of the downstream reach, resulting in serious riverbed erosion and the river (sea) mouth retreating towards the land.

7. The incidence of schistosomiasis and other epidemics has increased downstream because of the static water flow.

8. Immigration and its influence on the scenery and cultural relics in the reservoir area

Due to the rising water level, the reservoir area is flooded and needs to be resettled. Moreover, due to the construction of the reservoir, the scenic spots and cultural relics in the reservoir area have been flooded and need to be relocated and restored.

9. Impact on climate

After water storage in the reservoir area, the water area will expand and the water evaporation will increase, which will reduce the temperature difference between day and night in the nearby area and change the climate environment in the reservoir area.

10. Diplomatic influence

Building a reservoir on an international river is tantamount to the redistribution of water resources, which indirectly affects the relationship between the country where the reservoir is located and the downstream countries.

1 1, loss of value

Submerged cultural relics or caused the loss of the original natural landscape ornamental value.