Benefits of building a reservoir

The main principle of flood control and drought relief is that due to the variability and non-repetition of river runoff, the incoming water varies year by year, season by season and region by region. In this way, sometimes the flood floods and sometimes the drought stops, so the reservoir can store water when the flood floods and release water when the drought stops, thus playing a role in flood control and drought relief. This is the so-called regulation of seasonal runoff of rivers. Most other water departments, such as irrigation, power generation, water supply, shipping, etc. , require a relatively fixed water consumption and water consumption time, and their requirements often can not fully adapt to the natural water supply situation. In order to solve the problem of redistribution of runoff in time and space, people also need reservoirs to regulate the seasonal runoff of rivers. Disadvantages of building a reservoir 1. Frequent geological disasters in the reservoir area and their impacts. Building a reservoir may induce earthquakes and increase the frequency of earthquakes in the reservoir area and its vicinity. Due to the sudden long-term immersion of the lower parts of the mountains on both sides (there was no flood before), the frequency of landslides, landslides and mudslides will increase. This increase can not guarantee the safety of the reservoir, and once the reservoir has a safety accident, the impact on the downstream is many times greater than that without the reservoir, which is equivalent to rushing downstream after storing water, and the damage to the downstream will be enormous. 2. Sediment deposition in the reservoir area will inevitably be deposited in the reservoir, especially in the dam and reservoir tail (due to the influence of backwater) because of dam interception and water potential change to alleviate the influence of backwater at the reservoir tail. Sediment deposition in the reservoir area leads to the continuous reduction of the actual storage capacity of the reservoir, and the benefits are decreasing year by year. And directly lead to the impact on the downstream river. 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 lead to soil salinization. The water quality in the reservoir area and downstream is deteriorating. 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 groundwater and increasing the salt content of the downstream rivers. 5. Changes and impacts of downstream water environment 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. 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 the downstream river course Due to the change of water potential and sediment concentration, it may also change the river direction and alluvial degree of the downstream river section, resulting in serious riverbed erosion and the river (sea) mouth retreating towards the land. 7. Impact on the spread of diseases Due to the static water flow, the incidence of schistosomiasis and other epidemics in the downstream will increase, and mosquitoes, flies and other pathogenic microorganisms will be more likely to breed in the reservoir area. 8. Immigration and its influence on the scenery and cultural relics in the reservoir area. The water level rises, the reservoir area is flooded, and it is necessary to emigrate (a big problem). 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 expands and the water evaporation increases, which reduces the temperature difference between day and night in nearby areas and changes the climate environment in the reservoir area. 10. Diplomatic influence The construction of 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, the loss of value inundates cultural relics or causes the loss of ornamental value of the original natural landscape. If you only pay attention to the natural landscape, of course, more water will also add points to the landscape. The canyon is gone, and the high gorge comes out of Pinghu. 12. Changes in water temperature and water quality that affect the survival of aquatic organisms will affect the survival of the original aquatic organisms. If fish that need reproductive migration are blocked by reservoirs, they are in danger of extinction. 13. Impact on terrestrial organisms in the reservoir area: Flooding the land will not only lead to immigration, but also expel terrestrial animals, and land plants will also be flooded. Terrestrial plants may die in large numbers, especially in the case of endangered species. Submerged plants will ferment to form biogas, which will lead to air pollution and climate warming when discharged into the air. From the above analysis, we can see that the advantages and disadvantages of building a reservoir are interrelated, and all kinds of disadvantages also influence each other. This reminds us of a basic geographical viewpoint: the integrity of geographical environment. At the end of the article, I recommend an article, The Wall Street Journal China: Building a new dam for the world. The article comes from the first two paragraphs of the website of the dam safety center of the State Electricity Regulatory Commission. Almost half of the 45,000 large dams in the world are in China, and China has started to export its hydropower technology to developing countries, although it is still trying to cope with the environmental damage and social problems caused by the Three Gorges Dam. Many countries and international organizations have begun to stay away from building dams. However, China enterprises and Chinese banks are now involved in the construction of at least 47 dams in 27 countries, with a total cost of billions of dollars, some of which are located in Sudan and Myanmar, which have been criticized for human rights violations and poor environmental records.