Significance of dam

It is a kind of water retaining structure, which intercepts the water flow in the river to raise the water level or adjust the flow. It can form reservoirs, raise water levels, regulate runoff and concentrate water heads, and can be used for flood control, water supply, irrigation, hydropower generation and improvement of navigation. River training structure, which adjusts the river regime and protects the riverbed, is also called a dam, such as groins, shun dams and submerged dams.

Benefits of dam construction:

Taking the Three Gorges Dam as an example, it is a key measure for comprehensive flood control in the middle and lower reaches of the Yangtze River. It also has huge comprehensive economic benefits such as power generation, shipping, irrigation, water supply, and developing the economy of the reservoir area, which is of great significance to accelerating China's modernization process and improving its comprehensive national strength.

First of all, building dams can solve the problem of water shortage. Taking China as an example, due to the monsoon climate, heavy rains are concentrated, and although floods often occur, fresh water resources are very scarce on the whole.

With the development of economy and the increase of social water demand, one of the measures to solve the shortage of water resources in China is to build a number of large water storage reservoirs to increase the flood storage capacity of each basin in flood season, thus increasing the available amount of water resources.

Throughout history, any developed country in the world, without the full guarantee of natural water resources formed by special environment, almost without exception, must rely on dam storage to solve its water supply problem.

The crest elevation of the Three Gorges Dam is 185m, and the maximum dam height is 175m. The normal water level of the reservoir is1.75m, with a total storage capacity of 39.3 billion cubic meters, which alleviates the shortage of water resources in neighboring provinces.

The unfavorable factors brought by the completion of the dam:

Gravels and pebbles, not sediment, are the key bed-making materials that affect the evolution of the upper reaches of the river. The Three Gorges area belongs to limestone landform. How can this dam be built to prevent dripping water from passing through the stone?

The pressure of that water is so great that the veins in the Three Gorges area are criss-crossed, which is a plate compression area prone to earthquakes. There is so much water in the narrow valley that it is extremely dangerous. After the dam is repaired, none of the pebbles that were originally driven out of Kuimen every year will be discharged. It may block Chongqing Port within ten years and extend upstream year by year, flooding Jiangjin River area in flood season.

Reservoir inundation of cultivated land, migration and urban relocation will aggravate the already prominent contradiction between man and land, which may aggravate plant damage, soil erosion and ecological deterioration.