As a kind of water conservancy engineering building, the reservoir's main function is to serve as the domestic water source for many cities. On the other hand, many reservoirs are the source reservoirs of major water transfer projects, for example, the "South-to-North Water Transfer Project" has been applied to some reservoirs.

Reservoirs can play a role in flood control. Without reservoir storage, the water in the upper reaches of the river will change with rainfall, and people in the lower reaches will face floods at any time.

Reservoirs play an important role in agricultural irrigation. Small reservoirs are important water sources in rural areas, which can ensure the drinking water of rural population and can also be used for agricultural irrigation to ensure the normal growth of crops.

What conditions do you need to build a reservoir?

1. The dam site is located at the outlet of rivers, canyons, basins and depressions (bag-shaped areas are favorable for dam construction: small quantities, low cost and large storage capacity).

2. Choose places with good geological conditions and avoid karst landforms and faults.

3. Climatic and hydrological conditions: ensure sufficient water.

4. Consider whether it is necessary for immigrants to build reservoirs and the situation of land occupation and relocation, so as to minimize the inundation of residential areas.

3 Analysis of the advantages and disadvantages of building reservoirs

1, the benefits of building a reservoir:

Regulating river runoff and improving the climate in the reservoir area (reducing temperature difference and increasing air humidity); Flood control, shipping, power generation, irrigation, aquaculture, tourism, etc.

2. Disadvantages of building a reservoir:

(1) Increase the frequency of geological disasters in the reservoir area. The construction of the reservoir may induce earthquakes and increase the earthquake frequency in the reservoir area and nearby areas.

(2) Sediment deposition. Due to sediment deposition in the reservoir area, the actual water storage capacity of the reservoir is decreasing.

(3) The continuous irrigation of soil salinization in the downstream makes the groundwater level rise and brings the salt in the deep soil to the surface. The high content of salt and various chemical residues in the irrigation water lead 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 groundwater and increasing the salt content of the downstream rivers.

(5) The influence on the downstream river course may also change the river direction and alluvial degree of the downstream river course due to the change of water potential and sediment concentration, resulting in serious riverbed erosion and the river (sea) mouth retreating to the land.