Loss refers to the phenomenon that rainwater cannot be absorbed locally due to natural or man-made factors, and flows down the river, scouring the soil, resulting in simultaneous soil and water loss. The main reasons are steep slope, improper land use, vegetation destruction, unreasonable farming techniques, loose soil, deforestation and overgrazing. The harm of soil erosion is mainly manifested in the following aspects: (1) the cultivated layer of soil is eroded and destroyed, which makes the soil fertility exhausted day by day; Blocking rivers, channels and reservoirs, reducing the benefits of water conservancy projects, and even leading to floods and droughts, seriously affecting industrial and agricultural production; Soil erosion poses a serious threat to agricultural production in mountainous areas and downstream rivers.