Analysis of eutrophic nutrient sources and benefit of grain for green in Sancha Lake

Sancha lake is the second largest lake in Sichuan Province, the factors of affecting eutrophication are not only point pollution source, but also non-point pollution source. The results of the investigation show: drawing water is 50% of total phosphorus contribution, cage culture is 10.44%, 39.21% of precipitation and surface runoff, sewage is 0.35%, although the drawing water is 50% of the total phosphorus input, but the drawing water is 80% of the total amount of water, while the precipitation accounted for 20%, and surface runoff accounted for 39.21% of the total, so the main nutrient source of eutrophication in Sancha Lakes is surface runoff and cage culture. The different use way in the land will produce the different surface runoff. As the case of the land revenue in recent 6 years, forestry and animal husbandry is not only a small impact on the environment, and economic benefits of the former is 2 to 3 times. So, forestry and animal husbandry in Sancha lake not only has ecological benefits, but also has obvious economic benefits. The economic benefits and environmental benefits in the process of using water can be in unanimity.