上游检测点存在较多工农业生产生活排放、渔禽养殖等，导致大量有机污染物的

There are a lot of industrial and agricultural production and living discharges, fishing and poultry breeding in the upstream detection points, which lead to the accumulation of a large number of organic pollutants and the relative increase of eutrophication, and the warm water discharged from upstream hydropower stations increases the temperature conditions for eutrophication; In the middle reaches, the input of organic pollutants from external sources is relatively reduced. At the same time, the increase in water area effectively dilutes the concentration of pollutants, promotes the diffusion of nutrients and the self-purification of the water body, thereby reducing the level of eutrophication; when reaching the downstream, Under the adjustment of the opening and closing of the regulating gate of the reservoir, the man-made disturbance to the water body is greatly increased, and the diffusion and migration of nutrients are significantly strengthened, which effectively weakens the conditions for the production of eutrophication of the water body and further reduces the eutrophication level of the water body.

Upstream detection points there are more industrial and agricultural production and living emissions, fishing and poultry breeding, resulting in a large number of organic pollutants aggregation caused by the relative increase in the degree of autotrophication, as well as upstream hydropower plant emissions of warm water increased the temperature conditions of autotrophication occurred; Under the opening and closing regulation of reservoir regulation gate, the artificial disturbance of water bodies increases greatly, and the diffusion and migration of nutrients is significantly strengthened, which effectively weakens the conditions for the production of water permafrost and further reduces the level of pertrophication of water bodies.

There are more industrial and agricultural production and living emissions, fish and poultry breeding, etc. in the upstream detection points, which lead to the accumulation of a large number of organic pollutants, resulting in a relatively high degree of eutrophication, and the warm water discharged from the upstream hydropower station increases the temperature conditions for eutrophication; in the middle reaches, the external input of organic pollutants is relatively reduced, while the water area increases, effectively diluting the concentration of pollutants, It promotes the diffusion of nutrients and the self purification of water body, so as to reduce the level of eutrophication; when it reaches the downstream, under the regulation of the opening and closing of the reservoir regulating gate, the human disturbance to the water body is greatly increased, and the diffusion and migration of nutrients are significantly strengthened, which effectively weakens the generation conditions of water eutrophication and further reduces the eutrophication level of water body 。<br>