Influence of the hydraulic engineering construction in the upper reaches on the eco-environmental flow of the middle-lower reaches of the Yangtze River -based on the improved SWAT model

The basin water cycle affected by human activities presents the duality of natural and human characteristics. On the basis of improved a physically based distributed parameter model, Soil and Water Assessment Tool(SWAT) and Tennant method, the influence of the hydraulic engineering construction in the upper reaches on the eco-environmental flow of the middle-lower reaches of the Yangtze River is analyzed according to the hydraulic engineering construction plan, we established 4 scenarios. The results show that, in flood season, the evaluation of scenario 2 is good to maximum, scenario 3 is minimum to maximum, scenario 4 is fair to maximum; dry season period, the evaluation of scenario 2 is good to optimal range, scenario 3 is fair to optimal, scenario 4 is good to outstanding; In water storage period, the evaluation of scenario 2,3,4 are optimal range. The evaluation of the Tennant method is the exceed to the other scenarios when all the reservoirs involved in running. The results of the current study will be proved some references to the regional water resources management and reservoir ecological operation with the influence to eco-environmental flow of the low reaches, when the schema reservoir constructed in the upper reaches of Yangtze River.