Study On The Reservoir Group Ecological Operation In The Lijiang River Basin

The construction and operation of the reservoir relieves the contradiction between the supply and demand caused by the uneven distribution of water resources,but also changes the natural runoff of the downstream rivers.The change of the river water situation will have a negative impact on the ecosystem and interferes with the mitigation of biological survival and reproduction.After analyzing the influence of reservoir operation on downstream eco-environment,the Tennant method,monthly frequency runoff calculation method and habitat method were applied to calculate the ecological flow.Considering the ecological flow constraint in reservoir group scheduling,the optimized post scheduling scheme is compared with the current scheduling scheme.While ensuring the water supply task of the reservoir group,the negative impact of the reservoir scheduling on the ecological environment is alleviated and the healthy and sustainable development of the river is ensured.The main contents of this paper are as follows:(1)According to the hydrological data of Guilin Railway Station and qingzan reservoir,32 hydrological indexes with ecological significance are calculated by variation range method.These 32 indexes can reflect the changes of monthly flow value,annual hydrological extremum,annual extreme hydrological condition,frequency and duration of high and low flow,change rate of flow conditions and frequency,through the change of 32 hydrological indexes and synthesis.The water change degree is used to evaluate the reservoir operation of the Lijiang River tributaries of the river and the ecological environment influence.(2)MIKE11 is used to establish the hydrodynamic model of Lijiang River and simulate the hydraulics process of the river and the accuracy of the model is ensured by comparing the measured data.The representative species of Lijiang River were selected by analytic hierarchy process(AHP);the results of MIKE simulation and the fitness curve of the target species grass carp were used to establish the physical habitat model to simulate the relationship between the habitat area and the flow rate of the grass carp spawning field.(3)The monthly runoff and the habitat method were used to calculate the ecological flow of the tributaries of the main stream and reservoir of Lijiang River and evaluated by Tennant method.The river flow calculation was carried out by means of the method of "mean king" to determine the ecological flow process of the main stream and tributaries of the Lijiang River.(4)The optimal scheduling model of the reservoir with the maximum comprehensive water supply rate as the target and consideration of the ecological flow constraint is established.The adaptive genetic algorithm is used to solve the scheduling results of different years.The optimal scheduling scheme will be compared with the current scheduling scheme.The results show that the ecological benefit of the reservoir is greatly improved at the same time that the water supply benefits of the small part are sacrificed.