Study On Reservoir Ecological Regulation Of The Downstream Of Lancang River

In recent years,with the construction of the water conservancy projects in the lower reaches of the Lancang River,the operation of the cascade hydropower stations has brought tremendous economic benefits,but aggravated the problem of the ecological accumulation effects.The hydrological regime,water temperature,water quality,aquatic life,and habitat have been affected with different degrees,all of these indicating that the river is facing severe water ecological problems.The main purpose of this study is to find a suitable ecological flow process by ecological operation of the reservoirs in the lower reaches of the Lancang River Through the optimal operation of cascade reservoirs,the relationship between power generation and ecological goals is quantitatively analyzed to improve the imbalance between them,thereby reducing the downstream water ecological pressure.The results show that Therefore,the research results will have important practical significance for maintaining water ecological balance in the lower reaches of the Lancang River and guiding ecological optimal operation of cascade hydropower stations.This paper focuses on the ecological problems in the lower reaches of the Lancang River,and the research on ecologically optimal dispatch methods and theories of cascaded hydropower stations.The research results mainly include the following parts:(1)Based on the long time series runoff data of Lancang River,the statistical characteristics,distribution,trend,consistency and other characteristics of runoff are analyzed.Using the daily runoff before and after reservoir construction,the change of hydrological regime under current condition is analyzed,and the ecological change degree in the lower reaches of Lancang River is comprehensively evaluated.The ecological significance of each hydrological index is clarified and the main ecological problems in the lower reaches of Lancang River are pointed out.(2)Based on the requirements of the ecological water requirement of the fish habitat in the lower reaches of the Lancang River and the theoretical basis of the flow increment method,the two-dimensional hydrodynamic model of the habitat and the suitability index model are established by applying the fuzzy logic reasoning principle.The model of the physical habitat of the lower reaches of the Lancang River is coupled.Through this model,the flow under different protection targets is calculated.The ecological water demand process under three different protection scenarios of the lower reaches of the Lancang River is finally obtained by coupling the ecological water demand and the ecological water demand calculated by the range of variability approach.(3)Based on the the process of ecological water demand in the lower reaches of the Lancang River,the method of transforming the ecological flow process into ecological objective is proposed.The middle and long term scheduling model of the lower reaches of the Lancang River is established by using three target functions,and the multi-objective ecological scheduling schemes are obtained by using the improved genetic algorithm.The discharge process,the ecological change degree,and electricity generation of the hydropower station under different operation modes are analyzed.The linear mutual feedback relationship between ecology and electricity generation is obtained through statistical analysis.(4)Aiming at the evaluation of reservoir operation plan,the evaluation index of reservoir operation plan is put forward,and the evaluation model of reservoir operation plan based on ELECTRE-TRI is established.The preferences of the decision-makers are used as input,and the parameters of the model are calculated by the optimization algorithm.Finally,the model is used to classify and evaluate the multi target reservoir scheduling scheme.The multi-objective optimal scheme under different scenarios is analyzed,and the operation process of water level in different typical years is obtained,and the function expression between the ecological and power generation during the dry period is fitted.