Study On The Regulation Of Ecological Flow By Subsection-Classification For Rivers Of Multiple Gate Dam

In the river basin,an appropriate target ecological flow can effectively meet the needs of aquatic ecologically sensitive targets,which play an important role in maintaining the health of the rive ecosystem.With the speedly developed economy of the global society and the accelerated growth of the population,mankind is increasingly dependent on water resources.Among them,a large number of river dams have been built,which has led to the neglect of the demand of ecologically sensitive river water targets.As a result,the health and integrity of the river ecosystem was severely damaged.Therefore,the North Canal Basin is selected as the focus of the study,which is greatly affected by the sluice and dam group.Based on the urbanization and semiurbanization of the basin characteristics of the North Canal,multiple protection targets were identified and determined by the method of segmentation and classification.The hydrological and hydrodynamic model of one-dimensional river network suitable for urban and semi-urban rivers was established by MIKE11 software.In this case,according to the multi-objective ecological needs,the single-objective and multiobjective scenario scenarios were simulated and calculated by the gate and dam module.Subsequently,the multi-objective ecological flow demand plan and its satisfaction in the study area were analyzed.The main research findings of the thesis are as follows:(1)Based on the characteristics of the river system in the North Canal Basin,the study area and guarantee objectives were divided and classified according to the main control gates and dams and the ecological function requirements of the river.Subsequently,the ecological flow of the main sections of the main stream of the North Canal was calculated to determine the ecological flow thresholds of different river sections(upper,middle,and lower reaches)and different protection objects(aquatic ecological protection goals such as fish and landscape,and social needs such as navigation of cruise ships).(2)The hydrological and hydrodynamic model of river network based on ecologically sensitive target flow demand was constructed using DHI MIKE11 software.Based on the hydrological data of 2015 and 2011,the important parameters of the MIKE hydrodynamic model were calibrated and verified,and then the Naxi efficiency coefficient was calculated to evaluate the fitting situation,The simulation results were basically consistent with the change trend of the measured data.(3)For the protection target requirements of different river sections,set single target and multi-target scenarios to simulate aquatic protection target requirements.Based on the current situation and future water resources allocation in the North Canal Basin,the multi-objective scenario plan is optimized for water resources allocation.The dispatch plan and target flow satisfaction effect of each typical year in different scenarios are analyzed.The results show that the regulation of multiple gates and dams and the allocation of water resources in the basin can be used as the optimal regulation plan to achieve the protection of multi-objective ecological needs.In summary,The good agreement between the calibration and verification results indicates that the model construction is generally feasible.The simulation results show that the uneven water diversion in the upper reaches of the basin and the interception and storage of water by the sluices and dams are the key factors that affect the degree of satisfaction of the ecological needs of the North Canal basin.Combined with the optimal allocation of water resources in the basin,the built-up sluice and dam regulation model based on ecological target ecological flow demand can give reasonable sluice and dam dispatch rules to ensure the health and integrity of the water ecological target of all river sections in the river basin.It can provide a scientific basis for improving the goals of water ecological protection in the river basin under urbanization and semiurbanization,and the social needs of cruise ships for navigation.