Study On The Determination Of Ecological Base Flow And Dynamic Thematic Evaluation Of The Middle And Lower Reaches Of The Weihe River

In recent years,due to climate change,the massive construction of water conservancy projects,and the inefficient use of water resources,the inflow of river water has been decreasing year by year.Coupled with the large amount of ecological water use squeezed by domestic and production water,the amount of retained water in the river has been drastically reduced,even appearing The phenomenon of dry flow has caused a large number of environmental problems.In order to prevent the continuous deterioration of the ecological environment,the concept of ecological base flow is proposed.my country’s research on ecological base flow has a history of 50 years,and certain results have been achieved after years of development.However,there are still some problems in the study of ecological base flow in specific river sections,which are mainly manifested in not unique concepts,imperfect connotations,and calculation methods.Difficult to choose,difficult to determine whether the calculation result meets actual needs,etc.,there is still no universal calculation method.This paper proposes a dynamic thematic evaluation service model of ecological base flow based on the existing problems in the current ecological base flow research.Based on the analysis of the existing ecological base flow calculation methods,the dynamic thematic evaluation of the calculation results of each method is carried out,the theme selection and the target river Corresponding to the main ecological service objects of the section,the base flow value of the evaluation is not up to the standard is corrected,and finally the recommended value of the ecological base flow that meets the actual situation of the target river section is obtained.Based on a comprehensive integrated platform to build an ecological base flow determination and dynamic thematic evaluation system,users can choose calculation methods and evaluation methods according to the actual situation,and can also add or delete evaluation indicators,making the ecological base flow calculation more convenient and flexible Sex.The main research results include:(1)This article collects commonly used ecological base flow calculation methods,including hydrological methods,hydraulic methods,habitat methods,holistic methods,and other methods.The methods are summarized and classified,and the methods are classified according to different applicable conditions.Method data requirements and solution process are re-divided into method types,forming method selection generalization diagrams,and componentizing methods that can be programmed,and methods that cannot be programmed to form a knowledge graph,which facilitates the selection and invocation of methods when calculating ecological base flow;(2)This article proposes a dynamic thematic evaluation service model of ecological base flow based on the problem of many calculation methods of ecological base flow and large differences in calculation results.Based on the different service objects of ecological base flow,the evaluation is divided into four themes-connectivity theme,water environment theme,water ecology theme and water-sediment balance theme.Each theme has corresponding evaluation indicators and evaluation methods.The subject of connectivity is evaluated by matter-element extension method,the subject of water environment is evaluated by one-dimensional water quality model method,the subject of aquatic ecology is evaluated by habitat simulation method,and the subject of water and sediment balance is evaluated by sediment content method.The evaluation theme is selected according to the service objects of the ecological base flow of the target river section,and the base flow that does not meet the needs of the service objects after the evaluation is corrected to form a recommended ecological base flow.In this paper,the dynamic thematic evaluation service model of ecological base flow is applied to the middle and lower reaches of the Weihe River,and a set of recommended values of ecological base flow considering the water environment and sediment transport requirements are obtained.The results meet the actual water demand requirements;(3)This article builds an ecological base flow determination and dynamic thematic evaluation system based on a knowledge visualization integrated platform.Driven by the theme,under the traction of the theme,the evaluation business is realized through components,the evaluation application is organized through the knowledge graph,and the system is built through the platform.,To achieve the requirements of adaptive decision-making evaluation.The system is mainly divided into two modules:ecological base flow calculation and ecological base flow dynamic thematic evaluation.The ecological base flow calculation module includes ecological base flow calculation method query,ecological base flow calculation method selection,and ecological base flow analysis and calculation.The calculation result is ecological Base flow result set.The dynamic thematic evaluation module of ecological base flow is based on the result set of ecological base flow,combined with the main ecological service objects of the river section,matching the corresponding evaluation method,and evaluates the result set of ecological base flow,and evaluates the values that do not meet the evaluation results.Amendment to form a set of recommended values for ecological base flow.