Study On River Health Assessment Considering Different Functional Zones

River is the blood of the earth,the source of life and the cradle of civilization.It plays an extremely important role in maintaining hydrological cycle,energy balance,climate change and ecological development.It has natural function,ecological function and social service function,and provides material basis and guarantee conditions for human survival and social development.With the rapid development of economy and society and the aggravation of global climate change,the management and protection of rivers in some areas of China still face many challenges.The development of many rivers has approached or exceeded the carrying capacity of water resources and water environment.The problems of water pollution,river disconnection,wetland shrinkage and ecological degradation have become increasingly prominent,which has become a prominent bottleneck restricting the sustainable development of economy and society.As the northern gateway of Hefei metropolitan area,Changfeng County has a strong momentum of economic and social development,and the demand for water resources continues to grow.However,the regional water resources endowment conditions are general,the current water use efficiency is not high,and the overall shortage of water resources restricts the development of its national economy,and also brings great pressure to the management and protection of the ecological environment.As the largest river in Changfeng County,Zhuangmu River has a significant impact on its health status.The river characteristics are representative and the river problems reflected are typical.In this paper,the health status of Zhuangmu River considering different functional zoning is taken as the research object.Based on the analysis and summary of the existing research results at home and abroad on the connotation of river health concept and evaluation system,from the perspective of maintaining the stability and functional integrity of river ecosystem structure and realizing the sustainable development of natural ecological function and social service function,the technical system of river functional zoning is proposed.The river health evaluation system based on functional zoning is constructed,and the case study of Zhuangmu River health evaluation is carried out.It provides a scientific basis for clarifying the attributes and positioning of river functions,maintaining the health status of rivers and ensuring the sustainable utilization of river functions.The main research results are as follows:(1)By analyzing the theoretical basis of river function and zoning definition,the theoretical basis and conceptual connotation of river function zoning are proposed.In order to ensure the comprehensiveness,rationality,orderliness and feasibility of the zoning,the division principles of river functional zoning are clarified.Based on the application results and practical experience of ecological function zoning,water function zoning and river-lake shoreline function zoning,according to the characteristics of river natural and ecological functions and the demand of economic and social development for river development and utilization,the river function zoning is divided into five types: ecological protection area,water supply and water use area,flood control and drainage area,hydropower generation area and inland river shipping area,and the specific division steps of river function zoning are formulated.(2)By discussing the evaluation scale and principle of river health,the space,time scale and evaluation principle of this health evaluation study are determined.According to the influencing factors of river health in terms of landform,connectivity,hydrology,water quality,biology and land use,according to the principle of index selection,through the index screening steps,combined with the actual situation of the study area,the river health comprehensive index RHI is constructed as the state layer,covering the landform,hydrology,water quality,biology and social service functions.Five attribute layers and 26 indicators,based on five functional zoning of river health evaluation index system.Refer to the research results of national and local standards and specifications,and solicit expert opinions to set river health assessment grade standards.Based on the principle of minimum discriminant information,the subjective and objective combination weights of AHP method and CRITIC method are determined,and the fuzzy comprehensive evaluation model of river health is established.(3)By expounding the natural geography and other regional profiles in the Zhuangmu River Basin,the river is divided into sections along the longitudinal direction according to the technical system of river functional zoning.On the basis of data collection,investigation and monitoring,the river health evaluation system based on functional zoning is used to evaluate the overall characteristics of river health through ’ index calculation-membership analysishealth level evaluation ’.The results show that the current situation of the four evaluated river sections of Zhuangmu River belongs to the ’ health ’ level,the health degree of landform and water quality is obviously better than that of other attribute layers,the performance of social service function is relatively poor,and the comprehensive scores of each river section are relatively close.It reflects that Zhuangmu River plays a good social function value while maintaining the stability of river ecosystem structure and function.The concept of " humanwater harmony " and " sustainable development " has been basically realized,but there are still the following outstanding problems: the coastline of waters is vulnerable to human disturbance;the longitudinal stability of the riverbed is not good;the average deviation of monthly runoff is large;the water quality cannot be stably up to standard,and the biological habitat environment is poor;the wetland area shrinks and the ecological function weakens.The development and utilization of water resources is high,and the contradiction between supply and demand is increasingly prominent.In view of the above problems,corresponding measures and suggestions are put forward in the aspects of river water resources protection,water shoreline management and protection,water pollution prevention and control,water environment management and water ecological restoration.