Research On Water Quality Evaluation Methods Of Important Sections In Nenjiang River Basin

As the basis for building an ecosystem,water is the origin of civilization development,a basic element of production activities and an important engine that hinders economic development.At present,identifying the water quality characteristics of the river basin and analyzing its influencing factors are of great practical significance for grasping the status quo of water quality pollution of major rivers and rivers in the territory and comprehensively promoting the comprehensive treatment of the water environment in key river basins.This paper uses the current commonly used water quality evaluation methods such as single factor evaluation method and multivariate statistical method to statistically analyze the monitoring data of selected sections along the Nenjiang River Basin from 2016 to 2018,and explore the water quality pollution status in order to provide management for river basin managers.Basis for decision-making.This paper first uses the water quality evaluation method specified by the national standard and the single-factor evaluation method to evaluate the selected sections of the Nenjiang River Basin from 2016 to 2018.Through item-by-item comparison with the national surface water environmental quality indicators,the water quality category of the evaluation section is quickly determined.The evaluation results show that compared to 2016,the water quality of selected evaluation sections along the Nenjiang River Basin from 2017 to 2018 showed a generally better trend,although the water quality in 2018 was slightly worse than that in 2017.However,along the Nenjiang River Basin,there are reservoirs and water source areas.If only the single-factor evaluation method is used to evaluate the selected sections along the Nenjiang River Basin,the water quality of some sections has even reached Category V or worse than Category V.At this time,these sections have been lost.The basic water environment function is not consistent with the actual situation.In order to further explore the relationship between the evaluation indicators and the water quality of the selected sections,the gray correlation method was used to statistically analyze the monitoring data of the selected sections from 2016 to 2018.The results show that the chemical oxygen demand is the index with the lowest degree of correlation,that is,the index with the greatest impact on the evaluation section,which needs to be controlled.In addition,the correlation degree of total phosphorus is second only to chemical oxygen demand,and it should be listed as an indicator that needs to be controlled in the second echelon.SPSS25.0 was used to perform factor analysis on the monitoring data of important cross-sections in the waters along the Nenjiang River Basin from 2016 to 2018.The method of factor extraction was principal component analysis,and the method of factor rotation was the maximum variance method.The results show that,as a whole,the water quality pollution status of some evaluation sections showed great changes with the year.Among them,the water quality of Baishatan,Da'an and Tahucheng ferry sections showed a downward trend year by year,while the water quality of the two and Wutaki farm sections.The change of water quality showed the opposite trend,and it improved year by year.In addition,a comprehensive comparison of the evaluation sections shows that the Da'an and Limekiln sections are the sections with the most serious pollution during the evaluation period.In order to further clarify the distribution of pollution in the waters along the Nenjiang River Basin,cluster analysis was used to analyze and classify the sections with potential similarities in pollution types in the evaluation sections,so as to provide decision-making basis for river basin managers.The results show that the evaluation sections are roughly divided into three types: the first type of section Xingxian,Jinshewan Wharf,Miaojiapuzi,Jiazizi and Wutaki Farm are relatively clean sections,and the third type of section is Baishatan,Da'an,and Tahucheng.Dukou and Fengrong New Village are mainly affected by the permanganate index,chemical oxygen demand,and dissolved oxygen.The second type of lime kiln,Jiaxi and Mohu ferry are mainly affected by the permanganate index and chemical oxygen demand in 2018.The influence and the influence of dissolved oxygen are mainly affected by total nitrogen and phosphorus in 2017.In general,when formulating relevant pollution management and control plans,the difference in time can be appropriately considered.For the second type of section,the control of chemical oxygen demand may be given priority,and for the third type of section,targeted control can be based on the year difference.Corresponding indicators of serious pollution.