Study On Environmental Quality Assessment Of Surface Water In Ya'an Section Of Qingyi River Basin

The water resources of the Qingyi River Basin is the lifeblood of economic and agricultural development in western Sichuan.The rational development and utilization of water resources in the basin and ecological environment protection are important guarantees for achieving sustainable social and economic development.This paper takes the water environment of the Qingyi River Basin as the research object,and based on the analysis of water quality trend and water quality evaluation method at home and abroad,using SPSS principal component analysis?PCA?for Qingyi2015²017 Seven water quality indicators of seven monitoring sections in the Ya'an section of the river basin were analyzed to reveal the spatial and temporal distribution differences of water quality in the basin,identify the main pollution factors and the causes of pollution;use fuzzy comprehensive evaluation method,water quality labeling index method,surface based on index specification value The water quality fuzzy comprehensive evaluation method and the single factor index evaluation method have comprehensively evaluated the water environment quality.Aiming at the water environment pollution situation in the Qingyi River Basin,the control countermeasures and protection measures of water environment pollution are proposed.The main research results of the thesis are as follows:?1?The spatial and temporal distribution of water quality indexes in Ya'an section of the Qingyi River Basin is analyzed by multivariate statistical method,spatial composition of pollution status:high concentration of total nitrogen index in 7 sections,Feixianguan Town,Fenjiang River,Longxi River and Zhougong River section total nitrogen concentration is more than the monthly average for surface water IV^V,washing river,and the total phosphorus index in the sections of Fenjiang River and Longxi River is higher than other sections.?2?The results of water quality evaluation in 2017 show that the water quality of the main stream in the Ya'an section of the Qingyi River Basin is generally good,meeting the Class III standard of surface water.The water quality of the Fenjiang and Longxi river sections of the tributary of the Yucheng section is poor.The water quality category of the year is the surface water class V.The pollution is mainly nitrogen and phosphorus pollution caused by disorderly discharge of domestic sewage along the river channel and seasonal rainfall.The remaining sections have good water quality and meet the Class III standard for surface water.?3?Results of water quality trend analysis of main stream section from 2013 to 2017show that the concentration of DO index in each monitoring section showed a downward trend,the concentration of BOD₅ and NH₃-N showed an upward trend,and the concentration of TN showed a highly significant upward trend.The water quality of each section is composed of time:wet period>flat water period>dry period;the water quality of the space varies greatly,and the overall change trend is from excellent to poor:Duoying Town Section>Guidufu Section>Shuizhongba Section>Feixianguan Town section>Zhougonghe section>Longxi river section>Fenjiang section.?4?Aiming at the problem that the Yaan section of Qingyi River basin is mainly based on continuous nitrogen and phosphorus pollution,The segmental pollution prevention measures and water resources protection proposals based on the basin are proposed.