This paper combines the water quality monitoring data of 7 sections in the Ya’an section of the Qingyi River basin in 2019, and uses the principal component analysis method based on SPSS20 and Origin2018 to realize the visual analysis of the temporal and spatial distribution characteristics of the water quality. The DO, CODMn, CODCr, BOD5, NH3-N, TN, and TP are selected as water quality evaluation indicators, and the comprehensive water quality labeling index method is used to evaluate water quality in different periods. The results show that the TN index has exceeded the standard severely, and it belongs to surface water category IV - V for many months throughout the year. The temporal and spatial distribution of water quality is significantly different. Combined with the characteristics of hydrology and meteorology and geographical location in the study area, the time distribution shows that each section is abundant. The water quality in the water period is better than the normal water period and the dry period. From the spatial distribution, the water quality of the Fenjiang, Longxi and Zhougong river tributaries is the worst. The water quality is mainly continuous nitrogen and phosphorus pollution. The water quality of the remaining sections can reach surface water III Class standards.
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