MULTIPLE WATER QUALITY ASSESSMENT METHODS BASED ON PRINCIPAL COMPONENT ANALYSIS: A Case Study of Shallow Groundwater in the Middle Reaches of Yitong River

As the degradation of shallow groundwater quality in the middle reaches of Yitong River is becoming more and more serious, it is of great significance to investigate the current situation of water quality for protection and utilization of water resources. In view of the various water quality assessment methods at present, selecting an appropriate assessment model is of primary importance to study the status of groundwater quality. A total of 30 water quality samples are collected from low hilly area, undulating platform, terrace and flood plain in terms of geomorphologic types, and the hydrochemical characteristics of groundwater are analyzed by relevant statistical analysis such as Schukalev classification and Piper diagram. Principal component analysis(PCA) is used for the preliminary selection of assessment indexes, reducing the data dimension and getting the main components of water quality assessment. Then fuzzy evaluation method is used to assess groundwater quality, and compared with single index method and Nemerow comprehensive index method. The results show that the water quality in the study area is generally poor, dominated by Class V water quality, with good quality only in the low hilly areas. Among the various selected assessment methods, fuzzy comprehensive evaluation considers the interaction between evaluation factors and reflects the overall water quality, with relatively reliable evaluation results, which can be used as the first choice for water quality assessment.