抄録
Fluctuation of water quality in newly constructed Hayade Reservoir in Niigata Prefecture was observed from 1978 to 1982. Sampling was carried out at surface, middle and bottom layer respectively. Water quality data of each sample were determined for several items and 7 items (100/ DO%, COD, IC, TN, TP, EC, WT) were analyzed by the Principal Component Analysis (PCA) method. More than 75% of total variance of the original data were contributed to the first component by the PCA method.
Therefore, Water Quality Index (WQI) derived from the first component could be used to evaluate the pollution levels caused by natural factors in this reservoir. The pollution levels were related negatively to WQI. From the analysis of fluctuating changes in WQI, pollution level was remarkably progressed in the summer of the first year at bottom layer. Contribution for eutrophication at the initial stage of reservation to pollution level of reservoir was also obvious.
