Abstract
Water quality of a river changes variously due to natural environment's complex interactions and artificial environment so that numerous difficulties exist in figuring out the exact trait of fluctuation and evaluating quality of a river. In the research, I want to contribute to the water management by using principal component analysis and factorial analysis among multi-variate analysis in order to examine fluctuation trait and that of a water quality. Furthermore, the source is based on the water management reference of the Ministry of Environment about water system in Yeongsan river. As a result, following conclusion is deducted. Concentration of pollution tend to increase as the water penetrates Gwangju, Naju and Hampyung which is all the cities and Poongyoungjung substream of Yeongsan river contains relatively high concentration of pollution among confluents. Furthermore, the result of correlation analysis of water factors show BOD and COD to be (r=.882), TP to be (r=.879) and Chl-a (.659), $PO_4$-P (r=.826), also monthly evaluation of a representative branch show BOD and COD to be (r=.820), TP (r=.666), $PO_4$-P (r=.582) and at last, seasonal analysis show BOD and COD to be (r=.895), TP (r=.626) and $PO_4$-P (r=.513) which is a strong correlation. In addition, four of the principal components are deducted monthly and seasonally after principal component analysis has been done. Also, pollutant loads including organic matters and nutrient salts influence the water system of Yeongsan river.