The concentrations were classified by the multiple regression analysis and the factor analysis, monitored at the forest, the irrigation canal, the drainage canal and the lowest end of the agricultural basin. And the seasonal variations were analyzed by the principal component analysis.
Generally, EC, Na^+ and Cl^- were classified in the groups by the multiple regression analysis and the factor analysis. And T-COD and T-P (PO_4-P) were also classified. In the multiple regression analysis, the concentration groups at the lowest end were more complicated than those at others. The pollution during the irrigation period in 1989 was more serious than 1988, comparing the first principal component scores.