Abstract
Two rivers of different landuse-type were observed weekly to evaluate the amounts and changes of annual pollution loadings. The observation was made for the first two years and last one year during a 1978-88 period. The observed river discharges were not affected by the annual precipitation but by the influencing rainfall for ten days preceding the observation. The loadings of almost all water quality items usually increased with increasing the annual river discharges, except that those of PO4-P and T-P decreased by the use of synthetic detergents without phosphorus. The loading of an urban river decreased by the laying of sewer system which cut a part of gray water loading. The loadings of NO3-N and T-N showed a tendency to increase by the increments of rainwater loading, waste of imported foodstuffs, accumulation of land-applied fertilizer and so on. The ratios of NO3-N to T-N increased as a secular change, but those of NH4-N and Org-N decreased. To know the amounts of natural and artificial pollution loadings from three watersheds of different landuse-type (mountainous, agricultural and urban areas), those specific pollution loadings were compared each other and with rainwater loading as a common base loading of the watersheds.
