Abstract
It is important to understand effluent loads from river basins and to plan the water quality improvement and the runoff load reduction based on each watershed. In this study, Uso River with mainly agricultural loads and Horyu River with mainly industrial loads are made applicable for investigation among the Lake Biwa inflow rivers. Water quality and quantity of two rivers are measured.
In case of excepting runoff after rainfall, the mean values of the T-N, T-P, T-COD and SS concentration and the effluent loads during a puddling transplanting period are higher than mean values of those during the other period. T-test for the mean values shows the difference with a significant level of 1 or 5% in almost of water quality and effluent loads. On the other hand, the mean values of runoff after rainfall except a puddling transplanting period are higher than those during a puddling transplanting period in both watersheds.
Although muddy water by puddling and transplanting is generally regarded as the reason of the water problem in the country area. But, it became clear that the tendency of runoff after rainfall except a puddling transplanting period is higher concentration and runoff loads against the puddling transplanting period. Thus, the countermeasures of the water quality improvement and the load reduction of runoff after rainfall are more important than those of the puddling and transplanting period.
