抄録
The river water in high water flow, which has not been utilized for any purpose, could be new water resources for the areas which have not enough rainfall. As water resources, both the amount and the quality of water should be taken into consideration for water use. The characteristics of water quality changes during high water flow in rivers, especially in small rivers, depend on water quality components, nature of the soil in river basins and rainfall intensity. Therefore, the accumulation of case studies has been expected. This paper deals with the water quality (turbidity, pH, T-N, NO_3-N, NO_2-N, NH_4-N, T-P, PO_4-P, BOD) changes during high water flow in Ono River, Matsuyama City, Japan. Based on the investigations conducted for four rainfall events, two of which are heavy rain and the others are moderate, the following facts are obtained ; 1) The peaks of turbidity appear before the peaks of water discharge appear. The data plot of turbidity against water discharge shows a hysteresis loop. 2) For NO_3-N, interrelation between water discharge and concentration, and interrelation between water discharge and load are strong. 3) PO_4-P concentration decreases with increasing water discharge during heavy rain due to the dilution effect. 4) The load of BOD and water discharge are adequatelly correlated, though the fluctuations of BOD concentration during rain events are complicated.
