斐伊川から宍道湖へ流出する汚濁負荷量の推定

The runoff loads of pollutants such as nitrogen, phosphorus and COD in River Hii were estimated for 3 years from the weekly sampling data collected at the middle stream point (Kisuki) and the downstream point (Otsu) by using the L-Q equations. The annual runoff loads varied widely for the three years, because there were large differences in the amount of precipitation (from 1,308mm/y to 2,307mm/y) and runoff discharge. The largest annual loads at the downstream point for T-N, T-P and T-COD were calculated to be 1,090ton/y, 49.6ton/y and 3,290ton/y, respectively, whereas the smallest loads for T-N, T-P and T-COD were 483ton/y, 22.8ton/y and 1,530ton/y, respectively. The loads at the middle stream point were estimated to be about half of the loads at the downstream point.