砂防ダムからの排砂による溶存酸素濃度の低下とその予測
2006 年 59 巻 2 号 p. 13-20
詳細
2006 年 59 巻 2 号 p. 13-20
To evaluate the physiological impact of sediment flushing on fish, the prediction of the temporal variation in the dissolved oxygen concentration is very important. Previously, Kataoka et al. constructed a model that predicts temporal variation in the dissolved oxygen concentration after flushing in the Kurobe River. In this study, we made a model for a headwater stream.
First, we examined the temporal variation in the concentration of dissolved oxygen at two sites in a headwater area subject to sediment flushing. Then, we modeled the results. We investigated the components of sedimentation in the dam and confirmed that the Fe2+ in the flushed sediment caused the decrease in the dissolved oxygen concentration. We postulated that, as the volume of the pool decreases with flushing, the concentration of dissolved oxygen decreases resulting from aeration decreases. Finally, we showed that when there are pools with sufficient volume, the decrease in the dissolved oxygen concentration caused by flushing is little downstream from the dam.
Using the model, we were able to predict the temporal variation in the dissolved oxygen concentration after flushing in a headwater stream. We found that the decrease in the dissolved oxygen concentration caused by flushing is little downstream from the dam if there are sufficient large pools.
