Journal of the Japan Society of Erosion Control Engineering, Vol.59,No.2,2006
The decrease in the dissolved oxygen concentration caused by sediment flushing
from sabo dams and its prediction
Atsuhiko KINOSHITA Masaharu FUJITA Takahisa MIZUYAMA Toyoaki SAWADA
Abstract
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 FeQ{ 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.
Key words:sediment flushing, dissolved oxygen concentration, pool, reaeration
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