Hydraulic Phenomena and Water Quality Improvement Effects Produced by Flush Operations at Nagaragawa Estuary Barrage

Abstract

The flush operation was carried out in the summer of 1995 under the high temperature and very dry weather to improve the water quality in the upstream area of Nagaragawa Estuary Barrage.
The flush operation consists of the overflow operation to wash down phytoplankton, and of the underflow operation to increase DO at the bottom. When the flush operation was introduced, the water quality was reasonably improved, which was due to the change of flow patterns and to the increase of turbulent mixing diffusion caused by seiches and bores.