Study on the Phenomenon of the Settling Rate Increasing of the Suspended Sediment around the Salinity Front in the Chikugo River Estuary, Japan

Abstract

It is important that flocculation and settling of the suspended sediment (SS) on the formation mechanism of the bottom mud in the tidal river. In this study, the field observation on the settling rate was done in one tide in the tidal river of the Chikugo River, Japan at a spring tide. The new techniques for the measurement of the settling rate of SS were developed to compare settling velocity with the turbulence kinetic energy, SS concentration, chl-a/SS, and salinity. As a result of this study, it is clarified that the reason of the increase of the settling rate around the salinity front was owing to the mixing of the SS with algae, salinity intrusion and the rapid decrease of the turbulent around high tide.