Study on Behavior of Turbid Water around Dredged Navigation Channel at River Mouth

Abstract

Field measurements were carried out in the port of Niigata to elucidate sediment transport processes around navigation channel and turning basin in the port at river mouth. The measurements include salinity, suspended sediment concentration and in-situ mud density at several monitoring points along the navigation channel in the port. The survey successfully captured the formation of three layers structure during a river flood condition with high turbid fresh water in the upper layer and low turbid sea water in the middle layer. Furthermore, high concentrated mud or fluid mud layer was also found in the lowest layer at the deeper dredged channel area. Physical model experiments were also carried out with a circulating flume to elucidate the fluid mud transport on the slope at the edge of step-like bathymetry. The experiments indicate the behavior of near bed turbid water depends on the overlying flow conditions.