Temporal and Spatial Variation of Mixing and Movement of Suspended Sediment in the Macrotidal Chikugo River Estuary

Abstract

ABSTRACT Azhikodan, G. and Yokoyama, K., 2015. Temporal and spatial variation of mixing and movement of suspended sediment in the macrotidal Chikugo River estuary. The effect of mixing on the movement of the estuarine turbidity maximum (ETM) was examined in the highly turbid Chikugo River estuary, Japan, in consideration of four significant issues: semidiurnal and semilunar tidal variations, spatial distribution, and synchronism of data acquisition. Vertical profiles of salinity and turbidity were measured for 2 weeks at 1 km intervals from the river mouth (0 km) to 17 km upstream, with a short duration for every cruise. Spring-neap transition and the spatial variation of mixing, and suspended sediment concentration (SSC) was found during the semilunar tidal cycle. The estuary gradually changed from a vertically well-mixed condition during spring tide to a stratified condition during the neap tide via a partially mixed condition during the intermediate half tides. The relationship between the flow ratio a...