Tide-driven controls on maximum near-bed floc size in a partially-mixed estuary

Abstract

Determination of the size and settling velocity of particles in an estuary is important to prediction of many environmental issues. An underwater microscope has been used to measure near–bed floc size in four cross–sections along the mid reaches of the Ōta Diversion Channel. Using an acoustic Doppler velocimeter (ADV) and a turbidity–meter provided an effective non–intrusive approach to measure the settling velocity of suspended particles and turbulence characteristics. The physical processes that control floc size differ in each measurement site. Turbulent motion and suspended sediment concentration SSC, however, exert the most effect on flocculation and floc break–up processes. Turbulent kinetic energy TKE production and SSC were positively correlated in the all measured points.