Turbulence Measurements of Suspended Solids Concentration in Estuaries

Abstract

Measurements of turbulent fluctuations of horizontal and vertical components of velocity and of suspended solids concentration in the region of 0.50 to 1.25 m above the bed have been made in the upper reaches of the Conwy and Tamar estuaries. The charcteristics of the turbulence for the velocity components were found to be similar to those for laboratory flume data for appropriate steady and homogeneous conditions. The characteristics of the turbulence fluctuations of suspended solids concentration were found to be in some ways similar to those of the turbulent fluctuations of the horizontal and vertical components of velocity and salinity. The relative velocities are strongly dependent on relative depth and particle gradient Richardson number. The intensity of the suspended solids concentration fluctuations increases with the suspended solids concentration vertical gradient. The momentum and suspended solids flux correlation coefficients decrease with increasing gradient Richardson number, with the vertical suspended solids flux correlation coefficient decreasing more rapidly than the horizontal suspended solids flux correlation coefficient. These effects are tentatively explained by the concept of turbulent fluctuations being progressively replaced by wave‐like fluctuations in stable conditions.