Sediment Entrainment and Deposition Measurements in Long Island Sound

Abstract

Entrainment and deposition fluxes were measured in Central Long Island Sound. Data were collected with a 3‐MHz acoustic transceiver range gated to sample the sediment concentration in 1‐cm intervals in the bottom 70 cm of the water column. Horizontal and vertical velocities were sampled 68 cm above the bottom. A turbulent control volume derivation was used to estimate the fluxes and their variation over one 3.5‐hr deployment and a second deployment that spanned a tidal cycle. Time histories of three measures of the shear stress as well as the turbulent and wave kinetic energy were correlated with the entrainment fluxes. Turbulent and wave kinetic energy was the most reliable correlate with entrainment while the Reynolds' stress and drag coefficient estimates fared less well, the former failing at ebb tide, and the latter during periods of low average velocity.