Observed Suspended Sediments in Storm Conditions

Abstract

High resolution synchronous measurements of turbulence, waves and vertical suspended sediment (Ssed) concentration profiles have been obtained during a storm above a rippled bed comprising coarse/medium sand located close to the end of a large offshore sand bank in a water depth of approximately 20 m. These data are utilized to study the temporal characteristics of sediments in suspension. Sediment resuspension ʻeventsʼ, exhibiting vertical coherence up to approximately 30 cm above the sea bed, are observed to span a range of temporal scales encompassing half wave, wave and wave group periods. The vertical concentration of Ssed is shown to be enhanced significantly by wave groups. Average Ssed profiles are described using a simple Rouse-type and an new ʻconvectiveʼ model.