Observations of Mud‐Induced Periodic Stratification in a Hyperturbid Estuary

Abstract

AbstractThis study presents new observations of fluid mud transport and of the interaction between mud‐induced stratification and the flow. Data collected in a hyperturbid estuarine tidal channel reveal details of the intratidal entrainment asymmetry, characterized by quasi‐instantaneous entrainment and upstream pumping of mud during flood, and a gradual reduction of layer thickness by shear dispersion during ebb. Rapid restratification early during the flood phase restores the predominant two‐layer structure and delimits the transport period, which is then significantly shorter than the overall flood duration. The hydraulic cross section is reduced, causing an increase of the salinity intrusion into the estuary at the end of the flood. The fluid mud layer occupies on average 40% of the water depth, and stratification exceeds that of highly stratified salt wedge estuaries. These data show how mud‐induced periodic stratification influences flow structure and sediment transport and thereby contribute to the understanding of the dynamics of hyperturbid estuaries.