Multiscale Physical Processes of Fine Sediment in an Estuary : Dissertation

Estuaries are natural highly dynamic and rapidly changing systems, comprising a complex combination of physical processes on many different time- and space- scales. The research conducted a systematic study on the topic of fine sediment physical processes in a meso-tidal convergent alluvial estuary. By means of multi-approaches (field survey, laboratory experiment and numerical modeling) and from multi-angles (data-driven analysis and process-based modeling) we highlight that multiscale (including micro- and macro- scale) physical processes jointly characterize the current and sediment regime in a fine sediment estuarine system.

The study presented in this book investigates micro- and macro- scale physical processes of a large-scale fine sediment estuarine system with a moderate tidal range as well as a highly seasonal-varying freshwater inflow. Based on a series of measured, experimented and modelled data, the research highlights that (i) along-channel fresh-salt gradient near an estuarine turbidity maximum zone is a key parameter controlling local density stratification and sedimentation in the channel; (ii) the salinity-induced baroclinic pressure gradient forces are a major factor impacting internal velocity and suspended sediment concentration (SSC) structures; (iii) vertical profiles of current, salinity and SSC within a river plume are dependent on a correct prediction of the development of turbulence; (iv) both suspended particulate matter availability and local residual flow regime are of critical importance for trapping probability of sediment and the occurrence of fluid mud; (v) river discharge impacts the horizontal and vertical distribution of residual current; (vi) seasonally varying wind effect alters the residual currents near the riverine limit; (vii) seasonally varied mean sea level and wind climate jointly shape the saltwater intrusion length near the estuarine front.

Wan Yuanyang worked as a senior researcher on coastal engineering and waterway development in the Numerical Research Department of the Shanghai Estuarine and Coastal Science Research Center. During his professional experience, Wan was responsible for many important researches and engineering works related to numerical modeling, field observation and laboratory experiment. He published more than 40 peer-reviewed Chinese and English papers. Wan was awarded 3 provincial science and technology prizes in China from 2011 to 2013. He was officially granted 4 Chinese patents on sediment experiment facility.