The dynamic characteristics of turbulence in the Modaomen Estuary river plume based on the ADCP data

This thesis aimed to analyze the dynamic characteristics of turbulence with the field observation data getting by a 1 200 kHz, broadband RDI ADCP rigidly mounted in the front of the sand bar and in the deep-water zone in the Modaomen Estuary in July 2015, with the "variance method". The results show that the flow velocity presenta typical three-layer circulation structure, and high-speed velocity area appeared in the Modaomen Estuary river plume. The Reynolds stress estimated in the deep-water zone was between 10^-3-10^-5 m²/s², and smaller than that in the front of sand bar. The turbulence kinetic energy density parameter was larger in the river plume than in the bottom, and the size of it in both place was between 0.01-0.6 m²/s². In the front of the sand bar, the turbulence kinetic energy production rate was in the order of 10^-3 W/kg in the river plume, 2-3 orders of magnitude lager than that in the bottom and stronger than that in the deep-water zone. The vertical eddy viscosity coefficient was between 0-0.15 m²/s. In general, the river plume presents a state of stably stratified, with strongly mixed and high turbulence kinetic energy production rate, which provides a dynamical condition for the long-distance transport of high turbidity suspended sediment.