Numerical modelling of hyperpycnal flows in Yellow River Delta

The impacts of suspended sediment concentration (SSC) and river discharges on the formation and evolution of the hyperpycnal flows in the Yellow River Estuary (YRE) were studied using a three-dimensional circulation-sediment model. The model is well-calibrated using the field data of tidal elevation, current velocity, salinity and suspended sediment concentration (SSC) in the YRE. Results show that high SSC (>30-35 kg/m3) is the crucial factor to the formation of hyperpycnal flows. It was because high SSC can overcome the density increase due to salinity in ambient water. During the periods of flood and ebb, hyperpycnal flows show periodic characteristics in the bottom layer. High river discharge is essential for maintaining hyperpycnal flows in the YRE. This study helps to understand the initiation and maintenance of hyperpycnal flows in estuaries.