The processes in cohesive and non-cohesive sediment transport differ from each other significantly.
Different types of sediments are defined by different parameters. Pečovnik (2014) noted that the
PCFLOW3D model does not simulate transport of cohesive sediments correctly. We suggest a simple
equation which is appropriate for calculating cohesive sediments and does not contain additional
measured parameters. We integrated the equation in the PCFLOW3D model and tested the upgraded
model. We calculated critical shear stresses for cohesive and non-cohesive sediments and performed
simulations with combinations of different circulation patterns and wave parameters. Non-cohesive
sediments begin to resuspend at 0.5 m high waves, while cohesive stay at the bottom until waves reach
the height 0.9 m. Furthermore, the areas and the intensity of resuspension differ significantly. Using the
adopted data, the majority of bed-shear stress is induced by waves, whereas wind-induced currents
contribute only an insignificant part. However, the wind direction affects the direction of currents and
subsequently the direction in which suspended material is transported. We also depict the depth averaged
concentrations of suspended material. The results are close to our expectations; the concentrations are
increasing proportionally with wave height. Areas with the highest concentration of suspended sediment
occur in places with the largest shear stress.
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