ABSTRACT
Sediment in shallow lakes can affect the physical and chemical environment of the water column through resuspension and transportation. Suspension sediments in water column can reduce the light intensity and influence the growth of phytoplankton. Furthermore, nutrients, heavy metals, and pesticides can be absorbed to sediment particles and also desorbed from sediment to the water column. In addition, nutrients absorbed to the deposited sediment and organisms in the mud may be released from lake bed. In the present study, a three-dimensional hydrodynamic and suspended sediment transport model was developed and performed to simulate temporal and spatial variations of suspended sediment in the subtropical subalpine Yuan-Yang Lake (YYL) of Taiwan. The model was validated with measured water level and suspended sediment concentration in 2009 and 2010. The overall model simulation results are in quantitative agreement with the available field data. The validated model was then used to find out the important parameter which affected the suspended sediment concentration and to investigate the effect of wind stress on mean current and suspended sediment distribution in the lake. The simulated results also indicate that the bottom currents are in opposite direction as surface currents due to return flows. Remarkable lake circulation was found and affected by the wind speed and direction. Mean suspended sediment concentration at the bottom layer is less than that at the top layer. Strong wind would result in higher mean current and mean suspended sediment distribution at the top layer. The wind stress plays a significant influence on mean circulation and suspended sediment transport in a shallow lake.
