Three-dimensional modeling of suspended sediment transport in a subalpine lake

Suspended sediment in the lakes can impact the aquatic ecosystem and water resource management. A three-dimensional hydrodynamic and suspended sediment transport model was performed to simulate temporal and spatial variations of suspended sediment and applied to the subtropical subalpine Yuan-Yang lake 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. Modeling results of sensitivity analysis indicate that the settling velocity plays a crucial parameter in the suspended sediment transport. The simulated results also show 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.