不同水动力扰动下太湖沉积物的悬浮特征

Sediment Re-suspension under Different Hydrodynamic Disturbances in Lake Taihu

利用2002年7月及2003年4月分别在太湖乌龟山和梅梁湾的水动力观测资料,计算了波浪和湖流产生的湖底切应力,分析了二者对太湖沉积物悬浮的不同贡献.结果发现,在小扰动情况下,流切应力大于波切应力,但不能引起沉积物的悬浮;在强扰动情况下,底流对沉积物悬浮的影响可以忽略,且扰动越强,其作用越小,而波浪的影响却愈加突出;在中等扰动下,二者的相互作用产生沉积物的悬浮,但波浪的作用较为显著.该结论能为计算太湖水体悬浮物浓度和动态内源释放提供重要的参考依据.

Based on the collected wave and current data in July,2002 and April, 2003, Lake Taihu, the wave stress (Tw) and the current stress (Tc) were calculated for better understanding of sediment re suspension mechanism. The results show that Tc is much larger than Tw with the water surface slightly disturbed but no re suspension can be found. Under stronger disturbance, Tw is so much larger than Tc that the current effects can be ignored in the bottom stress calculation. The wave effect is more important than the current effect although Tc is slightly smaller than Tw when the water surface is forced by a moderate wind. In this case, the non linear wave current interaction was favored to be considered for the bottom stress calculation in Lake Taihu. The conclusion can benefit the coming research on nutrients release from sediment and suspended sediment concentration (SSC) response to the surface disturbance.