人类活动驱动下伶仃洋洪季大潮水沙异变

Variations of current and sediment transport in Lingding Bay during spring tide in flood season driven by human activities

针对大规模人类活动对伶仃洋水动力的干预,基于1978年、2003年、2011年洪季大潮实测资料,对比分析伶仃洋东西两槽及东四口门在不同阶段人类活动作用下的潮流及悬沙特征变化。结果表明:由于受伶仃水道浚深影响,与1978年相比,2003年和2011年伶仃水道及东四口门洪季大潮的涨潮动力增强,落潮动力减弱;受伶仃水道浚深产生的"吸流"作用及东滩围垦影响,矾石水道潮流动力减弱;东四口门及矾石水道洪季大潮的悬沙含量降低,伶仃水道悬沙垂向分层加强,且伶仃水道中南段净输沙由1978年的向海方向于2003年后逆转变为向陆方向,平均流输沙贡献剧减,斯托克斯漂流输沙、潮汐捕集输沙和垂向净环流输沙贡献增加。

Observation data of Lingding Bay during spring tide in flood season of 1978,2003 and 2011are used to analyze the variations of current and suspended sediment. The result indicates that flood currents in Ling- ding Waterway and east outlets in 2003 and 2011 are strengthen compared to 1978, while ebb currents subside in the Lingding Waterway dredging has enhanced the tide power. However, the tide power is weaken in Fanshi Waterway because of ＂absorbing＂ action of dredged Lingding Waterway and reclamation of the east shoal. The suspended sediment concentrations of east outlets and Fanshi Waterway decreased, while Lingding Waterway doesn＇t show the trend but with intensified stratification. As for the sediment transport in Lingding Waterway, the contribution of steady advection transport to net sediment transport is dramatically reduced with that of mass Stokes drift,tidal trapping and net vertical circulation increased, hence the orientation of net sediment trans- port has altered from seaward in 1978 to landward after 2003.