磨刀门盐水入侵特性及其动力机制研究

摘要

针对磨刀门盐水入侵特性异常问题,基于SCHISM模型,建立了磨刀门三维盐度数值模型,根据水位、流速及盐度的实测资料对其进行验证,利用该模型并结合盐通量分解方法,研究了磨刀门水道盐淡水混合特征及各驱动力对盐度通量变化的贡献作用.结果表明:磨刀门水道日平均盐量由稳定剪切输送和平流输送共同控制,盐量输运在大部分时间内处于不平衡状态.小潮期间,总盐通量向陆,稳定剪切输送作用占优,盐水分层明显,盐量在河道底部积蓄;中潮期间,总盐通量由向陆转为向海,盐水混合充分,入侵距离达到最远;大潮期间,总盐通量向海,平流输送作用占优,盐量退出河口.%To study the abnormal features of saltwater intrusion in Modaomen waterway, a three dimensional numerical model was established and then calibrated against the measured data of water level, flow velocity and salinity based on the SCHISM model.Combined with the salt flux decomposition method, the characteristic of stratification-mixing and the contribution of driving force to the change of salt flux were analyzed with this model. The results show that tidally-averaged salt flux is mainly driven by steady shear transport and advection transport and in an unbalanced state for most of the time in the Modaomen waterway.During the neap tide,the total salt flux is landward dominated by steady shear transport.The saltwater is highly stratified and gathers at the bottom of the waterway.During the middle tide,the total salt flux transforms the landward to the seaward.The saltwater is fully mixed and reaches its peak.During the spring tide,the total salt flux is seaward dominated by advection transport and the salt is washed out of the estuary.