【作者】 吴辉；

【导师】 朱建荣；

【作者基本信息】 华东师范大学 ， 自然地理学， 2006， 博士

【副题名】北支倒灌、深水航道工程和冬季季风的影响

【摘要】 本文采用三维数值模式和通量分析手段，定量研究了长江河口盐水入侵，特别是北支盐水倒灌及其动力机制，以及深水航道工程和冬季季风对盐水入侵的影响。主要成果如下： (1)建立了一个高分辨率、移动潮滩边界的长江河口三维水动力、盐度数值模式。运用模式对实测的潮位、流速、流向和盐度进行验证，验证结果良好。 (2)对北支盐水倒灌进行了通量机制分析，结果表明Lagrange余流输运和潮泵输运是北支盐水进入南支并往下游输送的主要动力机制，在多数地区前者起主导作用，局部地区两者作用相当。计算了南支各叉道的断面盐分通量以考查倒灌盐水团的输送途径，结果表明北支盐水出南北支分叉口后大部分沿白茆沙北水道下泻，少部分绕过白茆沙后沿着白茆沙南水道往下输送。两部分盐水在七丫口附近河段汇合，然后其中一小部分通过南门水道进入新桥水道，并在新桥水道涨潮优势流的作用下向上游输移，其余盐水继续沿南支主槽下泻。在新浏河沙以下，倒灌盐水通过南、北港分叉区域的几个叉道分别进入南港和北港。在大潮期间，进入南港的盐量较多，在小潮期间，进入北港的盐量较多。 (3)采用北支上端的断面水体净通量作为倒灌强度的代表，在单日和半月两个时间尺度上研究了断面净通量和径流量、潮差的定量关系。 在单日时间尺度上，引入水体倒灌判别指标： Isso=青龙港潮差—1.58×exp(0.2457×径流量/10000)Isso大于零时北支上端的断面净通量指向南支，倒灌发生；小于零时断面净通量指向北支，倒灌消亡；等于零时无净的水体通量。基于Isso得到了单日断面净通量： 单日断面净通量=533.1×exp(0.361×Isso)-533.1(Isso≥0)和 单日断面净通量=226.0×Isso(Isso＜0) 在半月时间尺度上，断面净通量和潮差无关而仅和径流量相关： 半月断面净通量=701.89×ln(-径流量/10000+6.2)-553.54 当径流量达到40000m~3／s时半月断面净通量降为零。利用以上各式、结合实更多还原

【Abstract】 This thesis studies the saltwater intrusion in the Changjiang Estuary quantatively by using a 3D numerical model and the method of flux analysis. The impact of the saltwater spilling over from the North Branch, the deep waterway project, and the winter monsoon are considered. The main fruits are as following.1. A 3D, high resolution, moving intertidal zone, hydrodynamic and salinity numerical model in the Changjiang Estuary is built up. Several field-measured elevation, current and salinity data are used to validate this model, and the result is reasonable.2. The transport mechanism of the saline water that spilled over from the North Branch in the Changjiang Estuary is analyzed quantitatively by use of the flux analysis method. The results suggest that Lagrange residual current and tidal pump are the main dynamic mechanism for the saline water mass from the North Branch spills over into the South Branch and drifts downstream. In most places the former is dominated but somewhere else these two factors are in equilibrium. To investigate the transport route of the spilled saline water mass, the cross-section salinity flux over each waterway in the South Branch is calculated, leading to a result that the most proportion of it is transported downstream through the North Baimao Sand Waterway and the rest through the south one. The two parts join together near Qiyakou, then the fraction of it enters the Xinqiao Waterway through the Nanmen Waterway and is transported upstream by the flood current, while the left keeps on drifting downstream along the main channel in the South Branch. At the lower reaches to the New Liuhe Sand, the spilled water mass enters into the South and the North Channels through several waterways around the bifurcation, respectively. In spring tide, the magnitude of salt flux during the South Channel is more than that in the North Channel, while on the contrary during the neap tide.3. The net transetional water mass flux （NTWF） at the upper reaches of the North Branch is used to present the intensity of salt water spilled over, then its quantative relationship with runoff and tidal range is studied on the diurnal and semimonthly basis.In the diurnal case, the NTWF can be determined by 533.1×exp（0.361×Isso）-533.1 （Isso≥0） and 226.0×Isso （Isso<0）, where Isso （index of SSO） is defined as TR-1.58×exp（0.2457×RF/10000）, TR is the tidal range （m） at the Qinglong Harbor and RF is the runoff (m³s^-1). The Isso has the same sign as the diurnal NTWF, when Isso is positive the NTWF points to the South Branch and the salt water spilling over takes place, while on the contray when Isso is negative. If Isso is equal to zero there is no net water mass transport existd.In the semimonthly case, the NTWF is determined by 701.89×ln（-RF/10000. +6.2）-553.54, which decreases with the increasing of runoff and declines to zero when the runoff reaches 40000 m³s^-1.The tidal range and runoff are measured at Qinglong Harbor Station and Datong Station everyday, respectively. Thus the NTWF can be easily obtained by using these更多还原