基于FVCOM的磨刀门水道盐水入侵三维数值模拟

Three-dimensional numerical simulation of saltwater intrusion in Modaomen estuary based on FVCOM

该文采用非结构化有限体积近岸海洋三维模型FVCOM(Finite-Volume Coastal Ocean Model),建立了磨刀门水道至伶仃洋盐水入侵数值模型,模拟2004年、2005年及2007年枯季的长序列流场过程,观察其水动力特性,研究盐度的时空变化规律,分析其垂向分层现象。结果表明仅对该文模拟范围的建模也能达到模拟珠江四口门或八口门时磨刀门水道的准确度,从而减少了建模工作量和模型计算量。对三个工况的模拟显示盐水入侵最远距离在2005年1月最大,越过了全禄水厂,2007年3月最小。垂向分层方面,由于盐水上溯的最远距离均处于内河道处,盐度垂向分层不明显,底表层盐水最远入侵距离的差距随入侵距离的增加而减小。海平面平均每升高1 cm,磨刀门水道咸潮入侵平均上移距离为0.85 km。

FVCOM, an unstructured grid finite-volume coastal ocean model, was applied to simulate the salinity intrusion from Modaomen estuary to the Lingdingyang. The model was used to simulate the dry seasons in 2004, 2005 and 2007 to observe the hydrodynamic force, research the salinity variation and distribution and analyse the vertical distributions of saltwaterwedge. The results showed that just modeling on the scope of this article＇s simulation also reached the precision of large scope modeling such as the modeling of four or eight entrances of the Pearl River. So that the workload of modeling and calculation of simulation decreased. Among the three simulated periods, the largest distances of saltwater intrusion reached the top in January, 2005 and the shortest in March, 2007. This proved the measures of adjusting fresh water discharge to desalinity taken since the end of the year 2005 relieved the saltwater intrusion during dry season. Due to the longest location of saltwater intrusion was in the channel far from the coast, the vertical stratification of salinity is not obvious. The difference of the longest distances of saltwater intrusion among water surface and bottom decreased via the increase of intrusion distance. With the current sea level as a benchmark, the salty boundary shift distance in Modaomen estuary was roughly 0.85 km for every sea level rise of 1 cm.