基于FVCOM的虎门水道盐水入侵三维数值模拟

Three-dimensional numerical simulation of saltwater intrusion into the Humen estuary based on FVCOM

采用不规则网格有限体积近岸海洋三维模型FVCOM(finite volume coastal ocean model),对2001年虎门水道至伶仃洋的盐水入侵现象进行数值模拟,并采用多个站的实测潮位、盐度对模型进行了率定和验证,然后对其水动力特性、盐度的时空变化规律及其垂向分层现象进行分析。结果表明,水位的模型预测值与实测值之间的相关系数达到0.93以上,绝对平均误差小于0.1m;盐度模拟的相对误差能控制在10%以内;大虎站表底层的流向较为一致,盐度表现出明显的分层现象;而漳澎站多次出现表底层流向相反的情况,盐度的垂向混合较充分;文章构建的模型能够较好地模拟盐水入侵的最大距离,虎门水道大潮时入侵距离和强度均大于小潮时,盐水楔活动受潮流强弱变化影响显著。

An unstructured grid finite-volume coastal ocean model (FVCOM) was applied to simulate the saltwater intrusion from Lingdingyang into the Humen estuary. Measurements of water level and salinity at multiple stations obtained in February 2001 were used for model calibration and verification, aiming at the hydrodynamic characteristics and spatiotemporal variation of salinity. The results showed that 1) the correlation coefficients between the predicted and measured water level exceeded 0.93 with a mean absolute bias less than 0.1 m, while the relative error of the simulated salinity was within 10%; 2) at Station Dahu, the flow direction in the surface layer was consistent with that in the bottom layer most of the time, but there was apparent salinity gradient in the vertical. However, for Station Zhangpeng, opposite flow directions between the surface and bottom layers occurred repeatedly while the salinity was more uniform vertically; and 3) the maximum distance of saltwater intrusion was well simulated. The intrusion distance as well as the strength at spring tide was greater than that at neap tide in the Humen estuary, and saltwater wedge movement was significantly affected by the tidal strength.