珠江口磨刀门水道咸潮入侵规律研究

根据2003—2008年的枯水期含氯度实测资料,以农历月份为统计周期,研究了珠江口磨刀门水道咸水入侵规律。研究结果表明,磨刀门水道含氯度变化周期为15d,主要由大、中、小潮组成的15d潮汛周期所控制,而每个周期内含氯度变化幅度则受上游径流大小影响;提出咸潮入侵系数K的概念,它可反映周期内平均径流和平均含氯度响应关系,当K小于0.2时,表示咸潮入侵程度小,不影响取水口取水,当K大于0.5时,咸潮入侵严重,K为0.2和0.5对应上游径流的临界流量分别为2450和1930m3/s;最后采用Delft3D模型区域分解技术将网格加密的磨刀门小区域嵌入到网格相对较大珠江口大区域模型中耦合计算,验证了咸潮入侵系数K的合理性。

Study on saltwater intrusion in Modaomen of the Pearl Estuary

The salt water intrusion in Modaomen of the Pearl Estuary was investigated based on the statistical analysis with the lunar cycle of the chlorinity data during the dry season from 2003 to 2008.The results show that,the chlorinity fluctuation period is 15d,which is controlled by the tide cycle,and the fluctuation magnitude within the period is influenced by the runoff.The saltwater intrusion factor K is introduced to reflect the relationship between 15d-averaged discharge of the runoff and 15d-averaged chlorinity.When K<0.2,it represents saltwater less intrusion,and most of the time chlorinity matches the standard of drinking water;when K>0.5,it represents saltwater seriously intrusion,and the salinity can not match the standard of drinking water.According to this relationship,the discharge of the runoff are 2 450 and 1 930m3/s for K=0.2 and 0.5,respectively.Three-dimensional hydrodynamic models for Pearl River and Modaomen were setup using domain decomposition based on Delft3D model.Computational results show the response curve is reasonable.