磨刀门水道盐水强烈上溯规律和动力机制研究

通过流体力学场的概念做出磨刀门水道咸界图, 得到3个月长时间序列的盐水运动上溯距离和潮位的关系, 从中发现总是在潮差最小的前后两天盐水上溯有一个突然增加的特点. 从2005年初实测资料中整理分析发现, 在整个珠江上游径流量较小时, 由于分流比的变化, 磨刀门水道在小潮期间有两天净泄量几乎为零, 从而导致涨落潮的流动状态发生显著变异, 涨潮历时为16 h, 落潮历时仅为9 h. 在此动力作用下盐水快速上溯, 随后几天由于小潮期间潮汐动力作用不大, 使得盐水滞留在磨刀门水道, 直到大潮期间较强的潮汐动力作用将盐水带出, 因而造成磨刀门水道异常的盐水上溯规律和严重的咸潮灾害.

Research of Law and Dynamic Mechanism for Strong Saline Water Intrusion in Modaomen Waterway

Depend on the concept of fluid field, the salinity borderline figure of Modaomen waterway was made, and the relationship between saltwater movement distance and tidal elevation with three months long time series was gotten. The feature that the intrusion strength of saltwater always suddenly increased during the two days before and after time of the smallest tidal range was found. In the analysis of observed data in early 2005, net discharge amount of Modaomen waterway was found to be almost zero during neap tides because of the change of diversion ratio when the small Pearl River runoff, so that the flow state had notable variation that the flood duration had 16 hours and the ebb duration had only 9 hours. Affected by these dynamics, saltwater invaded rapidly. Later a few days during neap tides saltwater remained in Modaomen waterway due to the small tidal dynamic role, until spring tides saltwater was out of Modaomen waterway step by step due to the strong tidal dynamic role. Therefore, the abnormal law of saltwater intrusion was formed and the serious saline intrusion disaster was occurred in the Modaomen waterway.