珠江口枯季盐通量数值模拟研究

Numerical Simulation of Salt Flux in Dry Season in the Pearl River Delta

采用数学模型手段对珠江河口的盐通量进行了计算和分析。该平面二维水流盐度模型范围包括珠江三角洲河网与八大口门在内,计算结果与实测值符合良好,较好地反映了模拟区域盐度场的时空分布特点。结果显示:珠江河口枯季大潮时的总盐通量为1954×104t,小潮时总盐通量为512×104t,仅为大潮时的26.2%;无论是在大潮还是小潮期间,大虎和官冲的盐通量所占比例最大,说明盐水入侵主要是通过虎门与崖门这两个通道进入;盐通量沿程明显减少,这是盐度、水通量等沿程变化的综合作用。不同类型水体的盐度等值线在枯季大小潮期间的分布情况表明,盐水入侵在大潮期间明显比小潮更严重,已经影响到番禺、广州部分地区的饮用水、灌溉用水和生态用水的正常使用。

The salt flux of the Pearl River Delta in dry season is simulated with a 2-D numerical model, the range of which includes both the river network of the delta and the eight river mouths of the Pearl. The results of the study match well with the observed data, that implies the model is capable of describing the temporal and spatial distribution of salt current and simulating the salt flux in the Pearl River Delta. The salt flux in dry season during spring tide is 1 950×10^4t, while that during neap tide is 510×10^4t, only 26.18% of the former. The salt flux in Dahu and Guanchong are the highest in the 8 stations of the river mouths, indicating that Humen and Yamen are the main entries for saltwater intrusion in the delta. Owing to the changes of the salinity, the river channel terrain and water flux in different cross sections. Decrease of salt flux along the Lion Bay is obvious. Salinity distribution during spring tide and neap tide shows that saltwater intrusion is much more serious during spring tide, and at that time water supply for drinking, irrigation or for ecological purpose in Panyu and Guangzhou is affected.