Author(s): Huazhi Zou; Guo Liu; Ling Wang; Yuxiang Chen
Linked Author(s):
Keywords: Estuary; Salt-water intrusion; Numerical simulation; Pearl River
Abstract: Salt-water Intrusion (SI) occurs when high-salinity water intruded abnormally upward into rivers in dry season. It is mainly induced by the imbalance between river discharge and tide. One of the most important causes for the freshwater shortage in the Pearl River Delta (PRD) is due to the increasing SI. Recent 20 years, an increase in the frequency and strength of SI is observed from the in situ measurements. It seriously threatens the safety of freshwater supplies for the cities of Macau, Zhuhai, Zhongshan, Guangzhou etc. The Pearl River Estuary (PRE) is a typical multi-outlets water system which is composed by three estuarine bays, eight outlets and an interlaced river network including more than two hundred rivers. Observed data indicate that the SI in PRE appears an obvious character of density-stratified and nonlinear currents. In order to study its dynamic mechanism of SI, a three-dimensional numerical model with baroclinic equations, large calculation domain, high-resolution and unstructured grid has been established and successfully applied to PRE based on FVCOM. Simulated results are calibrated and compared against filed measured data. Results show that simulated results agree well with measured data. Further analysis indicates that two important processes of SI in PRE, which are somewhat different from other estuaries, are properly captured by the numerical model. One is that the worse scenario of SI in Modaomen River (MR), which is one of the main channels of Pearl River, usually occurs during mid-tide, but neap and spring tide. Another is that the peak value of salinity at upstream appears earlier about seventy hours than downstream in MR. Finally, the dynamic mechanism of these two processes is analyzed and discussed according to simulated data. Results indicate that it is mainly due to the alternation of different mixing status that dynamically changes with not only different tidal phase of one tidal cycle but also different tide range of lunar cycle.
Year: 2013