前海湾填海区的水龄特征及改善措施模拟

Simulation of Water Age Characteristics and Improving Measures in the Sea Filling Region of Qianhai Bay

根据实际观测潮流与前海湾填海前后海域范围和海底地形条件,建立前海湾环境流体动力学模型（EFDC）,以水龄作为水交换能力的评价指标,利用EFDC模型中示踪和水龄模块模拟计算前海湾水龄的时空分布,分析评价填海工程对水龄的影响和不同工程措施对水交换的改善效果。结果表明,填海后前海湾北部的西乡河口附近海域水交换最差,水龄可达到9-10.8 d,5-8月份前海湾平均水龄要小于全年平均水龄;前海湾水龄主要受潮汐影响区域占72.2%,河流入流只对西乡河、新圳河和双界河河口附近较小区域有明显影响;填海后海湾平均水龄增加了67.7%,填海工程对西乡河口附近海域影响最大,水龄增加了6.8 d,对湾口和湾中心影响不明显;前海湾水动力改善的优选工程方案依次是：大铲湾港根部开槽50 m、暗涵注水5 m^3/s或暗涵抽水8 m^3/s。

According to the observation of actual tidal current and water domain and topography of Qianhai Bay before and after sea filling project, environmental fluid dynamics code （EFDC） model of Qianhai Bay is developed with water age being as the evaluation index of water exchange capacity. Simulation based on tracer and water age module is conducted to analyze spatial and temporal distribution of water age, impact of sea filling project and effects of different engineering measures on improving water exchange capacity. Results show that water exchange of the region near Xixiang estuary in the north of Qianhai Bay is the worst, with water age as 9-10.8 days. Average water age of May to August is less than the annual average water age. The area affected mainly by tide accounts for 72.2%. River inflows only affect small area of estuaries near Xixiang River, Xinzhen River and Shuangjie River significantly. Average water age of Qianhai Bay increases by 67.7% after sea filling project. The impact is largest in the area near Xixiang estuary, which water age increases 6.8 days, but the impact is little in the region of the mouth and center of Qianhai Bay. The optimum engineering solutions of hydrodynamic improvements of Qianhai Bay are slotting 50 m in Dachanwan Harbour, or culvert water injecting at the rate of 5 m^3/s, or culvert water pumping at the rate of 8 m^3/s.