基于水动力数值模拟的罗源湾水体交换周期及纳潮量计算

Calculation of water body exchange period and tidal prism in Luoyuan Bay based on hydrodynamic simulation

为了分析罗源湾水动力特性及流场情况,建立了基于Mike21的罗源湾水动力数学模型,经率定得到模型湾内海域Smagorinsky系数为0.28,糙率为0.024~0.035,风拖曳系数为0.0010~0.0015。利用该模型模拟计算了罗源湾水体交换周期及纳潮量,结果表明:涨落潮时,罗源湾流速在0.20~1.56 m/s,湾口及可门水道水动力条件好,北岸及西北角水动力条件较差,北岸受湾外海域潮波影响程度低于南岸;罗源湾水体半交换周期约为15 d,15 d、30 d、45 d和60 d后罗源湾水体平均交换率分别为48.5%、69.3%、78.8%和85.5%;秋季时罗源湾平均纳潮量为5.73亿m^(3),大潮纳潮量为7.07亿m^(3),小潮纳潮量为4.40亿m^(3)。建议在罗源湾入海污染源通量管控过程中,综合考虑海域自身水动力条件,合理控制罗源湾西北角入海污染物排放量。

A mathematical model of Luoyuan Bay was established based on Mike21 for analysis of the hydrodynamic characteristics and flow field in Luoyuan Bay,and the model parameters were calibrated,with the Smagorinsky coefficient in the bay determined as 0.28,the roughness ranged from 0.024 to 0.035,and the wind drag coefficient ranged from 0.0010 to 0.0015.Then,the model was used to calculate the water body exchange period and tidal prism in Luoyuan Bay,and the results showed that the flow velocity in Luoyuan Bay varied from 0.20 to 1.56 m/s for rising and falling tides,the hydrodynamic conditions were strong at the bay mouth and Kemen Channel,and poor at the north bank and northwest corner of Luoyuan Bay,and the influence of tides outside the bay on the north bank was lower than that on the south bank.The half-exchange period of water body in Luoyuan Bay was about 15 d,and the average exchange rates of water body in Luoyuan Bay were 48.5%,69.3%,78.8%and 85.5%after 15 d,30 d,45 d,and 60 d,respectively.In autumn,the average tidal prism in Luoyuan Bay was 5.73×10^(8) m^(3),and those of spring tide and neap tide were 7.07×10^(8) m^(3) and 4.40×10^(8) m^(3),respectively.It is suggested that in the process of controlling the flux of pollution sources into the sea,the discharge of pollutants into the sea from the northwest corner of Luoyuan Bay should be reasonably controlled with consideration of the hydrodynamic conditions of the sea area.