防城港湾物质输运时间尺度的数值模拟

摘要

In order to investigate the transport time scale in the Fangchenggang Gulf( FG) , a transport numeri-cal model was established and applied in FG and adjacent areas.The residence time and reaction to river dis-charge, tidal range and topography are calculated by conservative particles as agents.The results show that resi-dence time is about 10-70 h near the gulf mouth and increases to more than 300 h in central zone under differ-ent river discharge and tidal range.The residence time of FG increases gradually from the mouth to central and from the channel to the shoal obviously.The residence time data can be fitted satisfactorily with the river dis-charge by cubic polynomials.Part of the water from the Fangcheng River goes downstream through the north wa-ter passage and affects the exchange of the East FG.The residence time increases significantly as the tidal range decreases.The flushing capacity of tide is 3.2 times larger than that of river discharge in FG.%为研究防城港东、 西湾物质输运的时间尺度, 建立了防城港湾物质输运数学模型, 以保守物质为示踪物探讨了东、 西湾滞留时间的空间分布以及防城江流量、 潮差、 湾内地形等因素对湾内滞留时间的影响. 结果显示: 在防城港湾口海域, 滞留时间在不同计算条件下一般为10~70 h, 向湾顶方向逐渐增加可超过300 h; 防城港湾的滞留时间空间分布上呈现明显的湾顶大于湾口、 浅滩大于深槽的整体特征; 滞留时间与防城江径流量的三次方呈极好的函数关系; 防城江的部分来水通过东、 西湾顶的水道向东湾输运,对防城港东湾的水交换有一定的影响; 在西湾, 潮流的冲刷能力约为径流冲刷能力的3.2倍, 潮流的作用导致西湾的滞留时间大幅减少.