丰、枯水期珠江河口水体交换的数值模拟

摘要

基于一、三维耦合的溶解态保守性物质对流-扩散模型,计算了丰水期(1999年7月)和枯水期(2006年2月)珠江河口水体的平均停留时间。计算结果表明,珠江河口的水体交换有明显的季节特征,丰、枯水期珠江口的水体平均停留时间分别为8.9d和27.3d,内伶仃洋和外伶仃洋分别为丰水期与枯水期水体交换最强与最弱的子区域。仅考虑潮汐时,小潮时期珠江河口水体的平均停留时间小于大潮时期,而综合径流、季风等影响因素后则与之相反。空间上丰、枯水期均表现为口门附近水体停留时间较短,远离口门的水体停留时间较长。丰、枯水期珠江河口水体的平均停留时间均表现出从表层向底层递增的趋势,丰水期的垂向差异大于枯水期。%Coupled one- and three-dimensional advection-diffusion models of dissolved conservative tracer were used to simulate the average residence time of the Pearl River Estuary in July 1999 (wet season) and February 2006 (dry season). Results indicate that the average residence time shows significant variation between wet and dry seasons. The average residence time of the estuary is 8.9 days in wet season and 27.3 days in dry season. In both seasons, the water exchange is the strongest in inner Lindingyang and the weakest in outer Lindingyang. The residence time of the estuary is longer at the spring tide than at the neap tide; however, it generally acts reversely with river runoff and monsoon. Actually, the residence time is relatively shorter in the regions adjacent to the river outlets and relatively longer in the outer regions, and it increases with depth, with more evident difference in the vertical in wet season than in dry season.