The water exchange and its spatial and temporal variation in the Xiangshangang Bay were studied with an advection-diffusion water exchange numerical model. The model is based on the well-verified three-dimensional baroclinic model for hydrodynamic process and dissolved conservative material was used as the tracer. The initial tracer concentration was set to 1 mg/L inside the bay and 0 mg/L outside the bay and at the open boundaries inflow. According to the tracer concentration, half-life time and mean residence time of the water mass at different points of the bay were calculated, and the contribution of baroclinic power to the water exchange was studied by comparison with that at barotropic model. The results show that the water exchange, to the east of the Xize section, is fast with a half-life time of 5 days and a mean residence time of about 15 days. While the half-life time and mean residence time to the east of the Xihugang inlet are 15~20 days and 25 days separately. And the section near the Wusha Mountain has a half-life time of about 25 days and a mean residence time of about 30 days. Moreover, water exchange in the top of the bay is even slower, with a half-life time of 30~ 35 days and a mean residence time of 35~ 40 days in Tiegang harbor and Huangdungang harbor. The result shows that, both the half-life time and mean residence time increase gradually from the mouth to the top of the Xiangshangang Bay, suggesting the water exchange rate and governing mechanism differ spatially in the Bay. The region between the mouth of the bay and Xize is an area of strong tidal current, where the water flows out with the ebb current and mixes with the water outside, then flows back into the bay with flood current. So the exchange rate here is quite high, and the water closer to the mouth is mixed more fully. However, the inner part of the Xiangshangang Bay is dominated by gravitational circulation and tidal oscillation, where the mixing is much weaker and the period of water exchange is much longer than that in the outer part of the bay. The comparison of the water exchange in barotropic model with that in baroclinic model shows that the baroclinic hydrodynamic power has; considerable influence on the water exchange process inside the Xiangshangang Bay, and that the gravitational circulation and water stratification increase obviously the exchange rate, while, it has little effect on the outside part of the bay where it is controlled by advection and tidal diffusion.
Key words
Xiangshangang Bay /
water exchange /
baroclinic /
half-life time /
mean residence time.
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References
[1] China Bay Records Committee. Chinese bay records: The fifth section[M]. Beijing: Ocean Press, 1993:166.
中国海湾志编纂委员会.中国海湾志:第五分册[M].北京:海洋出版社,1993:166.
[2] LUO Yi-hua.Water quality actualities and water pollution control measures at Xiangshan Port[J]. Pollution Control Technology, 2008,21(3):88-90.
罗益华. 象山港海域水质状况分析与污染防治对策[J].污染防治技术,2008,21(3):88-90.
[3] GAO Shu, XIE Qin-chun.Physical model for water exchange process in Xiangshangang Bay[J]. Marine Science Bulletin, 1991,10(3):1-9.
高抒,谢钦春.狭长形海湾与外海水体交换的一个物理模型[J]. 海洋通报,1991,10(3):1-9.
[4] CHEN Wei, SU Ji-lan.A segmented tidal exchange model I. Model de velopment[J]. Marine Environmental Science, 1999,18(2):59-65.
陈伟,苏纪兰.狭窄海湾潮交换的分段模式I.模式的建立[J].海洋环境科学,1999, 18(2):59-65.
[5] CHEN Wei, SU Ji-lan.A segmented tidal exchange model I. Application to the Xiangshan Estuary[J]. Marine Environmental Science, 1999, 18(3):7-10.
陈伟,苏纪兰.狭窄海湾潮交换的分段模式II.在象山港的应用[J].海洋环境科学,1999,18(3):7-10.
[6] DONG Li-xian, SU Ji-lan.Numerical study of the water exchange in the Xiangshangang Bay I. Advection diffusion water exchange model[J]. Oceanologia et Limnologia Sinica, 1999, 30(4): 410-415.
董礼先,苏纪兰.象山港水交换数值研究I. 对流扩散型的水交换模式[J].海洋与湖沼,1999,30(4):410-415.
[7] DONG Li-xian, SU Ji-lan. Numerical study of the water exchange in the Xiangshangang Bay II. Model application and water ex-change study[J]. Oceanologia et Limnologia Sinica, 1999, 30(5): 465-469.
董礼先,苏纪兰.象山港水交换数值研究II. 模型应用和水交换研究[J].海洋与湖沼,1999,30(5):465-469.
[8] LOU Hai-feng, HUANG Shi-chang, XIE Ya-li.Numerical simu-lation of water exchange in Xiangshangang Bay[J]. Zhejiang Hydrotechnics, 2005,4:8-12.
娄海峰,黄世昌,谢亚力.象山港水体交换数值研究[J].浙江水利科技,2005,4:8-12.
[9] DU Yi, ZHOU Liang ming, GUO Pei-fang, et al. A simulation of sea water exchange in Luoyuan Bay[J]. Oceanologia et Limno-logia Sinica,2007,1:7-13.
杜伊,周良明,郭佩芳,等.罗源湾水交换三维数值模拟[J].海洋湖沼通报,2007,1:7-13.
[10] ZHU Jun-zheng. Numerical simulation of characteristic of 3-D tidal flow in Xiangshan Bay[J]. Journal of Hydroelectric Engi-neering, 2009,28(3):145-151.
朱军政. 象山港三维潮流特性的数值模拟[J].水利发电学报,2009,28(3):145-151.
[11] HUANG Xiu-qing, WANG Jin-hui, JIANG Xiao-shan, et al. Study on the marine environmental capacity and control of the total quality of soluble tracer for the Xiangshangang Bay[M]. Beijing: Ocean Press,2008:1-2.
黄秀清,王金辉,蒋晓山,等.象山港海洋环境容量及污染物总量控制研究[M].北京:海洋出版社,2008:1-2.
[12] CAI Wei-zhang, CHEN Gen-xin, DING Jin-ren.A discussion of the features of the tide and tidal current in the Xiangshan Har-bour and their cause of formation[J]. Marine Science Bulletin, 1985,4(3):8-12.
蔡伟章,陈耕心,丁锦仁.象山港潮汐潮流特征及成因探讨[J]. 海洋通报,1985,4(3):8-12.
[13] DONG Li-xian, SU Ji-lan. Salinity distribution and mixing in Xiang-shangang Bay I. Salinity distribution and circulation pattern[J]. Oceanologia et Limnologia Sinica, 2000,31(2):151-158.
董礼先,苏纪兰.象山港盐度分布和水体混合I.盐度分布和环流结构[J].海洋与湖沼,2000,31(2):151-158.
[14] DONG Li xian, sU Jji-lan. Salinity distribution and mixing in Xiangshangang Bay II. Mi xing analysis[J]. Oceanologia et Lim-nologia Sinica, 2000,31(3):322-326.
董礼先,苏纪兰.象山港盐度分布和水体混合I.混合分析[J]. 海洋与湖沼,2000,31(3):322-326.
[15] Delft Hydraulic.Delft3D-FLOW user manua1[M]. Delft: Delft Hydraulics,2010.
[16] LUFF R, POHLMANN T.Calculation of water exchange times in the ICES boxes with a Eulerian dispersion model using a half-life time approach[J]. Dtsch Hydrogr Z,1995,47(4):287-299.
[17] TALEOKA H.Fundamental concepts of exchange and transport time scales in a coastal sea[J]. Continental Shelf Research, 1984,3:331-336.
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