长江口和杭州湾污染物稀释扩散及交汇数值模拟研究
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摘要
河口水体中污染物稀释扩散是近海水环境研究的关键问题之一。针对长江口和杭州湾的污染物稀释扩散与交汇,利用有限体积法,建立了大范围二维潮流水质数学模型,结合拉格朗日法粒子追踪技术,模拟了不同径流下两河口的污染物(COD)稀释、扩散和交汇。结果表明,长江口石洞口排放的污染物口内经过10次往复运动,历时5天扩散至口门处,随后部分进入外海,另一部分经过6天扩散至杭州湾水域;杭州湾金山排放的污染物历时10天向上下游扩散约28 km,同时由北岸向南扩散约15 km。在各排污口同时排放COD浓度为100 mg/L的污水,交汇处COD达到相对稳定后,浓度增量约为1.2 mg/L,受长江口和杭州湾的影响之比约为5∶1。对不同径流量下COD稀释扩散进行模拟,得出径流量增大有助于污染物的稀释扩散。
Dilution and diffusion of pollutants in estuary is one of the key issues in offshore water environment research. In order to understand the dilution,diffusion and convergence of pollutants in the Yangtze estuary and Hangzhou bay,a two-dimensional water quality model is established based on finite volume method. In addition,a Lagrangian particle tracking technology is used to simulate the dilution,diffusion and convergence of the contamination( COD) in the two estuaries under different runoffs. The results show that the pollutants discharged from the Shidongkou at the Yangtze River estuary experience 10 times of reciprocating motions,which spread to the mouth after 5 days,and then some of them enter the outer sea,the others spread to the Hangzhou Bay after 6 days; the pollutants discharged from Jinshan spreads to about 28 km in both upstream and downstream directions after 10 days,and spread to about 15 km from the north bank to the south simultaneously; when all outlets discharge sewage with COD concentration of 100 mg/L at the same time,the COD concentration increases to around 1.2 mg/L at the junction,which is about 5 ∶ 1 by the influence of the Yangtze River estuary and Hangzhou Bay. In addition,the COD dilution and diffusion under different runoffs are simulated,and the results indicate that the increase of runoff helps the pollution to spread.
Dilution and diffusion of pollutants in estuary is one of the key issues in offshore water environment research. In order to understand the dilution,diffusion and convergence of pollutants in the Yangtze estuary and Hangzhou bay,a two-dimensional water quality model is established based on finite volume method. In addition,a Lagrangian particle tracking technology is used to simulate the dilution,diffusion and convergence of the contamination( COD) in the two estuaries under different runoffs. The results show that the pollutants discharged from the Shidongkou at the Yangtze River estuary experience 10 times of reciprocating motions,which spread to the mouth after 5 days,and then some of them enter the outer sea,the others spread to the Hangzhou Bay after 6 days; the pollutants discharged from Jinshan spreads to about 28 km in both upstream and downstream directions after 10 days,and spread to about 15 km from the north bank to the south simultaneously; when all outlets discharge sewage with COD concentration of 100 mg/L at the same time,the COD concentration increases to around 1.2 mg/L at the junction,which is about 5 ∶ 1 by the influence of the Yangtze River estuary and Hangzhou Bay. In addition,the COD dilution and diffusion under different runoffs are simulated,and the results indicate that the increase of runoff helps the pollution to spread.
引文
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[2]袁建忠.长江口杭州湾水体交换特性分析研究[C]//第三届长江论坛论文集.2009:183-191.(YUAN Jianzhong. Study on water exchange characteristics between Yangtze Estuary and Hangzhou Bay[C]//The Third Yangtze River Forum Proceedings.2009:183-191.(in Chinese))
[3]黄广.长江口、杭州湾水沙交换与输移特征研究[D].上海:华东师范大学,2007.(HUANG Guang. Study on the character of flow and sediment exchange and transport between Changjiang Estuary and Hangzhou Bay[D]. Shanghai:East China Normal University,2007.(in Chinese))
[4]许丹,孙志林.钱塘江河口突发污染物扩散数值模拟分析[J].浙江大学学报(工学版),2010,44(9):1767-1772.(XU Dan,SUN Zhilin. Numerical simulation and analysis of abrupt pollutants diffusion in Qiantang estuary[J]. Journal of Zhejiang University,Engineering Science,2010,44(9):1767-1772.(in Chinese))
[5]姚炎明,李佳,周大成.钱塘江河口段潮动力对污染物稀释扩散作用探讨[J].水力发电学报,2005,24(3):99-104.(YAO Yanming,LI Jia,ZHOU Dacheng. Analysis on tidal-driven dilution and transportation of contaminants in Qiantang estuary[J]. Journal of Hydroelectric Engineering,2005,24(3):99-104.(in Chinese))
[6] YANG Y,CHEN X,LI Y,et al. Modeling the effects of extreme drought on pollutant transport processes in the Yangtze River Estuary[J]. Jawra Journal of the American Water Resources Association,2015,51(3):624-636.
[7] TAO Sun,TAO Jianhua. Numerical simulation of pollutant transport acted by wave for a shallow water sea bay[J]. International Journal for Numerical Methods in Fluids,2006,51(5):469-487.
[8]聂红涛,陶建华.渤海湾海岸带开发对近海水环境影响分析[J].海洋工程,2008,26(3):44-50.(NEI Hongtao,TAO Jianhua. Impact of coastal exploitation on the eco-environment of Bohai Bay[J].The Ocean Engineering,2008,26(3):44-50.(in Chinese))
[9] KACHIASHVILI K,GORDEZIANI D,LAZAROV R,et al. Modeling and simulation of pollutants transport in rivers[J].Applied Mathematical Modelling,2007,31(7):1371-1396.
[10] GUPTA I,DHAGE S,CHANDORKAR A A,et al. Numerical modeling for Thane creek[J]. Environmental Modelling&Software,2004,19(6):571-579.
[11]张鑫,王智峰,董胜,等.污染物离岸排放输移扩散的数值模拟分析[J].海洋湖沼通报,2016(6):29-37.(ZHANG Xin,WANG Zhifeng,DONG Feng,et al. Numerical simulation on the transport and dispersion of the offshore discharged pollutants[J]. Transactions of Oceanology and Limnology,2016(6):29-37.(in Chinese))
[12]李曰嵩,潘灵芝,杨红.长江口海域污染物入海扩散模拟研究[J].海洋湖沼通报,2014(2):9-14.(LI Yuesong,PAN Lingzhi,YANG Hong. Numeric simulations of the pollutant diffusions of sewage outfalls in the Yangtze River Estuary[J].Transactions of Oceanology and Limnology,2014(2):9-14.(in Chinese))
[13] DEAN Wu,YAN Y. Numerical simulation of the transport and diffusion of dissolved pollutants in the changjiang(Yangtze)river estuary[J]. Chinese Journal of Oceanology and Limnology,2010,28(3):649-657.
[14]陆敏,孙志国,孙大鹏.人工岛对海湾水环境影响数值研究[J].海洋工程,2011,29(3):88-95.(LU Min,SUN Zhiguo,SUN Dapeng. Numerical study of the impact of water environment by artificial island in the gulf[J]. The Ocean Engineering,2011,29(3):88-95.(in Chinese))
[15]刘成,何耘,李行伟,等.上海市污水排放口污染物运动轨迹模拟[J].水利学报,2003(4):114-118.(LIU Cheng,HE Yun,LI Hangwei,et al. Numerical simulation on pollutant tracking released from the sewerage outfalls in Shanghai[J]. Jouranl of Hydraulic Engineering,2003(4):114-118.(in Chinese))
[16]王惠民,王艳红.潮汐水域油污染计算[J].水利水运工程学报,2006(1):1-7.(WANG Huimin,WANG Yanhong.Calculation of oil pollution in tidal areas[J]. Hydro-Science and Engineering,2006(1):1-7.(in Chinese))
[17]何青.杭州湾北部水域污染物扩散输移的数值模拟与分析[D].上海:华东师范大学,1998.(HE Qing. Pollutant transport modeling on the north coast of Hangzhou Bay[D]. Shanghai:East China Normal University,1998.(in Chinese))
[18]宋泽坤,程和琴,胡浩,等.长江口北支围垦对其水动力影响的数值模拟分析[J].人民长江,2012,43(15):59-63.(SONG Z K,CHENG H Q,HU Hao,et al. Numerical simulation analysis of influence of reclamation of north branch in the Yangtze River estuary on hydrodynamic characteristics[J]. Yangtze River,2012,43(15):59-63.(in Chinese))
[19] QIAO S,PAN D,HE X,et al. Numerical study of the influence of Donghai Bridge on sediment transport in the Mouth of Hangzhou Bay[J]. Procedia Environmental Sciences,2011,10(1):408-413.
[20]尹艳娥,沈盎绿,周进,等.春夏季长江口及其邻近海域表层和底层环境因素、氮分布分析[J].生态环境学报,2016,25(2):272-278.(YIN Yane,SHEN Aanglv,ZHOU Jin,et al. Analysis on the environmental factors and dissolved inorganic nitrogen in the Changjiang(Yangtze River)Estuary and in the adjacent East China Sea in spring and summer[J]. Ecology and Environment Sciences,2016,25(2):272-278.(in Chinese))