近60年来长江河口河势变化及其对水动力和盐水入侵的影响Ⅲ.盐水入侵
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摘要
本文应用本系列论文Ⅱ中建立的长江河口水动力和盐水入侵三维数值模式,模拟长江河口20世纪50年代、70年代和2012年盐水入侵,定量分析不同年代河势下盐水入侵状况和变化程度及其原因。在北支,不同年代盐水入侵的变化是由分流比和潮差共同作用造成的。50年代北支盐水入侵较强,70年代大幅下降,中上段出现淡水,2012年盐水入侵极为严重,整个北支被高盐水占据,上段出现强烈的盐度锋面。50年代和2012年,北支盐水倒灌南支,大潮期间远大于小潮期间,2012年远强于50年代,70年代没有北支盐水倒灌南支现象。在南支,50年代、70年代南支大部分为盐度都小于0.45的淡水,在2012年大潮期间由于出现了强烈的北支盐水倒灌,南支上段出现盐度大于0.45的盐水。在南北港,在50年代盐水入侵最严重;大潮期间,北港净分流比南港大21.6%,北港盐度小于南港盐度,外海盐水主要通过南港入侵,出现南港盐水倒灌进入北港的现象。至70年代,南支主流转向南港,南港净分流比增大,比北港大10.4%,南港盐度明显小于北港盐度;南北港盐水入侵较弱。在2012年,南支主流再次转向北港,北港分流比比南港大10.4%,南港的盐水入侵再次强于北港。小潮期间,50年代由于南港分流比相比于大潮时更小,南港盐水上溯距离更远,上段盐度比更大;至70年代,北港分流比减少,盐水入侵减弱;至2012年,由于大潮时期北支倒灌的盐水在小潮期间到达北港,北港净盐通量比大潮时期大。由于潮动力减弱,小潮期间各年代垂向盐度分层更明显,盐水入侵变化与大潮期间一致。
The 3D numerical model of the Changjiang Estuary built in the series paperⅡwas used to simulate the saltwater intrusion in 1950 s,1970sand 2012,and the changes of saltwater intrusion under different river regimes and their reasons were analyzed quantitatively in this paper.In the North Branch,the saltwater intrusion were controlled by the water diversion ratio and tidal range.In 1950 sand 2012,saltwater spilled over from the North Branch to the South Branch and the magnitude was greater during spring tide than during neap tide,and was greater in 2012 than in 1950 s.This phenomenon didn't appear in 1970 s.In 1950 s,saltwater intrusion was severe in the North Branch.In 1970 s,it decreased greatly,and a large amount of fresh water appeared in the upper and middle reaches.In 2012,the saltwater intrusion was very severe and the whole North Branch was occupied by saltwater,sharp salinity front appeared in the upper reaches.In the South Branch,fresh water occupied the most area in 1950 sand 1970s,and in 2012 saltwater with salinity greater than 0.45 appeared in the upper reaches because saltwater spilled over from the North Branch.In the North and South Channel,saltwater intrusion in the 1950 s was the most severe.During the spring tide,the net water diversion ratio in the North Channel was higher than that that in the South Channel by 21.6%,which caused the salinity in the North Channel was lower than that in the South Channel,resulting in the saltwater from the open sea intruded mainly through the South Channel,and returned over from the South Channel to the North Channel.In 1970 s,the mainstream of the South Branch turned to the South Channel,which caused the net water diversion ratio in the South Channel increased,and became higher than that in the North Channel by 10.4%,causing the salinity in the South Channel was lower than that in the North Channel;the saltwater intrusion was weakest in the South and North Channel.In 2012,the mainstream of the South Branch turned to the North Channel again and the net water diversion ratio in the North Channel was higher than that in the South Channel by 10.4%,resulting in the saltwater intrusion in the South Channel greater than that in the North Channel.Comparing with the situation in 1950 s,the saltwater intrusion in 1970 swas lower in the North and South Channel.Comparing with the situation in 1970 s,the saltwater intrusion in 2012 was lower in the North Channel and was higher in the South Channel.During the neap tide,the net water diversion in the South Channel was lower than that that during the spring tide in 1950 s,causing the saltwater intruded more farer and the salinity in the upper reaches was higher;in 1970 s,the salinity intrusion in the North Channel decreased because of the reduction of the net water diversion ratio;in 2012,the saltwater that spilled over from the North Branch in the spring tide arrived the North Channel,which caused the salt flux in the neap tide being greater than that in the spring tide.The salinity was more stratified in vertical because of the lower tidal dynamics in the three periods,and the changes of saltwater intrusion was almost same as that during the spring tide.
The 3D numerical model of the Changjiang Estuary built in the series paperⅡwas used to simulate the saltwater intrusion in 1950 s,1970sand 2012,and the changes of saltwater intrusion under different river regimes and their reasons were analyzed quantitatively in this paper.In the North Branch,the saltwater intrusion were controlled by the water diversion ratio and tidal range.In 1950 sand 2012,saltwater spilled over from the North Branch to the South Branch and the magnitude was greater during spring tide than during neap tide,and was greater in 2012 than in 1950 s.This phenomenon didn't appear in 1970 s.In 1950 s,saltwater intrusion was severe in the North Branch.In 1970 s,it decreased greatly,and a large amount of fresh water appeared in the upper and middle reaches.In 2012,the saltwater intrusion was very severe and the whole North Branch was occupied by saltwater,sharp salinity front appeared in the upper reaches.In the South Branch,fresh water occupied the most area in 1950 sand 1970s,and in 2012 saltwater with salinity greater than 0.45 appeared in the upper reaches because saltwater spilled over from the North Branch.In the North and South Channel,saltwater intrusion in the 1950 s was the most severe.During the spring tide,the net water diversion ratio in the North Channel was higher than that that in the South Channel by 21.6%,which caused the salinity in the North Channel was lower than that in the South Channel,resulting in the saltwater from the open sea intruded mainly through the South Channel,and returned over from the South Channel to the North Channel.In 1970 s,the mainstream of the South Branch turned to the South Channel,which caused the net water diversion ratio in the South Channel increased,and became higher than that in the North Channel by 10.4%,causing the salinity in the South Channel was lower than that in the North Channel;the saltwater intrusion was weakest in the South and North Channel.In 2012,the mainstream of the South Branch turned to the North Channel again and the net water diversion ratio in the North Channel was higher than that in the South Channel by 10.4%,resulting in the saltwater intrusion in the South Channel greater than that in the North Channel.Comparing with the situation in 1950 s,the saltwater intrusion in 1970 swas lower in the North and South Channel.Comparing with the situation in 1970 s,the saltwater intrusion in 2012 was lower in the North Channel and was higher in the South Channel.During the neap tide,the net water diversion in the South Channel was lower than that that during the spring tide in 1950 s,causing the saltwater intruded more farer and the salinity in the upper reaches was higher;in 1970 s,the salinity intrusion in the North Channel decreased because of the reduction of the net water diversion ratio;in 2012,the saltwater that spilled over from the North Branch in the spring tide arrived the North Channel,which caused the salt flux in the neap tide being greater than that in the spring tide.The salinity was more stratified in vertical because of the lower tidal dynamics in the three periods,and the changes of saltwater intrusion was almost same as that during the spring tide.
引文
[1]沈焕庭,茅志昌,朱建荣.长江河口盐水入侵[M].北京:海洋出版社,2003.Shen Huanting,Mao Zhichang,Zhu Jianrong.Saltwater Intrusion in the Changjiang Estuary[M].Beijing:China Ocean Press,2003.
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[9]陈泾,朱建荣.长江河口北支新村沙围垦工程对盐水入侵的影响[J].华东师范大学学报(自然科学版),2014(4):163-172.Chen Jing,Zhu Jianrong.Impact of the reclamation project of Xincunsha on the saltwater intrusion in the North Branch of the Changjiang Estuary[J].Journal of East China Normal University(Natural Science),2014(4):163-172.
[10]李林江,朱建荣.长江口南汇边滩围垦工程对流场和盐水入侵的影响[J].华东师范大学学报(自然科学版),2015(4):77-86.Li Linjiang,Zhu Jianrong.Impacts of the reclamation project of Nanhui tidal flat on the currents and saltwater intrusion in the Changjiang Estuary[J].Journal of East China Normal University(Natural Science),2015(4):154-162.
[11]Qiu Cheng,Zhu Jianrong.Assessing the influence of sea level rise on salt transport processes and estuarine circulation in the Changjiang River estuary[J].Journal of Coastal Research,2015,31(3):661-670.
[12]裘诚,朱建荣.低径流量条件下海平面上升对长江口淡水资源的影响[J].气候变化研究进展,2015,11(4):245-255.Qiu Cheng,Zhu Jianrong.Impact of sea-level rise on saltwater intrusion in the Changjiang Estuary in the low river discharge cases[J].Progressus Inquisitiones de Mutatione Climatis,2015,11(4):245-255.
[13]Zhu Jianrong,Ding Pingxing,Zhang Liquan,et al.Influence of the Deep Waterway Project on the Changjiang Estuary[M]//The Environment in Asia Pacific Harbours.Netherlands:Springer,2006:79-92.
[14]孙波,刘曙光,顾杰,等.三峡与南水北调工程对长江口水源地的影响[J].人民长江,2008,39(16):4-7.Sun Bo,Liu Shuguang,Gu Jie,et al.Numerical study on impact of water regulation of TGP and South-to-North Water Diversion Project on water source area of the Yangtze estuary[J].Yangtze River,2008,39(16):4-7.
[15]Xu Kun,Zhu Jianrong,Gu Yuliang.Impact of the eastern water diversion from the south to the north project on the saltwater intrusion in the Changjiang Estuary in China[J].Acta Oceanologica Sinica,2012,31(3):47-58.
[16]Qiu Cheng,Zhu Jianrong.Influence of seasonal runoff regulation by the Three Gorges Reservoir on saltwater intrusion in the Changjiang River Estuary[J].Continental Shelf Research,2013,71:16-26.
[17]肖成猷,沈焕庭.长江河口盐水入侵影响因子分析[J].华东师范大学学报(自然科学版),1998(3):74-80.Xiao Chengyou,Shen Huanting.The analysis of factors affecting the saltwater intrusion in Changjiang Estuary[J].Journal of East China Normal University(Natural Science),1998(3):74-80.
[18]张二凤,陈沈良,刘小喜.长江口北支异常强盐水入侵观测与分析[J].海洋通报,2014,33(5):491-496.Zhang Erfeng,Chen Shenliang,Liu Xiaoxi.Observation and analysis of abnormal strong saltwater intrusion in the North Branch of the Yangtze Estuary[J].Marine Science Bulletin,2014,33(5):491-496.
[19]Wu Hui,Zhu Jianrong,Chen Bingrui,et al.Quantitative relationship of runoff and tide to saltwater spilling over from the North Branch in the Changjiang Estuary:a numerical study[J].Estuarine,Coastal and Shelf Science,2006,69(1/2):125-132.
[20]朱建荣,吴辉,顾玉亮.长江河口北支倒灌盐通量数值分析[J].海洋学研究,2011,29(3):1-7.Zhu Jianrong,Wu Hui,Gu Yuliang.Numerical analysis of the inverted salt flux from the North Branch into the South Branch of Changjiang River Estuary[J].Journal of Marine Sciences,2011,29(3):1-7.
[21]茅志昌,武小勇,赵常青,等.长江口北港拦门沙河段上段演变分析[J].泥沙研究,2008(2):41-46.Mao Zhichang,Wu Xiaoyong,Zhao Changqing,et al.Evolution of the upper reach of mouth bars in the North Channel of the Changjiang Estuary[J].Journal of Sediment Research,2008(2):41-46.
[22]朱建荣,鲍道阳.近60年来长江河口河势变化及其对水动力和盐水入侵的影响Ⅰ.河势变化[J].海洋学报,2016,38(12):11-22.Zhu Jianrong,Bao Daoyang.The effects of river regime changes in the Changjiang Estuary on hydrodynamics and salinity intrusion in the past 60years I.River regime changes[J].Haiyang Xuebao,2016,38(12):11-22.
[23]鲍道阳,朱建荣.近60年来长江河口河势变化及其对水动力和盐水入侵的影响Ⅱ.水动力[J].海洋学报,2017,39(2):1-15.Zhu Jianrong,Bao Daoyang.The effects of river regime changes in the Changjiang Estuary on hydrodynamics and salinity intrusion in the past 60yearsⅡ.Hydrodynamics[J].Haiyang Xuebao,2017,39(2):1-15.
[2]肖成猷,朱建荣,沈焕庭.长江口北支盐水倒灌的数值模型研究[J].海洋学报,2000,22(5):124-132.Xiao Chengyou,Zhu Jianrong,Shen Huanting.Study of numerical modelling about salt water flow backward in the Changjiang Estuary north branch[J].Haiyang Xuebao,2000,22(5):124-132.
[3]茅志昌,沈焕庭,徐彭令.长江河口咸潮入侵规律及淡水资源利用[J].地理学报,2000,55(2):243-250.Mao Zhichang,Shen Huanting,Xu Pengling.The pattern of saltwater intruding into the Changjiang Estuary and the utilization of freshwater resources[J].Acta Geographica Sinica,2000,55(2):243-250.
[4]罗小峰,陈志昌.径流和潮汐对长江口盐水入侵影响数值模拟研究[J].海岸工程,2005,24(3):1-6.Luo Xiaofeng,Chen Zhichang.Numerical simulation study of effect of runoff and tide on the Changjiang River mouth saltwater intrusion[J].Coastal Engineering,2005,24(3):1-6.
[5]吴辉,朱建荣.长江河口北支倒灌盐水输送机制分析[J].海洋学报,2007,29(1):17-25.Wu Hui,Zhu Jianrong.Analysis of the transport mechanism of the saltwater spilling over from the North Branch in the Changjiang Estuary in China[J].Haiyang Xuebao,2007,29(1):17-25.
[6]Li Lu,Zhu Jianrong,Wu Hui.Impacts of wind stress on saltwater intrusion in the Yangtze Estuary[J].Science China Earth Sciences,2012,55(7):1178-1192.
[7]项印玉,朱建荣,吴辉.冬季陆架环流对长江河口盐水入侵的影响[J].自然科学进展,2009,19(2):192-202.Xiang Yinyu,Zhu Jianrong,Wu Hui.Impact of the shelf circulations in winter on the saltwater intrusion in the Changjiang Estuary[J].Progress in Natural Science,2009,19(2):192-202.
[8]Li Lu,Zhu Jianrong,Wu Hui,et al.Lateral saltwater intrusion in the North Channel of the Changjiang Estuary[J].Estuaries and Coasts,2014,37(1):36-55.
[9]陈泾,朱建荣.长江河口北支新村沙围垦工程对盐水入侵的影响[J].华东师范大学学报(自然科学版),2014(4):163-172.Chen Jing,Zhu Jianrong.Impact of the reclamation project of Xincunsha on the saltwater intrusion in the North Branch of the Changjiang Estuary[J].Journal of East China Normal University(Natural Science),2014(4):163-172.
[10]李林江,朱建荣.长江口南汇边滩围垦工程对流场和盐水入侵的影响[J].华东师范大学学报(自然科学版),2015(4):77-86.Li Linjiang,Zhu Jianrong.Impacts of the reclamation project of Nanhui tidal flat on the currents and saltwater intrusion in the Changjiang Estuary[J].Journal of East China Normal University(Natural Science),2015(4):154-162.
[11]Qiu Cheng,Zhu Jianrong.Assessing the influence of sea level rise on salt transport processes and estuarine circulation in the Changjiang River estuary[J].Journal of Coastal Research,2015,31(3):661-670.
[12]裘诚,朱建荣.低径流量条件下海平面上升对长江口淡水资源的影响[J].气候变化研究进展,2015,11(4):245-255.Qiu Cheng,Zhu Jianrong.Impact of sea-level rise on saltwater intrusion in the Changjiang Estuary in the low river discharge cases[J].Progressus Inquisitiones de Mutatione Climatis,2015,11(4):245-255.
[13]Zhu Jianrong,Ding Pingxing,Zhang Liquan,et al.Influence of the Deep Waterway Project on the Changjiang Estuary[M]//The Environment in Asia Pacific Harbours.Netherlands:Springer,2006:79-92.
[14]孙波,刘曙光,顾杰,等.三峡与南水北调工程对长江口水源地的影响[J].人民长江,2008,39(16):4-7.Sun Bo,Liu Shuguang,Gu Jie,et al.Numerical study on impact of water regulation of TGP and South-to-North Water Diversion Project on water source area of the Yangtze estuary[J].Yangtze River,2008,39(16):4-7.
[15]Xu Kun,Zhu Jianrong,Gu Yuliang.Impact of the eastern water diversion from the south to the north project on the saltwater intrusion in the Changjiang Estuary in China[J].Acta Oceanologica Sinica,2012,31(3):47-58.
[16]Qiu Cheng,Zhu Jianrong.Influence of seasonal runoff regulation by the Three Gorges Reservoir on saltwater intrusion in the Changjiang River Estuary[J].Continental Shelf Research,2013,71:16-26.
[17]肖成猷,沈焕庭.长江河口盐水入侵影响因子分析[J].华东师范大学学报(自然科学版),1998(3):74-80.Xiao Chengyou,Shen Huanting.The analysis of factors affecting the saltwater intrusion in Changjiang Estuary[J].Journal of East China Normal University(Natural Science),1998(3):74-80.
[18]张二凤,陈沈良,刘小喜.长江口北支异常强盐水入侵观测与分析[J].海洋通报,2014,33(5):491-496.Zhang Erfeng,Chen Shenliang,Liu Xiaoxi.Observation and analysis of abnormal strong saltwater intrusion in the North Branch of the Yangtze Estuary[J].Marine Science Bulletin,2014,33(5):491-496.
[19]Wu Hui,Zhu Jianrong,Chen Bingrui,et al.Quantitative relationship of runoff and tide to saltwater spilling over from the North Branch in the Changjiang Estuary:a numerical study[J].Estuarine,Coastal and Shelf Science,2006,69(1/2):125-132.
[20]朱建荣,吴辉,顾玉亮.长江河口北支倒灌盐通量数值分析[J].海洋学研究,2011,29(3):1-7.Zhu Jianrong,Wu Hui,Gu Yuliang.Numerical analysis of the inverted salt flux from the North Branch into the South Branch of Changjiang River Estuary[J].Journal of Marine Sciences,2011,29(3):1-7.
[21]茅志昌,武小勇,赵常青,等.长江口北港拦门沙河段上段演变分析[J].泥沙研究,2008(2):41-46.Mao Zhichang,Wu Xiaoyong,Zhao Changqing,et al.Evolution of the upper reach of mouth bars in the North Channel of the Changjiang Estuary[J].Journal of Sediment Research,2008(2):41-46.
[22]朱建荣,鲍道阳.近60年来长江河口河势变化及其对水动力和盐水入侵的影响Ⅰ.河势变化[J].海洋学报,2016,38(12):11-22.Zhu Jianrong,Bao Daoyang.The effects of river regime changes in the Changjiang Estuary on hydrodynamics and salinity intrusion in the past 60years I.River regime changes[J].Haiyang Xuebao,2016,38(12):11-22.
[23]鲍道阳,朱建荣.近60年来长江河口河势变化及其对水动力和盐水入侵的影响Ⅱ.水动力[J].海洋学报,2017,39(2):1-15.Zhu Jianrong,Bao Daoyang.The effects of river regime changes in the Changjiang Estuary on hydrodynamics and salinity intrusion in the past 60yearsⅡ.Hydrodynamics[J].Haiyang Xuebao,2017,39(2):1-15.