本文主要研究内容
作者乔立新（2019）在《分汊型河口悬沙浓度分布特征及影响机制研究》一文中研究指出：河口地区由于径流作用季节性差异、潮汐强度周期性变化以及河口地貌形态等因素影响,河口涨、落潮水动力过程、悬沙浓度以及盐度分布等存在区域性和季节性差异;此外由于河口地区径潮流相互作用、咸淡水混合等因素,河口细颗粒泥沙极易发生絮凝沉降和再悬浮,河口悬沙浓度在大、小潮涨落潮过程以及表、底层分布上也存在显著的不对称特征,并产生周期性净输沙过程。因此研究大型潮汐河口悬沙浓度时空分布及涨、落潮不对称特征和机制,对河口三角洲演变及河口航道治理具有重要意义。长江口是中等潮汐强度的分汊型河口,长江口自徐六泾以下至口外10 m等深线,河口逐渐展宽,并被崇明岛、长兴岛及九段沙分割为南北支、南北港及南北槽等多支典型分汊河槽,由于分汊河口地貌形态以及水动力、盐度等环境差异,河口悬沙浓度分布存在显著的季节性和区域性特征。本文研究基于2013年7月及2014年1月在长江口8个典型河槽、上游徐六泾节点及下游10 m等深线处共12个测站定点洪枯季、大小潮准同步水文综合调查,通过水文统计分析、Kriging空间插值、机制分解法等方法,研究长江分汊河口悬沙浓度平面分布、垂向分布、涨落潮过程以及悬沙通量特征和机制。主要结论如下:一、长江分汊型河口悬沙浓度平面变化特征及影响机制1、长江口各分汊河槽定点含沙量平均为0.60 kg/m~3,显著高于上游徐六泾站0.14 kg/m~3,以及下游口外10 m等深线处含沙量均值0.35 kg/m~3。从不同河槽看,北支河口含沙量高于南支河口。高含沙量出现在北港下段、北槽、南槽河口最大浑浊带区域,并呈自北向南递减趋势;含沙量低值区在南支河槽,与徐六泾站基本接近,其次为北港上段和南港河槽,含沙量与口外10 m水深线含沙量接近。2、长江口各典型河槽含沙量总体表现为枯季大于洪季。南、北支河口表现又有不同,北支河口含沙量洪季大于枯季,而南支河口含沙量则表现为枯季大于洪季。从沿程变化率上看,南港至南北槽沿程含沙量变化率呈剪刀差分布,反映洪季径流作用已影响到南港及北港上段河槽含沙量分布,而枯季该河段含沙量则仍受潮汐控制。3、长江口各典型河槽含沙量大潮显著高于小潮。分区域看,北支河口大、小潮含沙量均显著高于为南支河口,大、小潮变化在南支河口更为显著。南支河口不同河槽含沙量受潮汐作用影响具有显著差异,大、小潮变化对南支河口最大浑浊带含沙量影响更为明显。从大小潮沿程变化上看,自徐六泾至口外,大、小潮含沙量沿程变化主要集中在南港及以下段河槽,大潮对含沙量沿程变化贡献率更为显著。4、悬沙浓度与流速平面分布有较好的相关关系,两者峰值均出现在南支河口浑浊带水域,并向两侧递减。进一步研究表明:悬沙浓度分布与测站底层流速有明显的幂函数关系;此外盐度剧烈变化的位置对应着悬沙浓度迅速升高的位置,洪季时主要在南支河口浑浊带水域,枯季时则上移至北港上段、南港位置,河口细颗粒泥沙絮凝沉降过程对悬沙浓度分布具有重要影响。二、悬沙浓度垂向变化特征及影响机制5、总体上底层悬沙浓度显著高于表层悬沙浓度,这一现象在河口最大浑浊带区域更为明显。底层水体含沙量随涨落潮周期性变化较表层更为明显,底层含沙量峰值多出现在涨急后1-2 h附近,低值多出现在转流后1-2 h;表层悬沙峰值变化滞后于底层,趋势相对较弱。6、从洪枯季差异看,洪季表、底层差异主要集中在口门段河槽,枯季表底层差异峰值上溯到南、北港河段。洪季时口门段底部含沙量涨潮大于落潮,但表、底层含沙量差异落潮大于涨潮;枯季时,表底层含沙量显著差异主要分布在口门段和南、北港位置,与洪季趋势一致,但底部高浓度含沙量区域分布更广,峰值降低,差异缩减,反映径流作用减弱,潮汐作用增强。7、从大、小潮表底层差异看,大潮含沙量显著大于小潮,底部含沙量差异更明显。大潮时表、底层最大悬沙浓度分布在口门段,表底层含沙量差异落潮大于涨潮,反映大潮期间潮汐作用强劲,底部泥沙再悬浮特征明显;而小潮时含沙量峰值不显著,表、底层含沙量差异显著缩小,由于潮汐作用减弱,泥沙沉降,含沙量降低,底部泥沙沉降更快,涨、落潮及表、底层差异显著缩减。三、涨、落潮悬沙浓度不对称特征及影响机制8、长江口河势演变形成南、北支河口涨、落潮悬沙浓度不对称分布整体格局。近年来长江径流悬沙浓度呈明显下降趋势,观测期间上游徐六泾站悬沙浓度显著低于口外10 m等深线,河势演变影响径、潮流相互作用强度和范围,造成长江口悬沙浓度北支河口大于南支河口、涨潮大于落潮的整体格局。9、洪、枯季变化影响河口涨、落潮悬沙分布的再分配过程。长江口洪、枯季变化主要体现在径流变化上,由于径流量枯季远小于洪季,南支河口悬沙浓度分布均体现出枯季大于洪季的特征;从沿程变化上看,小于含沙量0.20 kg/m~3区域洪季可以到达南港及北港上段,而枯季则仅分布在徐六泾至南支河槽。10、大潮涨、落潮过程对悬沙分布不对称影响显著大于小潮,大潮时浑浊带水域涨、落潮泥沙再悬浮作用显著。河口上游徐六泾站至南支河槽含沙量均较低,反映潮汐动力对南支河段影响较弱;最大浑浊带区域,大潮涨、落潮含沙量出现明显差异,并显著高于两侧含沙量分布,表明大潮期间涨、落潮过程对泥沙具有再悬浮作用,并且涨潮泥沙再悬浮作用大于落潮。11、季节性风浪作用影响河口最大浑浊带涨、落潮悬沙不对称南北差异。洪季最大含沙量出现在南槽大潮涨潮过程,并向北槽和北港下段依次递减,反映洪季含沙量受夏季东南偏南向风浪作用强烈;而小潮阶段,含沙量普遍较低,多在0.20 kg/m~3以下,河口最大浑浊带特征已不明显。枯季大潮悬沙浓度分布则与洪季趋势相反,最大含沙量出现在北港下段,并向北槽、南槽呈递减趋势,反映枯季含沙量受冬季偏北向风浪作用强烈;枯季小潮含沙量变化趋势与大潮一致,但较洪季小潮高,主要是枯季径流作用减弱的原因。12、大潮底部高含沙浓度对口门段涨、落潮悬沙不对称贡献显著。洪季大潮底部高含沙量主要集中在口门段河槽,由于潮汐作用强劲,底部泥沙再悬浮特征明显,涨、落潮不对称现象显著;枯季大潮与洪季趋势一致,由于径流作用减弱,潮汐作用增强,表、底层含沙量差异峰值上移到南北港附近,底部高浓度含沙量区域分布更广,峰值降低。大潮底部高含沙浓度显著高于小潮,对口门段涨、落潮悬沙不对称贡献显著。四、长江分汊型河口悬沙输运通量特征及机制13、调查期间,北支河口潮周期平均单宽净输沙量为28.0 t,方向向陆;南支河口平均单宽净输沙量为24.4 t,介于徐六泾29.3 t和口外10 m等深线处的3.2 t之间,方向向海。从不同河槽来看,南支河口涨、落潮单宽输沙量峰值出现在北港、北槽、南槽最大浑浊带区域,但单宽净输沙量北港下段与北槽较高,南槽转为较小的向陆净输沙。14、长江口各典型河槽潮周期单宽输沙量总体来看枯季大于洪季,但净输沙量则表现为洪季大于枯季。洪季时北支河口单宽净输沙为向陆方向,南支河口为向海方向;枯季时南、北支单宽净输沙量均为向海方向。长江口分汊河槽大潮时涨、落潮单宽输沙量显著大于小潮,但净输沙量小潮大于大潮。15、从水体分层输沙来看,口内高输沙水层多出现在0.2h-0.8h,垂向上净输沙量多呈现为表底层低、中间高的特征;口外10 m等深线净输沙量,北港口外水体上层净输沙量较大,到南槽口外底层净输沙显著高于中、上层水体。16、长江口各分汊河槽输沙主要贡献项为平流项输沙,其次为潮泵效应输沙和垂向环流净输沙。南支河口潮泵效应与河口环流输沙贡献率自西向东呈递增趋势,至最大浑浊带区域,已成为泥沙输运的重要贡献项。
Abstract
he kou de ou you yu jing liu zuo yong ji jie xing cha yi 、chao xi jiang du zhou ji xing bian hua yi ji he kou de mao xing tai deng yin su ying xiang ,he kou zhang 、la chao shui dong li guo cheng 、xuan sha nong du yi ji yan du fen bu deng cun zai ou yu xing he ji jie xing cha yi ;ci wai you yu he kou de ou jing chao liu xiang hu zuo yong 、xian dan shui hun ge deng yin su ,he kou xi ke li ni sha ji yi fa sheng xu ning chen jiang he zai xuan fu ,he kou xuan sha nong du zai da 、xiao chao zhang la chao guo cheng yi ji biao 、de ceng fen bu shang ye cun zai xian zhe de bu dui chen te zheng ,bing chan sheng zhou ji xing jing shu sha guo cheng 。yin ci yan jiu da xing chao xi he kou xuan sha nong du shi kong fen bu ji zhang 、la chao bu dui chen te zheng he ji zhi ,dui he kou san jiao zhou yan bian ji he kou hang dao zhi li ju you chong yao yi yi 。chang jiang kou shi zhong deng chao xi jiang du de fen cha xing he kou ,chang jiang kou zi xu liu jing yi xia zhi kou wai 10 mdeng shen xian ,he kou zhu jian zhan kuan ,bing bei chong ming dao 、chang xing dao ji jiu duan sha fen ge wei na bei zhi 、na bei gang ji na bei cao deng duo zhi dian xing fen cha he cao ,you yu fen cha he kou de mao xing tai yi ji shui dong li 、yan du deng huan jing cha yi ,he kou xuan sha nong du fen bu cun zai xian zhe de ji jie xing he ou yu xing te zheng 。ben wen yan jiu ji yu 2013nian 7yue ji 2014nian 1yue zai chang jiang kou 8ge dian xing he cao 、shang you xu liu jing jie dian ji xia you 10 mdeng shen xian chu gong 12ge ce zhan ding dian hong ku ji 、da xiao chao zhun tong bu shui wen zeng ge diao cha ,tong guo shui wen tong ji fen xi 、Krigingkong jian cha zhi 、ji zhi fen jie fa deng fang fa ,yan jiu chang jiang fen cha he kou xuan sha nong du ping mian fen bu 、chui xiang fen bu 、zhang la chao guo cheng yi ji xuan sha tong liang te zheng he ji zhi 。zhu yao jie lun ru xia :yi 、chang jiang fen cha xing he kou xuan sha nong du ping mian bian hua te zheng ji ying xiang ji zhi 1、chang jiang kou ge fen cha he cao ding dian han sha liang ping jun wei 0.60 kg/m~3,xian zhe gao yu shang you xu liu jing zhan 0.14 kg/m~3,yi ji xia you kou wai 10 mdeng shen xian chu han sha liang jun zhi 0.35 kg/m~3。cong bu tong he cao kan ,bei zhi he kou han sha liang gao yu na zhi he kou 。gao han sha liang chu xian zai bei gang xia duan 、bei cao 、na cao he kou zui da hun zhuo dai ou yu ,bing cheng zi bei xiang na di jian qu shi ;han sha liang di zhi ou zai na zhi he cao ,yu xu liu jing zhan ji ben jie jin ,ji ci wei bei gang shang duan he na gang he cao ,han sha liang yu kou wai 10 mshui shen xian han sha liang jie jin 。2、chang jiang kou ge dian xing he cao han sha liang zong ti biao xian wei ku ji da yu hong ji 。na 、bei zhi he kou biao xian you you bu tong ,bei zhi he kou han sha liang hong ji da yu ku ji ,er na zhi he kou han sha liang ze biao xian wei ku ji da yu hong ji 。cong yan cheng bian hua lv shang kan ,na gang zhi na bei cao yan cheng han sha liang bian hua lv cheng jian dao cha fen bu ,fan ying hong ji jing liu zuo yong yi ying xiang dao na gang ji bei gang shang duan he cao han sha liang fen bu ,er ku ji gai he duan han sha liang ze reng shou chao xi kong zhi 。3、chang jiang kou ge dian xing he cao han sha liang da chao xian zhe gao yu xiao chao 。fen ou yu kan ,bei zhi he kou da 、xiao chao han sha liang jun xian zhe gao yu wei na zhi he kou ,da 、xiao chao bian hua zai na zhi he kou geng wei xian zhe 。na zhi he kou bu tong he cao han sha liang shou chao xi zuo yong ying xiang ju you xian zhe cha yi ,da 、xiao chao bian hua dui na zhi he kou zui da hun zhuo dai han sha liang ying xiang geng wei ming xian 。cong da xiao chao yan cheng bian hua shang kan ,zi xu liu jing zhi kou wai ,da 、xiao chao han sha liang yan cheng bian hua zhu yao ji zhong zai na gang ji yi xia duan he cao ,da chao dui han sha liang yan cheng bian hua gong suo lv geng wei xian zhe 。4、xuan sha nong du yu liu su ping mian fen bu you jiao hao de xiang guan guan ji ,liang zhe feng zhi jun chu xian zai na zhi he kou hun zhuo dai shui yu ,bing xiang liang ce di jian 。jin yi bu yan jiu biao ming :xuan sha nong du fen bu yu ce zhan de ceng liu su you ming xian de mi han shu guan ji ;ci wai yan du ju lie bian hua de wei zhi dui ying zhao xuan sha nong du xun su sheng gao de wei zhi ,hong ji shi zhu yao zai na zhi he kou hun zhuo dai shui yu ,ku ji shi ze shang yi zhi bei gang shang duan 、na gang wei zhi ,he kou xi ke li ni sha xu ning chen jiang guo cheng dui xuan sha nong du fen bu ju you chong yao ying xiang 。er 、xuan sha nong du chui xiang bian hua te zheng ji ying xiang ji zhi 5、zong ti shang de ceng xuan sha nong du xian zhe gao yu biao ceng xuan sha nong du ,zhe yi xian xiang zai he kou zui da hun zhuo dai ou yu geng wei ming xian 。de ceng shui ti han sha liang sui zhang la chao zhou ji xing bian hua jiao biao ceng geng wei ming xian ,de ceng han sha liang feng zhi duo chu xian zai zhang ji hou 1-2 hfu jin ,di zhi duo chu xian zai zhuai liu hou 1-2 h;biao ceng xuan sha feng zhi bian hua zhi hou yu de ceng ,qu shi xiang dui jiao ruo 。6、cong hong ku ji cha yi kan ,hong ji biao 、de ceng cha yi zhu yao ji zhong zai kou men duan he cao ,ku ji biao de ceng cha yi feng zhi shang su dao na 、bei gang he duan 。hong ji shi kou men duan de bu han sha liang zhang chao da yu la chao ,dan biao 、de ceng han sha liang cha yi la chao da yu zhang chao ;ku ji shi ,biao de ceng han sha liang xian zhe cha yi zhu yao fen bu zai kou men duan he na 、bei gang wei zhi ,yu hong ji qu shi yi zhi ,dan de bu gao nong du han sha liang ou yu fen bu geng an ,feng zhi jiang di ,cha yi su jian ,fan ying jing liu zuo yong jian ruo ,chao xi zuo yong zeng jiang 。7、cong da 、xiao chao biao de ceng cha yi kan ,da chao han sha liang xian zhe da yu xiao chao ,de bu han sha liang cha yi geng ming xian 。da chao shi biao 、de ceng zui da xuan sha nong du fen bu zai kou men duan ,biao de ceng han sha liang cha yi la chao da yu zhang chao ,fan ying da chao ji jian chao xi zuo yong jiang jin ,de bu ni sha zai xuan fu te zheng ming xian ;er xiao chao shi han sha liang feng zhi bu xian zhe ,biao 、de ceng han sha liang cha yi xian zhe su xiao ,you yu chao xi zuo yong jian ruo ,ni sha chen jiang ,han sha liang jiang di ,de bu ni sha chen jiang geng kuai ,zhang 、la chao ji biao 、de ceng cha yi xian zhe su jian 。san 、zhang 、la chao xuan sha nong du bu dui chen te zheng ji ying xiang ji zhi 8、chang jiang kou he shi yan bian xing cheng na 、bei zhi he kou zhang 、la chao xuan sha nong du bu dui chen fen bu zheng ti ge ju 。jin nian lai chang jiang jing liu xuan sha nong du cheng ming xian xia jiang qu shi ,guan ce ji jian shang you xu liu jing zhan xuan sha nong du xian zhe di yu kou wai 10 mdeng shen xian ,he shi yan bian ying xiang jing 、chao liu xiang hu zuo yong jiang du he fan wei ,zao cheng chang jiang kou xuan sha nong du bei zhi he kou da yu na zhi he kou 、zhang chao da yu la chao de zheng ti ge ju 。9、hong 、ku ji bian hua ying xiang he kou zhang 、la chao xuan sha fen bu de zai fen pei guo cheng 。chang jiang kou hong 、ku ji bian hua zhu yao ti xian zai jing liu bian hua shang ,you yu jing liu liang ku ji yuan xiao yu hong ji ,na zhi he kou xuan sha nong du fen bu jun ti xian chu ku ji da yu hong ji de te zheng ;cong yan cheng bian hua shang kan ,xiao yu han sha liang 0.20 kg/m~3ou yu hong ji ke yi dao da na gang ji bei gang shang duan ,er ku ji ze jin fen bu zai xu liu jing zhi na zhi he cao 。10、da chao zhang 、la chao guo cheng dui xuan sha fen bu bu dui chen ying xiang xian zhe da yu xiao chao ,da chao shi hun zhuo dai shui yu zhang 、la chao ni sha zai xuan fu zuo yong xian zhe 。he kou shang you xu liu jing zhan zhi na zhi he cao han sha liang jun jiao di ,fan ying chao xi dong li dui na zhi he duan ying xiang jiao ruo ;zui da hun zhuo dai ou yu ,da chao zhang 、la chao han sha liang chu xian ming xian cha yi ,bing xian zhe gao yu liang ce han sha liang fen bu ,biao ming da chao ji jian zhang 、la chao guo cheng dui ni sha ju you zai xuan fu zuo yong ,bing ju zhang chao ni sha zai xuan fu zuo yong da yu la chao 。11、ji jie xing feng lang zuo yong ying xiang he kou zui da hun zhuo dai zhang 、la chao xuan sha bu dui chen na bei cha yi 。hong ji zui da han sha liang chu xian zai na cao da chao zhang chao guo cheng ,bing xiang bei cao he bei gang xia duan yi ci di jian ,fan ying hong ji han sha liang shou xia ji dong na pian na xiang feng lang zuo yong jiang lie ;er xiao chao jie duan ,han sha liang pu bian jiao di ,duo zai 0.20 kg/m~3yi xia ,he kou zui da hun zhuo dai te zheng yi bu ming xian 。ku ji da chao xuan sha nong du fen bu ze yu hong ji qu shi xiang fan ,zui da han sha liang chu xian zai bei gang xia duan ,bing xiang bei cao 、na cao cheng di jian qu shi ,fan ying ku ji han sha liang shou dong ji pian bei xiang feng lang zuo yong jiang lie ;ku ji xiao chao han sha liang bian hua qu shi yu da chao yi zhi ,dan jiao hong ji xiao chao gao ,zhu yao shi ku ji jing liu zuo yong jian ruo de yuan yin 。12、da chao de bu gao han sha nong du dui kou men duan zhang 、la chao xuan sha bu dui chen gong suo xian zhe 。hong ji da chao de bu gao han sha liang zhu yao ji zhong zai kou men duan he cao ,you yu chao xi zuo yong jiang jin ,de bu ni sha zai xuan fu te zheng ming xian ,zhang 、la chao bu dui chen xian xiang xian zhe ;ku ji da chao yu hong ji qu shi yi zhi ,you yu jing liu zuo yong jian ruo ,chao xi zuo yong zeng jiang ,biao 、de ceng han sha liang cha yi feng zhi shang yi dao na bei gang fu jin ,de bu gao nong du han sha liang ou yu fen bu geng an ,feng zhi jiang di 。da chao de bu gao han sha nong du xian zhe gao yu xiao chao ,dui kou men duan zhang 、la chao xuan sha bu dui chen gong suo xian zhe 。si 、chang jiang fen cha xing he kou xuan sha shu yun tong liang te zheng ji ji zhi 13、diao cha ji jian ,bei zhi he kou chao zhou ji ping jun chan kuan jing shu sha liang wei 28.0 t,fang xiang xiang liu ;na zhi he kou ping jun chan kuan jing shu sha liang wei 24.4 t,jie yu xu liu jing 29.3 the kou wai 10 mdeng shen xian chu de 3.2 tzhi jian ,fang xiang xiang hai 。cong bu tong he cao lai kan ,na zhi he kou zhang 、la chao chan kuan shu sha liang feng zhi chu xian zai bei gang 、bei cao 、na cao zui da hun zhuo dai ou yu ,dan chan kuan jing shu sha liang bei gang xia duan yu bei cao jiao gao ,na cao zhuai wei jiao xiao de xiang liu jing shu sha 。14、chang jiang kou ge dian xing he cao chao zhou ji chan kuan shu sha liang zong ti lai kan ku ji da yu hong ji ,dan jing shu sha liang ze biao xian wei hong ji da yu ku ji 。hong ji shi bei zhi he kou chan kuan jing shu sha wei xiang liu fang xiang ,na zhi he kou wei xiang hai fang xiang ;ku ji shi na 、bei zhi chan kuan jing shu sha liang jun wei xiang hai fang xiang 。chang jiang kou fen cha he cao da chao shi zhang 、la chao chan kuan shu sha liang xian zhe da yu xiao chao ,dan jing shu sha liang xiao chao da yu da chao 。15、cong shui ti fen ceng shu sha lai kan ,kou nei gao shu sha shui ceng duo chu xian zai 0.2h-0.8h,chui xiang shang jing shu sha liang duo cheng xian wei biao de ceng di 、zhong jian gao de te zheng ;kou wai 10 mdeng shen xian jing shu sha liang ,bei gang kou wai shui ti shang ceng jing shu sha liang jiao da ,dao na cao kou wai de ceng jing shu sha xian zhe gao yu zhong 、shang ceng shui ti 。16、chang jiang kou ge fen cha he cao shu sha zhu yao gong suo xiang wei ping liu xiang shu sha ,ji ci wei chao beng xiao ying shu sha he chui xiang huan liu jing shu sha 。na zhi he kou chao beng xiao ying yu he kou huan liu shu sha gong suo lv zi xi xiang dong cheng di zeng qu shi ,zhi zui da hun zhuo dai ou yu ,yi cheng wei ni sha shu yun de chong yao gong suo xiang 。
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