长江口区河海划界自然条件及方案探讨  

On the natural conditions and program for river-sea delimitation in Changjiang River Estuary

作　　者：陈沈良[1] 胡方西[1] 胡辉[1] 谷国传[1] 

机构地区：[1]华东师范大学河口海岸学国家重点实验室,上海200062

出　　处：《海洋学研究》2009年第B07期1-9,共9页Journal of Marine Sciences

基　　金：海洋公益性行业科研专项经费资助项目(200705020);我国近海综合调查与评价资助项目(908-02-02-06)

摘　　要：河口是河流与海洋交互作用的过渡区域,河口水域河海划界是一个十分复杂而敏感的问题。通过对长江河口段自然条件的分析,选取了相对比较稳定的几个相关参数:水域性质、潮汐特征、盐水入侵、悬沙浓度、河槽特性和沙岛形成过程等,作为长江口区河海划界的指标。水域性质是宏观上确定河海划界范围最基本的自然参数。潮汐特征的沿程分布和变化是河海划界的重要要素。盐水入侵是河口地区的普遍现象。悬沙浓度的沿程变化从一个侧面反映了径、潮流共同作用的产物,也可作为河海划界的参数之一。南支以上河段,河床纵断面变化显著,深槽浅滩起伏分布;南支河槽在浏河口以下,水深变化不大,一般在20 m之内,床面较平坦、起伏甚小,至口门一带水深均在10 m之内,明显反映了径、潮流共同作用的结果,显示了这一带是河海过渡段的特点。河口沙岛是河海相互作用下的沉积地貌,其推进状况也是河海划界的重要标志之一。从历史的角度看,随着长江口沙岛的形成和推进,河海界线有不断下移的趋向。据此探讨性地提出河海划界的3种方案:方案Ⅰ位于河口段的中部,界线的中部走向基本上是长江口第一代沙岛(崇明岛)与第二代沙岛(长兴、横沙)的分界线;方案Ⅱ以浏河口-崇明岛上口-北支沪苏分界线;方案Ⅲ位于口门附近。推荐方案Ⅰ作为上海市(长江口)河海划界的界线,仅供有关部门参考。An estuary is the transitional region where river meets the sea. The delimitation between river and sea in the estuarine waters is a complicated and sensitive issue. Based on the analysis of the natural conditions of the Changjiang River Estuary, several relatively stable parameters, including waters characteristics, tidal feature, saline intrusion, suspended sediment concentration, riverbed property, and formation of estuarine sand islands, etc. , are chosen as indexes for the delimitation between river and sea in Shanghai in Changjiang River Estuary. The property of estuarine waters is the most basic natural parameter to determine macroscopically the boundary between river and sea. There exists a long distance in the Changjiang River Estuary from its tidal limit （at Datong） to the beach area outside mouth. The property of waters at different location is very different. The basic delimitation region is mainly considered from Xuliujing downward to the mouth bars. Tidal distribution and variation along the estuary is an important element for river-sea delimitation. The estuarine reach is relatively balanced waters of river-sea interaction, in which the waters near Wusong is the intermediate zone. Saline intrusion is a common phenomenon in tidal estuaries. Offshore salt-water intrusion has profound influence on the Changjiang River Estuary, thus it is also an important parameter for river-sea delimitation. Liuhe mouth is the upper boundary of saline intrusion during dry season. Variations of the suspended sediment concentration （SSC） along the estuary are resulted from the interaction of runoff and tidal current, therefore, can be used as one of the parameters of for river-sea delimitatio. The SSC in Changjiang River Estuary shows remarkable seasonal variations： SSC in the inner estuary is high in summer and low in winter, while in the estuarine mouth and outer estuary, it is high in winter and low in summer. The transitional zone, i. e. the zone that has no seasonal changes is round the upper sect

关 键 词：河口段 河海划界 自然条件 长江口 

分 类 号：P737.121[天文地球—海洋地质]