长江三角洲海岸剖面闭合深度的研究——Bruun法则及其应用的基本问题  

A STUDY OF CLOSURE DEPTH ON THE PROFILES OFTHE CHANGJIANG DELTAIC COAST ON THE FUNDAMENTAL PROBLEMS ASSOCIATEDWITH BRUUN RULE AND ITS APPLICATION

作　　者：陈西庆[1] 陈吉余[1] 

机构地区：[1]华东师范大学河口海岸研究所河口海岸国家重点实验室

出　　处：《地理学报》1998年第4期323-333,共11页Acta Geographica Sinica

基　　金：上海市科委重大项目

摘　　要：本文对Ｂｒｕｕｎ法则应用的前提——海岸均衡剖面的基本问题进行了深入探讨，提出长江三角洲海岸不发育经典理论中砂质海岸那种较为严格的均衡剖面，但海岸剖面也有其较为稳定的特性，具有确定的闭合深度，这为在这种海岸上应用Ｂｒｕｕｎ法则提供了一定依据与可能。同时从动力、地貌与沉积综合研究出发，提出长江三角洲海岸存在的二种不同时间尺度闭合深度，在此基础上。Both the theoretic consideration and the field experience suggest that the application of Bruun Rule in the muddy coast, especially in the Changjiang deltaic coast, is a complicated problem, for such coast presents a significant difference from sandy beaches in its coastal dynamics, geomorphology, sediment characteristics and transport. This paper presents a special study and discussion on the original equilibrium profile associated with Bruun Rule and its application. The study suggests that although the strict equilibrium coastal profiles, as described in the classical theory for sandy beach development, do not exist on the deltaic coast, the coastal profiles do show certain stable morphological features, such as, the closure depth, the most important parameter in Bruun Rule, which provide a basis for the application of Bruun Rule in this coast. Because the coastal profiles vary greatly, even within the same onshore offshore profile, the coastal slope shows a large variation and this may give a great difference in the estimate of shoreline retreat rate if an arbitrary distance L * is adopted. An integrated study of coastal dynamics, geomorphology and sedimentology in the coastal system suggests that, while estimating the shoreline retreat rate, the two closure depths of 8 m and 30 m should be considered in the open east coast of Shanghai, while on the north coast of Hangzhou Bay the single closure depth of 8m is enough due to the existence of 8m underwater platform of Hangzhou Bay: It is found that these two different closure depths are dynamically controlled by the two wave heights approximately with ≤1-year and≥10-year recurrence intervals, respectively. Furthermore, it is suggested that a study of longshore sediment budget is indispensable for obtaining a reasonable estimate of shoreline retreat rate within the studied coastal segment because historical evidence suggests that the dynamical changes in the middle to the upper part of coastal profile are largely controlled by this factor under

关 键 词：海平面上升 海岸侵蚀 闭合深度 长江三角洲 

分 类 号：P737.1[天文地球—海洋地质] P731.23[天文地球—海洋科学]