江苏淤泥质潮滩对海平面变化的形态响应

The Morphological Response of Typical Mud Flat to Sea Level Change in Jiangsu Coastal Plain

通过对江苏滨海平原淤泥质潮滩１９８０年以来１９个固定潮滩断面１１２个测次滩面高程测量的统计分析，探讨典型淤泥质潮滩剖面形态对海平面变化的形态响应过程。结果表明，典型淤涨岸段海平面上升，多年平均潮位线以上滩面仍将淤积加高，但淤高幅度除多年平均高潮线附近滩面相对较大外，其余均较小，表明随海平面上升该滩带总体淤积速率将趋于减小；与此相反，多年平均潮位线以下滩面则趋于蚀低，且侵蚀强度较大，表明该滩带的侵蚀有加剧趋向，最终滩面总体形态将因上带不断淤高和下带不断蚀低而逐渐变陡，剖面上凸形态的曲率不断加大。典型侵蚀岸段，海平面上升的效应则相反，海平面上升，多年平均潮位线以上滩面强烈蚀低；而多年平均潮位线以下滩面则强烈淤积加高，剖面的上凹形态最终将因上带不断蚀低和下带不断淤高而趋于平直。

The morphological and ecological response of tidal flat and coastal wetlands to sea level rise is one of the basic aspects of the impacts of global warming on coastal zones. Jiangsu coastal plain, located in the middle of China's coastal area, is the vastest area with most diversiform ecological types of mud flat in China, even all over the world. Therefore, research on the morphological response of mud flat to sea level change in this area undoubtedly is typical and of global significance. Based on the 112 times of field elevation measurements to 19 typical sections since 1980, using statistic methods, the morphological response of typical accretion and erosion section of mud flat to sea level rise was discussed in this paper. The estimated results show that, there are good correlations between accretion rate(both the horizontal and the vertical) of mud flat and sea level change in the study area, just the correlation is diverse in different sections or different parts of the same section due to the various distributions of current velocity and silt flux. The general tendency of the response of mud flat to sea level rise is that the accretion will tend to slow down and erosion will tend to be intensified. To typical accretion section, when sea level rises, the parts of mud flat above mean tidal line will still accrete, but the accretion rate will decrease except the part around mean high tidal line, the speediest rate of accretion occurs in the part between mean high tidal line and that one of the neaps. Whereas, the parts below mean tidal line will experience more intense erosion. The convex profile of mud flat will become more and more steeper and curving due to the upper side accreting and the down side eroding. To typical erosion section, the response of mud flat profile to sea level rise will present a opposite trend. The parts above mean tidal line will be eroded intensively, but the parts below mean tidal line will accrete. The concave profile will become more and more straight.