Dean模型在山东半岛西北岸滩动力地貌研究的应用

The Application of Dean Equilibrium Profile Model in the Study on Dynamic Geomorphology of the Northwest Shoal of Shandong Peninsula

根据山东半岛西北部25条实测岸滩剖面及相关表层沉积物、波浪、潮流资料,通过计算浪潮作用指数K和波浪-沉积物参数Ω,确定研究区主控动力因素并对海滩动力地貌类型进行划分,在此基础上应用Dean平衡剖面模型对实测剖面进行拟合,探讨了该模型的适用性及其参数物理意义等问题。山东半岛西北部整体为浪控海岸,刁龙嘴-三山岛岸段、海北嘴-石虎嘴岸段和三山岛-海北嘴岸段均属过渡型海滩,屺坶岛-栾家口岸段属消散型海滩。研究区实测剖面与Dean模型的拟合结果整体较好,部分剖面(剖面1、剖面2、剖面3、剖面5、剖面8)由于发育离岸沙坝,使其形态与Dean模型预测的平滑上凹的形态特点存在一定差别。屺坶岛-栾家口岸段(剖面19~剖面24)受外海侧桑岛及沿岸龙口人工岛群影响,与Dean模型预测结果存在较大差别,Dean模型对发育槽-坝体系的海滩的拟合仍具有局限性。Dean模型中m和A分别反映了海滩剖面反射性和泥沙沉速,与海滩动力地貌类型判别公式计算结果吻合较好。

Based on measured data,and related surface sediment,wave and tidal current data in 25 measured beach profiles in the northwest of Shandong Peninsula,this study calculated the tidal action index(K)and the wave-sediment parameter(Ω),to determine the main controlling dynamic factors in the study area and classify the dynamic geomorphological types of beaches.Then we used the Dean model to fit the measured profiles,and discussed the applicability of Dean model and the physical meaning of its parameters.The results showed that the beaches in the northwest of Shandong Peninsula is mainly controlled by waves.The beaches including Diaolongzui-Sanshandao section,Haibeizui-Shihuzui section and Sanshandao-Haibeizui section are transitional ones,and Qimudao-Luanjiakou beach is a dissipative beach.The fitting results were good.Compared with the smooth concave curves predicted by Dean model,some profiles(No.1,2,3,5 and 8)with one offshore sandbar or more,showed different curve shapes.There existed obvious differences in curve shapes between the measured profiles and the prediction results for Qimudao-Luanjiakou section(No.19-24),which was mainly influenced by the Sang Island and the Longkou man-made islands.The Dean model still has limitations in fitting beaches with troughs and sandbars.The parameters m and A in the Dean model represent the reflectivity and sediment settling velocity of beach profile respectively,which is in good agreement with the result of the discriminant formula for dynamic geomorphology types of beaches.