新鹤海湾的演变特征及水沙模拟分析

Evolution characteristics and flow-sediment simulation of the Xinhe Bay

为准确把握新鹤海湾的演变特征和水动力条件,采用现场观测和GIS技术对其地形变化、冲淤分布和冲淤量进行探讨,并利用数值模拟分析波浪、潮流和泥沙共同作用对海湾演变的影响。结果表明:海湾演变对连续台风的响应不同,表现为先冲后淤,其中苏拉作用下的冲刷量为台风过境后全年的2倍左右;受东南季风的影响,春夏冲淤幅度较大,海湾冲淤分布为南冲北淤,波高分布不均与涨潮流入湾时的向北偏转是其主要原因;波流共同作用下的底床切应力约为潮流单独作用时的10倍,波浪是导致海湾冲刷的主要因素,常浪下底床切应力小于临界冲刷应力,泥沙不易起动,因此海湾冲刷主要是由极端天气时的大浪所导致的。

Base on field observation and GIS,the changes in different isobaths,the distribution and the volume of erosion-deposition were discussed.In addition,the water and sediment conditions of the Xinhe Bay were simulated to explain the evolution.According to the results,the response of the bay evolution to the continuous typhoon shows deposition after erosion,and the volume of erosion under the action of Sula is around twice as high as the whole year after the typhoon.Affected by the southeast monsoon,the erosion and deposition in spring and summer are relatively large,the erosion occurs in the southern part of the bay and the deposition occurs in the north mainly due to the wave height distribution and the northward deflection when the tide enters the bay.The shear stress under the combined action of waves and currents is approximately 10 times of the individual tide current,so waves are the main factor leading to the erosion.Under the action of common waves,the bed shear stress is less than the critical erosion stress,and the sediment motion is not easy to start,therefore,the erosion of the Xinhe Bay is mainly caused by large waves during extreme weather.