湄洲湾北部海底地貌特征研究与分析

为对湄洲湾北部海底地形地貌特征及其影响因素进行系统的研究,作者利用多波束系统对湄洲湾北部海底地形进行探测,结合研究区内沉积物及潮流特征,对该区域海底地貌特征及其成因进行分析。研究区呈现中部低、南北高的地形格局,其中中部深水区又为近岸深、中间浅的特征,中轴为潮汐水道,水道两侧发育浅滩的海底地貌特征。研究区沉积物组分以砂和粉砂为主,由于研究区大部分表层沉积物中细粒沉积物占主要组分,沉积物具有较强的黏性,而实测资料显示潮流流速较小,因此研究区在常态水动力条件下,海底沉积物很难被冲刷,海底地形变化受潮流影响较小。通过将2012年与2013年研究区的调查结果进行对比发现,研究区海底地形整体变化不大,个别区域地形起伏变化较大,据推测可能是由于人为的挖沙、港口疏浚等因素造成的。因此,短期内影响研究区海底地形变化的主要因素为人为因素。

Topographical and geomorphological features of seafloor in northern Meizhou Gulf

In this study, we primarily study the features and influencing factors of the seafloor geomorphology in the northern Meizhou Bay using a multibeam system and the characteristics of the sediments and tidal currents. The relief in the middle of the study area is low and high in the northern and southern sections, respectively. The deep area in the middle of the study area features a deep nearshore zone and shallow center, and there is a tidal channel, where shallows occur on both sides of the axis. The sediments mainly comprise sand and silt. The surface sediments are viscous because they are mainly fine-grained and the tidal current velocity is slow. Therefore, the seafloor sediments are barely eroded under normal hydrodynamic conditions, and the topography of seabed is nearly never influenced by tidal currents. Comparing the 2012 and 2013 survey results, it was discovered that the seafloor topography did not totally change; however, some individual areas experienced obvious changes. This infers that the changes in relief were due to offshore dredging and port dredging. Therefore, the key factor influencing the seafloor geomorphology in short term is human activity.