1986–2019年粤东企望湾砂质海岸线演变过程与驱动机制研究

本文采用1986–2019年113景Landsat影像提取高潮线，辅以2015–2019年实测剖面数据，开展了海湾尺度上海岸线的中长期演变过程与驱动机制研究。结果表明:企望湾以中间小型基岩岬角为界划分出的西侧海滩和东侧海滩分别具备4种和3种不同的空间特征；超过一半的区域其海岸线演变表现为非线性行为；Mann-Kendall趋势检验和显著性分析方法较好地解决了已有研究中对研究时段划分缺乏依据的问题；近5年的实测剖面数据也验证了企望湾近期显著的淤积和侵蚀现象。进一步研究表明，自西向东的沿岸输沙过程是近期海岸线演变主要的驱动机制，东侧防波堤因为改变了控制性“岬角”的位置，造成了海湾平面形态不平衡，而中间小型基岩岬角也影响了企望湾侵蚀和淤积的空间差异性。研究结果对于预测未来岸线位置和控制岸线侵蚀风险具有重要的理论和现实意义。

Study on the evolution process and driving mechanism of the sandy shoreline of the Qiwang Bay in eastern Guangdong from 1986 to 2019

A dataset of the high water lines extracted from 113 Landsat images from 1986 to 2019 and the measured profile data from 2015 to 2019 were used to examine the middle-term to long-term shoreline process and driver at the embayment scale in this paper. The results show that the western and eastern beaches of the Qiwang Bay, which is separated by one small bedrock headland, have four and three different spatial characteristics, respectively. More than half of the shorelines behaved nonlinear in their variation trends. Thus, we use the Mann-Kendall method to solve the problem of the lack of basis for the division of time periods. In addition, the east breakwater resulted in the unstable embayment planform due to changing the position of the controlling “headland” and therefore the longshore sediment transport from west to east is the main driver of the most recent shoreline. And the intervening small bedrock headland also influenced the spatial variability of erosion and accretion at the Qiwang Bay. These findings will have important theoretical and practical significance for predicting further shoreline position and reducing the risk of shoreline erosion.