Study on the climbing height of double solitary waves along an oblique embankment around Shantou city

Tsunamis have a severe impact on marine coastal structures.Tsunami is generally simplified as solitary wave as they propagate,and the presence of the aftermath of Tsunami is similar to a second solitary wave.Waveform evolution occurs as solitary wave propagate down a gentle slope.This paper reveals the propagation of double solitary waves and slope climbing by numerical simulation where the prototype of the embankment is around Shantou city in the Guangdong Province,China.It not only enriches the theory of solitary wave,but also has important implications for the analysis of tsunami disaster mechanism and the hydrodynamic load characteristics of structures.Based on the average Navier-Stokes equation and the VOF approach,numerical simulation results are given,including changes in the velocity field of the climbing and falling process species.The results show that the double solitary waves produce a strong reflux effect,which results in the second solitary wave climbing significantly less than the height of the first solitary wave without the influence of the current.At the same time,double solitary waves can have a much stronger effect on the embankment.

汕头市海岸带湿地变化及驱动因素分析

本研究利用多期Landsat遥感影像数据,以人机交互解译及GIS分析等手段,获取了20世纪80年代以来汕头市海岸带湿地分布情况,参照湿地分类系统将汕头市海岸带湿地分为自然湿地和人工湿地两大类(一级分类),并在此基础上分为浅海水域、河流、湖泊、海岸/滩涂、红树林、水库/坑塘、水田、盐田、养殖池塘9种湿地类型(二级分类);利用单一湿地类型动态度、湿地转移矩阵和相关性分析研究9个时期汕头市海岸带湿地的变化特征和影响因素。结果表明,1982—2020年,汕头市海岸带湿地总面积略微增加,面积增加了19.08 km^(2),自然湿地面积明显萎缩,面积减少了51.18 km^(2),人工湿地面积显著增长,面积增加了70.26 km^(2),海岸带湿地生态系统退化明显。其变化的主要驱动力来自汕头市快速城镇化进程中发生的滩涂围垦、填海造陆、围海围河养殖、渔港码头以及水利设施修建等一系列人为活动,其次,区内主要河流输沙量以及海平面上升对汕头市海岸带湿地变化也有一定影响。