Morphological Changes Induced by Coastal Protection on the Coast of Maputo City, Mozambique

Coastal change has merited attention because of heated arguments in the literature on this subject at national,regional,southern African,and international levels.The city of Maputo,the capital of Mozambique,which had been undergoing intense coastal erosion actions,was the target of large-scale intervention aimed at halting the advance of the sea and the consequent destruction of infrastructure.Coastal protection consisted of soft forms,artificial feeding,and heavy,longitudinal and transversal structures.This study was carried out along the protected line,about 3 km long,and aims to understand the morphological transformations in the Maputo city shoreline that occurred after the coastal protection.For that,the following technical methods were used:observation,a topographic survey of the beach cross-sections,and the shoreline evolution before and after coastal protection using 2008 and 2010 Google Earth satellite imagery prior to protection 2015,project completion year and 2018 monitoring year.The findings of the study revealed that the causes of coastal erosion persist,like constant removal by deflation of the borrowed sediment.Besides,vertical structures(groynes)intensify erosion in the downdrift while adherent structures interrupt the return of sediment deposited on the sidewalk and the road.The beach that experienced a positive sedimentary balance with artificial feeding has been losing more sediment than it gets.The transversal profiles show the beach shore has depressions that are submerged in the presence of high tides,bringing the sea closer to the adherent structure.Despite the sped up erosion observed,embryonic dunes were detected in some parts of the beach,signs of the establishment of dynamic equilibrium,becoming sites of sand accumulation and sediment source to the beach,through the exchange between the dune and the beach.With these results,a pilot station for artificial dune construction is being designed for beach stability.

Coastal Protection Forest Construction Project

China’s coastal line starts at the Yalu River in Liaoning in the north and ends at the Beilun River mouth in Guangxi. It is 18,000 kilometres long and crosses 11 provinces, municipalities and autonomous regions, including Liaoning, Hebei, Tianjin, Shandong, Jiangsu, Shanghai, Zhejiang, Fujian, Guangdong, Guangxi and Hainan. In 1988, the Chinese government outlined the Coastal Protection Forest System Construction Project and defined the coastal line of 11 provinces as the main construction line. The project aims at developing a

Overview on Mangrove Forest Disaster Prevention and Mitigation Functions

This paper provides a comprehensive overview on coastal protection and hazard mitigation by mangroves.Previous stud-ies have made great strides to understand the mechanisms and influencing factors of mangroves’protection function,including wave energy dissipation,storm surge damping,tsunami mitigation,adjustment to sea level rise and wind speed reduction,which are sys-tematically summarized in this study.Moreover,the study analyzes the extensive physical models,based on indoor flume experi-ments and numerical models,that consider the interaction between mangroves and hydrodynamics,to help our understanding of mangrove-hydrodynamic interactions.Additionally,quantitative approaches for valuing coastal protection services provided by man-groves,including index-based and process-resolving approaches,are introduced in detail.Finally,we point out the limitations of previous studies,indicating that efforts are still required for obtaining more long-term field observations during extreme weather events,to create more real mangrove models for physical experiments,and to develop numerical models that consider the flexible properties of mangroves to better predict wave propagation in mangroves having complex morphology and structures.

新贸易保护主义对广东沿海经济带外贸出口的影响及其应对

后危机时代,全球范围内新贸易保护主义抬头且呈现加速发展的趋势。广东省在这场新贸易保护主义中面临着极大的挑战,广东沿海经济带的对外贸易作为广东省外贸的主体,不可避免地遭受新贸易保护主义的严重冲击。文章分析了国际"两反两保"措施、知识产权争端、技术性贸易壁垒、绿色贸易壁垒和劳工标准壁垒等新贸易保护主义形式对广东沿海经济带的影响,提出广东沿海经济带外贸出口应对新贸易保护主义的若干策略:适度限制出口和扩大进口;政府协同企业应对国外的"两反两保"措施;提升核心竞争力跨越知识产权贸易壁垒;依靠自主创新突破技术性贸易壁垒;发展环保低碳产业应对绿色贸易壁垒和加强社会责任意识化解劳工标准壁垒等。

Hydroelastic Investigation on A Pile Breakwater Integrated with A Flexible Tail for Long-Wave Attenuation

A novel concept of wave attenuator is proposed for the defense of long waves,through integrating a flexible tail to the lee-side surface of a pile breakwater.The flexible tail works as a floating blanket made up of hinged blocks,whose scale and stiffness can be easily adjusted.A two-phase-flow numerical model is established based on the open-source computational fluid dynamics(CFD)code OpenFOAM to investigate its wave attenuation performance.Incompressible Navier−Stokes equations are solved in the fluid domain,where an additional computational solid mechanics(CSM)solver is embedded to describe the elastic deformation of the floating tail.The coupling of fluid dynamics and structural mechanics is solved in a full manner to allow assess of wave variation along the deforming body.The accuracy of the numerical model is validated through comparison with experimental data.Effects of the flexible tail on performance of the pile breakwater are investigated systematically.Dynamic behaviours of the tail are examined,and characteristics of its natural frequency are identified.For safety reasons,the wave loads impacting on the main body of the pile breakwater and the stress distribution over the tail are specially examined.It is found that both the length and stiffness of the tail can affect the wave-attenuation performance of the breakwater.A proper choice of the length and stiffness of the tail can greatly improve the long-wave defending capability of the pile breakwater.The maximum stress over the flexible tail can be restrained through optimising the deformation and stiffness of the tail.