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Coastal erosion in the changing climate situation is a grievous concern. Global experience varies in this regard due to the variation of the coastal dynamics. Muddy coasts are exceptionally fragile for the welding of the ecological environment, soft sedimentation nature, anthropogenic and natural factors. Therefore, coastal erosion protection is a challenging and daunting task for most of the muddy coasts. Stark pitfalls of the hard structural engineering solution for coastal erosion protection are becoming more prominent. The propensity to adopt nature-based solutions (NbS) for coastal erosion protection, squeeze, and retreat is on the mark, as opposed to grey or engineering solutions. Yet a comprehensive understanding of NbS for coastal protection in the muddy coasts and evidence building from a global perspective is a vacuum. This paper aims to look into the global contexts and experiences of NbSs for coastal protection to provide a cutting-edge analysis of the role of NbS in coastal erosion protection, biodiversity protection, renewing natural habitats, and shielding coastal populations in a changing climate situation. This research uses a systematic review method to explore the global to regional landscape of NbS in coastal erosion, policy framework, and the national experience. The plethora of NbS experience shows the effectiveness in protecting eroding coasts if properly applied in the right conditions under a pragmatic and/or policy-governance approach. Muddy coast in the peri-urban area of littoral countries like Thailand evolves even more critical bio-spheric condition that requires special and urgent attention. The complexity of the muddy coast of the upper Gulf of Thailand has to be critically understood for NbS-driven pivotal pathways to assure sustainable coastal erosion protection and climate-resilient development. • Coastal erosion in the muddy coasts is a grievous concern in the face of climate change. • Protecting coastal erosion is a daunting task as conventional structures are not suitable for fine sediments andexacerbate negative impacts. • Pitfalls of the grey structures necessitate nature-based solutions (NbS) for sediment trap and erosion control. • Global examples of NbS for erosion protection in the muddy coasts are there but not highlighted, overlooked, and less promoted. • The successful implementation of NbS for erosion protection on muddy coasts requires holistic fusion of science, knowledge, skill, and good governance. [ABSTRACT FROM AUTHOR]

It is largely acknowledged that global mean sea level is rising and accelerating increasing low-lying coastal communities' exposure and vulnerability. The IPCC AR5 identified the Mediterranean Sea as one of the semi-enclosed seas with projected high rate. Impacts of sea level rise (SLR) at local scale affect the number of visitors in highly vulnerable beaches and previous paper have quantified these adverse effects. In this paper we want to say that coastal climate change is not just sea level rise and other climatic factors can affect the optimal beach carrying capacity in complex and uncertain ways. Specifically, the paper shows that the effects of selected climatic factors as wave, rainfall and wind can be opposite to that of SLR and the beach management could even benefit from those trends. • The paper is part of a large research on the management and planning of vulnerable beaches in Sardinia (IT) under climate change. • The main objective of the study was to provide a comprehensive quantification and characterisation of the impacts of climate change on optimal beach carrying capacity. • To the best of our acknowledge, this is the first paper that considers multiple climatic factors. This is in accordance with IPCC advices for more comprehensive studies, wider than sea level rise. • We found that in Southern Sardinia the effects of selected climatic factors as wave, rainfall and wind can be opposite to that of sea level rise and the beach management could even benefit from those trends with more facilities and services. [ABSTRACT FROM AUTHOR]

Breakwater scour seriously affects the safety and stability of breakwater foundation. Previous research has primarily focused on breakwater scour of sandy coasts, and to date, limited studies exist on silty–muddy coasts. This study analyzed the causes of scour around the breakwater head in Binhai Harbor, Jiangsu Province from the perspective of hydrodynamic changes and sediments based on years of field observation data and a two-dimensional tidal current numerical model. The observation results showed that four years after breakwater construction, a scour hole with a scour depth over 20 m formed in the northeast of the breakwater head. The development of the scour experienced a process of sudden acceleration, followed by slowing. After the construction of the breakwater, the tidal flow velocity near the breakwater head exceeded the critical motion velocity of the muddy clay layer, which was the main factor for the formation of the scour hole. Our findings indicate that when the scour tended to an equilibrium, the scouring area expanded to the northern and southern sides. This research provides a reference for studying morphodynamic change processes caused by the construction of marine structures on silty–muddy coasts. • This paper focused on the scour near the breakwater head on silty-muddy coast. • Years of terrain data was collected to study the scour development process. • Critical motion condition of sediment was calculated to explain the scour mechanism. • Numerical model was used to predict the potential scour range. [ABSTRACT FROM AUTHOR]

One of the most used measures to counteract coastal erosion is beach nourishment. It has advantages with respect to the use of rigid structures that sometimes entail non desired impacts on the surrounding areas. However, beach nourishments are often unsuccessful, requiring frequent refills due to the use of sediments that are not suitable. In this paper, a methodological framework for increasing the probability of success of beach nourishment projects is presented. First, this framework consists of detecting potential borrowing areas, by analysing shoreline evolution and selecting the stretch that shows a more accretive character. Once the borrowing area has been identified, several sand extraction options are defined. The beach response (in terms of erosion and flooding) to each sand extraction alternative is analysed by using two numerical models, which simulate the hydro-morphodynamic patterns in the studied area. The numerical model results allow to find the best extraction alternative, which is that producing the least impact in the borrow area. As an example, the methodology is applied to a stretch of the Catalan coast (NW Mediterranean) to illustrate its potential. The proposed methodology shows to be a useful tool for helping coastal managers to optimize their available resources. • Beach nourishments are often unsuccessful due to the use of non-suitable sediments. • A methodological framework for selecting the best sediment sources for beach fills is developed. • The framework includes the identification of the borrowing area and the best sand extraction option. • The methodology is applied to a stretch of the Catalan coast (NW Mediterranean). • The methodology shows to be a useful tool for helping coastal managers to optimize their resources. [ABSTRACT FROM AUTHOR]