Anthropocene Coasts最新文献

Urban cover-collapse sinkholes pose a significant global challenge due to their destructive impacts. Previous studies have identified groundwater fluctuations, subsurface soil conditions, pipeline leakage, precipitation, and subterranean construction activities as key contributors to these phenomena. However, unique geological settings across different urban environments lead to variations in the primary factors influencing sinkhole formation. This study focuses on Shanghai, a city notable for its extensive urbanization and rich historical context, to explore the dynamics of sinkholes within urbanized areas worldwide. We employ spatial analysis and statistical methods to examine data on sinkholes recorded in the past two decades in Shanghai, correlating these events with the city’s shallow sand layer, ground elevation, and proximity to surface water. Our goal is to identify the dominant factors governing sinkhole occurrence in Shanghai and to lay the groundwork for their effective scientific management and prevention. Key findings indicate that most sinkholes in the area are associated with a thin shallow sand layer, low to moderate ground elevations, and the absence of nearby rivers. Additionally, many sinkholes correlate with subterranean voids within the confined aquifer beneath the cohesive soil layer. The lack of historical river channels, obscured by urban development, also indirectly contributes to sinkhole formation. We recommend enhancing urban river management and drainage systems to mitigate potential damage from water accumulation.

Since 1958, there have been significant changes in the Yangtze River estuary. Due to extensive reclamation and construction of ports and channels, the water area has drastically decreased, resulting in corresponding changes in hydrodynamics and riverbeds at the mouth of the river. According to the analysis of measured topographic data and Delft3D-FLOW model for seven typical historical periods since 1958 at the Yangtze River Estuary, this study investigates the characteristics of riverbed evolution and tidal flow dynamics. From 1958 to 2019, driven by strong human activities, the total area of the Yangtze River Estuary decreased from 2084 km² to 1403 km², with a decrease of 32.7%, while the total volume of the corresponding river channel changed slightly and remained stable. Compared with 1958, the volume of the Yangtze River Estuary in 2019 only increased by 345 million m³, with an increase of about 4.1%. The tidal dynamic change of the Yangtze Estuary is closely related to the riverbed evolution of each reach, which not only shapes the estuary landform, but also is affected by the riverbed evolution. Tidal level, tidal range and water area change are closely related. With the decrease of water area in the Yangtze River Estuary, tidal range tends to increase. Tidal prism change is closely related to channel volume. In the past 60 years, the tidal volume at the mouth of the Yangtze River has decreased by 8%. The research findings will provide technical support for enhancing flood control and tide resistance measures at the Yangtze River Estuary, as well as formulating comprehensive management plans for estuaries, contributing to the protection and sustainable development of the Yangtze River Estuary.

The present paper aimed to assess the sediment distribution pattern, mode of transport, and its interaction with hydrodynamic and topographic conditions at different depths and regions along the east coast of India. About 900 surficial sediment samples were collected and analysed on a monthly basis for the Chennai coastal region at 32 stations from 2013 to 2015. The study region is classified into four types, such as beach, inlet, 5 m, and 10 m depth. Sediment textural and grain size trend analyses were conducted to achieve the objectives. Sediment characteristics for the region were recorded as sandy, equally dominated by unimodal and bimodal at the beach, while unimodal at shallow depths (5 and 15 m). The sediments were medium sand to coarse sand at the beach, mostly fine followed by medium at 5 and 15 m depths. The sediment sorting is dominated by moderately well-sorted sediments; the skewness of beach sediments was negative, while nearshore sediments were found positive; average kurtosis values of sediments were noticed to be mesokurtic. The CM plot depicts that the sediments were mostly derived by tractive current, and the modes of transport are “bottom suspension and rolling” and “graded suspension no rolling” at beach locations and shallow water depths, respectively. The GSTA analysis reveals the annual average sediment transport pattern is northerly. The numerical hydrodynamic study confirms the GSTA and CM plot analysis. The study reveals a stable sedimentary environment south of the Chennai port and instability in the northern part. The study includes large spatiotemporal nearshore sediment data with hydrodynamic conditions, immensely helpful to coastal stakeholders and researchers.

Worldwide, coastlines have been replaced and altered by hard infrastructures to protect cities and accommodate human activities. In addition, human settlements are common and increasing in lowland areas threatened by coastal risk hazards. These urbanisation processes cause severe socioeconomic and ecological losses which demand policy reforms towards better coastal management and climate resilience. A first step in that direction is to comprehend the status of coastal hardening and occupation of vulnerable areas. Here, we mapped the coastline of the most populous and developed state of Brazil: São Paulo (SP). Our goal was to quantify the linear extent of natural habitats, artificial structures (AS), and occupations in low-elevation coastal zones (≤ 5 m) within 100 m from marine environments (LECZ_100m) along the coastline and within estuaries. SP coast has a total extent of 244 km of AS, of which 125 and 119 km correspond to AS running along the coastline (e.g., seawalls, breakwaters) and extending from the shoreline into adjacent waters (e.g., jetties, pontoons, groynes), respectively. 63% of the total extent of AS is located in the most urbanised region. Breakwalls were the most common infrastructure (108 km), followed by jetties and wharves (~40 km each), and aquaculture and fishing apparatus (~24 km). Over 300 km of the SP coastline has inland occupations in LECZ_100m: 235 and 67 km are adjacent to sandy beaches and estuarine/river margins, respectively. Coastal hardening is advanced in the central region of SP resulting from intense port activities and armoured shorelines. In other regions, much of coastal urbanisation seems to be driven by secondary usage of the cities, such as real estate development for beach houses and tourism. Our findings suggest that coastal urbanisation poses a major but often neglected source of environmental impact and risk hazards in SP and Brazil.

Seaports are critical for global trade and development but are at risk of climate change-driven damages, operational disruptions and delays with extensive related economic losses. The aim of the present contribution is to (a) provide an overview of the main impacts of climate variability and change (CV&C) on ports; (b) present recent research on trends and projections involving the main climatic factors/hazards affecting global ports; (c) provide an analytical overview of emerging international and regional policies and legislation relevant to port risk assessment and resilience-building under climate change; and (d) consider issues and areas for further action. As shown by projections under different climatic scenarios and timelines, many global ports will increasingly be exposed to significantly growing hazards under increasing CV&C, including extreme sea levels (ESLs), waves, and extreme heat events. Depending on scenario (RCP 4.5 and RCP 8.5) by 2050, 55% to 59% of the 3630 global ports considered could face ESLs in excess of 2 m above the baseline mean sea levels (mean of the 1980–2014 period); by 2100, between 71% and 83% of ports could face ESLs of this magnitude. Ports in most tropical/sub-tropical settings will face the baseline (mean of the 1976 – 2005 period) 1-in-100 year extreme heat every 1 – 5 years, whereas with 3 ^oC global warming, most global ports (except some in higher latitudes) could experience the baseline 1-in-100 years extreme heat event every 1 – 2 years. A range of policy and legal instruments to support climate change adaptation, resilience-building and disaster risk reduction have been agreed internationally as well as at regional levels. At the EU level, relevant legal obligations and related normative technical guidance aimed at ensuring the climate proofing of new infrastructure are already in place as a matter of supra-national law for 27 EU Member States. These could significantly enhance levels of climate-resilience and preparedness for ports within the EU, as well as for EU funded port projects in other countries, and may serve as useful examples of good practices for other countries. However, further action is needed to advance and accelerate the implementation of effective adaptation measures for ports across regions.

The nonlinear interactions between river discharge, astronomical tidal wave, and local geomorphology during storm passage or water release from upstream dams can produce severe floods in the Río Negro lower basin (Argentina). For this reason, this paper aims to detect and study nonlinear processes in this area. The watercourse hydrodynamics was described using hourly water level data from three limnigraphs during 2003 – 2021 and flow time series. The tide gauge dataset was employed to describe the influence of tidal cycles on the hydrological regimen. Nonlinear processes' impact on the astronomical tidal cycle and river discharge was analyzed using Harmonic Analysis, and Fourier higher-order spectra, also it was complemented with the selection of two study cases. Harmonic Analysis results showed that the tidal wave entry upstream of the Río Negro modulates its hydrological regime, presenting the water column semidiurnal variations. Also, high-order spectral analysis detected nonlinear interactions in the signal in storm conditions with an energetic redistribution among the linear tidal constituents toward shallow water harmonics. Additionally, nonlinear interactions provoked a delay in the tidal ebb phase with a consequential extension of flooding duration time. This type of study contributes to the knowledge of the flood mechanisms activated during a storm.

Future sediment transport from the North Sea coasts to the Dutch Wadden Sea for various future sea level scenarios has been studied because it influences the future sand nourishment demand for the maintenance of the coastline and because it determines bio-geomorphological development of the Wadden Sea. The present study focuses on two questions which have not yet been considered in the previous modelling studies using ASMITA: How will the transport develop around drowning of the intertidal flats in the Wadden Sea? How will tidal range change influence the future sediment exchange? By using SLR scenarios with faster acceleration and running the simulations for longer periods of time some inlets exhibited drowning, i.e., where the tidal flat volume vanishes. When drowning occurs, the sediment import rate approaches a maximum or a minimum, depending on the initial morphological state of the tidal inlet system. This maximum or minimum rate for a certain tidal inlet system depends on the SLR scenario. Theoretical analysis as well as modelling results show that tidal range change will influence the sediment import to the Wadden Sea. A tidal range increase will cause a decrease of the sediment demand in the Wadden Sea resulting into less sediment import to the Wadden Sea. It is thus important to study the tidal range development in the Wadden Sea by considering the interaction between SLR, tidal range change and morphological development in the system. It is further concluded that the empirical relation used in the previous studies is not representative of conditions in a tidal basin with fixed basin area, even though this relation has been derived from field observations in many tidal inlet systems worldwide. The equilibrium channel volume should be proportional to the tidal prism instead of to its 1.5^th power.

Bluff landforms, sought-after for housing and development, present a hazard management challenge due to erosional processes despite the perceived safety of elevated land. This study focuses on the Neuse River Estuary in North Carolina, exploring coastal risk perception and erosion. A survey protocol was developed, and questionnaires targeted 246 residents with property within 100 m of the shoreline and 54 land use professionals in Craven County. To explore the connection of individual experiences with erosion, we use openly accessible LiDAR to quantify bluff retreat and erosion between 2014 and 2020, a period that encompasses Hurricane Florence in 2018. Our findings show: 1) survey results reveal a consensus among residents, with 90% observing alterations attributed to storm impacts, 2) preferences for addressing erosion lean towards structural measures, aligning with existing protection strategies (e.g., bulkheads, rip-rap) as opposed to nature-based solutions, 3) bluff tops are eroding at a higher median rate of -0.59 m per year, compared to -0.19 m per year for high sediment banks, and 4) an overall net volume decrease of approximately -1.89 cubic meters per year for Craven County, slightly more than the overall net loss for the Neuse River Estuary, which was -1.74 cubic meters per year. The findings underscore the need for a cohesive bluff erosion management plan, emphasizing the complexity of challenges and the importance of a holistic approach that combines technical studies with effective risk communication.

Coastal waters are complex, dynamic, and sensitive, and any change in the system impacts the marine environment and life. Coastal water quality has been decreasing due to the incursion of anthropogenic derived waste and toxins into the ocean. This study investigates water quality along the Kollam coast of Kerala State, India, using Sentinel-2 Multispectral Imager (MSI) data for the period of 2019–2022. Four key water quality parameters, chlorophyll (Chl-a), total suspended matter (TSM), turbidity, and coloured dissolved organic matter (CDOM), were analysed for seasonal variations and driving factors. The study highlights the potential of web-based platforms like Google Earth Engine for facilitating large-scale water quality assessments. The results reveal a distinct seasonal pattern in all parameters, primarily influenced by monsoonal riverine discharge and anthropogenic activities as contributing factors to water quality degradation. Overall, the study emphasises the need for comprehensive monitoring and management strategies to ensure the long-term sustainability of the coastal ecosystem.