Hasil untuk "Harbors and coast protective works. Coastal engineering. Lighthouses"

Patricia Moreno-Casasola, Andrés De la Rosa, Luis Alberto Peralta Peláez et al.

Urban wetlands in coastal cities are under growing strain from urban growth, climate change, and governance that is often fragmented. This study evaluates the condition of the freshwater dune lakes located in the Veracruz–Boca del Río–Medellín conurbation in Mexico, a protected corridor made up of 33 dune lakes that is increasingly pressured by urban expansion. We used an interdisciplinary approach that combined ecological monitoring, legal analysis, and participatory management tools. Fieldwork included 24 h monitoring of dissolved oxygen, measurements of Biochemical Oxygen Demand (BOD₅) in representative systems, a diachronic review of the legal evolution of five Natural Protected Areas (NPAs), and community workshops to jointly design interventions. The results showed strong day–night swings in oxygen (4.0–14.8 mg/L) linked to vegetation dynamics, with nighttime hypoxia posing risks for aquatic fauna. BOD₅ ranged from 4.8 to 150.3 mg/L, pointing to severe organic pollution in the most degraded system. The legal review identified repeated patterns of environmental regression, expressed through reductions in protected polygons, the legalization of irregular settlements, and the fragmentation of protected areas through judicial processes. In response, we propose a hybrid management model that brings together riparian restoration, Sustainable Urban Drainage Systems (SUDS), green infrastructure, and participatory monitoring, emphasizing a key 100 m buffer zone. This integrated strategy aims to improve flood regulation, reduce urban heat island effects, and enhance water quality, while also reinforcing community stewardship and legal protection. We conclude that conserving these urban wetlands effectively requires adaptive approaches that connect landscape-scale and local-scale actions, which are essential for climate adaptation in rapidly urbanizing coastal regions.

Liqun Lyu, Yunqi Wang, Xinyue Liang et al.

Tongde Basin, situated on the east edge of Tibetan Plateau, has accumulated substantial deposits of pebble-sand. The uplift of the Tibetan Plateau has initiated incision in the upper reaches of the Yellow River, subsequently causing incision in tributaries like the Daheba River within Tongde Basin. This transitioned Tongde Basin from a sedimentary to an erosional context from 150,000 years ago. However, debris flow gullies began to develop along Daheba River since the 1970s and migrate upstream fast. The relationship between the location, outbreak time, and migration of debris flow gullies was analyzed using dendrogeomorphic dating techniques. The results indicate that the distribution of debris flow gullies is concentrated in the lower reaches of Daheba River, and the frequency of outbreaks is high. The distribution of debris flow gullies in the middle reaches is relatively small, and the frequency of outbreaks is low, but there is an accelerating trend. The distribution characteristics and frequency of debris flows are closely related to the depth of incision of the debris flow gullies and the thickness of the gravel-sand-layer. In the middle and upper reaches of Daheba River, the river incised through the pebble-sand-layer, resulting in exposed bedrock. The slope of the pebble-sand layer is steep but difficult to support large heights. The slope of the bedrock is gentle but can support a large height. Therefore, the gravel-sand sediment layer is prone to instability and continues to provide a source of debris flows under the action of river incision. The migration of debris flow gullies is related to the potential volume changes of unstable pebble-sand layers caused by the river incision.

Morteza Movahhedi, Amir Reza Zarrati, Abbas Ghaedi Haghighi et al.

Many experiments were done over a relatively wide range of effective parameters to determine the stable size of riprap stones around wing-wall abutments. The experiments involved five sizes of riprap stones, three abutment lengths, and various flow depths and velocities. The results of this study indicate that in the range of tested parameters, the most important factors influencing riprap instability are the upstream Froude number, the ratio of abutment length to flow depth, and the ratio of abutment width (thickness) to flow depth. Based on the experimental results, a relation for designing the stable size of riprap around wing-wall abutments is presented and compared with previous equations developed for different shapes of bridge abutments.

Yenesew Assaye, Gizaw Desta, Eyayu Molla et al.

The Beles River Basin is facing severe soil erosion driven by human-induced activities, leading to significant losses of soil organic carbon (SOC) and nutrients (nitrogen (N) and phosphorus (P)). Effective land management practices (LMPs), including mechanical, biological, and agronomic techniques, are potential strategies for mitigating this degradation, but their effectiveness depends on site-specific and agroecological conditions. However, limited information is available on this aspect of the study area. The objective of the current study was to evaluate the effects of LMPs in the warm subhumid lowlands of the Beles River Basin on runoff, soil loss, and sediment-associated losses of SOC, N, and P from agricultural land. Four LMPs (vetiver grass strips (VGS), conservation agriculture (CA), soil bunds (SB), and fanya juu (FJ)) were evaluated via runoff plots arranged in a randomized complete block design (RCBD) with three replicates. Farmer practices were used as a control (C). The experiments, which were performed over three years (2021–2023), generated runoff, soil loss, and nutrient loss data. The three-year mean annual runoff ranged from 58.5 to 407.5 mm, and the soil loss ranged from 4.3 to 45.4 t/ha, whereas the annual rainfall varied between 1,402 mm in 2021, 1,254 mm in 2022, and 1,261 mm in 2023. On average, runoff was reduced by 36%–85%, and soil loss was reduced by 53%–91% in the LMP-treated plots. Additionally, sediment-associated losses of SOC, N, and P were reduced by 55%–90%, 52%–90%, and 28%–72%, respectively. The results revealed significant differences (p < 0.05) among the treatments in terms of reducing runoff, soil loss, and sediment-associated losses of SOC, N, and P. The mean annual runoff and soil loss rates during the study were 407.5, 230.3, 136.3, 59.6, and 58.5 mm and 45.4, 21.5, 11.1, 4.5, and 4.3 t/ha under the control, VGS, CA, SB, and FJ practices, respectively. The highest rates of runoff and soil loss were observed under the control conditions (407.4 mm and 45.4 t/ha). Runoff, soil loss, SOC, and nutrient (N and P) losses were significantly lower (p < 0.05) in the plots treated with FJ and SB than in the other plots. However, CA and VGS also significantly varied (p < 0.05) in reducing runoff, soil, SOC, and nutrient losses over the years. These results highlight the key role of LMPs in warm subhumid lowland rainfed agroecosystems as effective land management techniques for controlling soil and nutrient loss.

Evgeny Savosin, Zakhar Slukovskii

Assessing the benthic communities in water bodies under increasing anthropogenic pressure seems to be an urgent task of scientific research aimed at short-term and long-term monitoring of water bodies. This study focuses on the chemical composition of modern sediment and the current state of macrozoobenthos of small lakes in the Republic of Karelia (Kitaiskoe and Plotichie) influenced by anthropogenic factors. It was discovered that the lakes of Medvezhyegorsk have a higher concentration of heavy metals (such as lead (Pb), cadmium (Cd), molybdenum (Mo), and antimony (Sb)) compared to the Earth’s crust and natural background levels. The current study established the significant impact of industry and transportation on the movement and build up of pollutants in these lakes. The qualitative and quantitative parameters analyzed for the benthic communities in the littoral and profundal zones included the species diversity, the structure of dominant species, and their percentage in the samples. According to the level of macrozoobenthos development, both reservoirs (lakes) were classified as mesotrophic, and according to the values of the chironomid index “K” as moderately polluted. The Pantle–Buck method (saprobic index) showed that the lakes can be classified as polluted (water quality class 4). Macrozoobenthos groups most tolerant to environmental conditions, for example, Chironomidae larvae, prevailed in the studied urban lakes. The economic development of the lakes leads to ecosystem transformation and long-term eutrophication over time affecting the biotic indicators of surface water quality. The results obtained can serve as a basis for complex environmental monitoring of the urbanized territories in the taiga zone.

Ana Vila-Concejo, Lachlan A. Perris, Ana Paula da Silva et al.

The long-term stability of coral reef islands and associated reef top sedimentary landforms requires the delivery of sediment from the forereef, but the rates and pathways of sediment delivery to these systems remain unclear. Spurs and grooves (SAGs) are ubiquitous geomorphic features fringing coral reefs, characterised by shore-normal coral ridges (spurs) separated by channels (grooves) with either bare substrate or a relatively low sediment infill. SAGs dissipate wave energy, facilitate offshore sediment transport and enhance nutrient exchange. Here we present the first evidence that SAG can also act as channels for onshore transport of rubble during high-energy events, contributing to maintaining reef islands and rubble-based ecosystems.

Marina d’Avdeew, Louis Janin, Lydie Goeldner-Gianella et al.

Coastal nature-based solution (NBS) projects have been on the rise over the past few years. In France, the expression is being increasingly used at a local level, and new projects are developing on the coast. However, they face various limitations, involving both technical challenges and social acceptability issues. Based on data from the perception survey conducted by the DIGUES research programme in the Authie Bay in 2021 and a numerical model used to assess the efficiency of flood protection measures developed as part of a flood action and prevention programme, this study aimed to highlight the gap between perceptions and misconceptions surrounding NBS-like scenarios and more objective modelling data. It offers a cross-comparison of these two datasets. For this purpose, the scenarios used to assess public perception in the DIGUES survey were translated in the numerical model to study the difference between perceived protection and actual protection in the Authie Bay, the opportunity for dyke relocation in an NBS scenario, and the effectiveness of the NBSs according to their scale. Overall, these results demonstrated a real benefit for implementing dyke relocation through breaches, compared to other scenarios for the Authie Bay.

Emma Chalençon, Fiona Cawkwell, Michael O’Shea et al.

Coastlines worldwide are coming under increasing pressure due to climate change and human activity. Data on shoreline change are essential for coastal managers and when no long-term monitoring programs are implemented and shoreline change is typically on the order of less than 1 m/yr., as observed in Ireland, aerial photography is the most valuable source of information. A well-established literature exists for automated vegetation extraction from digital images based on the near infrared reflectance, but there is less research available on spectrally limited colour photography. This study develops a methodology for automating vegetation line extraction from a series of historical aerial photography of the Cork coastline in the South-West of Ireland. The approach relies on the Normalised Green–Blue Difference Index (NGBDI), which is versatile enough to discriminate disparate coastal vegetation environments, at different resolutions and in various lighting and seasonal conditions. An iterative optimal threshold process and the use of LiDAR ancillary datasets resulted in an automated vegetation line measurement with uncertainties estimated to be between 0.6 and 1.2 m. Change rates derived from the vegetation lines extracted present uncertainties in the range of ±0.27 m/yr. This robust and repeatable method provides a valuable alternative to time-consuming and subjective manual digitisation.

Sierra Garcia, Antonella Rivera

Despite the global expansion of coral restoration initiatives that depend on volunteer divers in supporting these programs, research exploring their motivations, sentiments and knowledge remains scarce. This study employed a mixed-methods analysis of surveys (n = 83) and interviews (n = 15) of a heterogeneous population of coral restoration volunteers and a control group of divers in Roatan, Honduras to explore these aspects. Experienced coral restoration volunteers did not perceive their contributions to coral health protection as being greater than control group non-volunteer divers, despite displaying a deeper understanding of the threats to coral reefs. Notably, both new volunteers prior to training and experienced restoration volunteers were more than twice as likely as control divers to highlight reducing carbon emissions as critical for coral health. While volunteer divers exhibit a strong baseline awareness and concern for coral reef threats, they report that participation in restoration efforts leads to significant learning gains regarding coral conservation. The insights gained from the motivations and learning outcomes of volunteers in coral restoration in Roatan may inform similar initiatives globally, potentially impacting a wide range of volunteer-based ecosystem restoration programs and diver-involved projects, thereby enhancing volunteer engagement and educational outcomes in environmental conservation efforts.

Ama Wakwella, Amelia Wenger, Aaron Jenkins et al.

Tropical coastal ecosystems are in decline worldwide due to an increasing suite of human activities, which threaten the biodiversity and human wellbeing that these ecosystems support. One of the major drivers of decline is poor water quality from land-based activities. This review summarises the evidence of impacts to coastal ecosystems, particularly coral reefs, from sediments, nutrients, chemicals and pathogens entering coastal zones through surface and groundwater. We also assess how these pollutants affect the health of coastal human populations through: (1) enhanced transmission of infectious diseases; (2) reduced food availability and nutritional deficit from decline of fisheries associated with degraded habitat; and (3) food poisoning from consumption of contaminated seafood. We use this information to identify opportunities for holistic approaches to integrated watershed management (IWM) that target overlapping drivers of ill-health in downstream coastal ecosystems and people. We demonstrate that appropriate management requires taking a multi-sector, systems approach that accounts for socio-ecological feedbacks, with collaboration required across environmental, agricultural, public health, and water, sanitation and hygiene sectors, as well as across the land–sea interface. Finally, we provide recommendations of key actions for IWM that can help achieve multiple sustainable development goals for both nature and people on coasts.

Marco Andrello, Stéphanie Manel, Maurine Vilcot et al.

Coastal marine environments are subject to a variety of anthropogenic pressures that can negatively impact habitats and the biodiversity they harbor. Conservation actions such as marine protected areas, marine reserves, and other effective area-based conservation measures, are pivotal tools for protecting coastal biodiversity. However, to be effective, conservation area networks must be planned through a systematic conservation planning (SCP) approach. Recently, such approaches have begun to orient their goals toward the conservation of different biodiversity facets and to integrate different types of data. In this review, we illustrate how genetic data and molecular techniques can bring useful knowledge for SCP approaches that are both more comprehensive (sampling the full range of biodiversity) and more adequate (ensuring the long-term persistence of biodiversity). With an emphasis on coastal organisms and habitats, we focus on phylogenetic analysis, the estimation of neutral and adaptive intraspecific genetic diversity at different spatial levels (alpha, beta, and gamma), the study of connectivity and dispersal, and the information obtainable from environmental DNA techniques. For each of these applications, we discuss the benefits of its integration into SCP for coastal systems, its strengths and weaknesses, and the aspects yet to be developed.

Francesca Porri, Boudina McConnachie, Kerry-Ann van der Walt et al.

Increasing anthropogenic pressure on the sea and alteration of coastscapes challenge the functioning of marine ecosystems and long-term reliance on blue economies, especially for developing southern economies. The structural hardening of shores can result in ecological disruptions, with cascading effects on the wellbeing and livelihoods of marginalised groups who depend on marine resources. Mitigation, adaptation and rehabilitation options for coastal developments should include innovative, socially responsible solutions to be used to modify shorelines and ensure long-term functionality of metropolitan coastal ecosystems. Nature-based innovations are being developed to improve surrogacy for natural marine ecosystems. The co-creation of nature-based structures, entailing partnerships between scientists and a local rural community is currently being considered in South Africa and we present this regional case study as a transdisciplinary framework for research in nature-based, ecological engineering of coastal systems. Novel transdisciplinary approaches include ecomusicological interventions, where traditional cultural expressions (TCEs) create opportunities for transgressive pedagogy. This step aims to ensure that the knowledge gathered through nature-based scientific research remains a part of community developed Indigenous knowledge systems. The merging of innovative, eco-creative approaches and TCEs has the potential to sustainably and ethically improve the functioning and diversity of coastal urban habitats. This review tackles the potential of transdisciplinary settings to transform urban coastlines using “low-tech” engineering and Indigenous eco-creative innovations to pedagogy, to benefit the people and biological communities as well as reduce social and gender inequalities.

Veronica D’Addazio, Monica Maria Pereira Tognella, Adriano Alves Fernandes et al.

The effects of iron, manganese, zinc, copper, and lead on the chlorophyll content, carbon assimilation, and the antiradical activity of <i>Rhizophora mangle</i> and <i>Laguncularia racemosa</i> were evaluated in regions affected by the Fundão dam disruption in Brazil. The mine waste which settled and accumulated in the sediments could represent long-term contamination. It can be expected that the iron oxyhydroxides deposited in the sediments will be solubilized, leading to chronic contamination by trace metals and the accumulation of these metals in the biota. In this sense, biological indicators prove to be important tools to assess this type of damage. The different bioaccumulation of metals by the species revealed that <i>R. mangle</i> was more impacted by Mn and Cu and that <i>L. racemosa</i> showed alterations in its physiological responses in the presence of Cu, Zn, and Fe. The concentration of these metals in the leaves, with values above previous local reference limits, was associated with reductions in the chlorophyll-a and chlorophyll-b content and carbon assimilation, mainly in <i>L. racemosa</i>. The antiradical activity was also altered, suggesting a lower ability of both species to eliminate reactive oxygen species (ROS). A possible reason for the symptoms of oxidative stress may be due to the reduced efficiency of antioxidant defense by Cu²⁺ and Zn²⁺. In addition, the presence of Pb in the leaf tissue may be toxic to the fauna and the bioaccumulation of this metal and trace elements can be a way to transfer them into the food web by biomagnification.

Jessica L. Blythe, David A. Gill, Joachim Claudet et al.

The term “blue justice” was coined in 2018 during the 3rd World Small-Scale Fisheries Congress. Since then, academic engagement with the concept has grown rapidly. This article reviews 5 years of blue justice scholarship and synthesizes some of the key perspectives, developments, and gaps. We then connect this literature to wider relevant debates by reviewing two key areas of research – first on blue injustices and second on grassroots resistance to these injustices. Much of the early scholarship on blue justice focused on injustices experienced by small-scale fishers in the context of the blue economy. In contrast, more recent writing and the empirical cases reviewed here suggest that intersecting forms of oppression render certain coastal individuals and groups vulnerable to blue injustices. These developments signal an expansion of the blue justice literature to a broader set of affected groups and underlying causes of injustice. Our review also suggests that while grassroots resistance efforts led by coastal communities have successfully stopped unfair exposure to environmental harms, preserved their livelihoods and ways of life, defended their culture and customary rights, renegotiated power distributions, and proposed alternative futures, these efforts have been underemphasized in the blue justice scholarship, and from marine and coastal literature more broadly. We conclude with some suggestions for understanding and supporting blue justice now and into the future.

Sarah M. Hamylton, Hannah E. Power, Shari L. Gallop et al.

Women face disproportionate challenges while undertaking coastal fieldwork. We draw on 18 responses that specifically raise fieldwork issues from an international survey about perceptions and experiences of gender inequality for those working in coastal sciences to discuss two common themes. These themes are barriers to fieldwork participation and challenges for women working in coastal field settings such as boats or working on beaches, including discrimination and sexual harassment. We suggest five priority behavioural and policy changes to improve the fieldwork experience for women in coastal sciences: (i) publicise field role models and trail blazers, (ii) improve opportunities and capacity for women to undertake fieldwork, (iii) establish field codes of conduct, (iv) acknowledge the challenges women face in the field and provide support where possible, and (v) foster an enjoyable and supportive fieldwork culture.

fatemeh ghanbari, Mehdi Adjami, Soheil Ataei H.

Measuring cross-shore profiles is very important in coastal engineering studies, since the cross-shore profile determines the behavior of the sea in the coastal area and determines the process of depth changes in this region. As a result of waves, cross-shore profiles change, which will vary in stormy waves (erosion profile) in compare to normal wave conditions (cumulative profile). Considering the great changes in the Caspian Sea level, the purposes of this study are to investigate and determine the erosion or accumulation of coastal profiles based on Sunamura and Horikawaꞌs studies , determine the number of bars in profiles by Short and Aagaardꞌs equations and also determine the relations between coastal parameters with the wave steepness and changes in water level. The results show that for all the coastal areas in the Caspian Sea, the C-parameter is above 8; in other word a stormy erosional nature is dominant. Also according to  -parameter, for all regions the values are above 100 which means a very high possibility to form multi bars profiles (three bars) very high. As the wave's steepness rises, the location of the formation of the bars moves toward the coast, and the depth of water decreases at the beginning and the ends of the bars; also, in terms of lowering in the water level with the change in the height of the waves, the position and the geometric shape of the bars will not follow a certain trend

Siamak Jamshidi

Assessing the impact of physical properties on active reaction changes in the coastal and offshore area is one the most important aspect of marine environment of the Caspian Sea. Therefore, updated techniques and modern instruments have been used in order to evaluating the coastal and offshore area conditions. In the current research, collected data with spatial and temporal variety have been evaluated for investigation on seawater characteristics in the shallow and intermediate layers over the southern Caspian Sea. Some phenomena such as mixing, turbulence, water column stability and stratification are the effective elements on variability of physical and natural structures of the sea. Active reaction and dissolved oxygen as two properties of seawater are very important items for coastal engineering, piping in seabed, breakwaters and port constructions. Thus, in the current study, the above mentioned parameters were assessed over the southern shelf of the Caspian Sea. Vertical and horizontal variations of chemical characteristics such as active reaction of seawater were observed in several stations between coastal and offshore stations across surface, intermediate and deep layers. Results of the field operations showed that the normal values of pH in the study almost varied around 7.9-8 while during some seasons increased ore decreased more than 0.5 units due to human activates.

Mesbah Sayehbani, Danial ghaderi

The wave and current patterns of the Beris port and its surroundings before and after construction of the breakwater structure was investigated by numerical model, MIKE 21. For this purpose, the required data was provided and the model was prepared for implementation within a month from July 22 to August 21, 2016. In order to verify the modeling results, the extracted data were compared with the data derived from the global wave model; WAVEWATCH III and ECMWF. The simulation results show the significant effect of the breakwater on the stillness of the basin and the change in flow direction. According to the position of the port and the morphology of the coast, is expected to parallels sedimentation caused by waves and currents of the region focused on the long arm breakwaters and adjacent to the entrance mouth of breakwaters, as well as in the coastal part of the small arm of the breakwater.

Mohammad Pakhirehzan, Maryam Rahbani, Hossein Malakooti

Marine areas are affected by different atmospheric phenomena such as wind and storm. In this research the effect of a large scale atmospheric phenomenon, known as Winter Shamal Wind, is investigated on the regime of currents and waves in the northwest part of the Persian Gulf. This wind normally occurs for the period of three to seven days, during December to early March. MIKE21 Coupled Model FM was applied to study the pattern of current and waves for this period. To provide the hydrodynamic data for the model and validate the simulated results, the wind data of ECMWF and mast meteorology of coastal synoptic station of Bushehr and wave data of buoy located offshore of Bushehr was used. The results indicated only a slight increase in current speed with no significant change in current direction during Winter Shamal Wind, showing a stable current pattern in northwest of the Persian Gulf. The significant wave height and wave propagation speed for the period of Winter Shamal Wind in comparison with the days prior to the wind show significant changes. The maximum wave speed in the area under investigation reaches up to 1 m/s and the significant wave height is almost 1 meter higher than that of normal situation.