The Digital Information System for Polish Maritime Areas (CSI-POM) project is an advanced initiative aimed at monitoring and forecasting the environmental conditions of the Southern Baltic Sea, focusing on hydrodynamic, physical, chemical, and biological processes. Physical and hydrodynamic processes were implemented during the first stage of the project (CSI-POM 1), while biochemical processes are analyzed within the currently ongoing stage two (CSI-POM 2). This presentation will showcase the functionalities of this extended system on the marine environment, emphasizing its relevance to the dynamic coastal processes and human-climate interactions.
The project employs high-resolution 3D ecohydrodynamic model (CEMBS-PolSea) with a horizontal resolution of 575 m, incorporating satellite data assimilation for SST and chlorophyll-a concentration. This capability enables precise spatiotemporal analyses of key processes, such as nutrient distribution, primary production, and cyanobacterial blooms. The system features a dedicated tool for the automated detection of cyanobacterial blooms, combining satellite and model data to predict their spatial distribution and forecasted evolution. This tool is crucial for addressing the ecological and societal impacts of harmful algal blooms in coastal waters.
The CSI-POM system's tools provide vital insights into the ecological and physical interactions across coastal interfaces, aiding in understanding the variability of biochemical parameters like nitrate, phosphate, and silicate concentrations, dissolved oxygen levels, and chlorophyll-a distributions. Such tools not only enhance the predictive capacity for ecosystem management but also support decision-making in maritime economy sectors, such as fisheries, environmental protection, and coastal hazard mitigation.
The presentation will highlight the integration of advanced modeling techniques and observational data to create a holistic framework for monitoring coastal dynamics in the face of changing climate and human activities. By fostering interdisciplinary collaboration, the CSI-POM project aligns with the session's focus on sustainable coastal zone management and resilience-building.
This study is financed from the state budget under the programme of the Minister of Education and Science (Poland) entitled "Science for Society" No. NdS/546027/2022/2022, amount of funding PLN 1 702 130.65, total value of the project PLN 1 702 130.65 and "Science for Society II" No. NdS-II/SP/0003/2023/01, amount of funding PLN 1 996 763.77, total value of the project PLN 1 996 763.77.
How to cite: Janecki, M., Dybowski, D., Nowicki, A., and Dzierzbicka-Głowacka, L.: CSI-POM 1 & 2: An Integrated System for Monitoring and Predicting Coastal Dynamics in the Southern Baltic Sea, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15907, https://doi.org/10.5194/egusphere-egu25-15907, 2025.
This presentation focuses on the introduction of newly developed tools for studying the marine environment of the Southern Baltic Sea using model-based data. The foundation of this work is the development of novel tools for monitoring and forecasting biochemical conditions within the 3D CEMBS-PolSea ecohydrodynamic model, which integrates hydrodynamic and biochemical components.
The biochemical component of the model represents key parameters, including phytoplankton and zooplankton biomass, living and detrital organic matter, chlorophyll-a concentration, dissolved oxygen (O₂), and chemical components such as nitrates (NO₃), phosphates (PO₄), and silicates (SiO₃). The implementation of environmental variables is achieved through the definition of source and sink functions for all biochemical variables, governed by a second-order partial differential equation describing turbulent diffusion with an advective term. This equation serves as the interface between the hydrodynamic and biochemical components of the model.
The presentation highlights several novel tools that provide new functionalities for marine research. These include the identification of habitats or regions with user-defined hydrodynamic, physicochemical, and biological parameters, utilizing numerical simulation results to deliver precise spatial information. Additionally, tools for tracking the trajectories of passive particles in the surface layer under varying hydrodynamic conditions are introduced. By employing numerical forecasts, the tools estimate metrics such as maximum transport range, transit time, and the predicted final location of particles based on their initial positions. These tools are designed for operational use and will be accessible to end-users in an open-access format.
We assume that analyses conducted using these tools will significantly enhance our understanding of the functioning of marine ecosystems, including those in coastal zones. The integration of biochemical and hydrodynamic modeling within the 3D CEMBS-PolSea framework improves the ability to predict and analyze the spatiotemporal dynamics of the marine environment in the Southern Baltic Sea. The model aims to provide a robust decision-support system for scientific research and environmental management.
This study was financed from the state budget under the program of the Minister of Education and Science under the name "Science for Society II" No. NdS-II/SP/0003/2023/01, funding amount PLN 1,996,763.77, total project value PLN 1,996,763.77.
How to cite: Dybowski, D., Janecki, M., Nowicki, A., and Dzierzbicka-Głowacka, L.: Advanced Tools for Investigating the Marine Environment of the Southern Baltic Sea Using Model Data, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15703, https://doi.org/10.5194/egusphere-egu25-15703, 2025.
Denitrification and anammox (anaerobic ammonium oxidation) are the main nitrogen removal pathways. Denitrification is a microbial process in which NO3- is sequentially reduced to dinitrogen gas (N₂) while anammox is the anaerobic microbiological process in which NO2- and NH4+ are converted to N2 under anoxic conditions. Both processes are critical in regulating nitrogen (N) availability in marine ecosystems, particularly in the stratified and oxygen-depleted aquifers such as Baltic Sea. The Baltic Sea, highly complex and semi-enclosed marine ecosystem that contains brackish water due to high freshwater discharge and limited water exchange with the North Sea. The sedimentary nitrogen cycling was studied extensively in the Baltic Sea but still, understanding the nitrogen loss process, especially in the coastal area is challenging. Additionally, studies usually use different methods to assess the N removal rates which disables the comparison of obtained rates and limits the overall understanding of the N cycle. The main aim of the study was to quantify denitrification and anammox rates in surface sediments from various locations in the Baltic Sea. Three coastal sites MP2 (Puck Bay), PB3 (Puck Bay under submarine groundwater discharge (SGD) impact), lagoon MS2 (Szczecin lagoon) and two open-sea sites IDEAL, P1 (Baltic Proper) were selected for this study. Slurry incubation experiments were conducted at each site with the addition of labelled substrates ¹⁵NO₂⁻ and ¹⁵NH₄⁺ to measure denitrification and anammox rates. The addition of ¹⁵NO₂⁻ produced ¹⁴N¹⁴N, ¹⁴N¹⁵N, and ¹⁵N¹⁵N for denitrification, while ¹⁵NH₄⁺ produced ¹⁴N¹⁴N and ¹⁴N¹⁵N for anammox. The denitrification rate in the coastal sites ranged from 1440.82 to 7.21 nM N L-1 d-1, for the open sea sites (IDEAL) 533.42 nM N L-1 d-1 and at P1 consumption of N2 was observed. Apart from MP2, anammox activity was detected at PB3 (32.67 nM N L-1 d-1), MS2 (0.41 nM N L-1 d-1), IDEAL (0.46 nM N L-1 d-1), and P1 (0.67 nM N L-1 d-1). The anammox rates were lower than denitrification at all sites, indicating its minor role in nitrogen removal in the surface sediments of Baltic Sea. However, the presence of anammox highlights the contribution of a diverse microbial community that can increase with the future expansion of anoxic areas in the Baltic Sea. The observed spatial variability in N removal rates is likely influenced by site-specific factors such as organic matter availability, nutrient discharge, and oxygen conditions. However, hypoxic submarine groundwater discharge (SGD), enriched in nutrients and dissolved organic carbon appears to be a key driver of nitrogen removal. Further studies employing similar methodological approaches are essential to better understand nitrogen cycling in marine ecosystems, particularly in coastal areas.
Acknowledgments
The results were obtained within the framework of the statutory activities of the Polish Academy of Sciences Institute of Oceanology and the research project IDEAL (2019/34/E/ST10/00217) funded by the Polish National Science Centre.
How to cite: Sivasamy, P., Szymczycha, B., and Diak, M.: Sedimentary nitrogen removal processes across coastal, lagoon and open waters of the Baltic Sea, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1110, https://doi.org/10.5194/egusphere-egu25-1110, 2025.
Coastal and offshore areas are highly relevant in the context of globalized economies and their demands for fisheries, transport and sustainable energy production. However, the ecological impacts of increasing human activity, such as noise disturbance and sediment dispersal from construction works and shipping traffic, could pose a threat to the biodiversity of marine ecosystems. By balancing marine food webs, controlling pests and dispersing seeds, marine birds are not only important for the conservation of biodiversity, but are also often seen as an early warning indicators of environmental change, as behavioural and physiological characteristics of bird populations are linked to changes in habitat quality. Spatial obervations of the distribution and size of bird populations are therefore needed to conserve biodiversity. Due to the vast extents and sometimes inaccessible nature of coastal and offshore areas, repeated airborne remote sensing surveys provide an efficient means of monitoring marine birds. However, the detection and classification of features on the ocean surface, such as animals, waves or man-made structures, remains challenging and is often achieved through time-consuming manual image inspection and annotation by trained experts.
Here, we present first results of an AI-based approach to automatically detect and identify different features and facilitate the monitoring of marine bird species and populations: Our study is based on approximately 2.5 million optical images with a ground resolution of 2 cm from 60 airborne surveys which were conducted by the German Federal Agency for Nature Conservation (BfN) along the German North Sea and Baltic Sea coasts between 2017 and 2021. Previously, images with bird sightings from some surveys have been annotated manually, enabling the training of a deep learning algorithm. Technical challenges for AI-based bird detection include a wide range of image exposure conditions, from low to high brightness contrast between objects and background, insufficient spatial resolution for relatively small species and tracking specific birds that appear in successive overlapping images to avoid double counting. Thus, our method uses a neural network approach (Faster R-CNN) to localise potential object candidates (e.g. bird) within an entire image, while a subsequent network classifier identifies the broad classification category of the detected object. In addition, spatio-temporal tracking of the detected features is included by estimating the most likely object displacement within successive images based on flight speed and camera motion along each survey transect. This workflow allows relatively efficient processing of large amounts of high-resolution imagery, as well as general classification of objects at an early processing stage.
Ultimately, our automated analysis workflow will contribute to the preservation management of biodiversity in the German North Sea and Baltic Sea by facilitating the repeated monitoring of bird populations.
How to cite: Sommer, C., Seuret, M., Gourmelon, N., Bahrami, M., Christlein, V., and Braun, M.: AI-based animal monitoring for marine biodiversity conservation along the North Sea and Baltic Sea coasts, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16694, https://doi.org/10.5194/egusphere-egu25-16694, 2025.
The coastal ocean is a key component of the global carbon cycle, transferring carbon from land to the open ocean and supporting blue carbon accounting and climate change mitigation efforts. Coastal carbon dynamics remain however poorly constrained. This results from the complex biological and physio-chemical processes that occur in coastal seas which drive the spatial and temporal variability of the exchange of carbon dioxide (FCO2) between the coastal seas and the atmosphere. To address this knowledge gap, region-specific and highly resolved analyses in time and space are required.
The dense network of in-situ measurements of seawater partial pressure of CO2 (pCO2) obtained from e.g. buoys and research vessels in the North Sea offers a unique opportunity to study coastal FCO2 dynamics. Here, we combine high-resolution satellite observations of ocean colour (ESA Ocean Colour Climate Change Initiative, OC-CCI) and sea surface temperature with all available in situ pCO2 observations (Surface Ocean CO2 Atlas, SOCAT) to study the spatial and temporal variability of pCO2 in the North Sea over the past decade. Using regionally optimized retrieval algorithms, we estimate key biogeochemical drivers of pCO2 dynamics, including chlorophyll-a, suspended particulate matter and particulate organic carbon. Our findings suggest the presence of distinct biogeochemical regions within the North Sea, detectable from remote sensing data, shaped by primary productivity, riverine plume inputs, and sediment dynamics. These processes have varying impacts on regional pCO2 dynamics, from locally enhancing the CO2 uptake to degassing CO2. Overall, this study advances our understanding of the complex processes driving coastal carbon dynamics and demonstrates a framework that can be applied beyond the North Sea in coastal regions globally.
How to cite: van Langen Rosón, A., Goyens, C., Roobaert, A., Landschützer, P., and Neukermans, G.: Using ocean color satellite data to examine spatial and temporal coastal CO2 dynamics in the North Sea, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5803, https://doi.org/10.5194/egusphere-egu25-5803, 2025.
The increasing demand for marine sand, driven by urbanization, infrastructure development, and coastal defense against sea-level rise due to climate change intensifies environmental pressures on marine ecosystems. Large-scale sand extraction disrupts benthic habitats and alters hydrodynamics by modifying water depth and current velocities. These changes weaken natural tidal mixing processes, increasing susceptibility to thermal stratification. Such stratification limits oxygen and nutrient exchange between water layers, affecting local phytoplankton dynamics and benthic communities.
To investigate the potential occurrence of thermal stratification in sand pits, we applied the Simpson-Hunter method, originally developed for predicting tidal mixing fronts, to establish a theoretical framework for determining the critical depth at which well-mixed waters may stratify within sandpits in mid-summer. Using this method, we developed a map for the southern North Sea that identifies the maximum allowable sandpit depths before stratification occurs.
To further refine our findings, we conducted one-way nested, high-resolution numerical modeling of the hydrodynamics using the Delft3D model, incorporating boundary conditions derived from the existing GETM model of the Northwest European Shelf. Simulations were performed for various sandpit sizes and depths under realistic hydrodynamic conditions for mid-summer. The results agreed with the theoretical predictions but in addition revealed a strong dependence on sandpit size, showing that larger pits are more prone to stratification related to a relative reduction in mixing at the pit’s edges.
This research highlights the critical role of sandpit depth and size in influencing stratification dynamics. Understanding and preventing these processes is essential for minimizing ecological risks and ensuring the sustainable extraction of marine sand in dynamic shelf seas like the North Sea.
How to cite: Daliri, M. and van der Molen, J.: Thermal Stratification Dynamics in Sandpits: Impacts of Marine Sand Extraction in the Southern North Sea, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2287, https://doi.org/10.5194/egusphere-egu25-2287, 2025.
This study examines how antecedent geology influences soil mechanics and consolidation in estuarine subsurface deposits, highlighting its potential as a marine geohazard in the context of large infrastructure projects. The Bolivar Roads Gate System is a proposed surge barrier extending across Bolivar Road, which is the mouth of Galveston Bay, to mitigate risks associated with increased storm surges and rising sea levels under a changing climate. Inspired by the Dutch Maeslant Barrier, this study investigates subsurface responses to such large structures, focusing on settlement and consolidation dynamics using existing borehole data and simplified one-dimensional soil calculations. Findings reveal that the saturated clays and cohesive soils at the Bolivar Roads site are prone to settlement rates exceeding those at the Dutch site by over 100-fold, driven by differences in geotechnical properties. Such elevated subsidence could disrupt the stability and operational integrity of the proposed Bolivar Roads navigational structure, potentially affecting land-sea interactions and storm surge protection efficacy. These changes underscore the need for adaptive management strategies, to mitigate differential settlement and ensure long-term functionality. This study contributes to understanding how engineered coastal management solutions interact with dynamic coastal processes, providing insights into sustainable infrastructure in the Anthropocene.
How to cite: Robbins, C.: The Role of Estuarine Antecedent Geology in Shaping Marine Geohazards and Storm Surge Infrastructure: A Comparison of the Dutch Maeslant Barrier and the Proposed Bolivar Gate System in Galveston Bay (USA), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14178, https://doi.org/10.5194/egusphere-egu25-14178, 2025.
Global warming is expected to increase the frequency and severity of compound weather, ocean and climate events. These can lead, due the interplay of multiple climate drivers and/or hazards, to far greater societal and environmental impacts than the sum of the isolated individual events. Multiple strong consecutive tropical cyclones occurring in quick succession can be classified as temporally compounding events. These events are associated with heavy rainfall, river flooding and storm surges. In the ocean, they have a combined and cumulative impact on the local hydrodynamic conditions, e.g. reduced salinity by the increased freshwater input, which in turn affects local ecosystems.
This study aims to evaluate the combined effect of strong winds and increased freshwater input during those compound events on the local salinity and circulation, while focusing on the area around Dongshan Bay, Fujian (China). The bay serves as an ideal case study, as the northern South China Sea has been increasingly hit by two or more strong consecutive typhoons in recent years.
For the investigation, the regional shelf ocean circulation model HAMSOM is used to downscale global climate scenarios to an appropriate regional scale through a nested, uncoupled modelling approach. The outer model setup covers the southern East China Sea, the Taiwan Strait and the northern South China Sea (SCS). It resolves the most important oceanic features for this study, including the circulation in the SCS, the influence of the Kuroshio and the throughflow in the Taiwan Strait. The outer model provides the lateral boundary conditions for the inner model, which has a high resolution of approximately 400m to adequately resolve the area around Dongshan Bay to the west coast of Taiwan. The atmospheric forcing and river discharges are provided by an hourly East-Asia Cordex dataset, which has proven to reproduce past typhoon tracks in the SCS quite realistically. The model setup allows to run control simulations with and without freshwater input to assess the effect of strong consecutive typhoon events on the local salinity. The results can then be used to assess the vulnerability of local ecosystems to these type of compound events.
How to cite: Enneper, N. D. C.: The impact of consecutive typhoons on the hydrodynamic conditions in a small bay in the Taiwan Strait, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12790, https://doi.org/10.5194/egusphere-egu25-12790, 2025.
Arctic coastlines are changing rapidly with warming climate. This has implications for land use, infrastructure, archeological heritage and impacts carbon and nutrient budgets for Arctic seas and nearshore wetlands. Despite the Arctic currently warming four times faster than the rest of the world, Arctic coasts are generally poorly monitored and lack baseline studies.
Our recently published dataset “Arctic landforms and processes around the coast of Svalbard” (Blok et al., 2024) is the first high resolution baseline dataset for coastal change in the Svalbard archipelago, at the junction between the western Barents Sea and the Arctic Ocean. The dataset is based on morphological mapping of landform assemblages around the entire coastline of the archipelago. Landform assemblages are linked to dominant physical processes, based on extensive fieldwork on different coastal types in Svalbard. The coastal landform assemblages are categorized in 13 classes reflecting combinations of wave, tide, fluvial, glacial and gravity processes influencing the morphology and dynamics of the coastline. Mapping has been done in 1:30.000 scale on aerial images combined with satellite imagery. This open-source dataset adds regional high-resolution data to the western Barents Sea sector of the pan-Arctic Coastal Dynamics database (Lantuit et al., 2012; 2020).
Most of the Svalbard coastline is currently shaped by combined processes. The more dynamic parts of the coast by combinations of wave, tide and fluvial processes. With diminishing sea ice, shortened frozen ground season, deepening active layer, increased river runoff and open rivers duration, the balance between dominant processes at each site will determine future development of the coast. The coastal landform dataset allows to asess expected consequences with increase of individual processes or changing balance between processes at any site. We will present examples of use for cultural heritage mangement and for studies of carbonstocks in coastal wetlands and discuss use for remote assessment of coastal change.
References:
Blok, Carlette N; Missana, Amandine F J M; Rubensdotter, Lena; Jensen, Maria A (2024): Arctic landforms and processes around the coast of Svalbard [dataset]. PANGAEA, https://doi.pangaea.de/10.1594/PANGAEA.973595 (DOI registration in progress)
Lantuit, H. , Overduin, P. P. , Couture, N. ,Wetterich, S. , Are, F. , Atkinson, D. , Brown, J. ,Cherkashov, G. , Drozdov, D. , Forbes, D. , Graves-Gaylord, A. , Grigoriev, M. , Hubberten, H. W. ,Jordan, J. , Jorgenson, T. , Ødegård, R. S. ,Ogorodov, S. , Pollard, W. , Rachold, V. , Sedenko, S. , Solomon, S. , Steenhuisen, F. , Streletskaya, I. and Vasiliev, A. (2012): The Arctic Coastal Dynamics database. A new classification scheme and statistics on arctic permafrost coastlines , Estuaries and Coasts., 35 (2), pp. 383-400 . doi: 10.1007/s12237-010-9362-6
Lantuit, Hugues; Overduin, Pier Paul; Couture, Nicole; Wetterich, Sebastian; Are, Felix; Atkinson, David; Brown, Jerry; Cherkashov, Georgy A; Drozdov, Dimitry S; Forbes, Donald Lawrence; Graves-Gaylord, Allison; Grigoriev, Mikhail N; Hubberten, Hans-Wolfgang; Jordan, James; Jorgenson, M Torre; Ødegård, Rune Strand; Ogorodov, Stanislav; Pollard, Wayne H; Rachold, Volker; Sedenko, Sergey; Solomon, Steve; Steenhuisen, Frits; Streletskaya, Irina; Vasiliev, Alexander (2020): The ACD Classification of Arctic Coasts [dataset]. PANGAEA, https://doi.org/10.1594/PANGAEA.919573
How to cite: Jensen, M. A., Blok, C. N., Rubensdotter, L., and Missana, A.: The first high-resolution dataset of Arctic coastal landforms and processes for the entire Svalbard archipelago, Western Barents Sea. , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17481, https://doi.org/10.5194/egusphere-egu25-17481, 2025.
The High Arctic, and Svalbard in particular, is currently experiencing rapid warming, which has serious consequences for various geosystem components, especially the cryosphere. Coastal areas are especially sensitive to these changes due to their position at the interface of marine and terrestrial geosystems. Retreating glaciers, degrading permafrost, prolonged sea ice-free seasons, and increasing weather extremes are all key factors influencing the development of coastal areas. In this study, we focus on the accumulation of coastal features and their stability during the instrumental record period following the Little Ice Age. We demonstrate that, despite abrupt climatic changes, the major features of the coastal landscape are surprisingly stable, unlike their counterparts in Greenland. We argue that the most dramatic development of coastal areas occurred in the Early Holocene, during the melting of the massive Barents Sea Ice Sheet. The current deglaciation, however, is not producing sufficient meltwater or releasing enough sediments to form new accumulation coastal landforms. On the contrary, we observe episodic rapid events connected to glacier dynamics, such as glacier surges or glacial lake outburst floods, where new deltas can form within weeks or months. We provide a regional overview of Svalbard delta systems, highlighting the most striking examples of their current dynamics, and propose a conceptual model for the development of coastal areas in this region.
How to cite: Kavan, J. and Strzelecki, M.: Extreme events shapping Svalbard coast: emergence of new coastal landscapes, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6649, https://doi.org/10.5194/egusphere-egu25-6649, 2025.
Particle pollution is a well-recognized threat to air quality, but its impacts on aquatic, coastal and marine environments remain poorly understood. Among the sources of particle pollution, blasted rock particles—mineral fragments generated e.g. during tunnel or road construction—are an emerging and relatively unknown contributor. When deposited in coastal areas, these mineral particles may pose unique challenges due to their potential to alter a.o. sediment dynamics, introduce contaminants, and disrupt the ecological balance. Today, blasted rock is frequently utilized in coastal applications such as land reclamation, erosion control, flood prevention, or as foundation material. While the effects of nitrogen and plastic particles associated with the blasting explosives are comparatively well-studied, the role of rock mineralogy, particle morphology, and the leaching of mineral-associated metals on coastal waters and ecosystems remains largely unexplored. This review focuses on the impacts of blasted rock disposal on coastal environments, synthesizing findings from peer-reviewed scientific literature and publicly available reports to Norwegian authorities. Specifically, we (1) analyze the mechanisms by which blasted rock particles affect coastal ecosystems, (2) place Norwegian findings into a global context, (3) propose preliminary thresholds for ecological impacts on coastal environments, (4) suggest improvements in management practices for coastal particle disposal, and (5) identify key research gaps requiring further investigation. Our analysis emphasizes knowledge advancements over the past decade while incorporating foundational studies and reports to ensure a comprehensive evaluation.
How to cite: Deininger, A., Eek, E., Sætre, C., Skretting, E., and Totland, C.: Impacts of Blasted Rock Disposal on Coastal Environments: A review and Norwegian perspective on Pollution Mechanisms, Ecological Impacts, and Management Practices, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8283, https://doi.org/10.5194/egusphere-egu25-8283, 2025.
Understanding shoreline variability and trends over time is essential for effective coastal management. However, studying the dynamic nature of the shoreline, defined as the intersection of water and land surfaces, can be quite complex due to various non-linear processes that operate across different temporal and spatial scales. In this context, the advent of satellite imagery has created new opportunities for long-term shoreline analysis by providing global coverage with high temporal resolution and enabling the acquisition of historical datasets. Typical methodologies using these data sources commonly involve the creation of satellite-derived shorelines (SDS) time series, which offer multidecadal records of variability, trends, and changes with a cross-shore accuracy of approximately 10 m on microtidal beaches.
In this study, SDS positions along the Emilia–Romagna (ER) coast in the northern Adriatic Sea were reconstructed using the CoastSat toolbox, incorporating both Landsat (5–9) and Sentinel–2 images for the entire period from 1984 to 2023. The ER coast is not only a significant tourist destination in Italy, but it is also increasingly exposed to erosion and coastal flooding due to the combined effects of low average heights, subsidence, sea–level rise, and urbanization. Consequently, a large portion of the coastline is artificially protected through various defense strategies, including both defense structures and nourishment measures, and stacked by long piers and jetties. This setting was considered in the analysis since it introduces a main bias in the coastal evolution and in shoreline variability.
A dataset of 2200 cross-shore transects, spaced 50 meters apart, was automatically generated based on the local orientation of the beach, and shoreline positions were reconstructed from the cross-shore distances computed along each transect. In particular, the large number of available instantaneous shorelines was used to compute annually averaged positions. Corrections for tidal and wave setups were applied to reduce the main sources of error in SDS. To achieve this, the average beach face slopes were derived from available topo-bathymetric data by Arpae-ER. Local measurements from tide gauges (TG) in Marina di Ravenna and Porto Garibaldi and from the Nausicaa (I and II) buoys were used to derive the other processing parameters.
The resulting annually averaged shorelines enabled the analysis of long-term shoreline trends from 1984 to 2023, as well as the assessment of interannual shoreline variability. Shoreline advancement during the study period, despite sea-level rise and subsidence, is primarily due to repeated nourishment interventions aimed at preventing coastal erosion, which helped the maintenance of an “artificial stability” along the coastline.
To evaluate the reliability of the generated shoreline products, a technical validation process was conducted. Given the complex interpretation of an annually averaged shoreline position, accuracy was assessed through visual interpretation of the processed shorelines and comparisons with the datasets available for the same period from topo-bathymetric monitoring. The time-averaging strategy in this study provides reliable averaged shoreline positions, minimizing the effects of short-term fluctuations and temporary runup excursions. This highlights the potential of satellite-optical imagery for coastal applications.
How to cite: Vecchi, E., Meli, M., and Romagnoli, C.: Satellite-Derived Shoreline Analysis of the Emilia-Romagna Coast (Italy) from 1984 to 2023, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-21514, https://doi.org/10.5194/egusphere-egu25-21514, 2025.
Some of the most disruptive effects of climate change are projected to be felt along the coastlines. The combined effects of future changes in water levels and wave climate along the coastal areas constitute one of the most serious threats to their sustainable evolution, compromising critical infrastructures, resources, ecosystems, and communities. Understanding long-term changes in coastal areas remains challenging, however, due to their multivariate and multi-time-and-space-scale nature. In this study, we propose an innovative methodology for a complete vulnerability assessment of sandy low-lying coastal areas, based on dynamic, ensemble-based projections from the Coupled Model Intercomparison Project phase 5 (CMIP5). The effects of sea level rise (SLR) and nearshore wave climate changes on future shoreline evolution are firstly assessed at five key-locations along the Portuguese coastline. Longshore sediment transport (LST) projections are computed, and sedimentary imbalances are quantified. Robust shoreline retreat of up to 300 m is projected, especially along the Portuguese northern and central coastal areas, with continued erosion driven mainly by sediment imbalance and SLR. The projected decrease in future nearshore wave energy is responsible for a slight alleviation in erosion trends, up to 6.33%, whereas the increase of northerly incoming waves is expected to lead to northward beach rotations along western Mainland Portugal. The resulting shoreline evolution is responsible for the loss of up to 0.786 km2 of dry land by 2100 along the 14 kilometers of analyzed coastline. Based on the shoreline projections, new digital terrain models are built for the five key-locations, and future extreme total water levels are obtained through a probabilistic approach, defining wave events considering high wave energy thresholds in a changing climate. The results reveal that extreme coastal flooding is projected across several urbanized sections along the Portuguese coastline, especially in areas without artificial protection infrastructures. As dune erosion is expected along the sandy stretches, the natural protection against extreme coastal events is projected to be reduced by up to 13.3%, promoting widespread overtopping, leaving populations more exposed. Future projections reveal the episodic flooding of up to 1.47 km2 of land across the five key-locations (and up to 604 km2 at a national scale), threatening households and commercial hubs, besides services and communication routes. Overall, as physical and human losses may increase substantially in the future, our results call for the implementation of adequate coastal management and adaptation plans, strategically defined to withstand changes until 2100 and beyond.
This work is supported by the Portuguese Fundação para a Ciência e Tecnologia, FCT, I.P./MCTES through national funds (PIDDAC): UID/50019/2025 and LA/P/0068/2020 https://doi.org/10.54499/LA/P/0068/2020).
How to cite: Lemos, G., Bosnic, I., Antunes, C., Vousdoukas, M., Mentaschi, L., and MM Soares, P.: The future of the Portuguese most vulnerable coastal areas under climate change – shoreline evolution and future extreme coastal flooding from downscaled bias corrected ensembles, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9999, https://doi.org/10.5194/egusphere-egu25-9999, 2025.
The coastal zone of the sea is a dynamic and complex environment where geological and geomorphological processes interact, shaping both terrestrial and marine landscapes. Understanding these processes is essential for sustainable coastal zone management, particularly in the face of climate change and increasing human activity.
The aim of this study is to develop a holistic framework for geological integrated coastal zone mapping that encompasses both the terrestrial and marine components of the coastal zone.
The research employs advanced methods, including geological mapping, 3D modeling, and data integration techniques, combined with predictive modeling of erosion-accumulation processes and shoreline changes. These methodologies are supported by state-of-the-art visualization tools to enhance the interpretation and usability of the data.
The main results of the study include detailed geological maps, 3D models, and specialized analyses that provide new insights into the structure and dynamics of the southern Baltic coastal zone. The research identifies key geohazards and offers predictive models for shoreline evolution, contributing to a more comprehensive understanding of the region.
This innovative approach is unique in its integration of terrestrial and marine aspects of the coastal zone, addressing the entire system as a cohesive unit. By bridging this gap, the study offers practical tools for sustainable management and risk mitigation.
The implications of this work extend beyond the Baltic region, providing a transferable methodology for integrated coastal zone management globally. The results contribute to bridging the gap between scientific research and practical application, equipping policymakers and stakeholders with actionable insights for addressing contemporary coastal challenges.
How to cite: Uscinowicz, G.: Innovative Holistic Approach to Studying and Managing the Coastal Zone Environment: A Case Study from the Southern Baltic Sea, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5494, https://doi.org/10.5194/egusphere-egu25-5494, 2025.
Coastal wetlands in the Pacific Islands are extremely vulnerable to climate change, due to the combined effect of sea level rise (SLR) and the increasing activity of tropical cyclones (TC). They are also affected by human activities in the catchments, including agriculture and flood management. These wetlands have the capacity to accrete following SLR if they can capture enough sediment, which is determined by catchment processes. Increase TC activity and intensification of agricultural practices will potentially result in increased sediment load from the catchment, while flood control to protect populated coastal areas can reduce sediment loads.
In this contribution, we present a numerical framework to assess future morphodynamic changes in mangrove wetlands combining an ecogeomorphological model of the mangrove wetlands and a hydro-sedimentological catchment model to analyse effects of SLR and increased TC activity under different catchment management scenarios. We first assess the contribution of TC to the annual sediment budget of the catchment using the hydro-sedimentological model and project increases by the end of the century based on expected increases in TC activity and changes in land use due to increased agricultural and flood control activities. We then run our ecogeomorphological wetland model over 100 years incorporating the changes in sediment supply from the catchments and due to the effects of SLR, TC and human activities.
How to cite: Rodriguez, J., Saco, P., and Jorquera, E.: Impacts of changing climate and changing human activities on coastal wetlands in the Pacific Islands, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19440, https://doi.org/10.5194/egusphere-egu25-19440, 2025.
In response to the global decline of native bivalve populations, non-native Pacific oysters (Magallana gigas) are increasingly colonizing former habitats of native bivalves. In the Wadden Sea, M. gigas reefs replaced blue mussel beds (Mytilus edulis) as the predominant biogenic structure on the intertidal mudflats. These reefs, covering 2 – 6% of the tidal basin area, attenuate flow energy through frictional dissipation, affecting local hydro- and morphodynamics. Despite their potential to influence intertidal mudflat elevation and function as nature-based coastal protection against sea level rise, the spatio-temporal effects of oyster reef-induced frictional dissipation remain underexplored. This study evaluates the impact of oyster reef expansion in back-barrier tidal flats on hydro- and morphodynamics.
A generic tidal basin model was developed using the Delft3D framework, synthesizing average morphological and sedimentological characteristics of the seven tidal basins sheltered by the German East Frisian islands. The model features a convex-up hypsometry, five sediment fractions (mean grain size of d50,GTB = 205 μm), and a fixed sediment roughness (Manning coefficient of n = 0.023 m- 1/3s), closely mirroring the input parameters. Oyster reef coverage scenarios were modeled for 2% (current average), 6% (current maximum), and 10% (projected future) of the tidal basin area. Reef roughness was parameterized by applying a drag coefficient CD = 0.025 and roughness length z0 = 7.8 mm. The distribution of oyster reefs within the tidal basin is determined by evaluating potential areas for reef distribution based on abiotic stressors (e.g., aerial exposure time and bed shear stress) and utilizing the Cahn-Hilliard equation to create realistic spatial patterns. A generic neap-spring tidal cycle, developed using the key tidal constituents for sediment transport, was applied at the seaward boundary.
The generic tidal basin and hydrodynamic boundary conditions are utilized to project the impact of oyster reefs on hydro- and morphodynamics. The results reveal substantial impacts of these reefs on hydrodynamic patterns and magnitudes. Furthermore, the oyster reefs cause alterations in sediment transport patterns and the resulting sea-bed level changes. The effects vary across scenarios, highlighting the diverse impacts of these reefs under spatio-temporally varying conditions.
The model presented provides a framework to estimate the biomorphodynamic feedback resulting from the bioinvasion of the Pacific oyster in the Wadden Sea, advancing the understanding of ecohydraulic processes, particularly in relation to sediment transport pathways. The results thus suggest that the presence of oyster reefs may contribute to the vertical growth of the intertidal mudflats of the Wadden Sea, providing a natural countermeasure to accelerating sea level rise.
How to cite: Hitzegrad, J., König, C. L., Brendel, A., Lojek, O., and Goseberg, N.: Effects of oyster reefs on back-barrier tidal flats on the local hydro- and morphodynamics, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20663, https://doi.org/10.5194/egusphere-egu25-20663, 2025.
Coastal flooding affects the lives and prosperity of millions of people living by the sea, and rising sea levels will only increase this risk. Coastal defences are already subject to more extreme and frequent storm events and may not be able to withstand future conditions. Consequently, designing suitable flood protection policies and schemes is becoming ever more crucial. Coastal practitioners across sectors have started to champion ‘greener’ nature-based solutions as alternatives to traditional hard coastal defences. Coastal wetlands (e.g., salt marshes, mangroves) can act as buffers and help mitigate storm impacts because their vegetation dissipates wave energy. Multiple studies have confirmed that wetlands effectively attenuate short period waves (i.e., wind waves), but their efficiency against long period waves (e.g., tidal waves, storm surges) remains in doubt. It is generally assumed that tens of kilometres of wetland width are required to achieve sufficient storm attenuation in these cases. However, coastal squeeze and urbanization often limit the creation of such large wetlands, and the necessary conversion of agricultural land causes social resistance to nature-based solutions. In this study, the effectiveness of hybrid solutions was tested as an alternative. A 2D numerical model is built in Delft3D-FM to simulate flooding in the inner Forth Estuary (UK), in an area that suffers from frequent flooding. The hybrid defence scheme comprises an existing embankment enhanced by vegetation patches of various sizes and locations in front, on top and behind the embankment. In the model, the vegetation consists of grasslands including salt tolerant plants of substantial height and density. Model simulations were designed to replicate conditions during the December 2013 storm, which devastated the study area. The results indicate that vegetation can significantly increase the energy dissipation already provided by the embankment and, in turn, reduce water depths and flood extents.
Our results also show that combining vegetation and embankment requires vegetated zones with less cross-shore width to achieve desired protection. In this specific example, this reduces the loss of agricultural land, and more generally points at limiting necessary land use conversion. It also lowers repair and maintenance costs of seawalls and dikes. The effectiveness of vegetation in storm attenuation is enhanced when it interferes with the main flow path and alters flow circulation. As such, the location of vegetation is a key consideration when implementing these solutions. Finally, this study suggests that wet grasslands can be a viable option for flood mitigation as an alternative to salt marshes and mangroves when implemented aside of hard engineering solutions. These findings offer valuable insights for coastal managers and practitioners interested in implementing hybrid or composite defences and highlight the potential benefits of these approaches, including testing more socially acceptable solutions.
How to cite: Matsoukis, C., Payo Payo, M., Becker, A., Evans, C., Brown, J., and Amoudry, L.: Enhancing coastal flood mitigation through hybrid defences integrating hard engineering and nature-based solutions , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9356, https://doi.org/10.5194/egusphere-egu25-9356, 2025.
To protect vulnerable coastal dunes from the growing pressures of climate change and human activities, effective and sustainable management through Nature-based Solutions (NbS) is essential. The Living Dunes Python package (https://users.ugent.be/~frevdael/) is a novel spatially explicit, process-based model that simulates coastal dune dynamics by coupling vegetation dynamics with aeolian transport and key environmental drivers. Developed in collaboration with the Dunefront and SUSANA projects, which aim to enhance coastal protection through NbS, Living Dunes is being parameterized with trait data from dune-building plant species, which are at the basis of bio-geomorphological feedbacks. Species-specific parameters for key life stages, including germination, growth, dispersal, and mortality, are incorporated to represent the diversity of coastal dune communities and their role in delivering NbS. These demographic processes are driven by environmental variables derived from global datasets and online APIs, enabling the simulation of fine-grained vegetation dynamics under various climate change and NbS implementation scenarios. By integrating trait data, process-based modeling, and global datasets, the Living Dunes package demonstrates how computational tools can be used to understand and predict coastal dune responses to environmental change, directly informing the design and optimization of NbS for dune restoration and coastal protection in the face of climate change and anthropogenic pressures.
How to cite: Van Daele, F. and Bonte, D.: Living Dunes: a trait-based modelling approach to optimize dune-based Nature-based Solutions, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7442, https://doi.org/10.5194/egusphere-egu25-7442, 2025.
Coastal sand dunes are critical components of coastal zones, delivering essential ecological,
geomorphic, and societal services. Over at least the last 100 years, climate change and shifting
land use patterns have driven widespread “dune greening,” characterised by increasing
vegetation cover and, subsequently, stabilisation of dune systems. While this stabilisation can
be beneficial for some management objectives, in some locations, it has reduced the
availability of valuable bare sand and early successional habitats, as well as diminished the
resilience of dune systems to environmental and climatic changes. To address these
challenges, constructed foredune notches have been increasingly implemented as coastal
management interventions. These notches aim to restore dune dynamism, promote sediment
movement, and (re)create habitats by providing a pathway for aeolian sediment transport from
beaches into the middle and back dune areas.
Despite their growing application, research on the design, functionality, and long-term impacts
of foredune notches remains limited, particularly at a global scale. In this study, we
systematically identified and analysed 133 foredune notches across four countries using aerial
imagery to assess variations in their constructed morphology. Our findings reveal significant
regional differences in notch dimensions: notches in France and New Zealand tend to be
smaller and more uniform in design, while those in the United Kingdom and the Netherlands
exhibit larger and more variable morphological characteristics. These regional variations,
especially notable in the Netherlands, are underexplored in current literature, leaving important
gaps in understanding how initial design influences the performance and persistence of these
features.
To complement this analysis of the constructed morphology of foredune notches, this study
also investigates how the identified differences in constructed morphology affect notch
evolution over time, using a time series of aerial imagery from selected sites in Europe. Initial
results suggest that constructed morphology significantly impacts the spatial dynamics and
longevity of foredune notches, with important implications for achieving ecological and
geomorphic management objectives.
To improve the consistency and transferability of research and management practices, this
study proposes a standardised classification framework for foredune notches based on key
morphological characteristics. The proposed framework provides a systematic approach to
describing and comparing notches across sites and regions, allowing existing and future
research to be better applied across notches and sites, therefore hopefully enabling
researchers and practitioners to design notches with a better understanding of their likely long-term impact.
How to cite: Pagon, T., Smyth, T., Wilson, R., and Fox, B.: Coastal Foredune Notches – Adoption, Constructed Morphology and Classification, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4575, https://doi.org/10.5194/egusphere-egu25-4575, 2025.
Freshwater, marine, and terrestrial ecosystems are experiencing significant changes as a result of human activity and anthropogenic climate change. The ability of ecosystems to tolerate changes in state variables and processes while continuing to maintain core ecological functions in the wake of disturbances is defined as resilience. Tipping points are observed in systems with strong positive feedback, providing early warning signals of potential instability. These points can be detected through metrics associated to a theoretical notion described as critical slowing down (CSD), such as increased recovery time, variance, and autocorrelation. Here we present CSD analysis of the Coastwide Reference Monitoring System (CRMS) dataset which covers the extent of the Mississippi Delta and coastal area in Louisiana, USA. CRMS consists of a defined sampling schedule and standardised data collecting methods across 390 sites. The CRMS stations span the whole coast of Louisiana, situated across nine coastal basins. Four transects were selected, of which fifteen stations across 3 Transects along the coastline and another six stations located closer to the Mississippi river, located further inland. Using a set of quantitative, analytical methods based on the assessment of changes in variance and autocorrelation we determine the current state and likelihood to be at CSD, so to demonstrate how to operationalise what to date has been developed as a theoretical framework. We use wavelets as a measure of identifying changes in the variance term, and autocorrelation was modelled using a Bayesian dynamic linear model. We are able to describe the long term ecological impact of climate high energy disturbance events such as intense tropical storms or low energy events such as extensive droughts through the analysis of the spatio-temporal patterns in the long term water quality monitoring stations.
How to cite: Corstanje, R., Toumasis, N., and White, J.: Resilience in Coastal Weltand Systems – Why it matters and how it can be determined, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16766, https://doi.org/10.5194/egusphere-egu25-16766, 2025.
Wetlands are dynamic ecosystems where land and water environments intersect, playing a vital role in maintaining ecological balance. These areas are critical for the conservation of biodiversity and regulation of water regime. The Kızılırmak Delta, is recognized as a wetland complex consisting of rivers, lakes, swamps, coastal, and marine regions is recognized as one of the "Strictly Protected Areas" and listed on the UNESCO “World Heritage Tentative List” due to the presence of wetlands and its significance as a crucial bird migration route.
The Holocene evolution of the Kızılırmak Delta (Northern Türkiye) is controlled by accumulation and alongshore transportation of sediment flux by the largest river of Anatolia draining to the Black Sea. The distinct successive beach ridges (~2 km length) formed along the eastern part of the delta (north and east) form the geomorphological boundaries of the wetland systems. The formation of these beach ridges reflects the variations of sediment influx, alongshore transport, and coastal dynamics. Optically Stimulated Luminescence (OSL) dating revealed that the formation of the beach-ridge system initiated during the last millennium.
Since the mid-20th century, a dense network of drainage canals (~1400 km) have been constructed to drain the delta for agricultural purposes. The successive construction of large-scale dams along the river have caused interconnected issues, such as decrease of sediment flux and negative balance underground water table of the delta.
In this regard, we have conducted an analysis of wetland changes over the past 10 years, during which climate change and anthropogenic impacts have been heavily observed. Sentinel-2 imagery (#92) and meteorological data (daily) were used to classify, map and understand the spatiotemporal hydrological dynamics of the wetlands and anthropogenic control. The present study aims to contribute to the analysis of the geomorphological development and evolution of the delta and its recent hydrological dynamics.
How to cite: Salman, I. and Erturaç, M. K.: Monitoring the natural and anthropogenic environmental changes in the Kızılırmak Delta using remote sensing methods over the last 10 years, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1070, https://doi.org/10.5194/egusphere-egu25-1070, 2025.
Prestige reclamation is defined as coastal reclamation carried out for the purpose of high-end real estate development and luxury recreation. The planiforms of these reclamations are often highly complex ideograms, showcasing the investor’s wealthand maximising the number of waterfront properties. Over time, increasingly elaborate designs are being built, leading to ever more complex coasts of which the wider impact to the coast is poorly understood.
As these constructions are becoming more common, we raise a series of critical questions on the ecological, societal and environmental status of these highly anthropomorphised coasts. In this presentation we highlight ten key global prestige reclamation sites; showcasing trends in design, diversity of symbolic representation and resource demands, to demonstrate common themes found widely across the existing prestige reclamations. Time series analysis of reclamation shows both the construction timeframes, but also the large gap in time between construction and further development, questioning the drivers for development. This presentation aims to spark conversations on these unique coastlines, and bring further attention and global collaboration to collectively study their impact on the wider coastal environment.
How to cite: Sengupta, D., Townsend, D., Brown, S., Haigh, I. D., and Townend, I.: Claiming Prestige: Shaping the Future of Artificial Coastal Development", EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1123, https://doi.org/10.5194/egusphere-egu25-1123, 2025.
The large radial sand ridge (RSR) system located in the southern Yellow Sea near the Jiangsu coast, China, is highly impacted by tropical cyclones (TCs). However, the temporal and spatial variations of sediment dynamics and associated morphodynamics in this region under the influence of TCs have been little explored due to the difficulty of implementing direct observation during these extreme events. Taking typhoon Lekima in August 2019 (No. 1909) as an example, this study simulated and comprehensively investigated the dynamic processes in the RSR area under the impacts of TCs based on the Finite Volume Coastal Ocean Model (FVCOM). During the passage of Lekima, the spatial patterns of residual flow (RF), sediment flux (SF) and morphology changes in the RSR area were totally different from that during the pre- and post-Lekima periods, especially in the offshore areas (the seaward edge of sand ridges). This is because TC Lekima can generate strong wind-driven currents and waves, increasing the bottom stress and influencing the sediment transport. Due to the shallow water depth of RSRs, wave height decreased significantly towards the coast, and tidal effects gradually dominated the nearshore sedimentary dynamic processes instead of wave effects. Furthermore, the effects of TCs with different tracks and intensities were discussed in this study, and we found that TCs passing the west/east side of the study domain can induce opposite directions of sediment transport and lead to the spatial asymmetry of geomorphological evolution. This research can contribute to an improved understanding of sedimentary dynamic processes during extreme events and indicates the importance of exploring sediment dynamics response to TCs with different characteristics for reducing TC-induced coastal risks in future climate change scenarios.
How to cite: Yang, G.: Impact of tropical cyclones on the hydrodynamics and sediment dynamics of the radial sand ridge system in the southern Yellow Sea, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1614, https://doi.org/10.5194/egusphere-egu25-1614, 2025.
Coastal farmland is becoming increasingly exposed to flooding due to climate change. Inundation can lead to groundwater and soil degradation through saltwater intrusion. Much of the research investigating saltwater intrusion is focused along the marine coast; however, as storm intensity and sea levels rise, transitional coastal areas not previously susceptible to salinization may be at risk. Flood-derived sediment deposits may provide an overlooked salinity source in estuarine and upriver areas, even where floodwater salinity is relatively low. This study was conducted to evaluate the impact of subaerial flood deposits on underlying soil and porewater. A parcel of agricultural land in an estuarine floodplain in Nova Scotia, Canada, was selected to assess the subsurface response to repeated, low-salinity flooding. The site experienced inundation by fortnightly tidal floodwater following a managed dike realignment, resulting in dynamic surficial alteration. A three-year field campaign, including soil and water monitoring, geophysical surveying, and drone-based LiDAR surveying, was conducted to monitor changes to the site geomorphology and water and sediment chemistry. A one-dimensional numerical solute transport and vertical water flow model informed by field data was applied to investigate the hypothesis that saline sediment deposits can drive downward saltwater intrusion in areas experiencing brackish or low-salinity flooding. Results revealed that the soil concentrations exceeded that of the brackish floodwater by up to 50 times, with the highest salinization occurring preferentially in areas experiencing persistent deposition. Model results showed that soil salinization may persist for decades longer than the duration of flooding; however, removing these deposits through erosion resulted in soil and groundwater recovery. This study highlights the potential importance of flood-derived sediments for exacerbating saltwater intrusion in riparian areas along estuaries, which were not previously thought to be at risk of saline flooding.
How to cite: Tackley, H., Kurylyk, B., Lake, C., van Proosdij, D., and Jamieson, R.: Sediment deposition in riparian zones exacerbates saltwater intrusion, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2593, https://doi.org/10.5194/egusphere-egu25-2593, 2025.
Fjords are strongly affected by climate change and direct anthropogenic impacts. Their location at the land-ocean interface makes them particularly vulnerable to a wide range of stressors. Rapid changes, such as increasing water temperatures, changes in oxygen conditions, increased run-off from land and decreasing sea ice in the Arctic will inevitably have profound effects on marine biodiversity and productivity. However, so far, our knowledge on the impact of these changes on marine communities remains limited, despite their important roles in food webs and nutrient cycling. To understand ongoing and future changes in fjord ecosystems and the resilience of marine communities, it is essential to assess their response to past changes in environmental conditions. To date, such studies are limited to lineages with a fossil record, leaving an incomplete picture of the remaining diversity. To address this issue, in the project PASTIME we are now applying sedimentary ancient DNA as a new tool for reconstructing past changes in entire marine communities in relation with past environmental changes. We focus on marine sediment cores from Arctic and western Norwegian fjords and assess environmental and biodiversity changes over the last centuries. Our work extends the timescales far beyond traditional observational data and allows assessing the impact of various environmental factors (e.g. temperature, freshwater inflow, sea ice, oxygen) under in-situ conditions to elucidate key drivers of change. In addition, the high sedimentation rates in fjords allow for high temporal resolution sampling and thus for tracing the rate of ecosystem change. Here, we will present preliminary data on one sediment core collected in Kongsfjorden, Svalbard, and one core from Masfjorden, Western Norway. Both cores cover the last three centuries with a high vertical resolution and show marine community responses to past environmental changes.
How to cite: Husum, K., Saetersdal, I., Lacka, M., Risebrobakken, B., Haflidason, H., Dunthorn, M., Cordier, T., Larsen, A., Varpe, Ø., de Schepper, S., and Weiner, A.: Assessing the impact of past environmental change on fjord biodiversity using sedimentary ancient DNA, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4284, https://doi.org/10.5194/egusphere-egu25-4284, 2025.
Offshore freshened groundwater (OFG) is well-documented in the shelf sediments of Canterbury Bight (New Zealand), with an estimated maximum volume of 213 km³, extending up to 60 km offshore from the coast. However, the evolution and emplacement dynamics of the OFG system remains poorly constrained. To advance the current state of understanding OFG systems, this study seeks to utilize the previously underutilized IODP geochemical and geological data from the Canterbury Bight to constrain the timing and emplacement mechanisms of the OFG system. Specifically, the main objectives of this paleo-hydrogeochemical transport-reaction modelling study are: (1) to identify key factors/processes influencing groundwater salinization and flushing in the continental shelf; (2) to improve understanding of the influences of OFG on subseafloor biogeochemical processes by transport-reaction modelling; (3) to explore the interactions between paleo-groundwater system and seawater; and (4) to propose a conceptual mode for shelf groundwater system evolution in relation to glacial/interglacial processes.
Preliminary results suggest that present-day recharge does not fully account for the OFG, particularly in the outer shelf, which is the fossil groundwater emplaced during the lowstands since the late Pleistocene. The intensified sulphate depletion observed in freshening sections is attributed to enhanced anaerobic oxidation of dissolved organic matter brought by the OFG. Modern salinity conditions are not in equilibrium with present-day sea level conditions, as the OFG is gradually being salinized through downward solute transport from overlying seawater. Submarine groundwater discharge and OFG volume are interconnected components of the offshore paleo-groundwater system, both closely tied to sea-level fluctuations. The findings from this study are expected to enhance our understanding of the Canterbury Bight’s offshore groundwater system and provide broader insights into OFG formation and evolution under changing climatic and sea-level conditions worldwide.
How to cite: Sheng, C., Micallef, A., Schmidt, M., Müller, T., and Hensen, C.: Unravelling groundwater salinization and flushing in the Canterbury Bight during glacial-interglacial cycles: Insights from paleo-hydrogeochemical modeling, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4809, https://doi.org/10.5194/egusphere-egu25-4809, 2025.
Topographic change, its dynamic mechanism, and the long-term evolution of a coastal sand dune in northwestern Taiwan was discussed through the monitoring of the seasonal and interannual topographic changes and sedimentological studies. The strong northeast monsoon in winter often blows up the dry sand on the back beach, and transports the sand landward along the coast. The sedimentary structure analysis of the foredunes also shows that different types of parallel and cross laminations are dominant at different dune locations.
In summer, the foredune is susceptible to the influence of typhoon waves and storm surges, and often erodes the fore slope to form dune scarp. However, in the following winter, the scarp can gradually return to the dune slope through the accumulation of the dune ramp and the slope slumping. Overall, the foredune ridge has been moving inland toward southeast over the decades. Several sites of sand encroachment onto the windbreak forests are identified. The artificial sand fences on the fore slope make the surrounding sand surface piled up, and the fore slope becomes steeper that more likely to cause large-scale slumping.
The results of the ground penetrating radar survey showed that the surface sediments of the foredunes were about 5-10 meters thick, showing low-angle parallel bedding. Below the existing dune sediments, the distribution of the strata under the dunes (i.e. algal reef layer, old dune sediments, and salt marsh mud) can be observed. Vibration sediment core samples also show that there is an algal reef platform below the beach and dune deposits in this area, which is exposed at the lower fore beach and could extend at least few hundred meters to the inland side. The sea level at the time of the formation of the algal reef platform (about 3,000-4,000 years ago) may have been higher, and the secondary sand dunes on the current inland side may be the foredunes at that time.
How to cite: Lin, T.-Y., Lu, S.-P., and Liou, J.-M.: Morphodynamics and Evolution of a Coastal Sand Dune in Northwestern Taiwan, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5126, https://doi.org/10.5194/egusphere-egu25-5126, 2025.
Accelerated climate warming has caused the majority of marine-terminating glaciers in the Northern Hemisphere to retreat significantly during the 21st century. While glacier retreat and changes in mass balance are widely studied on a global scale, the impacts of deglaciation on adjacent coastal geomorphology is often overlooked. We examined changes in proglacial zones of marine-terminating glaciers across the Northern Hemisphere in period 2000-2020 to provide a complete GIS dataset of new coastline released from glacial ice on the hemisphere during that time as well as coastline lost due to glacier advance. We identified a total of 2466 ± 0.8 km of new coastline, giving an average length of 123 km every year. Two-thirds of this coastline was exposed in Greenland. At the same time, only 53.1 ± 0.1 km of coastline present in 2000 was covered by glaciers in 2020. We analyse the results by region and compare them with retreat areas of the corresponding glaciers. Additionally, we identified 35 new islands larger than 0.5 km2 that were completely uncovered or which lost their glacial connection with the mainland during the period 2000-2020. Finally, we characterize these juvenile coasts by rock type, recent climatic conditions and location in particular permafrost zone. These environmental factors affect recently initiated paraglacial coastal evolution and enable to show hotspots in terms of expected geomorphological coastal dynamics.
Funding: The research is supported by the National Science Centre in Poland (project: ‘GLAVE- transformation of paraglacial coasts by tsunamis - past, present and warmer future’ No. UMO-2020/38/E/ST10/00042).
How to cite: Szczypinska, M., Kavan, J., Kochtitzky, W., Farquharson, L., Bendixen, M., and Strzelecki, M.: New coasts emerging from the retreat of Northern Hemisphere marine-terminating glaciers in the 21st century, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6107, https://doi.org/10.5194/egusphere-egu25-6107, 2025.
Lagoon coasts are regarded as among the most vulnerable ecosystems to the effects of climate change, serving as conduits for interconnectivity between terrestrial, marine, and atmospheric systems. The stability of lagoons is contingent upon several factors, including the influence of storm waves, ocean currents, sediment supply, and sea level changes. To date, however, little research has been conducted on the processes shaping the evolution of Arctic coastal lagoon systems (Smith et al., 2020). The present study utilises a comprehensive array of remote sensing data sources, encompassing aerial photographs from the 1930s, orthophotographs from 1936–1938, and satellite imagery from 2021, to identify lagoon formation and systematically classify their typology.
The construction of a database comprising over 430 lagoons revealed that at least 98 of these were formed after 1936, with eight disappearing within a century. Since the end of the last ice age (LIA), at least 98 new lagoons have been formed, resulting in the current Svalbard coastal environment comprising 434 lagoons spanning 147 km2. A new lagoon type currently rapidly forming across the archipelago, is the moraine-controlled paraglacial lagoon. These lagoons form as a consequence of glacial retreat and subsequent inundation of the area between moraines and glacier ice-cliffs by the sea. The majority of observed lagoons are characterised by resistant barriers capable of withstanding strong storms. In general, the factors controlling the stability of Svalbard lagoons remain poorly understood. This is partly due to the fact that permafrost has not yet been thoroughly studied in the area and partly due to the fact that the distribution of sub-lagoon permafrost is not yet fully understood.
Keywords: lagoon systems, moraine-controlled paraglacial lagoons, coastal change,
glacier retreat, Svalbard, Arctic.
Funding: This research was funded in whole by the National Science Centre in Poland (project: Arctic storm impacts recorded in beach-ridges and lake archives: scenarios for less icy future “ASPIRE” – UMO-2020/37/B/ST10/03074)
How to cite: Owczarek, Z. and Strzelecki, M.: Post-Little Ice Age evolution of Svalbard's lagoon systems – types, changes, and responses to storms, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6108, https://doi.org/10.5194/egusphere-egu25-6108, 2025.
The Bohai Sea, a semi-enclosed inland sea located in China, has experienced a notable decline in bottom water oxygen levels over the past decade. This phenomenon is linked to the inadequate replenishment of oxygen, which is constrained by the formation of summer thermoclines that impede water renewal. The impact of global climate change on oceanic thermoclines has been pronounced. This research employs a sophisticated three-dimensional hydrothermal model in conjunction with a vertical water age model to investigate the formation and spatiotemporal characteristics of thermoclines in the Bohai Sea, as well as their response to climate change, including shifts in wind patterns and air temperature. Water age is conceptualized as the duration since a water parcel last contacted the free surface. Findings indicate that the bottom water age in the Bohai Sea remains less than 2 days in spring, suggesting that the cold bottom waters are not remnants from the winter season. The intensified surface heat flux during summer points to a thermal lag as the underlying mechanism for thermocline formation, with bottom waters warming at a slower rate than surface waters. The study reveals marked spatial heterogeneity and seasonal fluctuations in the thermocline’s distribution within the Bohai Sea. Over time, the thermoclines have exhibited a vertical descent towards the seafloor and a horizontal shift from the continental slope towards the central basin. Regarding the impacts of climate change, a trigonometric function fitting method was utilized to discern a trend of increasing wind speeds and temperatures in the Bohai Sea over the past forty years. The temperature rise leads to a downward shift of the thermocline and an intensification of its strength. Moreover, enhanced wind speeds facilitate greater vertical mixing of water masses, culminating in a weakening of the strength of the thermocline.
How to cite: Wu, M. and Sun, J.: Spatiotemporal Distribution and Climate Change Sensitivity of Thermoclines in a Semi-Enclosed Sea, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7788, https://doi.org/10.5194/egusphere-egu25-7788, 2025.
To understand the evolution of the Qiongzhou Strait and ancient coastlines in the Beibu Gulf - Leiqiong area since the Cenozoic era, and to reveal its implications for regional land-sea pattern changes and global climate change. This article reconstructs the changes of ancient coastline and the evolution process of Qiongzhou Strait in the Beibu Gulf - Leiqiong area since the Cenozoic era based on borehole data. In the Paleogene, the Beibu Gulf formed a NEE trending disconnected fault basin and filled with river lake sedimentary facies. In the late Oligocene, seawater intermittently invaded the ancient Beibu Gulf lake and connected the isolated fault basin;In the Early-Middle Miocene（23.3~10.4 Ma）, the coastline in the northwest of the South China Sea rapidly retreated, and the ancient lake in the Beibu Gulf evolved into the ancient Qiongzhou Strait. In the Late Miocene to Pliocene （10.4~2.58 Ma）, the coastline continued to retreat, forming a wide ancient Qiongzhou Strait, Early Pleistocene regression and volcanic eruptions led to the shrinkage of the ancient Qiongzhou Strait；Frequent climate fluctuations during the late Early Pleistocene to late Pleistocebe controlled the continuous transformation of fjords and land. The significant regression during the last glacial maximum directly led to the transformation of the Beibu Gulf-Leiqiong area from sea to land; Since 15 ~ 12 ka BP, the coastline has rapidly retreated and briefly stopped between 12 and 11 ka BP, and the Beibu gulf has once again transitioned from land to sea, Afterwards, the sea level continued to rise, and the Qiongzhou Strait fully opened from west to east at 11 ka BP. By 6 ka BP, the sea level reached about 2 meters above the current sea level, forming the current sea land pattern. The results indicate that the Beibu Gulf - Leiqiong Area underwent four evolutionary stages in the Cenozoic, including the Paleogene Beibu Gulf ancient lake, the Neogene to Early Pleistocene ancient Qiongzhou Strait, the late early Pleistocene to late Pleistocene fjords, and the Holocene Qiongzhou Strait.
How to cite: Wang, C., Yang, X., and Hu, D.: Reconstruction of the Cenozoic Paleocoastline and Evolution of the Qiongzhou Strait, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7828, https://doi.org/10.5194/egusphere-egu25-7828, 2025.
Climate change is driving significant temperature increases in the Arctic region—over four times the global average—impacting fish populations that are highly sensitive to thermal variations. Elevated water temperatures enhance the metabolic oxygen demands of fish while simultaneously decreasing oxygen solubility in seawater. This dual effect may force fish to migrate to more favorable habitats or face higher mortality rates. While previous studies have primarily focused on the relationship between water temperature and fish catches, the influence of dissolved oxygen has remained understudied due to limited data availability. In this study, we utilized reconstructed ocean biogeochemical data from the Geophysical Fluid Dynamics Laboratory Earth System Model (GFDL-ESM2) covering the Arctic and Subarctic Exclusive Economic Zones (EEZs) from 1970 to 2017 to calculate a metabolic index that integrates both temperature and dissolved oxygen levels. Our findings demonstrate a strong correlation between the metabolic index and the catches of large demersal fish species. Permutation importance analysis revealed that dissolved oxygen often plays a more critical role than temperature in determining fish catches across numerous regions. Additionally, fish catches in subsurface areas with higher dissolved oxygen importance exhibited longer lead times in predictability, likely due to the prolonged persistence of biogeochemical conditions. Projecting into the future under various Shared Socioeconomic Pathway (SSP) scenarios up to 2100, our results consistently indicate a continued decline in fish catches across all scenarios. These outcomes highlight the urgent need to incorporate the physiological characteristics of fish into sustainable fisheries management practices to mitigate the adverse effects of changing ocean conditions in the Arctic and Subarctic regions.
How to cite: Kim, E., Park, J.-Y., and Lim, H.-G.: Projected Decline in Arctic and Subarctic Commercial Fish Catches: Insights from Reconstructed Ocean Biogeochemical Modeling, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7842, https://doi.org/10.5194/egusphere-egu25-7842, 2025.
Wetlands serve as coastal protection structures via hydrological and biogeochemical processes (Junk et al., 2013), preventing soil erosion (Barcelona et al., 2018) and promoting sedimentation and soil stabilization (Montakhab et al., 2012). Wetlands contribute to mitigate the impacts of peak flows caused by pluvial or fluvial floods or storm surges. The increase in global warming will affect coastal areas with an increase in sea level and erosive processes (Reed et al., 2018), and an increase in the frequency of hydrometeorological phenomena such as coastal flooding and maritime storms (Hoggart et al., 2014). Inland wetlands are also to be increasingly affected by pluvial and fluvial floods (Kundzewicz and Pinskwar, 2020). It is then necessary to add knowledge on the impacts of both the wetland inundation level and the vegetation water resistance on hydrodynamics and sedimentary patterns in front of a peak flow to know the wetland benefits in front of flooding events. In this study, particle ladden floods were reproduced by flume experiments were a peak flow (of water height H) flowed into a wetland with a water height h (where H > h) populated with two natural species (Juncus maritimus and Arthrocnemum fruticosum). The peak flow was found to pass through different regimes with different sedimentation patterns: peak flow adjustment; peak flow; drag-dominated peak flow; ending to the gravity current regimes. During the peak flow regime, low-inundated wetlands induced higher sedimentation rates for the coarse sediment fraction than for the fine sediment fraction, while high-inundated wetlands resulted in similar settling rates for both sediment fractions, coarse and fine. Because the coarse portion has already settled, at greater distances sedimentation rates corresponded to the fine fraction and dropped monotonically along the flume. It was also found that the presence of vegetation enhanced the sedimentation rates compared to bare soil conditions.
This finding demonstrates how crucial vegetation is to protect the bed and prevent bed erosion in coastal regions when facing peak flows and how higher inundation levels reduces the harmful effect of the front pass by enhancing the sediment deposition.
References
Barcelona, A., Serra, T., Colomer, J., 2018. Fragmented canopies control the regimes of gravity currents development. J. Geophys. Res-Oceans, 123, https://doi.org/10.1002/2017JC01314
Hoggart, S.P.G., Hanley, M.E., Parker, D.J., Simmonds, D.J., Bilton, D.T., Filipova-Marinova, M., Franklin, E.L., Kotsev, I., Penning-Rowsel, E.C., Rundle, S.D., Trifonova, E., Vergiev, S., White, A.C., Thompson, R.C., 2014. The consequences of doing nothing: The effects of seawater flooding on coastal zones. Coast. Eng. 87, 169–182. https://doi.org/10.1016/j.coastaleng.2013.12.001
Junk, W.J., An, S., Finlayson, C.M., Gopal, B., Kveˇt, J., Mitchell, S.A., Mitsch, W.J., Robarts, R.D., 2013. Current state of knowledge regarding the world’s wetlands and their future under global climate change: a synthesis. Aquat. Sci. 75, 151–167. https://doi.org/10.1007/s00027-012-0278-z.
Kundzewicz, Z.W., Pinskwar, I., 2022. Are Pluvial and Fluvial Floods on the Rise? Water 2022, 14, 2612. https://doi.org/10.3390/ w14172612
Montakhab, A., Yusuf, B., Ghazali, A. H., Mohamed, T. A., 2012. Flow and sediment transport in vegetated waterways: a review. Rev. Environ. Sci. Bio. 11(3), 275-287. https://doi.org/10.1007/s11157-012-9266-y
How to cite: Soler, M., Colomer, J., Folkard, A., and Serra, T.: Inundation levels and vegetation: keys to control peak flows in wetlands, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10042, https://doi.org/10.5194/egusphere-egu25-10042, 2025.
Climate change is transforming coastal ecosystems by altering key processes such as freshwater inputs, salinity, and stratification, which drive nutrient dynamics, primary productivity, and carbon cycling. This study explores the dynamics of chlorophyll concentration (as a proxy for local planktonic biomass) in the Gulf of Naples (GoN) within the Mediterranean Sea. Leveraging long-term monitoring data and machine learning, we identify the local drivers of chlorophyll concentrations as a combination of physical and biogeochemical conditions. Notably, salinity emerges as a key predictor of chlorophyll, emphasizing the critical role of freshwater inflows and mixed layer dynamics. We develop an empirical model to estimate salinity based on freshwater discharge and stratification, which proves robust even with simplified inputs. By combining these predictors with future climate projections (RCP4.5 and RCP8.5), we assess the potential impacts of changing precipitation and wind patterns on salinity and chlorophyll. Results suggest increasing salinity and declining chlorophyll concentrations, particularly in spring, while uncertainties persist for autumn trends. Crucially, changes occurring on land may have a greater impact than those at sea (e.g., temperature) on coastal ecosystems, particularly their microbiomes, which form the foundation of the main trophic webs. These findings highlight the importance of long-term monitoring and infrastructure development to enhance ecosystem management under future climate scenarios.
How to cite: Kokoszka, F., Lefebvre, C., Asdar, S., Buongiorno Nardelli, B., Mercogliano, P., Ribera d'Alcalá, M., Margiotta, F., and Iudicone, D.: Chlorophyll variability in a Coastal Ecosystem: Insights from Recent Decades and Future Projections, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11715, https://doi.org/10.5194/egusphere-egu25-11715, 2025.
Wind-induced currents are the major forces responsible for sediment resuspension and transport in micro-tidal bays. The hydrodynamics and sediment transport mechanisms were investigated in Onsan Bay, a heavily contaminated, micro-tidal area on the southeastern coast of Korea, designated as a “Special Management Coastal Zone” due to severe pollution. At two mooring stations (M1: central part of the bay; M2: entrance of the bay), in-situ measurements using acoustic Doppler current profilers (ADCPs) were conducted to examine the impact of wind-induced residual currents on the sediment flux over four weeks. During the mooring period, residual currents (ū) in both stations showed classical estuarine circulation characterized by seaward (landward) flows at the surface (bottom) layers. The suspended sediments at both stations were transported seaward (landward) at the surface (bottom) layer mainly through the residual currents (mean-flow flux Fmean: > 70% of the total flux). Under northerly winds, the bottom ū at M1 and M2 strengthened, with a higher increment at M1. This result implies that the intrusion of alongshore currents through the bottom layer strengthened under northerly winds. The landward Fmean at M1 (M2) was 1.4 (1.2) times higher under northerly winds than southerly winds, resulting in the quadruple “intensification” of net sediment flux. This observation was attributed to the enhanced landward water transport and the weak sediment resuspension by wind-induced residual currents. This suggests that the northerly winds might be a primary factor intensifying the landward sediment fluxes, potentially resulting in the increased sediment deposition into the bay. The findings provide insights into managing sedimentation in contaminated coastal bays and highlight the importance of wind effects on sediment transport in micro-tidal bays.
How to cite: Eun, C. Y., Choi, S. M., Seo, J. Y., Ryu, J., and Ha, H. K.: Wind-induced residual current as a driver of sediment flux intensification in a shallow, micro-tidal bay, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15209, https://doi.org/10.5194/egusphere-egu25-15209, 2025.
Typhoons significantly influence sediment resuspension through the mixing induced by strong winds, which alters the local current patterns and sediment dynamics. An acoustic Doppler current profiler was moored in Yeosu Bay from August 19 to September 20, 2022, to investigate the effects of typhoon on sediment transport mechanisms. Before the typhoon, the mooring station exhibited a strong stratification of water column caused by freshwater inflow from the Seomjin River. On September 6, 2022, Typhoon Hinnamor passed through the study area, disrupting the semi-diurnal current regime and associated sediment transport. Under the influence of the typhoon, the residual current profile transitioned from a two-layered structure to a fully mixed structure. Strong winds (~16 m s–1) affected the stability of bed sediments and stratification, resulting in significant differences in suspended sediment concentration (SSC) during spring tides before (SI) and after (SII) the typhoon. Despite similar current-induced bed shear stress, the SSC during the SII period reached up to 350 mg l–1, which was about four times higher than during the SI period (87 mg l–1). Near-bed sediment fluxes controlled by tidal pumping increased during the SII period (54%) compared to the SI period (29%) and transport landward. This suggests that suspended sediments advected from the Seomjin River due to the typhoon settled in Yeosu Bay, resulting in the bed stability decrease. Along with suspended sediments, the typhoon led to an input of terrestrial nutrients from the Seomjin River, which could affect the biological productivity of Yeosu Bay. The results from this study indicate that Typhoon-induced disturbances of coastal currents could significantly affect sediment resuspension and transport, highlighting the complex interactions between meteorological forcing and sedimentary processes in coastal environments.
How to cite: Kim, S. I., Choi, S. M., Jeong, S. W., Park, J.-H., Kim, P. J., and Ha, H. K.: Typhoon-induced sediment dynamics: Effects of extreme winds on resuspension and transport in Yeosu Bay, Korea, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15389, https://doi.org/10.5194/egusphere-egu25-15389, 2025.
Coastal areas are high dynamic environments which, especially considering the present climate conditions, are undergoing huge morphological changes mostly in terms of erosion. The retreat of coastal slopes, either progressive or sudden, is the result of the interaction between marine and terrestrial processes acting on specific litho-structural contexts.
The analyses of retreat style and relative rate can be lead combining field measurements and high-resolution remote sensing techniques. These approaches allow the quantification of erosion trend and the identification of the key factors driving the observed changes over time. The integration of multi-techniques measurement strengthens the evaluation of the interplay between terrestrial and marine processes and litho-structural factors, such as lithological variability, enabling a detailed understanding of how different coastal typologies respond to these processes.
Within the framework of the extended partnership RETURN (multi-Risk sciEnce for resilienT commUnities undeR a changiNg climate - Italy’s National Recovery and Resilience Plan), our study focuses on the evolution of a segment of the southern coast of the Lazio region (Italy). The study area is characterized by a soft-rocky cliff and shore platform system, partially emerged and partially submerged, where a high cliff retreat rate has been observed. To this end, multitemporal surveys were conducted using various remote sensing techniques, including optical photogrammetry via Unmanned Aerial Vehicle (UAVs), LiDAR surveys using UAV-mounted laser scanners, imagery captured with a MicaSense RedEdge-P multispectral camera equipped on a UAV, and portable laser scanner with Simultaneous Localization and Mapping (SLAM) technology (FJD TRION P1 model). Optical photogrammetry and LiDAR, both conducted via drones, enabled us to produce high-resolution 3D point clouds, orthophotos (<2 cm/pixel), and Digital Terrain Models (DTM, <5 cm/pixel). Through repeated surveys over two years, a multitemporal change detection analysis was conducted, revealing significant changes in response to storm events and providing rates of cliff retreat up to 1 m in localized sectors. SLAM technology allows to examine outcrop portion, less visible from UAV surveys, as the bottom of the rocky cliff. Here, the impact of storm waves was monitored, and the specific SLAM results were useful for unravelling the role of extreme event on the cliff retreating and associated rock-fall triggering along the cliff wall. The use of the multispectral sensor, particularly through the Green and Blue bands, provides useful data for better understanding the morphodynamics along the submerged portion of the shore platform. In particular, the submerged platform exhibits the same rock fracturing patterns observed in the emerged section and is composed of blocks that detach and partially slide into the sea, contributing to the retreating trend of the cliff and shore platform system.
The integration of multi-techniques not only enabled the quantification of the retreat rates of the cliff under analysis, but also allowed their correlation with predisposing and triggering factors, providing the foundation for the comprehension of potential future evolution in a changing climate context.
How to cite: Piacentini, D., Torre, D., Iacobucci, G., and Troiani, F.: Multi-technique approach for the reconstruction of rocky coast evolution, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17297, https://doi.org/10.5194/egusphere-egu25-17297, 2025.
Increasing pressure on the coastal zone, driven by urbanization and related adoption of hard engineering protection structures, has frequently contributed to a gradual amplification of beach erosion. This is the case of Vale do Lobo beach (Algarve, Portugal), where sand retention caused by the Quarteira groin field and Vilamoura jetties led to soft cliff recession and reduction of the beach width downdrift (Teixeira, 2019). To mitigate these effects, an artificial beach nourishment program along with a monitoring plan have been implemented by the predecessor institution of the Portuguese Environment Agency since 1997 (Pinto & Teixeira, 2022), which involves systematic surveys of six beach profiles and has limited spatial scope and temporal resolution. These limitations could be overcome by satellite remote sensing (RS), which has been recognized as an alternative.
We aim to verify whether RS is suitable for measuring changes of beach width after beach nourishment operations, contributing to cost-effective monitoring with greater spatial and temporal coverage. The study was conducted along the Vale do Lobo coastline, focusing on the evolution of the average beach width from February 2000 to February 2024. During this period, the beach evolution was marked by a rapid increase in beach width following two beach nourishments and a gradual narrowing driven by a sediment deficit imposed by the updrift retention structures.
Images from the Landsat 5, 7, 8 and 9 satellites and Sentinel-2 Level 1C were obtained and classified, using the python toolkit CoastSat (Vos et al., 2019), which also made it possible to obtain the shorelines of the beach during the study period. The USGS DSAS (Himmelstoss et al., 2024) software was used to acquire beach width values, at the six profiles surveyed in the monitoring program. Although the relatively low spatial resolution of the images (30m and 10m), and the existing differences between the measured shoreline indicators (beach width at MSL and instantaneous water line in RS, which includes the effects of tide and swash signals), the relatively high temporal resolution of RS images allowed for the filtering of uncertainties. As a result, the time-averaged RS values were found to closely match those obtained from field monitoring. In response to the 2006 nourishment, the beach advanced 29m (33m for RS) followed by a gradual beach width reduction of 5.8m/yr (5.7m/yr for RS), while in the 2010 nourishment the beach advanced 29m (28m for RS) followed by a gradual reduction of 1.8m/yr (1.9m/yr for RS). The comparison between the data obtained showed congruence of field and RS results, proving evidence that remote sensing techniques and semi-automatic methods can be an asset for monitoring beach nourishment evolution. This work is supported by the Portuguese Fundação para a Ciência e Tecnologia, FCT, I.P./MCTES through national funds (PIDDAC): UID/50019/2025, UIDB/50019/2020 (https://doi.org/10.54499/UIDB/50019/2020) and LA/P/0068/2020 (https://doi.org/10.54499/LA/P/0068/2020). The work is a contribution to the CREST project, funded by FCT through Grant 2022.05392.PTDC (doi:10.54499/2022.05392.PTDC). Authors also recognize the support of national funds through FCT, under the project LA/P/0069/2020 (doi:10.54499/LA/P/0069/2020), granted to the Associate Laboratory ARNET, and UID/00350/2020 (doi:10.54499/UIDB/00350/2020) granted to CIMA.
How to cite: Neves Silva, M., Vaz, A., Taborda, R., Nobre Silva, A., Pinto, C. A., Santos, J., Teixeira, S., and Costas, S.: Monitoring beach nourishment evolution using satellite data: the case of Vale do Lobo (Portugal) , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17669, https://doi.org/10.5194/egusphere-egu25-17669, 2025.
Understanding the spatial and temporal variation of the shoreline position is key to both research and engineering projects contributing to an efficient management of the coast. Accelerated climate change and its related impacts can further destabilize coastal systems, highlighting the need for studies that quantify coastal evolution, while discussing the application of satellite remote sensing datasets and GIS methods for coastline extraction, mapping, and analysis along regional coasts.
The Gulf of Cadiz is brimming with human intervention and as such has been the target of many studies. The focus of this work covers part of this region, extending from Olhos de Água (Portugal) to the mouth of the Guadalquivir River (Spain) (~180 km). The study area is characterized by a variety of coastal morphological features, including cliffs, beaches, foredunes and inlets. Regardless of its great diversity of landforms, sandy beaches still constitute the dominant coastal environment of this region. We aim to grasp a better understanding of the Cadiz Gulf coastal dynamics through the comparing two shoreline mapping methods and indicators, covering the time span between 2014-2024 for Portugal and 2016-2022 for the Spain coast. The applied methods include 1) the manual digitation of Wet/Dry Line (WDL) and the Instantaneous Water Line (IWL) indicators within a GIS environment, and 2) the automatized extraction of the IWL using the CoastSat toolkit (Vos et al., 2019). The WDL Marks the darkest edge of the wet area of the beach, while the IWL is the line where the water meets the sand. The manually digitized shoreline was carried out in ArcGIS Pro 3.4.0 over the orthophotomaps obtained from “Direção Geral do Território” (Portugal) and “Instituto Geografico Nacional” (Spain) websites. CoastSat python toolkit (Vos et al., 2019) was used to extract shorelines from open-source satellite imagery (Landsat and Sentinel-2).
Overall, the Gulf of Cadiz has shown average end point rates (EPR) of 1.65 m/yr and 0.6 m/yr for the manually mapped WDL and IWL, respectively. The automated approach yielded a rate of 1.84 m/yr. All the methods show net shoreline accretion, with the results heavily influenced by the significant accretion observed in the downdrift sector, Matalascañas to Guadalquívir. When all the sectors are analyzed individually it is possible better compare the methodologies, according to all indicators. Comparisons reveal that, in most cases, the automated shorelines align more closely with the manually identified WDL rather than the expected IWL. This discrepancy raises questions about the nature of the indicator detected by the automated tool. The findings suggest that the automated extraction may primarily capture the WDL, highlighting the need for further investigation into the physical significance of indicators identified by automated methods.
This work is supported by the Portuguese Fundação para a Ciência e Tecnologia, FCT, I.P./MCTES through national funds (PIDDAC): UID/50019/2025, UIDB/50019/2020 (https://doi.org/10.54499/UIDB/50019/2020) and LA/P/0068/2020 (https://doi.org/10.54499/LA/P/0068/2020). The work is a contribution to the CREST project, funded by FCT through Grant 2022.05392.PTDC (doi:10.54499/2022.05392.PTDC). Authors also recognize the support of national funds through FCT, under the project LA/P/0069/2020 (doi:10.54499/LA/P/0069/2020), granted to the Associate Laboratory ARNET, and UID/00350/2020 (doi:10.54499/UIDB/00350/2020) granted to CIMA.
How to cite: Vaz, A., Neves Silva, M., Valverde, F., Taborda, R., Nobre Silva, A., Santos, J., and Costas, S.: Shoreline evolution of the Gulf of Cadiz through manually digitized and automated extraction methods, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17681, https://doi.org/10.5194/egusphere-egu25-17681, 2025.
The Adriatic Sea, located in the northeastern Mediterranean basin, is well representative of processes and pressures that typically affect mid-latitude coastal seas.
The Adriatic Ensemble (AdriE), a multi-decadal, kilometre-scale ocean model, has recently been developed to describe ocean processes in the Adriatic Sea under a severe (RCP8.5) climate scenario extending to the end of this century. Addressing 3-D circulation and thermohaline dynamics within the Regional Ocean Modelling System (ROMS), AdriE consists of 6 climatic runs encompassing the period from 1987 to 2100 in a RCP8.5 scenario forced by the SMHI-RCA4 Regional Climate Model, driven by as many different General Climate Models made available within the EURO-CORDEX Initiative. In the present contribution we complement eulerian and lagrangian analysis techniques to investigate how climate change will affect the main hydrodynamic processes in this basin, with particular reference to key features for this area such as dense water production, pollutant transport, and ecological connectivity.
This work lays the foundation for a deeper interdisciplinary assessment of future scenarios in the region and the development of potential management strategies.
How to cite: Bonaldo, D., Bongiorni, L., Carniel, S., Colucci, R., Denamiel, C., Ghezzo, M., Pesce, A., Pranić, P., Raicich, F., Ricchi, A., Sangelantoni, L., Vilibić, I., and Vitelletti, M. L.: Circulation patterns in the Adriatic Sea under a severe climate change scenario: projections from the AdriE ensemble., EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19510, https://doi.org/10.5194/egusphere-egu25-19510, 2025.
The N2 fixation and primary production rates were measured simultaneously using 15N2 and 13C incubation assays in the northern South China Sea influenced by the Kuroshio intrusion (KI) seasonally. The degree of KI (KI index, range from 0 to 1) was assessed by applying an isopycnal mixing model. The water column integrated N2 fixation and primary production for stations with KI index larger than 0.5 were 463 ± 260 μmol N·m−2·day−1 and 62 ± 19 mmol C·m−2·day−1, respectively, significantly higher than those for stations with KI index lower than 0.5 (50 ± 10 μmol N·m−2·day−1 and 28 ± 10 mmol C·m−2·day−1, respectively). Trichodesmium was the dominant diazotroph at stations with KI index larger than 0.5, with 2 orders of magnitude higher nifH gene abundance than that at stations with KI index lower than 0.5. However, the highest N2 fixation rates were found in waters with moderate KI index around 0.6, suggesting that frontal zone mixing might stimulate N2 fixation. Our results demonstrated that diazotrophs (mainly Trichodesmium) were tightly associated with the KI, which modulated the biogeographic distribution of N2 fixers. In summary, we found the transportation of Trichodesmium by KI, then, we quantified the fraction of KI and N2 fixation rates in the northern South China Sea. The results suggested that KI generated a new biogeographic regime which could significantly influence the carbon and nitrogen cycles far away from the main stream.
How to cite: Lu, Y.: Biogeography of N2 Fixation Influenced by the Kuroshio Intrusion in the South China Sea, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20220, https://doi.org/10.5194/egusphere-egu25-20220, 2025.
Posters virtual: Wed, 30 Apr, 14:00–15:45 | vPoster spot 4
EGU25-3582 | ECS | Posters virtual | VPS18
Geochemical characterization of coastal sediments: a preliminary study of seasonal variations at Lido degli Estensi (Ferrara, Italy)Wed, 30 Apr, 14:00–15:45 (CEST) | vP4.9
This study is part of a doctoral research project aimed at characterizing coastal sediments in relation to the presence of microplastics and marine litter. Within this framework, the present research seeks to establish an up-to-date knowledge base regarding the geochemical characterization of sediments across different seasons along the Ferrara coastal area, specifically at Lido degli Estensi (Ferrara, Italy). The objective is to identify potential vulnerabilities and/or critical aspects related to environmental pollution that require further investigation. Building upon the methodology of Aquilano et al. (2023) and adapting it to the experimental requirements of the current study, a research area was selected at Lido degli Estensi, outside zones allocated for tourism-related public concessions. This site is located on the southern side of the Porto Garibaldi navigation channel (Comacchio municipality, Ferrara), in a coastal section experiencing accretion due to the construction of artificial jetties at the port-channel entrance. These jetties trap sediment transported from the south as a result of longshore drift. Given the beach's width (approximately 150 m), a cross-shore profile was divided into five zones based on specific geomorphological characteristics: swash zone, lower backshore, upper backshore, dune scarp, and dune. Along this beach profile, variations in carbonate content, major oxide composition, and heavy metal concentrations were investigated across different seasons using eight sampling points per season. To evaluate sediment quality in terms of heavy metal contamination, the following indices were employed: Enrichment Factor (EF; Reinmann and De Caritat, 2005), Geoaccumulation Index (Igeo; Buccolieri et al., 2006), Contamination Factor (CF; Loska et al., 2004), and Pollution Load Index (PLI; Ferreira et al., 2022). Furthermore, heavy metal concentrations detected in the samples were compared with the limits established by current Italian legislation (Legislative Decree 152/06). This study was conducted as part of the ECS_00000033_ECOSISTER project, funded under the National Recovery and Resilience Plan (NRRP), Mission 04 Component 2 Investment 1.5 – NextGenerationEU (Call for Tender No. 3277, dated 30/12/2021).
How to cite: Buoninsegni, J., Marrocchino, E., Tassinari, R., Tessari, U., and Vaccaro, C.: Geochemical characterization of coastal sediments: a preliminary study of seasonal variations at Lido degli Estensi (Ferrara, Italy), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3582, https://doi.org/10.5194/egusphere-egu25-3582, 2025.
EGU25-434 | ECS | Posters virtual | VPS18
Inputs of Terrestrial Material, Kaolin and Ash into Coastal Patagonian Waters and their Effects on the Attenuation Coefficient of the Chubut River Estuary (Argentina)Wed, 30 Apr, 14:00–15:45 (CEST) | vP4.10
Climate Change is expected to increase the intensity and frequency of extreme rainfall events in the coastal areas of Patagonia (Southwest Atlantic Ocean, SWAO). These events carry heavy loads of terrestrial materials and nutrients, and minor components such as kaolin and ash, into coastal areas through riverine inputs. The Chubut River estuary was used a reference coastal ecosystem in the SWAO. In its lower course, the river is diverted into irrigation channels that supply water for agricultural activities. These channels are open from spring to early autumn, increasing the runoff of terrestrial material, and are closed during the rest of the year. Furthermore, kaolin mines are located in the upper course of the river and ash deposition coming from volcanos have been registered. A monitoring of terrestrial material of the Chubut River estuary was conducted and the attenuation coefficients of the different components were evaluated, including terrigenous material, kaolin, and ash. The findings show that the terrestrial material, estimated as dissolved organic carbon (DOC), doubles during rainfall conditions and when irrigation channels are open. During extreme rainfall events, DOC concentrations increased by up to fivefold compared to normal conditions, being the main attenuator in the river. This resulted in a PAR attenuation coefficient variable between 1.3 m-1 under baseline conditions (closed channels, no rainfall) to over 8 m-1 following extreme rainfall events in the outer regime (seawater side) of the estuary. Further monitoring of the different under-studied estuarine components in the SWAO and their effects on the attenuation coefficient is crucial for primary productivity studies.
How to cite: Vizzo, J. I., Helbling, E. W., and Villafañe, V. E.: Inputs of Terrestrial Material, Kaolin and Ash into Coastal Patagonian Waters and their Effects on the Attenuation Coefficient of the Chubut River Estuary (Argentina), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-434, https://doi.org/10.5194/egusphere-egu25-434, 2025.
