ICG2022-12

The gravel barrier spit of the Sillon de Talbert (North Brittany, France) is a single-ridge swash-aligned barrier stretching over 3.5 km long and it is composed of a volume of sandy-gravel sediments of 1.23 10⁶ m³. Based on annual topomorphological surveys, the morphosedimentary evolution of the Sillon de Talbert was analyzed over the period 2002-2019. The results shown that the barrier spit is driven by both longshore and cross-shore dynamics. However, since cross-shore sediment transfers are dominant comparing to longshore sediment, respectively 430,000 m³vs 52,000 m³. For the last 80 years (1930-2010), the median section of this barrier spit has displayed an average landward migration rate up to –1.2 m.yr^-1. However, this barrier retreat rate has increased for the last fifteen years (2002-2017), reaching –2 m.yr^-1. This evolution of the Sillon de Talbert for the last decades led us to conduct a higher frequency (weekly to bi-weekly) morphological survey based on beach profile measurements along two radials. It was also based on tide and offshore and shallow wave records using modeling (WW3) and OSSI pressure sensor. By increasing the frequency of measurements, the objective was to record the impact of each storm on the morphological evolution of the barrier. It was also a question of better understanding the hydrodynamic functioning modalities involved in the measured morphological changes. Finally, the storm impact scale model of Orford and Carter (1982) was tested using these field measurements. The results show a barrier retreat of –23 to –30 m (i.e., –3.3 to –4.3 m.y^-1) over the 7-year survey (Sep 2012-Dec 2019). This retreat is related to microscale (10⁰ yr) morphogenic events combining storm wave and high spring tide. Over 87% to 90% of the barrier retreat is due to three significant events (February 1-2, 2014, February 9, 2016, and January 3, 2018). The storm impact scale model of Orford and Carter (1982) is tested using the flow depth (O_d,q) overtopping the crest of the barrier (B_h). Flow depth is thresholded by taking into account the morphological response of the barrier in order to define regimes corresponding to overtopping, discrete overwash, and sluicing overwash. While the Orford and Carter model is generally successful in reproducing the morphodynamic evolution of the Sillon de Talbert, this study shows that the wave energy flux (F) must be considered as an additional parameter in order to improve the fit of the model, so far as it contributes in some cases to change the morphodynamic regime. Thus, the wave energy flux constitutes a key component in the quantification of the water flow across the barrier (O_d,q) corresponding to the hydrodynamic forcing of the model, which becomes (O_d,F).

How to cite: Suanez, S., Stéphan, P., Floch, F., and Houron, J.: Overwashing and rapid retreat of the gravel spit barrier assessment based on the Orford and Carter (1982) storm impact scale model, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-254, https://doi.org/10.5194/icg2022-254, 2022.

The morphodynamic response of coastal sedimentary barriers to sea level changes is determined by a multitude of factors that range from dynamic forcing by waves and currents, sediment type and supply and their complex interaction through morphodynamic process-response mechanisms. These factors and mechanisms are significantly influenced or even controlled by the underlying geological framework, which remains mostly disregarded when modelling decadal to centennial barrier evolution. As sea level rises and barriers migrate landwards, the shoreline is transgressed and the shoreface is subjected to wave ravinement (erosion and scour by waves along the shoreface). The stratigraphic surface created by wave ravinement becomes an important geological control, as it defines the basal surface over which transgressive shoreface deposits accumulate.

In this work, we explore a variety of geophysical datasets obtained from multibeam and shallow sub-bottom seismic surveying in diverse coastal areas, and model shoreface profiles based on sediment type and dominant sediment transport processes to investigate the significance of wave ravinement surfaces in the morphodynamic state of contemporary shorefaces and discuss the implications for barrier evolution. Our results demonstrate that in many cases the modern shoreface closely mirrors the slope and topography of the wave ravinement surface, even in contexts of abundant sediment supply. This reflects depositional patterns that preferentially follow the antecedent shoreface topography. The dependence of the modern shoreface on the underlying surfaces implies that contemporary shoreface morphodynamic state and large-scale coastal behavior are at least partially controlled by antecedent wave ravinement. Likewise, the future evolution of coastal barriers under accelerated sea level rise will be at least partially controlled by the geological framework of the coastal area to be transgressed and the extent to which future wave ravinement is effective in modifying the shoreface configuration. This work highlights that progress in understanding and predicting barrier response to future sea level rise requires the explicit consideration of the geological framework, including the configuration of significant stratigraphic surfaces.

How to cite: Loureiro, C., Green, A., and Cooper, A.: Geological controls on shoreface morphodynamic state and implications for coastal barrier evolution, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-379, https://doi.org/10.5194/icg2022-379, 2022.

Storms and storm surges could increase their impact on rocky coasts in the next years due to global warming. In recent years, the study of boulders moved by storm waves seems to have played an important role. A key indicator that can follow extreme storm events on rocky shores includes coastal boulders detached from the bedrock. These deposits became in focus of a several studies since play a significant role in coastal hazard assessment. First studies regarded deposits of boulder related to tsunami events, but recently many sites with large clasts related to storm waves have been discovered, also in semi-enclosed shallow basin, such as the Adriatic Sea, in the Mediterranean area.

In this study we widened the mapping of boulders recently studied at Premantura promontory (southern Istria, Croatia) in order to better assess the role of coastal morphology in boulder sedimentation. In particular, we present and discuss the role of boulder deposits in several islets close to the promontory, also considering that at the island of Sekovac boulders are definitively of artificial origin and later moved by extreme waves.

The investigation of the position, size, and mass of each boulder was created through the application of Uncrewed Aerial Vehicle Digital Photogrammetry (UAV-DP) and Structure from Motion (SfM) technique, defining the GCPS points, and providing high-resolution data.  

Boulders were identified and categorized using UAV-DP products, and their validation was done through the comparison with outputs of traditional geomorphological investigations such as field surveys including direct axis measurement and the use of Google Earth images for boulder mapping.

How to cite: Vaccher, V., Devoto, S., Mantovani, M., Korbar, T., Macovaz, V., and Furlani, S.: Extreme Wave Boulders at Premantura: the stamp of the storms in the northern Adriatic Sea, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-462, https://doi.org/10.5194/icg2022-462, 2022.

The continental shelf region West of Ireland contains a rich geomorphic and sedimentary record of glacially-influenced marine processes, including ice sheet extension from Ireland into the Atlantic during the last cold period (Late Midlandian glaciation in Ireland).  Intricate sets of curvilinear ridges of varying form and scale across the outer shelf have been recently associated with grounded glacial ice withdrawal from maximum limits.  The region lies at the southern limit of the glaciation of the Atlantic margin of northwest Europe, and thus occupies an important position in palaeoglaciological reconstructions.  Studies of seabed morphology west of Ireland have been greatly enhanced by exhaustive multibeam bathymetric coverage of the Irish National Seabed Survey, associated sediment sampling and high-resolution shallow seismic profiles; in places, these have been complemented by the use of industry 3D seismic data cubes to visualise the internal structure and geomorphology of glacigenic ridges and large-scale sediment aprons. This paper presents observations from combined sediment ground truthing, high-resolution geophysical and bathymetric data, focusing on the Porcupine Bank, Saddle and Inner shelf areas of the Western Irish Shelf, in order to examine available models of shelf glaciation.

How to cite: McCarron, S., Praeg, D., Monteys, X., Craven, K., and Thébaudeau, B.: Geomorphology of the continental shelf west of Ireland, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-65, https://doi.org/10.5194/icg2022-65, 2022.

During the Last Glacial Maximum, a large part of the eastern Adriatic shelf was exposed, resulting in a distinctive landscape. With postglacial sea level rise, many coastal landforms were drowned and filled with Quaternary sediments. Here, we describe the geomorphological features and sedimentary processes shaping the submerged landscape of the Prokljan Lake, a part of the karst Krka River Estuary (KRE). KRE is a 24 km long microtidal salt-wedge estuary located in central Dalmatia. The estuary extends to the last active tufa waterfalls, Skradinski buk, which is a part of the National park Krka. High resolution multibeam bathymetry, sub-bottom profiling and side-scan sonar were used to determine the evolution of the seafloor morphology of the estuary shaped by postglacial sea level variability. The dataset covered approx. 6 km² of a shallow seabed area with depths of up to 25 m. The observed paleolandscape is unique and well preserved, consisting of the former terrestrial landforms. The most prominent feature is a 3.5 km long complex tufa barrier system, with adjoining basins, at depths ranging from 5 to 20 m bsl. Other distinct features are numerous carbonate mounds and incised river valley. These features are covered or partially filled with fluvial/lacustrine and estuarine sediments. In addition, 36 grab samples and video observations provided ground truth for sediment determination and classification of the estuarine bottom, while 5 piston sediment cores enabled correlation with seismic data. Based on analyzed landform morphology and sediment stratigraphy, the flooding of the river canyon due to sea level rise in the Prokljan Lake started at approx. 10000–9500 y BP and the formation of the estuary at approx. 7500 y BP. The results of ongoing study provide a better understanding of past environments in this submerged system related to the postglacial sea level rise.

This study was supported by the Croatian Science Foundation Project “Sediments between source and sink during a late Quaternary eustatic cycle: the Krka River and the Mid Adriatic Deep System” (QMAD) (HRZZ IP-04-2019-8505).

How to cite: Šenolt, N., Hasan, O., Miko, S., Brunović, D., and Ilijanić, N.: Submerged karst landscape of the Prokljan Lake (Krka River estuary in the central Dalmatia), 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-189, https://doi.org/10.5194/icg2022-189, 2022.

Rip currents occur on many wave-exposed coasts worldwide, expressed as both morphological and hydrodynamic elements of the nearshore circulation system (surf zone). They comprise of onshore mass transport over the bars, longshore currents in the feeder channels and relatively narrow and concentrated offshore flows in the rip channel. They are variable in space and time due to changes in incident wave conditions and nearshore morphology. These dynamic conditions often threaten the safety of the beach, beachgoers or the infrastructure.

Despite the low to moderate wave energy environment of the Romanian Black Sea coast, the relatively high potential of rip currents formation, the rapid hydrodynamical and morphological change (e.g. minutes to months) of the beach state, the very little knowledge of rip currents distribution and behaviour and the very low public’s awareness related to rip currents associated dangers make a deadly combination each year on many beaches.

We present the first results about rip currents distribution, characteristics, and dynamics along the Romanian coast, which is, to our knowledge, also a first run for the entire Black Sea basin. The analysis of rip currents spatial distribution revealed that more than 50% of the Romanian touristic beaches (18 out of 35 sectors – totalizing 28.6 km in length) are affected, under certain conditions, by various types of rip currents. Most of them were identified on beaches with 3D sandbar morphology, the dominant type being represented by channel rip currents.

The most affected sector is the Eforie Nord beach (Techirghiol Barrier), where 10 individual rip currents are constantly developing along 1-km area, associated with the largest number of deaths and rescues during the summer season each year. A field experiment during low-energy wave conditions (offshore average Hs between 0.35 and 0.55 m; average periods between 3.6 and 4.5 seconds; propagating from ENE) in October 2021 highlighted the circulation patterns and dynamics of three of these rip currents. Drifters and ecological dye deployments along this area, complemented by UAV surveys and video camera footage, revealed both ‘circulatory flow’ and ‘exit flow’ circulation regimes, with alongshore feeding channels developing between adjacent rips. The average surface velocities registered during drifters’ deployments ranged between 0.34 and 0.43 m/s, with maximum instantaneous values exceeding 1 m/s. These circulatory patterns and surface flows were then successfully reproduced for similar hydrodynamic conditions by employing a preliminary modelling framework (Delft3D) for this area.   

We hope that our results will raise the public’s awareness of rip currents and their related hazards on the Romanian Black Sea coast to reduce beach management and lifeguarding costs, risks to public health and safety and losses of human lives.

How to cite: Tatui, F., Zainescu, F., Miron, F., Vespremeanu-Stroe, A., and Mateescu, R.: Rip currents on the Romanian Black Sea coast – distribution, characteristics and dynamics, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-375, https://doi.org/10.5194/icg2022-375, 2022.

The Red Sea is an isolated active rift in the latest stages of continental rifting. The basin is close to the transition to the following stage of oceanic seafloor spreading. These peculiar characteristics make it one of the warmest, most saline, and most oligotrophic marine ecosystems currently on Earth, supporting high rate of endemism of marine life from shallow to deep waters. In this work, we present a baseline description of the mesophotic and deep-sea environment from the Saudi Arabian continental margin of the North Red Sea and the Gulf of Aqaba with emphasis on shelf-slope transitions and shelf-edge reefs. A high-resolution acoustics dataset with coverage of 34,000 km² has been collected in the NEOM gigaproject area, from 30 to 1770 m water depth. More than 60 benthic transects have been performed using submersibles and Remote Operated Vehicle (ROV) coupled with high-resolution underwater positioning systems. Over 650 samples of sediment, benthos, and rocks were collected to characterize the benthic environment. Data from CTD casts were used to characterize the water column. Our results reveal a complex mosaic of benthic habitats, related to depth range, substrate type, continental slope morphology, water masses, and sediment delivery into the basin. Habitat composition varied along the depth gradient from the shelf break to the deep basin, with a high level of diversity in the lower mesophotic zone. Our findings allow us for the first time to characterize the diversity of benthic habitats in the NEOM area from shallow to deep waters. Here, we also provide a fundamental contribution to a better understanding of the key role of geomorphology with respect to the largerly uknown mesophotic and deep-sea habitats in the Red Sea. Finally, we propose a classification of benthic habitats valuable for management purposes, including the design of monitoring programs, for ecosystem-based management, and for documenting the effects of climate change on ecosystems in a region undergoing rapid economic development.

How to cite: Marchese, F., Purkis, S., Chimienti, G., Ouhssain, M., Shernisky, H., Terraneo, T., Peters, C., Rodrigue, M., Jones, B., Eweida, A., and Benzoni, F.: A Baseline Assessment Of Seafloor Geomorphology And Benthic Habitat Distribution Along The Neom Coast (Northern Saudi Arabia, Red Sea), 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-705, https://doi.org/10.5194/icg2022-705, 2022.

Located at the doors of the Sahara Desert, the Senegal is an allogenic river originating in the Fouta Djallon (Guinea) in the Guinean subclimate (rainfall greater than 1000mm), crosses the Sudanian (900-1000mm), and Sahelo-Sudanian (500-900mm) influences before reaching the Atlantic Ocean under Sahelian (around 350mm) climate. This terminal section of the Senegal estuary is well known for its hydroclimatic variabilities, where the interaction between continental driving forces (ITCZ movements, harmattan winds, rainfalls) and Atlantic drivers (trade-winds, local wave climate conditions) influence the estuarine hydrodynamics. Results from geochemical analysis (grain size, elemental composition (XRF)) of the sediment cores collected during the flooding and dry seasons (August 2021 and February 2022) may give a better understanding of the alternating dominance of fluvial and marine hydrodynamics (including swells) dominance in the Senegal estuary over the recent period. Coupling this analysis with earth observation products may highlight the seasonality of the Langue Barbarie (sand spit) accretion/erosion cycles according to local variations such as bathymetry, wave climate variations, river discharges and human infrastructures.

How to cite: Dramé, A. B., Burningham, H., and Sall, M.: Contribution of fluvial and marine sediment to the Senegal estuary (West Africa): a geochemical evaluation, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-111, https://doi.org/10.5194/icg2022-111, 2022.

The Hiroshima Delta is formed at the mouth of Ota River in western Japan. We conducted the grain analyses and radiocarbon dating of uppermost deposit of delta, along with detailed geomorphological mapping.  Grain analyses showed that particles in the uppermost part are of granitic origin, while lower part are of accretionary prism origin. Iron slag particles are confirmed in the uppermost part. Radiocarbon ages suggest they deposited after the 15th century. Geomorphological features of the lower Ota River plain show the development of sandy deposits. We concluded that the iron-sand mining and smelting in the upper reach caused rapid growth of the Hiroshima Delta.

How to cite: Kubo, S., Sadakata, N., Kumahara, Y., Iwasa, Y., and Matsumoto, A.: Anthropogenic effect on the formation of Hiroshima Delta -Focusing on historical iron-sand mining in the upper reaches, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-345, https://doi.org/10.5194/icg2022-345, 2022.

Wave-influenced deltas are morphological characterized by beach ridges disposed from different sides from the river mouth, governed by the increasing or decreasing of the proportional of high-angle waves and increasing wave asymmetry. The concept of asymmetrical evolution in a delta plain-view reveals the role of high-angle waves in a shoreline pattern, using the offshore wave approach, where the diffusivity can be positive or negative. In positive shorelines the wave angles are less that critical, and the shoreline tend to be smooth. On the other hand, if high-angles waves prevail, the coastline become unstable by the impact from ani-diffusive waves, creating a negative diffusivity shoreline. Morphological speaking, series of beach ridges normally are associated by positive diffusivity, and spits and sandwaves are typical features from negative or anti-diffusive waves high-angle waves. The east coast of Brazil present some of most representative wave-influenced deltas (São Francisco, Jequitinhonha, Doce and Paraíba do Sul) that since 1980’s several works describe the Holocene palaeogeographical evolution. In this work, we present some insights revealed by Optically Stimulated Luminescence (OSL) geochronological data, ground-penetrating radar (GPR) profiles and geomorphological characteristics, to evaluated the asymmetrical Holocene evolution of Paraiba do Sul. We collect 20 samples distributed from both sides of the river delta, to describe the geochronological evolution. In each sample site, series of GPR profiles were surveyed in a common-offset mode, varies from 200 to 450 meters. The GPR signal adjustment of units provide by electromagnetically reflectors to meters, was use three common-mid-point survey. The geomorphology was interpreted by aerophotogametric photos, obtained in 2005, with 1 meter resolution. The results showed that the Holocene evolution start after maximum relative sea-level (MRSL) ~5ka, with symmetrical pattern, i.e. with beach ridges observed in both sides of river mouth. After the MRSL the sea-level gradually decrease in altitude, and around ~2ka the morphology changes dramatically. The northern part became anti-diffusive, where series of spits emerge from sandwaves, enclosure coastal lagoons, accompanying the migration towards the north. On the other hand, the southern part experience higher prograding rates, by series of beach ridges. The migration of the river mouth toward the north, caused by oblique waves, indicate more accommodation space towards the south, filled by beach ridges formed by diffusive waves. The GPR signs reveals these differences in terms of morphostratigraphic patterns, where the beach ridges are altimetric higher than the spits, because the incorporation of aeolian sands, and overwash process and spit growth are detected in the north. The gently decrease in the altitudes in the both sides of the river mouth suggested the association with sea-level curves in Brazil, but the impact of high-angle waves describe morphological differences in the regressive barriers along Paraiba do Sul River delta.

How to cite: Borges Fernandez, G., Baptista da Rocha, T., Cadena Vasconcelos, S., and Goçalves Pereira, T.: Holocene asymmetrical evolution in wave-influenced deltas: insights from OSL, shallow geophysics and geomorphology, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-381, https://doi.org/10.5194/icg2022-381, 2022.

The Bhasan Char, a 68-km² offshore island (2021) of the Meghna Estuary, is situated in the eastern Ganga–Brahmaputra–Meghna Delta of Bangladesh. The island has gained prominence after its selection as a major relocation centre for the displaced Rohingya refugees of Myanmar.

25 images of the 2001–2021 period, pertaining to nine satellites (IRS 1D; Resourcesat 1, 2, 2A; Sentinel 1A, 2A, 2B; Landsat 5, 7) and the Google Earth repository, were used to trace the evolution and reclamation stages of the Bhasan Char. Cyclone tracks and intensities at the vicinity of island for 1970–2021 were considered to show its susceptibility to storm damage. Geological structures were also studied to assess its future stability.

The results show that the Bhasan Char was formed in 2002 with an area of 5.46 km² and it was shifted towards the southeast at a rate of 0.63 km/yr till 2007. The island became largely stable by 2012. Subsequently, rapid sedimentation was seen in its northern areas with some erosion in the south. Since 2017, 8.2 km² of the island was reclaimed to build shelters for the refugees. The Government of Bangladesh has implemented several protection measures to reduce erosion of the southern part of the island and policies to create land through sediment harvesting at its vicinity. The situation of the Bhasan Char on an active anticlinal axis aids to this endeavour. The recurrence interval of cyclonic storms (wind speed >= 62 km/hr) at the Bhasan Char is once every 3.5 years; a 2.5-km breakwater and the 2.74-m high paved embankment provide adequate protection from these.

Considering the above facts, it is concluded that the Bhasan Char is likely to remain stable in the foreseeable future and it is not unsuitable for locating rehabilitation shelters.

How to cite: Das, A. and Bandyopadhyay, S.: Evolution of the Bhasan Char Island (Meghna Estuary, Bangladesh) and its Suitability for Refugee Resettlement, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-584, https://doi.org/10.5194/icg2022-584, 2022.

Large river deltas are the among the most dynamic and complex natural systems, with a  complicated evolution which explain the relative small number of deltas which formation has been fully understood (reconstructed). However, deltas evolution is governed by a series of laws and patterns starting from their formation to the present. The aim of this study is to define the specific growth models of the Danube Delta and to discuss them in association with the other deltas of the world which share similar patterns of evolution. Thus, 7 evolutionary patterns have been identified in the Danube Delta as follows: (i) starting the deltaic units formation (as a bayhead delta around 7500 BP) before the sea-level stabilization, (ii) the preference of delta development into the deeper sectors (of the Danube bay), (iii) the river mouths of the open-coast lobes get a policyclic evolution, (iv) open-coast lobes are asymmetric and share the same evolution, (v) deltaic lobes have large (multi-secular) periods of decay despite the short-time triggering events (i.e. avulsions, sediment reduction), (vi) neotectonic subsidence reshaped the southern delta, (vii) the land-use controls the sediments discharge and impose the rhythms of delta development. Although each delta has its own particularities, certain patterns that are found in the evolution of the Danube Delta have also been found in other deltas, apparently different from the morphological point of view. The specific cases of the large Asian deltas (e.g.: Changjiang, Mekong, Godavari, Krishna, Red River) and many other from around the world (Mississippi, Rhone, Po, Kuban, Rioni) are discussed in relation with different evolutionary patterns identified for Danube. A special attention is paid to the role of human influence (via deforestation, agricultural practices, river damming and channeling) on delta formation and evolution during different historical periods, from Neolithic to modern times.

How to cite: Vespremeanu-Stroe, A., Berbecariu, A., Zăinescu, F., Tătui, F., Preoteasa, L., and Anthony, E.: On the evolutionary patterns of the large river deltas. Examples from Danube delta and other deltaic systems, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-663, https://doi.org/10.5194/icg2022-663, 2022.

How to cite: Baum, M., Kennedy, D., and McSweeney, S.: Holocene Evolution and Distribution of Large Structural Estuaries, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-713, https://doi.org/10.5194/icg2022-713, 2022.

The ongoing climate changes are determining an increase of sea-level rise with potential effects on the low-lying coasts. Future projections show the sea-level rise scenarios with an increase of about 1 m than present sea level at 2100. These scenarios are of great interest considering that low-lying coastal areas could be fully submerged with annexed damages at the socio-economic activities. This applies for the low-lying coasts particularly affected by subsidence processes, which could be attributed to the anthropogenic impact, in particular those areas influenced by well exploitations, infrastructure and resort buildings, dams and long-coast interventions. In this work, the coastal plain of Tavoliere delle Puglie (Apulia, Southern Italy) was surveyed to assess the impact of sea-level rise at 2100. The main factors considered for the assessment of sea-level rise impact are the following: future sea-level projections, high-resolution topographic data, vertical land movements (VLMs), and erosion rates. The sea-level projections were assessed through the recent climate models of Intergovernmental Panel of Climate Change 2021 for the Gulf of Manfredonia. Topographic data were obtained through Terrestrial Laser Scanner (TLS) surveys for the coastal zone of the Tavoliere delle Puglie and Light Detection and Ranging (LiDAR) for the landward areas. The VLMs were obtained through an integrated analysis between Global Navigation Satellite System (GNSS) stations and Interferometric Synthetic-Aperture Radar (InSAR) data. Erosion rates were assessed analysing the historical maps and aerial photographs and integrating them with TLS and LiDAR data. The topography at 2100 was reconstructed considering the VLM and erosion rate values in order to assess the coastal surface prone to submersion. The submersion surfaces were assessed through a mathematical model that considers the sea-level projections, erosion rates and VLM existing in specific areas. The results highlighted significant submersion in the coastal areas characterized by high land subsidence and erosion rates, with surface loss extending over 1 km landward. In this work, the modelled impact of sea-level rise highlighted the high vulnerability of touristic resorts and socio-economic activities along the coastal plain of Tavoliere delle Puglie.

How to cite: Petio, P., Scardino, G., Serpelloni, E., Refice, A., De Santis, V., Rizzo, A., Zingaro, M., Capolongo, D., Anzidei, M., and Scicchitano, G.: Sea-level rise and land subsidence of low-lying coasts: the study case of Tavoliere delle Puglie (Southern Italy), 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-176, https://doi.org/10.5194/icg2022-176, 2022.

Presently, 272 partly or completely submerged caves and pits have been recorded along the Croatian’s eastern Adriatic Sea coast. Marine conditions are found in 153 caves, anchialine in 84, whereas the others, related to submarine springs are still unclassified caves. Speleothems are found in more than 140 caves, providing potential records for reconstructing the Quaternary relative sea-level changes. Recently, phreatic overgrowths on speleothems (POS) have been discovered in the Kvarner region (eastern coast of Lošinj island). POS are carbonate incrustations that deposit around submerged speleothems and cave walls in coastal caves, where groundwater level is controlled by sea level. Since the POS precipitate at the very top of the water column, i.e. at the water-air interface, their occurrence is limited to a very narrow band of the tide-induced groundwater level fluctuation. POS can be precisely dated with U-Th as well as with radiocarbon method, and their occurrence in caves guarantees protection from weathering. The combination of their narrow occurrence, datability, and preservation makes POS excellent sea-level indicators, which have been so far reported only from five locations across the globe (Onac et al., 2012).

A POS recovered from ~1 m below the surface in Medvjeđa špilja Cave was dated by U-Th method to ~3000 years, indicating a relative sea-level stability for a few hundred years ~1 m below modern sea level. The obtained results were compared with available GIA models and other studied RSL indicators in the broader surrounding area. We expect that the collected POS data along with the information obtained from algal rims will allow a precise reconstruction of the relative sea-level changes over longer periods of time. Increasing the number of sea-level index points obtained from different markers can further contribute to our understanding on the mechanisms driving sea-level changes (climate change, hydro- and glacio-isostatic adjustment, and tectonics) along the Croatian coast.

The research of POS along the eastern Adriatic is conducted within the SEALeveL project (HRZZ-IP-2019-04-9445) funded by Croatian Science Foundation.

How to cite: Lončar, N., Miklavič, B., Faivre, S., Onac, B., Kovač Konrad, P., and Polyak, V.: First relative sea-level index points obtained from phreatic overgrowths on speleothems (POS) in the Kvarner area, Croatia, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-245, https://doi.org/10.5194/icg2022-245, 2022.

Coralligenous (C) bioconstructions include calcareous build-ups of biogenic origin that typify selected regions of the Mediterranean Sea. These peculiar habitats thrive from shallow waters (15-20 m of water depth (w.d.) up to the limit of the mesophotic zone, and they formed since the Holocene transgression. They are from few to tens of meters large, displaying variable lateral continuity and thickness. Peculiar C outcrops are present offshore Marzamemi (southeastern Sicily, Ionian Sea). Their extension and distribution across the shelf were investigated within the project CRESCIBLUREEF - Grown in the blue: new technologies for knowledge and conservation of Mediterranean reefs. We produced a new 17 km2 high-resolution bathymetric map using a R2-Sonic 2022 system, ground-truthed by ROV video inspections. From a geomorphological point of view, the shelf is typified by four distinct marine terraces. Climate change and tectonic uplift are the dominant forcing mechanisms responsible for the formation of long and narrow terraced landforms in a variety of geomorphic settings; and marine terraces are largely used to reconstruct the Quaternary glacial and interglacial climates. The coupling of documented uplift rate in this region (ca. 0.2 mm/yr since the Tyrrhenian time) and the evidence reported in literature for late Quaternary relative sea-level curves shows a good correlation between the distribution of C outcrops and local, short stasis of sea level transgression periods, culminated with the rapid Flandrian transgression. C outcrops are mainly spread over the first and last terraces at two specific depth ranges: from 36 to 42 m of w.d., and from 86 to 102 m of w.d., respectively. Settlement and growth were mainly favored by a low sedimentation regime. Indeed, lowstand stages were likely characterized by erosional forces. This is particularly noticeable in the middle of our study area, where we have a paleo-incision typified by peculiar erosional features we were able to map. The role of the inherited continental shelf landscape in creating favorable substrate for the settlement and growth of C during the Holocene is here investigated.

How to cite: Varzi, A. G., Fallati, L., Savini, A., Bracchi, V. A., Bazzicalupo, P., Rosso, A., Sanfilippo, R., Bertolino, M., Muzzupappa, M., and Basso, D.: Late quaternary evolution of the continental shelf offshore Marzamemi (southern Sicily, Ionian Sea) and implications on the distribution of associated mesophotic bioconstructions, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-272, https://doi.org/10.5194/icg2022-272, 2022.

The Western Iberian passive margin is under compressive tectonic reactivation resulting in spatial and temporal variations in surface uplift. This uplift can be quantified in coastal settings using staircases of wave-cut platforms developed onto rocky headlands. This study focuses on two marine terrace staircases of central Portugal: Cape Raso (west of Lisbon) and Cape Espichel (western Arrábida mountain chain). Geomorphic and stratigraphic analyses identified four marine terraces above sea level at Cape Raso area and twelve at Cape Espichel. ESR and pIRIR dating were used to develop a chronological framework for the staircases, from which uplift rates were calculated.

Using the interaction between the global mean sea-level elevations in the Quaternary and the local uplift rate (Roberts et al., 2013) the marine terraces were correlated with Marine Isotope Stages (MIS). At Cape Raso, Tm1 (+38 m) corresponds to MIS 17 (712-676 ka), Tm2 (+34 m) corresponds to the MIS 15 (621-563 ka) and was reworked during the MIS 11 (399-408 ka), Tm3 (+ 22 m) correlates with MIS 13 (533-478 ka) and was reworked during the highstand of MIS 9 (330-316 ka) and Tm4 (+9 m) correlates with MIS 7 (243 -191 ka). At Cape Espichel, a correlation was found between the relative sea-level elevations of the eight lowest terraces with several MISs (MIS 5 until MIS 17). The correlation becomes unclear for terraces older than MIS 17, translating into an apparent decrease in uplift rate towards older times. Either in Cape Raso or Espichel, the terrace staircases do not correlate in all cases with sea level high stands sequentially. For instance, the palaeoshoreline elevation of MIS 11 is higher than the palaeoshoreline of MIS 13. This suggests that marine terraces have been formed by superposition of multiple sea-level fluctuations in a long-term uplift context, but with an uplift rate low enough to allow the reworking of older shorelines during subsequent MISs.

At Cape Raso, the dating of Tm2 correlated with MIS 15 allows for an estimation of an uplift rate of ~0.07 m/ka for this coast, seemingly decreasing over the last ~125 ka. At Cape Espichel, the chronological framework of Tm5 and Tm6 allows associations with MIS 15 and MIS 11, respectively. The estimated mean uplift rate from MIS 5e to MIS 17 was ~0.14m/ka. For times older than MIS 17 (up to ca. 3.7 Ma) the uplift rate was lower than during the last ~125 ka (~0.04 m/ka). The present elevations of the late Zanclean wave-cut platform, represented by the Raso Cape Platform (~100 m) and the Cape Espichel (up to ~220 m) platforms, further express the differential uplift between the study areas for the last ~3.7 Ma.

References:

Roberts, G.P., Meschis, M., Houghton, S., Underwood, C., Briant R.M., 2013. The implications of revised Quaternary paleo-shoreline chronologies for the rates of active extension and uplift in the upper plate of subduction zones. Quaternary Science Reviews 78, 169-187.

How to cite: Antunes Martins, A., Porto Gouveia, M., Proença Cunha, P., Gomes, A., Falguères, C., Voinchet, P., Stokes, M., Caldeira, B., Cabral, J., Buylaert, J.-P., S. Murray, A., Bahain, J.-J., Figueiredo, S., and Yang, P.: Marine terrace staircases of western Iberia: uplift rate patterns from rocky limestone coasts of central Portugal (Cape Espichel and Raso), 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-358, https://doi.org/10.5194/icg2022-358, 2022.

The Punta Licosa promontory is located in the northern part of Cilento coast in the southern Tyrrhenian basin. In this attractive landscape, depositional and erosional landforms, located both above and below sea level, can be considered a challenge of scientific interest to reconstruct the geomorphological evolution under the control of sea-level changes occurred during the late Quaternary period. The geomorphological study of this area took into account data provided by literature, aerial photo interpretation, GPS measurements, geological surveys, GIS elaborations of high-resolution DTMs, bathymetric data and high-resolution orthophotos taken by unmanned aerial vehicles. The detected landforms were grouped based on morphogenetic and morphoevolutive criteria, paying particular attention to several orders of shore platforms recognized both in the emerged and submerged sectors. Thanks to their analysis, the response of this coastal system to sea-level stands and changes since MIS 7 was detailed reconstructed. According to our reconstructions, three different phases of sea-level stand were identified along the emerged coastal sector. The first sea-level stand is documented by the inner margins of shore platform remnants detected at 9.5 m MSL, ascribed to the MIS5e highstand, according to several authors. The second sea-level stand is poorly testified in our study area but is chronologically well-constrained at Cala Infreschi (southern part of Cilento promontory) thanks to aeolian sands located at 2.7 ± 0.1 MSL and dated by Bini et al. (2020) to 109.1 ± 0.8 ka BP (MIS5d). The third sea-level stand was extensively mapped along the entire coastal sector at about 4.5 m a.s.l. and dated by Iannace et al. (2001) to 102 ± 4 ka BP (MIS5c). The heights at which the above-mentioned sea-level stands are located suggest that the study area gained substantial tectonic stability since MIS 7. This deduction was the starting point of the second research phase in which the morphometric analysis of bathymetric data, coupled with a reinterpretation of literature data, provided clear evidence of sea-level stands occurred since the post-glacial sea-level rise and recognized at depths of about -43/-56 m, -16/-20 m and -8/-10 m MSL. Particular attention was paid to the wide platform formed after the Holocene slowdown in sea-level rise positioned between - 6 m MSL and the present MSL. By comparing our spatial analysis of this landform and the GIA models calculated for the southern Tyrrhenian area, we established that this platform was shaped during the last 6500 years, experiencing retreating rates of 0.030 m/yr, 0.046 m/yr, and 0.039 m/yr in the northern, central, and southern sector of Cilento promontory, respectively. In conclusion, our approach demonstrates the effectiveness of a multi-temporal geomorphological analysis, in order to reconstruct the coastal response to RSL variations in stable contexts along high rocky sectors.

References

Bini, M., et al. "An end to the Last Interglacial highstand before 120 ka: Relative sea-level evidence from Infreschi Cave (Southern Italy)." Quaternary Science Reviews 250 (2020): 106658.

Iannace, A., et al. "The OIS 5c along Licosa cape promontory (Campania region, southern Italy): morphostratigraphy and U/Th dating." Zeitschrift fur Geomorphologie 45.3 (2001): 307-320.

How to cite: Tursi, M. F., Mattei, G., Caporizzo, C., Del Pizzo, S., Minervino Amodio, A., Rosskopf, C. M., and Aucelli, P. P. C.: Late Quaternary sea-level variations and geomorphic coastal responses in southern Italy: the Punta Licosa case study (Campania region), 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-467, https://doi.org/10.5194/icg2022-467, 2022.

Marguerite Bay is located in the South-central part of the Antarctic Peninsula. The archipelago of the bay is rich in terms of coastal geomorphological features such as raised beach ridges as geomorphic markers of relative sea-level change. In this study, we focussed on Horseshoe Island and Calmette Bay where raised beach ridge levels were already identified. We employed a topographical survey to define the elevation and cosmogenic 10Be surface exposure dating method to define the age of major paleo shoreline levels. In the Gaul Cove located eastern coast of the Horsehoe Island we identified three major topographical levels and in the Calmette Bay four major topographical levels that raised beach ridges cluster. Paleoshoreline levels at 1, 7, 12, and 16 m asl yield 0.3 ka, 1.59, 3.31, and 3.33 kyr BP, respectively, in the Gaul Cove when we remove 2.9 ka inheritance that we obtained from the modern shoreline samples. However, shoreline levels are higher and ages are older on the Calmette Bay coast. Major levels are at 5, 8, 17, 27 and 35 m asl, and their cosmogenic 10Be ages yield 3.46, 3.19, 5.3, 5.9, and 7.2 kyr BP, respectively, in the Calmette Bay when we remove 1.94 ka inheritance that we obtained from the modern shoreline samples. Since the present sea level was eustatically stabilized at approximately 7 kyr BP we estimated uplift rates according to modern sea level. The uplift rate in the Horseshoe Island yields 5.53±0.88 mm/yr in the last 3.3 kyr, and in the Calmette Bay, it yields 4.52±0.40 mm/yr in the last 7.2 kyr.This study was carried under the auspices of Turkish Republic Presidency, supported by the Ministry of Science, Industry, and Technology, and coordinated by Istanbul Technical University (ITU) Polar Research Center (PolReC) and Turkish Academy of Science. 

How to cite: Yildirim, C., Ciner, A., Sarikaya, M. A., Aslan, A. E., Yavasoglu, H., and Hidy, A. J.: Cosmogenic Surface Exposure (10Be) Dating of Raised Beach Ridges in Marguerite Bay, Antarctic Peninsula: Implications for Relative Sea Level Curve, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-679, https://doi.org/10.5194/icg2022-679, 2022.

This study provides a detailed geomorphological study of the Peniche Peninsula, located in westernmost Iberia, a resistant rocky limestone headland subjected to high energy Atlantic Ocean coastal processes. We have used field mapping, surveying, sedimentary facies analysis, geochronology (electron spin resonance [ESR]; U-Series), but also identification of fossils and lithic artefacts, in order to: 1) reconstruct styles and timing of paleoenvironmental changes, 2) correlate to Marine Isotope Stages (MIS), and 3) quantify coastal uplift rates during the Quaternary. The marine terrace deposits, comprising calcite cemented conglomerates and siliciclastic sandstones, sometimes capped by travertines, were studied in detail along the SW sector of the peninsula, at the Furninha Cave site.

The mapping (1/10,000 scale) and dating results obtained allow to identify several marine levels and to correlate them to MIS’s: 1) a culminant wave-cut platform at 29-33 m (above mean sea level) (Pm), with a probable age of 3.7 Ma; 2) a wave-cut platform at 24-28 m (Tm1), dated as 883±120 ka, probably correlated with high sea level conditions spanning ca.1000-790 ka (MIS25-19); 3) a wave-cut platform at 19-21 m (Tm2), with a beach conglomerate and sandstone, dated as 707±32 ka and correlated to 790-680 ka (MIS17); 4) a wave-cut platform at 14-16 m (Tm3), with a beach conglomerate and sandstone, and capping travertine, probably recording aggradation during 620-460 ka (MIS15-13) (ESR: 598±160, 563±63, 490±44 ka; U-series: >620 ka); 5) a wave-cut platform at 11-13 m (Tm4), with beach conglomerate and sandstone followed by travertine, dated as 315±48 ka, probably recording 430-275 ka (MIS11-9); 6) a wave-cut platform at 6-9 m (Tm5), with beach conglomerate, sandstone and travertine, dated as 288±53 ka, probably spanning 290-180 ka (MIS7); 7) a wave-cut platform at 4.0 m (Tm6), probably spanning 125-85 ka (MIS5); 8) aeolian sand units, respectively, of Late Pleistocene and Holocene age; 9) modern beach sediments, ranging from sands to boulders.

A long term Plio-Quaternary corrected uplift rate of 0.004-0.006 m/ka is obtained using the Pm level as a key geomorphic marker (eustatic level = +10-20 m). In contrast, for the last ~1 Ma the inset Pleistocene marine terrace levels (Tm1-Tm6) indicate apparent short-term uplift rates between 0.02 and 0.05 m/ka (means of 0.03 to 0.04 m/ka) and corrected short-term uplift rates between -0.05 and 0.05 m/ka (means of -0.02 to 0.05 m/ka).

This study demonstrates that the Quaternary compressive reactivation of the Western Iberian Margin has determined coastal low to moderate uplift rates; active tectonics play an important role in the geomorphic expression and distribution of Pleistocene marine terraces, recording vertical ground motions (uplift/subsidence) superimposed onto global sea-level oscillations.

How to cite: Gouveia, M., Cunha, P., Martins, A., Falguères, C., Voinchet, P., Gomes, A., Bahain, J.-J., Stokes, M., Pereira, T., Figueiredo, S., Shao, Q., Tombret, O., and Yang, P.: Plio-Quaternary coastal uplift along the western Iberian margin: insights from dated marine terraces (Peniche, central Portugal), 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-253, https://doi.org/10.5194/icg2022-253, 2022.

Sand coastal landforms occur commonly around the world, and the western, southern and eastern Baltic Sea coast is one of them. The latter is rich in nearly parallel and rhythmic beach-ridges, which are related with the Holocene Baltic Sea history and serve as an archive of storminess and climate and sea level changes in the past. Sand sediment of beach-ridges in Gulf of Riga (Latvia) have not gained an attention in these terms, and thus were sampled and subjected to sediment particles (grains) analyses in a microscale. Scanning electron microscopy (SEM) has a great potential in determining the depositional environment and was applied to check out the grain shape, its surface, type of microtextures and their frequency. Parallel with this, an automated particle shape analyser was used to measure thousands of particles in dozen directions. Based on this, several grain parameters were produced, which provide an information about duration and type of sediment transportation. Combination of these two methods followed by the statistical methods led to robust insight in the sediment particle characteristic and past storm detection.

This study was supported by the Mobilitas Pluss Returning Research Project MOBTP34 “Time-transport-storminess – an experimental geological study of coastal system” funded by the Estonian Research Council in years 2017–2018, and the Research University – Initiative of Excellence: the Emerging Field “Global Environmental Changes” at Nicolaus Copernicus University in Toruń.

How to cite: Kalinska, E. and Weckwerth, P.: Looking for a storm in the beach-ridges: a microscale perspective from eastern Baltic, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-86, https://doi.org/10.5194/icg2022-86, 2022.

In tropical environment, studies concerning pocket beaches dynamics are scare compared to open sandy beaches. Consequently, seasonal morphological adjustment of pocket beaches is still poorly understood and seasonal evolution rates are poorly quantified in these specific environments. Mayotte, a coral reef-fringed island in the Mozambique channel, western Indian Ocean, is characterised by a highly indent shoreline, submitted to important seasonal weather and sea variation conditions (monsoon and trade wind). Since 2018, Mayotte has undergone a seismic crisis characterized by clustered epicentres located offshore between 10 and 50 km east of the Main Island (Grande-Terre). This sismo-volcanic activity caused rapid subsidence and eastward movement of up to 20cm, leading to a relative sea level rise, the hydro-geomorphological consequences of which are the subject of investigations.

Beach profiles, sedimentary analysis and hydrodynamic surveys were conducted over four beaches located on the different facades of the island. The analyse of those survey data revealed that the alternation between monsoon and trade winds lead to a drift in the sediment transport, inducing seasonal beach rotations. During trade winds (austral winter), beaches show a tendency to erosion in their south part and accretion in their north part, this dynamic reverse during the wet season (austral summer).

This study provides the first elements of understanding the reef fringed pocket beaches morphodynamics at a seasonal scale, subsequently allowing an attempt to discriminate interannual variations and the possible impacts of subsidence as well as morphogenic thresholds.

How to cite: Charroux, S., Jeanson, M., Morisseau, S., Mercky, Y., and Pennober, G.: Seasonal evolution on reef fringed pocket beaches in a context of relative sea level rise., 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-210, https://doi.org/10.5194/icg2022-210, 2022.

Permafrost is a crucial element in the cryosphere and an essential climate variable (ECV) of the Global Climate Observation System (GCOS). The Arctic represents 34% of the global coastlines (Lantuit, 2012). In the context of the RCP 8.5 scenario for 2040-2060, the IPCC projects for the Arctic an average increase of the annual air temperature of 7 ºC compared to 1880-1920 (Guyet al., 2021). Hence, the Arctic is one of the most vulnerable regions to climate change in the world. The Arctic is undergoing rapid transformations (Nielsen et al., 2020). This tendency will grow with the increasing frequency and magnitude of coastal erosion events, as processes are enhanced by reduction of sea ice extent, subsiding and warming permafrost landscapes, along with increasing open water periods, storminess, air and sea surface temperatures, absolute and relative sea level rise, and warmer ocean (Irrgang et al., 2018).

The main focus of this study is to evaluate the applicability of Sentinel-2 multispectral data for the delineation of Arctic coastlines and subsequent calculation of shoreline change rates. Recently, several methods have been proposed and are being developed for the automatic delineation of shorelines. However, the nature of Arctic coasts, with high cloudiness, high variability in turbidity, sea-ice, snow banks, variable cliff heights and increased shading due to low solar altitude, poses significant challenges to automatic algorithms.

We compare the application of different automatic shoreline delineation algorithms with validation data based on the manual identification of the shorelines. The latter is done on the Sentinel-2 images and using very high-resolution Pleiades (CNES/Airbus) imagery. The study area is located on the Beaufort Sea coast stretching from the Alaska-Yukon border to Banks Island.

The manual and automatic shoreline delineation with Sentinel-2 imagery comprise two years: 2016 and 2020. Pleiades analysis was done for 2018, 2020 and 2021. The automatic methods that were tested are the WaterDetect (Cordeiro et al., 2021) and XGBoost (Chen et al., 2016) methods. The results from the performance assessment of the automatic methods and identification of the limiting factors and errors associated with sea and atmosphere conditions will be used to create recommendations for improving the development of automatic coastal classification algorithms for Arctic coasts.

This research is part of the Nunataryuk project. Funding under the European Union's Horizon 2020 Research and Innovation Program under grant agreement no. 773421 and from the Climate Change Preparedness in the North Program (Government of Canada). Further funding has been received through the European Space Agency Polar Science Cluster Program (project EO4PAC). Access to Pleiades imagery is promoted by the WMO Polar Space Task Group.

How to cite: Bilbao, S., Vieira, G., Bartsch, A., and Efimova, A.: ASSESSING THE USE OF SENTINEL-2 FOR EVALUATION OF ARCTIC COASTAL EROSION: Potential and Limitations (Beaufort Sea Coast, Canada), 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-662, https://doi.org/10.5194/icg2022-662, 2022.

Coastal vulnerability can be defined as its proneness to be damaged by changing climatic  and/or geomorphic conditions. In this study, coastal vulnerability focuses entirely on the  physical impact of erosion, distinguishing the coastal behaviour between negative  (susceptibility) and positive (resilience) responses to climate change-induced conditions,  without taking into account any socio-economic variables. 

The Coastal Vulnerability Index (CVI) approach has become one of the most used and simple  assessing method for coastal regions around the world. CVI approach requires the selection  of a set of critical variables which are expected to significantly drive system processes, which  are then reclassified assigning to each obtained class a score expressing its expected  incidence, following to an expert based analysis. In this study we propose a modified version  of the CVI approach, for application to the entire coastline of Sicily as a first-pass regional scale coastal-vulnerability assessment. In particular, we modified the set of considered  variables, maintaining coast classification and slope, but excluding the shoreline change,  which was rather used for validating the obtained model. At the same time, long term or  negligible variables (sea level change and tidal range, respectively) were not considered and substituted by three covariates much more directly related to the short-term sea wave energy  (number of storm surges; mean wave power; dominant wave direction). Finally, a new  variable expressing the sediment yield from the fluvial system was also included, exploiting  the estimation offered by the Watem-Sedem model. To apply the CVI at a regional scale,  centroids along the coastline were generated and the vulnerability class for each factors  captured, so to compute the composite vulnerability CVI, which was reclassified into its four  quartiles. 

By crossing the obtained CVI classes and the observed 2000-2019 shoreline variation, a largely  satisfactory validation of the heuristic model was obtained, with the advancing and retreating  coastal sectors being strongly concentrated in the I and IV CVI classes, respectively. A general  negative trend between advancement and CVI score prediction arose from class I to class IV,  with a less marked discrimination between class II and class III. At the same time, it was  observed how the sediment yield factor allowed to correctly classify some advancing coastal  sector, which otherwise would have been predicted as subjected to retreatment. 

The obtained results produced a reliable picture of the regional coastline status, posing also  the basis for potential steps toward a stochastic modelling of coastal erosion processes in  Sicily.

How to cite: Azzara, G., Manno, G., Martinello, C., Basile, M., Mercurio, C., Lo Re, C., Ciraolo, G., and Rotigliano, E.: Optimizing CVI-based heuristic approach for regional coastal vulnerability assessment in  Sicily and 2000-2019 shoreline change calibration., 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-712, https://doi.org/10.5194/icg2022-712, 2022.

Beaches as dynamic coastal forms occur in different shapes, areas and lengths. They form at the interface between sea and land, where natural and socioeconomic processes interact. Their morphology changes on different temporal scales, from hours to centuries. In this work, the evolution of 25 beaches on the island of Hvar in Croatia was studied, covering the period from 1834 to 2021. The evolution of beaches was studied through three different periods. The oldest, starting from the year 1834, was analysed using the Franciscan cadastre (0.5 m error) mapped during the Austro-Hungarian Empire. Their surface areas were calculated using GIS software. Some of the beaches were already mapped as individual cadastral parcels. The obtained calculations significantly correlate with data from the Cadastral supplement (expressed in Klafter quadrimetre unit). The surface areas of beaches for the second period were estimated from archival orthophotos, provided by the State Geodetic Administration, using the method of repeat photography. The archival aerial photographs date from 1958 to 1968 and are in black and white colour with a relatively satisfactory resolution. The repeat photography method relies on more than 150 old photographs (1910-1980) that were used for benchmarking, beach boundary determination, and the reconstruction of mid-20th century situation. For the most recent period, which is the most accurate, we used UAV DJI Phantom 4 Pro in combination with a Trimble GNSS receiver. The fieldwork was conducted from November 2020 to March 2022. As a final product, very accurate orthophotos, DEM and DSM were produced by photogrammetric techniques in ESRI Drone2Map and Agisoft software. The analysis showed that beaches had the largest area during the cadastral survey, were slightly smaller in the mid-20th century and were the smallest in recent times. Consequently, beach erosion was found in all 25 sites surveyed. On average, the beaches have eroded by about 32% since the 19th century. Mina and Sveti Ante beaches were the most affected with more than 70%. Overall, the shoreline has moved inland of about 4.3 metres on average. It was found that cadastral data, archival maps, and old photographs proved to be useful and reliable data sources for analysing beach surface changes in the past.

This research was made with the support of the Croatian Science Foundation (HRZZ-IP -2019-04-9445).

How to cite: Mićunović, M. and Faivre, S.: Evolution of pocket beaches on the island of Hvar during the last 200 years (Croatia, Eastern Adriatic Coast), 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-313, https://doi.org/10.5194/icg2022-313, 2022.

The Campi Flegrei is one of the widest and dangerous active volcanic complexes in the Mediterranean basin, worldwide known for the sudden vertical ground movements (bradyseismic crisis) characterizing its post-calderic volcanic activity since the Late Pleistocene. Despite its intense volcano-tectonic activity, the area has been densely inhabited since the Greek-Roman time and still preserves in its submerged sector many archaeological remains whose particular features can be interpreted as high-precision sea-level markers.

This research presents the results from a multidisciplinary study aimed at reconstructing the coastal landscape of Campi Flegrei and its surroundings during Roman Time by using a complex multi-technique approach.

The study area, ranging from the western margin of Torregaveta Promontory to the eastern area of Castel dell’Ovo in the City of Naples, was surveyed by a team of specialized divers (archaeologists and geomorphologists) and by using different indirect methods. High-precision data related to the underwater morphologies were obtained by coupling extensive morpho-acoustic surveys (Multibeam and Side Scan Sonar) with integrated detailed surveys using an Unmanned Surface Vessel (USV) equipped with acoustic and optical sensors.  3D reconstructions of seabed morphologies and submerged archaeological remains were integrated with sedimentological analysis of several boreholes, in order to obtain the geological, geomorphological, and archaeological interpretation related to the Roman coastal seascape.

The landscape evolution was evaluated both in terms of coastline variations, with related prograding/retreating trends, and quantification of the effects of the local volcano-tectonic activity recorded by the high-precision sea-level markers, leading to the identification of a differential behavior in terms of vertical ground movements along the different sectors of the study area.  Indeed, the RSL variation in the area is non-monotonic being controlled by the alternation of phases of positive and negative VGMs associated with multiple bradyseismic crises.

In particular, by comparing the collected RSL data with different GIA models, it was possible to observe that 2.1 ka BP the central part of the caldera was affected by a general subsiding trend with peak of acceleration up to -3.4 mm a^-1 between 2.1 and 1.9 ka BP. On the other hand, along the Posillipo and Chiaia coastal sectors, outside the eastern margin of the Campi Flegrei caldera, the RSL datapoints testified an overall subsiding trend during the Holocene which indicate general subsidence with rates between -1.2 and -2.5 mm ^a-1 at least in the last 2.0 ka.

Moreover, the combination of this multi-technique approach allowed the realization of a geoarchaeological map of the coastal landscape of Campi Flegrei and its surroundings between the II century BC and the I century AD, highlighting how the Romans gave rise to a new approach to the coastal outline and utilization becoming the precursors of an ever-increasing anthropization.

How to cite: Caporizzo, C., Mattei, G., Amato, L., Cinque, A., Pappone, G., Sorrentino, A., Stocchi, P., Troisi, S., and Aucelli, P. P. C.: A journey through the Roman coastal landscape of Campi Flegrei and its surroundings: new insights from geomorphological, stratigraphic, geophysics, and geoarchaeological surveys, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-327, https://doi.org/10.5194/icg2022-327, 2022.

Downwearing rates of shore platform have been quantified with a number of ground-based techniques (such as the micro-erosion meter (MEM)), providing knowledge of the evolution of coastal landforms. However, it remains problematic to extrapolate the micro erosion results to the landform scale. This is because only a very small proportion of the platform is monitored and usually biased to flat rock surfaces. In this study, we used the shore platforms in south-eastern Australia, which has the world’s longest continual erosion records, as an example to solve the fundamental question on result extrapolation across spatial scales. Surveying using an unoccupied aerial vehicle (UAV) – post-processing kinematic (PPK) – structure-from-motion (SfM) workflow, indicates the shore platforms at Marengo and Jump Rock having similar morphology. The generated mm-scale dataset was used to contextualize 4 and 12 MEM sites into the orthomosaics and digital surface models (DSMs) at each location. By using two different methods, we assessed how these monitored surfaces were representative of the morphology of the entire platform. On average, the 4 MEM sites represented 52.2% of platform surfaces at Marengo and 73.2% with the 12 MEM sites at Jump Rock. To improve the representativeness of sampled surfaces, it was found that 20 randomly sampled MEM-size (4.33 × 10^-3 m²) surfaces could well represent (c. 90%) the landform morphology at the scale of 10⁴ m². The representativeness was only slightly improved by upscaling the surface size from original cm², to dm² (0.16 m²) and m² (1 m²) scales, implying the importance of sample number over sample size. Using the cm-scale dataset covering a larger geographic region, a bias of MEM installation was found with all 43 MEM sites concentrated at the fast-eroding upper intertidal zone. An elevation-weighted erosion rate of 0.21 mm/yr was calculated, lower than the original mean of 0.25 mm/yr provided by the MEM network. Moreover, a spatial pattern of rock surface morphology was observed across the platform with higher slope and roughness at the seaward end, suggesting more intensive wave processes and varying weathering agents compared to those surfaces further inland.

How to cite: Yuan, R., Kennedy, D., and Ierodiaconou, D.: Spatial scaling in geomorphology: Extrapolating micro-erosion measurements to the landform scale on shore platforms using unoccupied aerial vehicles, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-13, https://doi.org/10.5194/icg2022-13, 2022.

In global geochemical cycles, the solid flux from the continent to the ocean is usually reduced to the input of sediments from rivers [1]. However, regional studies have shown that the input of sediments from rocky coast erosion may be a significant part of this flux [2]. So, it is important to consider this input into global cycles and to quantify it over different timescales.

On short-term timescales, from the year to the century, coastal erosion is currently quantified with direct measurement of the coastline retreat, between successive time intervals [3]. Extrapolating on timescales longer than a thousand years is difficult. This leads to a lack of data and therefore a gap in knowledge in longer term coastal erosion [4].

A solution to quantify long-term erosion of rocky coast is to reconstruct the initial geometry of the coastline and to know the age of its formation. Volcanic islands are suitable objects for this method. Indeed, their initial shape is simple and can be easily reconstructed, and their maximum extension can be dated [5,6,7]. Thus, the topographic reconstruction of a volcanic island allows, by comparison with its current topography, the quantification of volumes lost by erosion. In turn, it becomes possible to obtain values of the rocky coast total retreat on timescales from thousands to hundreds of thousands of years [8].

Another and complementary approach to quantify long-term erosion is the use of cosmogenic isotopes. This approach is widely used to date surface exposure and quantify long-term denudation rates in drainage basins [9]. The use of this approach to directly quantify sea-cliffs retreat is completely new. By sampling colluvial deposits resulting from coastal erosion of sea-cliffs, measuring cosmogenic ¹⁰Be and ³He concentrations, depending on the cliff lithology, may provide values on the retreat rate of the cliffs on the millennia timescale.

It is interesting to test both approaches on volcanic islands. Indeed, their wide geographic distribution provides a diversity of climatic and geodynamic settings allowing to analyze the effects of various factors on long-term coastal erosion. We compare and discuss the results obtained by both methods on the island of Fogo (Cape Verde).

[1] Milliman and Farnsworth (2013). Cambridge University Press.

[2] Regard et al. (2022). Earth and Planetary Science Letters 579, 117356.

[3] Bird (2011). John Wiley & Sons.

[4] Prémaillon et al. (2018). Earth Surface Dynamics 6, 651-668.

[5] Lahitte et al. (2012). Geomorphology 136, 148-164.

[6] Ramalho et al. (2013). Earth-Science Reviews 127, 140-170.

[7] Karátson et al. (2016). Geomorphology 253, 123-134.

[8] Bossis et al. (in press).

[9] Bierman et al. (1996). Earth Surface Processes and Landforms 21, 125-139.

How to cite: Bossis, R., Regard, V., Carretier, S., Large, E., Blard, P.-H., and Charreau, J.: Quantifying long-term coastal erosion: from topographic reconstruction of volcanic islands to cosmogenic isotopes, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-241, https://doi.org/10.5194/icg2022-241, 2022.

Submarine mass-movements are a major hazard on continental margins, particularly on collisional tectonic settings where recurrent earthquakes may trigger catastrophic collapses. Associated mass-transport deposits (MTDs) are typically heterogeneous, often characterised by a mixture of allochthonous slope lithologies transported to the abyssal depths, being further mixed with autochthonous basin sediments. Examples of such complex MTDs on thrust-controlled slopes are the North Gorringe Avalanche on the flank of the Gorringe Ridge, located on the Southwest Iberian Margin (NE Atlantic), and the Ruatoria MTD on the Hikurangi Subduction Margin, offshore New Zealand. Both MTDs present morphological similarities, such as a large evacuation area with significant height differences (between 2500 m to 3000 m for both cases), numerous blocky debris still observable on the seafloor despite the post-collapse burial and marked deformation of basin sediments over large areas. With a volume of circa 4500 Km³ and covering 9850 km², the Ruatoria is particularly impressive and comprises one of the largest MTDs in the world. A geomorphological analysis is complemented by models to assess the tsunamigenesis of such impressive collapses and the hazards for margins across the oceans where they occur.

This work was funded by the Portuguese Fundação para a Ciência e a Tecnologia (FCT) I.P./MCTES through national funds (PIDDAC) – UIDB/50019/2020, and through project MAGICLAND – PTDC/CTA–GEO/30381/2017.

How to cite: Gamboa, D., Omira, R., Terrinha, P., Barnes, P., and Davidson, S.: Geomorphology and tsunamigenesis of blocky MTDs on collisional tectonic settings: Insights from Southwest Iberia and the Hikurangi Margin (New Zealand), 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-434, https://doi.org/10.5194/icg2022-434, 2022.

Coastal monitoring is a continuously developing topic, which has been addressed in several ways. Among the different techniques, the coastal video monitoring together the recent machine learning and computer vision techniques have become widely used to evaluate the meteo-marine features. On the other hand, the video monitoring allows to obtain a large amount of data spatially and temporally well distributed on the coasts. The video records allowed to obtain a series of continuous frames where tide phases, wave parameters and storm features are clearly observable. In this work, video records of the Mediterranean coasts have been acquired through the surveillance cameras located in the proximity of south-eastern Sicily coasts (Italy). Tide, wave and storm parameters were assessed through a combined approach between Convolutional Neural Network (CNN) and optical flow techniques. Tide phases and storm surge were obtained through CNN classification techniques, while optical flow techniques were used to assess the wave flow and wave height impacting on the coasts. Neural network predictions were compared with tide gauge records, while, the water level and wave height were validated through spatial reference points obtained from topographic surveys in the proximity of surveillance cameras, so to improve the agreement between network results and field data. The goodness of the results was evaluated through a Root Mean Square Error analysis and by evaluating the correlation coefficient between results and field data. Subsequently, CNN and optical flow were applied on the Atlantic coasts of Portugal through action cameras, in order to show the difference in terms of wave flow and wave height respect to the Mediterranean coasts. The application of CNN and optical flow techniques allowed to automatically obtain the marine insights and to increase the amount of data that usually are not densely distributed along the coasts.

How to cite: Scardino, G., Scicchitano, G., Chirivì, M., Costa, P., Luparelli, A., Mazza, G., Piscitelli, A., and Mastronuzzi, G.: A combined approach between Convolutional Neural Network and optical flow for the assessment of wave and tide parameters on the Mediterranean and Atlantic coasts, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-25, https://doi.org/10.5194/icg2022-25, 2022.

Coral reefs are now one of the most threatened marine ecosystems, due to local anthropogenic pressures and global changes in ocean conditions. Until recently, research has focused on the vulnerability of shallow coral ecosystems, however effects on deeper coral-dominated ecosystems become more severe with climate change. Deep-sea corals form large bioconstructions, including dense frameworks and mounds, which can remain even when the organisms are dead. The presence of these ecosystems alters the local seafloor morphology. To understand the changes that deep-sea coral ecosystems are undergoing, and the impacts these changes may have on local seafloor morphology, we must first know where they are located. Exploration of deep-sea habitats is costly, challenging and time-consuming, reducing the geographic extent at which it is possible. Methods are also often difficult in remote areas. Therefore, as such ecosystems are relatively sparse, extensive resources may be used attempting to locate them. Species distribution models can be used to identify key areas of interest with much less information, focusing surveys to a smaller extent, and making it much more cost-effective to study. MaxEnt is a habitat suitability modelling software which uses a unique maximum entropy algorithm to find the most dispersed distribution. It requires only presence data, allowing accurate results with less input data. Here we present the first habitat suitability models for deep coral habitats, as deep as 720 m, in the Red Sea. During the OceanX-NEOM ‘Deep Blue’ expedition in the Northern Saudi Arabian Red Sea and the Gulf of Aqaba in 2020, deep-sea coral ecosystems were identified and characterised by ROV and submersible dives. Geomorphometric variables were derived from bathymetry, including measures of aspect, curvature and local-scale rugosity. These variables were used as input data for MaxEnt, along with backscatter, which can provide information about the seafloor substrate, and environmental data from CTD casts and current models. The potential of such models to identify areas of interest is clear, and could become an important tool in order to focus limited conservation funding.

How to cite: Nolan, M. K. B., Marchese, F., Kheireddine, M., Chimienti, G., Purkis, S., Terraneo, T. I., Rodrigue, M., Eweida, A. A., Jones, B., and Benzoni, F.: MaxEnt modelling as a tool to inform discovery of deep-sea coral ecosystems, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-441, https://doi.org/10.5194/icg2022-441, 2022.