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Brazdžiūnas, P.; Pupienis, D.; Jarmalavičius, D., and Žilinskas, G., 2024. Space–time tendencies of coastal dynamics based on morphometric and hydro-meteorological data (Curonian Spit, Lithuania). In: Phillips, M.R.; Al-Naemi, S., and Duarte, C.M. (eds.), Coastlines under Global Change: Proceedings from the International Coastal Symposium (ICS) 2024 (Doha, Qatar). Journal of Coastal Research, Special Issue No. 113, pp. 300-304. Charlotte (North Carolina), ISSN 0749-0208. Varying tendencies of coastal development are observed in the Lithuanian part of the Curonian Spit. Since the past research were unable to assess the spatial variance of the factors shaping the coast, the reasons for varying tendencies are still hard to explain. Therefore this study aims to determine the dominant controlling factors leading to spatial variance of coastal tendencies in the Lithuanian part of the Curonian spit. Wind and wave reanalysis data were utilized to serve this purpose. It was used together with 12 cross-shore profile. Yearly changes in sediment volume and shoreline position were compared to the changes in wind and wave parameters using pearson correlation method. Results revealed prevailing sediment accumulation with varying magnitude between different sections. This may be linked to the steep angle of wave approach. Wind may be the main factor controlling the changes in sediment volume. The influence comes via hydrodynamics (waves and sea level). Local beach and nearshore morphometry conditions are responsible for the effect of these hydrodynamic factors, creating the spatial variance in coastal development.

Healthcare providers and law enforcement utilize spit socks to prevent exposure to communicable diseases transmitted by bodily fluid projection from agitated individuals. There are cases in which death is reported due to breathing being limited by a spit sock. There are no formally published studies on their use and safety. The aim of this study was to evaluate whether wearing a spit sock causes a clinically significant impact on breathing. Subjects sat with the spit mask over their heads for 15 min and their vital signs and ventilatory parameters were recorded after 5 min, 10 min and 15 min. Data were compared to baseline using Student's t-test with 95% confidence intervals using SPSS. The median age of the 15 subjects was 28 years and 53% were male. There was no significant difference between baseline and wearing the spit sock for 5, 10 or 15 min for heart rate (p = 0.250, p = 0.181, p = 0.546), oxygen saturation (p = 0.334, p = 1.00, p = 0.173), end-tidal pCO2 (p = 0.135, p = 0.384, p = 0.187), and diastolic blood pressure (p = 0.485, p = 0.508, p = 0.915). The respiratory rate was not significantly different after 5 and 10 min (p = 0.898, p = 0.583), but decreased at 15 min (p = 0.048). The systolic blood pressure was lower after 5 and 10 min (p = 0.028, p = 0.045), but not significantly different at 15 min (p = 0.146). No subject indicated distress nor did the study need to be terminated due to pre-determined concerning vital signs or ventilatory parameters. In healthy subjects there were no clinically significant changes in the physiologic parameters of breathing while wearing a spit sock.

Beach morphology and sediment characteristics were investigated on a seasonal scale (January, May, and September 2013) along the shorefront of Chilika lagoon. Shorefront of Chilika lagoon covers 65 km and includes barrier spit and the inlet region (three spits: south, middle, and north). Dynamics of the inlets during pre (1973–1999) and post (2000–2020) hydrological intervention period were studied based on time series satellite data. Seasonal and inter-annual spit dynamics (2009–2020) were investigated based on observed data. Results indicate depositional environment on the barrier spit and south spit while erosional environment on the middle and north spit. After the hydrological intervention period (2000–2020), the south spit enhanced by 5.37 km, resulting in northward migration of the Sipakuda inlet, while the morphological changes of the middle and the north spit were observed considerable both in spatiotemporal scale. The variability of the middle and north spit is attributed to their position on the downdrift side of the inlet leading to short supply of sediments. As a result, the width and elevation of the middle and north spit significantly decreased. Depositional environment of the barrier and south spit can be attributed to their sediment characteristics which are predominantly fine and medium. On the other hand, the erosional environment of the middle and north spit are attributed to the prevalence of coarse sediments. Significant variability in inlet position and morphology along with vulnerability of the middle and north spit are matters of concern for the lagoon environment. Therefore, the study suggests that limiting the northward growth of south spit and adopting measures to control erosion at middle and north spit as two management interventions to restore the stability along the shorefront of Chilika lagoon.

With large-scale human interventions and climate change unfolding as they are now, coastal changes at decadal timescales are not limited to incremental modifications of systems that are fixed in their general geometry, but often show significant changes in layout that may be catastrophic for populations living in previously safe areas. This poses severe challenges that are difficult to meet for existing models. A new free-form coastline model, ShorelineS, is presented that is able to describe large coastal transformations based on relatively simple principles of (1) alongshore transport gradient driven changes as a result of coastline curvature and (2) spit formation at high-angle wave incidence. An arbitrary number of coast sections is supported, which can be open or closed and can interact with each other through relatively straightforward merging and splitting mechanisms. Rocky parts or structures may block wave energy and/or longshore sediment transport. These features allow for a rich behavior including shoreline undulations and formation of spits, migrating islands, merging of coastal shapes, salients and tombolos. The main formulations of the (open-source) model are presented. Test cases show the capabilities of the flexible, vector-based model approach, while field validation cases for a large-scale sand nourishment (the Sand Engine; 21 million m3) and an accreting groyne scheme at Al-Gamil (Egypt) show the model’s capability of computing realistic rates of coastline change as well as a good representation of the shoreline shape for real situations.

The drilling of 17 boreholes in the coastal zone of Yasenskii Bay of the Sea of Azov has yielded new data on the lithological composition and structure of the upper part of the sedimentary strata and the thickness of the layers composing it. The structure of malacological communities was analyzed, and changes were traced in the taxonomic composition of mollusks along the studied geological sections on various accumulative forms. It has been shown that the carbonate material of the beach ridges consists 90–95% of fragments or, less often, whole valves of shells of the Cerastoderma glaucum mollusk. Numerous valves of halophilic Black Sea species, including whole shells of Gastrana fragilis , were noted in the underlying sand and shell deposits of the Yasenskaya Spit and the bay bar of Khanskoye Lake. They are markers of the Ancient Azovian stage in the sea development. The surface terrain of the Kamyshevatskaya Spit was studied in detail, and three variably aged generations of beach ridges were identified.

Previously, paired spits have been described at the mouths of bays, estuaries, and deltas. This study analyzed the worldwide distribution and morphodynamic patterns of paired spits located at the mouths of interdistributary bays of deltas (three systems) and within coastal channels (24 systems). The methodology was based on the detailed analysis of satellite images, nautical charts, and tidal-range databases. The paired spits found were mainly located on microtidal coasts at high or mid latitudes. Waves were the main factor controlling convergent progradation and breaching of the spits, while the hydraulic blockage for the development of these paired spits was mainly due to tide-induced currents, as well as minor fluvial outlets in the interdistributary bays. Three morphodynamic patterns were identified: (i) stable, with low progradation rates, generally without breaching or degradation of any of the spits; (ii) stationary, with high progradation rates, alternating degradation or breaching of any of the spits with the formation of new spits or closure of the breaches; and (iii) instable or ephemeral, which included three subtypes, the severe erosion of one or both spits, the joining of the head of the two spits forming a single barrier, and the merging of each with its channel margin.

Barrier coastlines and their associated ecosystems are rapidly changing. Barrier islands/spits, marshes, bays, and coastal forests are all thought to be intricately coupled, yet an understanding of how morphologic change in one part of the system affects the system altogether remains limited. Here we explore how sediment exchange controls the migration of different ecosystem boundaries and ecosystem extent over time using a new coupled model framework that connects components of the entire barrier landscape, from the ocean shoreface to mainland forest. In our experiments, landward barrier migration is the primary cause of back‐barrier marsh loss, while periods of barrier stability can allow for recovery of back‐barrier marsh extent. Although sea‐level rise exerts a dominant control on the extent of most ecosystems, we unexpectedly find that, for undeveloped barriers, bay extent is largely insensitive to sea‐level rise because increased landward barrier migration (bay narrowing) offsets increased marsh edge erosion (bay widening). Plain Language Summary Barrier coastlines consist of barrier islands or spits, salt marshes, bays, and mainland forest. To understand how the migration and change in size of one ecosystem influences the others, we develop a new computer model that simulates the exchange of sediment between all ecosystems. Using this model, we find that salt marshes adjacent to barriers are rapidly lost when the barrier migrates and its sediment is washed onto the marsh, but can potentially expand and recover when the barrier is not migrating. Additionally, we find that changing the rate of sea‐level rise in the model does not significantly change the size of the bay because the effects of sea‐level rise on barrier migration and marsh edge erosion offset each other. Our simulations suggest that these interactions among different ecosystems result in complex evolution of coastal barrier systems and can be a leading cause of change. Key Points Cross‐landscape interactions are explored in new model framework connecting entire barrier system from shoreface to mainland forest Simulations suggest barrier migration leads to rapid back‐barrier marsh loss, while barrier stability enables back‐barrier marsh recovery Bay extent is insensitive to sea‐level rise rates because of offsetting responses from barrier migration and marsh‐edge erosion processes

The deltas serve as the primary interactive zone where terrestrial and marine environments converge, playing a pivotal role in the coastal deposition. In the Holocene, climate changes and sea level fluctuation are the principal driving factors in the evolution of deltas. However, human activities such as the construction of dams and reservoirs in the Anthropocene have significantly altered sediment transport in rivers, leading to depositional pattern variation during deltaic evolution. In this study, we have conducted a comparative analysis of the morphological variations (1986–2021) in the barrier system of the Hanjiang River Delta (HRD) using satellite remote sensing (SRS) method. Additionally, we have examined the lithological changes and facies alterations observed in eight boreholes on the present barrier spit. Our findings indicate that the intensification of anthropogenic activities led to a significant reduction in the sediment flux of the Hanjiang River (HR), resulting in depocenter landward migration at the estuary. SRS analysis reveals their periodical morphological characteristics and spatial variations of estuarine sandbars (1986–1992), barrier islands-lagoons (1993–2009), and barrier spits (2010–2021) during 1986 to 2021. The stratigraphy of boreholes demonstrates a south-to-north facies transition from lagoon to lagoon-barrier spit and barrier spit in vertical lithology. Therefore, the depositional evolution of the HRD barrier system is categorized into three phases: estuarine sandbar-barrier island phase (1986–1998); barrier island-lagoon phase (1999–2009); and barrier spit phase (2010–2021). During the estuarine sandbar-barrier island phase, fluvial processes played a predominate role in the deposition. Consequently, with a significant decrease in river sediment load, the dominant factors driving depositional processes shifted towards wave action and alongshore current. Based on the conceptual model in the Holocene, we propose a modified depositional model of wave-dominated deltas during Anthropocene that encompasses three evolutionary phases: estuarine sandbars and delta front platforms, barrier island-lagoon formation and landward migration of barrier spits. This pattern highlights that human-induced reduction in river sediment flux has led to a seaward deltaic progradation driven by barrier landward migration.

Miranda, I.M.; Toldo, E.E., Jr.; Klein, A.H.F., and Vieira da Silva, G., 2019. Shoreline evolution of lagoon sandy spits and adjacent beaches, Lagoa dos Patos, Brazil. Journal of Coastal Research, 35(5), 1010–1023. Coconut Creek (Florida), ISSN 0749-0208. The development of lagoon sandy spits is dependent on sediment supply (mainly through longshore transport) and is often related to erosion of updrift beaches under high-angle waves. This paper provides an understanding of the short- to medium-term shoreline evolution of three symmetrical lagoon sandy spits and the related erosion of the adjacent bay beaches of Lagoa dos Patos, Brazil. To do so, two of the most widely used methods to quantify shoreline changes were applied: the transects-from-baseline method and the change polygon method. A historical analysis of the shoreline movement of approximately three decades (1984–2013), was carried out, aiming to track the source of sediments to the spits. Alternate phases of shoreline stability, deposition, and recession (less frequent) in short time intervals (years) showed correlation with the El Niño–Southern Oscillation and Southern Annular Mode indexes. Shoreline stability along beaches in the medium term (60.4% of Arambaré and 73.9% of Graxaim beaches, by the linear regression rate calculation), together with the very low average shoreline change rate of +0.7 m y–1 found using both methods, demonstrates that the sediment supply to the spits has been significantly reduced in the past three decades. Furthermore, the large-scale subaqueous portions of the spits are under wave-induced sedimentary reworking accompanied by the up-building of sandbanks from the submerged bars, followed by its landward migration and merging to the spit's shoreline. These results suggest that the spits of Lagoa dos Patos have their growth limited once the amount of sediment supply has been significantly reduced.

An areal distribution of sensors can be used for estimating the direction of incoming waves through beamforming. Beamforming may be implemented as a phase-shifting and stacking of data recorded on the different sensors (i.e., conventional beamforming). Alternatively, beamforming can be applied to cross-correlations between the waveforms on the different sensors. We derive a kernel for beamforming cross-correlated data and call it cross-correlation beamforming (CCBF). We point out that CCBF has slightly better resolution and aliasing characteristics than conventional beamforming. When auto-correlations are added to CCBF, the array response functions are the same as for conventional beamforming. We show numerically that CCBF is more resilient to non-coherent noise. Furthermore, we illustrate that with CCBF individual receiver-pairs can be removed to improve mapping to the slowness domain. An additional flexibility of CCBF is that cross-correlations can be time-windowed prior to beamforming, e.g., to remove the directionality of a scattered wavefield. The observations on synthetic data are confirmed with field data from the SPITS array (Svalbard). Both when beamforming an earthquake arrival and when beamforming ambient noise, CCBF focuses more of the energy to a central beam. Overall, the main advantage of CCBF is noise suppression and its flexibility to remove station pairs that deteriorate the signal-related beampower.