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Sá, L.P.; Oliveira, U.R.; Albuquerque, M.G.; Façanha, M.C., and Cruz, L.F., 2024. Beach-dune frontal limit variability between 2012-2022 at Cassino beach, southern Brazil. 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. 351-355. Charlotte (North Carolina), ISSN 0749-0208. The coastal zone faces natural and anthropic challenges, with beaches highly susceptible to extreme events. In southern Brazil, frontal systems and extratropical cyclones have caused significant changes in beach dynamics. This study aims to characterize the variation of the beach-dune limit adjacent to Cassino beach, southern Brazil, over the last decade. Based on a time series satellite images (GeoEye Sensor) from 2012, 2015, 2019, and 2022, it was possible to characterize whether the sections of the urban perimeter of Cassino beach are subject to accretion, retraction, or remain stable. From the beach-dune limit vectorization, the seasonal movement process was characterized using a method that emulates the Digital Shoreline Analysis System (DSAS) tool. The study area was divided into three sectors: north, middle, and south, each with 20, 30, and 20 transects, respectively. The results show that the average movement over a decadal was 21.3 meters of progradation. The southern sector presented the highest accretion rate, totaling approximately 35.4 meters, while the northern sector recorded the lowest rates (6.01 meters). The central portion of the study area presented 22.2 meters of accretion. The period from 2012-2015 was where the greatest progradation occurred, a total of 15.3 meters for the period, followed by the period from 2019-2022, totaling 7 meters prograded. The interval between 2015 and 2019 recorded retreat rates of 6.8 meters in the northern sectors, and 2.02 meters in the central portion. On the other hand, the southern sector presented an average progradation of 8.2 meters, totaling for the period an average of 0.4 meters retreated. Cassino beach presents a sedimental balance predominantly positive, although sporadic retreat episodes can occur. Finally, this study offers perspectives for coastal management and the prediction of future changes, as the locality is among the most sought after by users in the summer season.

Gharnate, A.; Taouali, O., and Mhammdi, N., 2024. Shoreline change assessment of the Moroccan Atlantic coastline using DSAS techniques. Journal of Coastal Research, 40(2), 418–435. Charlotte (North Carolina), ISSN 0749-0208. Coastal zones are critical from a physical, social, and economic point of view; however, most of the world's coastal zones are highly vulnerable to coastal erosion because of high population density, tourist attractions, and developed economies. To support mitigation strategies, a coastal erosion vulnerability assessment is essential to generate accurate information on this significant phenomenon. This study presents an integrated approach to coastal erosion vulnerability using a geospatial assessment of coastal dynamics in the Moroccan Atlantic coastal region between Rabat and Casablanca. To contribute to current and future knowledge of the study area's coastline dynamics, a cartographical and statistical approach was used to calculate historical rates of coastline change using aerial photos and satellite images from 1969 to 2022. To accomplish this, the images have been followed by the digitalization of the coastlines, as contained in the images created by using software ArcGIS10.8. These digitalized shorelines were subsequently incorporated into the digital shoreline analysis system, which provided multidate maps with graphical end point–rate (EPR) values. The results for Oued Cherrat estuary and the adjacent sandy beach indicate a general phase of erosion, with the average overall EPR value having reached –2.00 m/y, with the notable exception of a small part of the sandy beach, where progradation manifested itself in the form of an EPR value of +0.10 m/y. The Oued Nfifikh estuary is showing more erosion than the Oued Cherrat estuary. The retreat has affected the greater part of the area, reaching a maximum EPR speed of –5.00 m/y, with the possible exception of a smaller portion that has seen the shoreline progress at an average speed equal to +0.75 m/y. The resulting data may be used by the appropriate authorities to help effectively protect coastlines from erosion and to mitigate its impact on the environment and coastal properties.

Low-lying islands are vulnerable to coastal erosion, and mangroves, which can mitigate erosion, have suffered enormous losses in recent decades owing to human impacts. Previous studies have little investigated mangrove shores on atolls, which may face combined multiple threats. We analysed the large Marshall Islands atoll of Jaluit, at a higher resolution than previous spatial change studies, finding that mangrove shorelines prograded seawards over the last seven decades. Biogeomorphic colonisation processes were characterised from transects along ~ 14.6 km of shorelines. Mangrove progradation occurred in patterns of arc-shapes evident of long-shore drift deposition, patch expansion of offshore mangrove colonisers, and linear shoreline advance. Significant differences in the rates of expansion were identified, with arc-shaped colonisation showing the fastest rates of expansion. However, linear shoreline advance was the most frequent expansion pattern showing greater than three-fold more classified transects than arc-shaped colonisation and patch expansion. These results have implications for low island mangrove restoration. Applying mangrove planting patterns mimicking these different natural colonisation processes may enhance restoration success in ecosystem-based adaptation projects to mitigate sea level rise vulnerability. Results from this study show that atoll mangrove shorelines demonstrate resilience during past sea level rise rates, and that rates of expansion vary according to patterns of biogeomorphic colonisation.

It is shown that the language of spatiotemporal values (LT methodology) can be used in soil science for assessing degradation and progradation processes in soils and lands, as well as for describing evolution of soils accompanied by variation in the soil ecosystem capacity.

Marginal basins provide sensitive yet incomplete records of climate and tectonic forcing, and the southern North China Basin provides an ideal setting to decode these interactions since the late Pliocene. A 135.6‐m borehole sequence, the XiaoQian (XQ) core, recovered from the Fuyang region, was dated using AMS 14C, OSL, and ESR, supplemented by magnetostratigraphic correlations to the parallel WLB core. Integrated analyses of physical and geochemical proxies were then employed to reconstruct the depositional evolution over the past ∼3 million years. The succession records three main stages. Stage I (∼3–1.6 Ma) comprises sandy delta‐front deposits, indicating active progradation into a lacustrine basin. Stage II (∼1.6–0.128 Ma) consists of rhythmically bedded silty clays, recording hydrological instability on a delta plain. Stage III (∼0.128 Ma to present) is dominated by floodplain muds, reflecting low‐energy alluviation under stable tectonic conditions. Variations in sediment continuity and thickness reflect the combined influence of tectonic segmentation and autogenic reworking, which modulated the completeness of the stratigraphic record. Within well‐preserved intervals, elemental and magnetic proxies show coherent trends that parallel regional and global reference curves, indicating that monsoon hydroclimate and base‐level fluctuations were the primary external controls, while local tectonic setting and depositional dynamics influenced how these environmental signals were recorded.

Akter, J.; Sarker, M.H.; Popescu, I., and Roelvink, D., 2016. Evolution of the Bengal Delta and its prevailing processes. Bangladesh, occupying low-lying floodplains and tidal plains, has one of the largest and the most disaster-prone populous deltas in the world. The Bengal Delta is a tide-dominated delta, where tides play the key role in the sediment dispersal process and in shaping the delta. There are many studies and reports on river-dominated deltas, but research is sparse on tide-dominated deltas. The Ganges and Brahmaputra Rivers, which combined form one of the three largest riverine sources of water and sediment for the world's oceans, have developed the Bengal Delta to its present form with an aerial extent of 104 km2. About 1012 m3 of water with 109 tonnes of sediment per year make this system morphologically active. In the last five decades, the Bengal Delta has prograded at a rate of 17 km2/y, whereas most large deltas elsewhere in the world suffered from sediment starvation. Delta progradation always makes the river system unstable, and rapid changes cause the delta to become dynamic. Sea level rise induced by unequivocal climate change and subsidence would make the delta more vulnerable in the coming decades. Although some literature is available on the millennium-scale development process of the Bengal Delta, sound knowledge on the decade- to century-scale processes of the delta development for facing the threats of climate change and deltaic subsidence is limited. In addition, there are significant differences in opinions and widely varying findings in the literature to the response of the delta to different natural and human interventions. Against this backdrop, relevant available literature on Bengal Delta and deltas elsewhere in the world, is reviewed and evaluated to provide direction for future research that would help to form a way out of the present situation and a way into sustainable planning for this delta.

Since the Quaternary Period, paleo-seawater intrusions have been suggested to explain the observed saline groundwater that extends far inland in coastal zones. The Luanhe River delta (northwest coast of the Bohai Sea, China) is characterized by the distribution of saline, brine, brackish, and fresh groundwater from the coastline inland. The groundwater in this region exhibits a wide range of total dissolved solids (TDS): 0.38–125.9 g L−1. Meanwhile, previous studies have revealed that this area was significantly affected by Holocene marine transgression. This study used hydrochemical, isotopic, and sedimentological methods to investigate groundwater salinization processes in the Luanhe River delta and its links to paleo-environmental settings. Isotopic results (2H, 18O, 14C) allowed old groundwater recharge to be distinguished from new groundwater recharge. Hydrochemical analysis using the PHREEQC code indicated that the salt in saline and brine groundwater originates from a marine source. The 18O–Cl relationship diagram yields three-end-member groundwater mixing, and two mixing scenarios are suggested to explain the freshening and salinization processes in the study area. When this was interpreted along with data from paleo-environmental sediments, we found that groundwater salinization may have occurred since the Holocene marine transgression. The brine is characterized by radiocarbon activities of ∼ 50–85 pMC and relatively depleted stable isotopes, which are associated with seawater evaporation in the ancient lagoon during delta progradation and mixing with deeper fresh groundwater, which was probably recharged in the cold Late Pleistocene. The brackish and fresh groundwaters are characterized by river-like stable isotope values, where high radiocarbon activities (74.3–105.9 pMC) were formed after the washing out of the salinized aquifer by surface water in the delta plain. This study presents an approach that utilizes geochemical indicator analysis with paleo-geographic reconstruction to better assess groundwater evolutionary patterns in coastal aquifers.

We hypothesize that brackish groundwater within unconfined aquifers located in active river deltas may have resulted from rapid shoreline progradation during the Holocene. To explore this hypothesis, we develop a coupled model of variable‐density groundwater flow and solute transport within a prograding sedimentary delta. In this model, the continuously evolving sedimentary delta domain is developed by laterally advancing a geometrically defined clinoform into an ocean with a changing sea level. To numerically solve the model, we used the control volume finite element method, where the numerical grid evolves in response to the changing delta geometry, while enforcing local mass balance around each grid node point. Results show that, if the lateral groundwater velocity is slower than the shoreline propagation rate, transient trapping of saline water occurs onshore. This process can be characterized by the product of two dimensionless number groups (a) the ratio of the shoreline velocity to the lateral average linear groundwater velocity and (b) a Peclet number quantifying the level of mixing between recharge freshwater and existing saline water. The presence of confining units enhances the sequestration of onshore seawater behind an advancing shoreline. Our results complement prior numerical modeling studies that demonstrate that salinity within onshore aquifers is enhanced by vertical diffusion of solutes out of marine confining units.

The thick Lake Pannon sedimentary record provides insights into the downdip and lateral development of stratigraphic surfaces through the analysis of the basin-scale clinoform progradation. The clinoform architecture from the eastern part of the Drava Basin (Pannonian Basin System) was interpreted to reflect the base-level changes. A major downlap surface interpreted as a flooding event followed by rejuvenation of slope progradation was recognized on 2D seismic sections. Detailed 3D seismic interpretation combined with well data revealed that the large sigmoidal and the overlying small oblique clinoform sets that downlap the large one only apparently produce the geometry of a maximum flooding surface. Instead, the 3D mapping revealed the influence of two competing slope systems arriving from the north and northwest. Lateral switching of sediment input, similar to many recent deltaic systems. e.g., Danube and Po rivers led to the variability of stratigraphic surfaces, lithology, and thickness, which resulted in non-uniform shelf-edge migration. These observations were supported by forward stratigraphic modeling simulating different scenarios, which led to the generation of the depositional architecture with an apparent maximum flooding surface. This study also implies the potential pitfalls in basin analysis based only on scarce 2D seismic and emphasizes the role of lateral variations in sediment input controlling the depositional architecture.

The early Cenozoic marine sedimentary record is punctuated by several brief episodes (<200 kyr) of abrupt global warming, called hyperthermals, that have disturbed ocean life and water physicochemistry. Moreover, recent studies of fluvial–deltaic systems, for instance at the Palaeocene–Eocene Thermal Maximum, revealed that these hyperthermals also impacted the hydrologic cycle, triggering an increase in erosion and sediment transport at the Earth's surface. Contrary to the early Cenozoic hyperthermals, the Middle Eocene Climatic Optimum (MECO), lasting from 40.5 to 40.0 Ma, constitutes an event of gradual warming that left a highly variable carbon isotope signature and for which little data exist about its impact on Earth surface systems. In the South Pyrenean foreland basin (SPFB), an episode of prominent deltaic progradation (Belsué–Atarés and Escanilla formations) in the middle Bartonian has been usually associated with increased Pyrenean tectonic activity, but recent magnetostratigraphic data suggest a possible coincidence between the progradation and the MECO warming period. To test this hypothesis, we measured the stable-isotope composition of carbonates (δ13Ccarb and δ18Ocarb) and organic matter (δ13Corg) of 257 samples in two sections of SPFB fluvial–deltaic successions covering the different phases of the MECO and already dated with magnetostratigraphy. We find a negative shift in δ18Ocarb and an unclear signal in δ13Ccarb around the transition from magnetic chron C18r to chron C17r (middle Bartonian). These results allow, by correlation with reference sections in the Atlantic and Tethys, the MECO to be identified and its coincident relationship with the Belsué–Atarès fluvial–deltaic progradation to be documented. Despite its long duration and a more gradual temperature rise, the MECO in the South Pyrenean foreland basin may have led, like lower Cenozoic hyperthermals, to an increase in erosion and sediment transport that is manifested in the sedimentary record. The new data support the hypothesis of a more important hydrological response to the MECO than previously thought in mid-latitude environments, including those around the Tethys.