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Mangrove forests are critical coastal ecosystems that provide great socio‐ecological services, which are also highly vulnerable to climate change, particularly to sea level rise (SLR). Here we assess changes in mangrove forests in four distinct river/tide/wave‐dominant large deltas along the Indo‐Pacific coast based on 1,336 remote sensing images by machine learning techniques. We find that mangroves are migrating seaward at a rate of 18% ± 12% m/yr, which can offset landward mangroves loss, 67% of which caused by land use conversion. The fact that mangroves are expanding seaward with accretion rates exceeding SLR suggests that climate change has not yet triggered substantial loss in deltaic mangrove forests. Assuming that present environmental conditions do not change and that sediment and organic deposition in the deltaic topsets match SLR rates, we project that 90% of deltaic mangrove forests may start to retreat after 132–194 years. Early inundation of mangroves will occur in wave‐dominated delta. Plain Language Summary: Mangrove forests provide significant ecological and societal services, and mitigation global warming. However, large‐scale loss in mangroves could be induced by anthropogenic drivers and sea level rise (SLR). Our study based on deltas along the Indo‐Pacific coast, highlight that mangroves are expanding seaward at a rate of 18% ± 12% m/yr, indicating that there is little impacts from SLR and has not been substantial loss in mangrove forests in these deltas so far. Mangrove expansion here can efficiently offset 67% landward mangrove losses indicates that our new model project that 90% of mangrove shorelines will may start retreating within 132–194 years. We conclude that favoring mangroves expansion seaward would enhance coastal protection and reduce the need of landward mangrove restoration. Key Points: Mangroves along typical deltas are expanding seaward of about 18% ± 12% m/yr, indicating that there is little impacts from sea level riseMangrove expansion here can efficiently offset 67% landward mangrove lossesNew model project that 90% of mangrove fringes may start retreating within 132–194 years, and wave‐dominated delta present early inundation [ABSTRACT FROM AUTHOR]

Notch development at the base of sea cliffs is an important control on cliff recession rates, but a detailed mechanistic understanding of notch formation by swash abrasion is lacking. We conducted physical experiments, using homogeneous erodible rock simulants, to study notch‐forming mechanisms under periodic sediment‐laden bore impacts. Our findings reveal shifts in the temporal dynamics of notch development. Initially, swash uprush and vortex formation contribute to a positive feedback loop that creates a shallow and wide notch. Subsequently, upward erosion ceases, and notch backwear and downwear are dominated by the vortex. Eventually, sediment deposition armors the notch floor; this negative feedback loop reduces erosion. The sediment size determines the amount of erosion, with a range of grain sizes generating maximum erosion. This indicates a dependence on the momentum of the sediment particles entrained within the bore. This research reveals fundamental notch formation mechanisms driven by swash abrasion. Plain Language Summary: When waves attack a rock cliff, they gradually undercut the cliff and remove materials, forming a wave‐cut notch. Studying how notches form and develop in natural settings takes a very long time, so we created a weaker cliff in the laboratory using easily eroded foam. The cliff was exposed to repeated impacts from bores carrying sediment, representing the impact of broken waves. Notch formation is observed over a few hundred hours. Initially, the notch is wide and shallow. As it grows, abrasive sediment cannot be propelled into the roof, stopping the upward expansion of the notch, and sediment piles up at the bottom, blocking further downward erosion. The notch continues to deepen, but at a decreasing rate. The size of the beach sand or gravel has an important influence on the erosion rate. If the sediments are too large or too small, little erosion occurs, whereas sediments of a certain size can cause rapid erosion. This is because waves need to be able to entrain sediment and hurl it with sufficient force against the cliff to cause erosion. Key Points: Controlled laboratory experiments with repeated swash impacts reveal positive and negative feedback mechanisms in abrasion notch formationNotch geometry varies over time and is determined by swash impact location, vortex formation and sediment depositionGrain size modulates beach shape and sediment‐laden bore momentum, collectively influencing notch development [ABSTRACT FROM AUTHOR]

Salt diapirs dominate the structure in many sedimentary basins and control the preservation and migration of hydrocarbon. The formation of salt diapirs generally falls into two endmember models: active (up-building) and passive (down-building) diapirism. In the active model, salt diapirs rise from salt buoyancy to pierce through the sedimentary overburden, whereas in the passive model, salt diapirs result from differential loading of sediments during deposition. These endmember models are mostly conceptual or kinematic, the mechanics of active and passive diapirism and their relative roles and interactions in the formation of salt diapirs remain uncertain. Here, we use two-dimensional high-resolution numerical models to investigate the primary factors and critical conditions for active and passive diapirism. Our results indicate that it is improper to use driving mechanisms to classify salt diapirs, because the buoyancy-driven active salt diapirism involves differential loading, while the passive diapirism requires salt buoyancy. The rise of salt diapirs is more sensitive to the effective viscosity of the overburden than to the salt viscosity. Stiff overburdens could prevent the rise of salt diapirs, but they could be pierced by salt diapirs if plastic yield of the overburden is allowed. During deposition, the coupled salt-sediment deformation, driven by both salt buoyancy and differential loading of sediments, can lead to various diapiric salt structures and minibasins. Regional tectonic stress generally promotes salt diapirism by enhancing strain weakening of salts and overburdens. We suggest that the classification of active and passive salt diapirism is an oversimplification in most cases. We propose a general model of the formation of salt diapirs that usually begins with dome initiation driven by salt buoyancy, followed by syndepositional down-building controlled by sedimentation and differential loading and ends with canopy formation when sedimentation stops. [ABSTRACT FROM AUTHOR]

Utilizing over 31   000 Lg waveforms from 136 crustal earthquakes recorded at 346 regional stations, we conduct detailed tomographic mappings of the Lg Q structure across Eastern Asia in a frequency range from 0.5 to 4.0 Hz. By improving the standard two-station (TS) method, we effectively correct non-unity site response ratios using site responses estimated at individual stations. This innovative approach combines the flexible recording geometry of the TS method with the precision of reversed two-station (RTS) and reversed two-event (RTE) methods, producing a comprehensive data set devoid of source and site effects for Q tomography. To address unsolvable 3-D structural effects in the Lg spectral amplitude modelling, we justify these as modelling errors with a Gaussian distribution. This approach supports our SVD-based tomographic method, allowing for effective inversion of attenuation parameters and quantitative assessment of model resolution and errors. Our results reveal a complex relationship between Lg Q and the tectonic characteristics of Eastern Asia. In well-resolved regions, low Q o (1-Hz Q) values correspond to areas with high heat flow, partial melt, thick sediment and recent tectonic-thermal activities, in contrast to high Q o values in stable, ancient crusts lacking recent tectonic activity. Rift basins are characterized by low Lg Q o, whereas flexural basins generally have high Q o basements. We also note that post-formation factors, such as sedimentation and crustal flow intrusion, significantly impact Q o values. Furthermore, Lg Q shows a complex frequency relationship, though the power-law approximation with positive power η remains useful. The frequency dependence power η is inversely related to Q o: the regions with low Q o typically have high η and vice versa. This study provides reliable attenuation tomographic and relative site response models for Lg waves in Eastern Asia, pertinent for relative geophysical studies. [ABSTRACT FROM AUTHOR]

This study presents a comprehensive analysis of shoreline dynamics in the Thanjavur district, focusing on erosion and accretion trends from 1992 to 2022. The coastal region was partitioned based on Taluk boundaries to discern distinct patterns in erosion and accretion. The Peravurani region displayed stability, while the Mettupalayam Coast exhibited modest accretion, influenced by sediment deposition from the Tedakkiar River. Mettupalayam had the highest net shoreline movement (NSM), contrasting with the Mandiripattinam coast’s prevalent erosion trend. Areas such as Ammani Chattram and Setubava Chattram coast remained relatively stable, while Ganeshapuram, Sendalapattinam, and Sembalpattinam coasts experienced low accretion linked to the Ambuliar River. The study found that the maximum erosion in the study area is 4.1 m/yr (end point rate (EPR)) and 4.21 m/yr (linear regression rate (LRR)) at the Maravakkadu coastal region, and the maximum accretion is 3.75 m/yr (EPR) and LRR of 4.12 m/yr at the Mettupalayam coast. Employing the Kalman filter, future shoreline projections for 2032 and 2042 revealed heightened erosion and accretion trends, identifying vulnerable areas and distinct accretion patterns. It has been predicted that the eastern part of the coastal stretch erodes towards the land, and the western part is accreting. The dynamic interaction of erosion and accretion in Sendalapattinam underscored historical influences on future projections. However, ongoing erosion on the Maravakkadu coast may entail potential economic consequences. The findings emphasize the need for informed coastal management strategies, integrating historical data and future predictions. This will help maintain the coastal ecosystem and community resilience in the changing shoreline dynamics. [ABSTRACT FROM AUTHOR]

In the study of natural waterways, the use of formulas such as Manning's equation is prevalent for analyzing flow structure characteristics. Typically, floodplains exhibit greater roughness compared to the main river channel, which results in higher flow velocities within the main channel. This difference in velocity can lead to increased sedimentation potential within the floodplains. Therefore, accurately determining Manning's roughness coefficient for compound channels, particularly during flood events, is of significant interest to researchers. This study aims to model the Manning roughness coefficient in compound channels with both converging and diverging floodplains using advanced soft computing techniques. These techniques include a multi-layer artificial neural network (MLPNN), Group Method of Data Handling (GMDH), and the Neuro-Fuzzy Group Method of Data Handling (NF-GMDH). For the analysis, a dataset from 196 laboratory experiments was used, which was divided into training and testing subsets. Input variables included parameters such as longitudinal slope (So), relative hydraulic radius (Rr), relative depth (Dr), relative dimension of flow aspects (δ*), and the convergent or divergent angle (θ) of the floodplain. The relative Manning roughness coefficient (nr) was the output variable of interest. The results of the study showed that all the models performed well, with the MLPNN model achieving the highest accuracy, characterized by R² = 0.99, RMSE = 0.001, SI = 0.0015, and DDR = 0.0233 during the testing phase. Further analysis of the soft computing models indicated that the most critical parameters influencing the results were Sr, Rr,Dr*, and θ. These findings highlight the effectiveness of soft computing techniques in accurately modeling the Manning roughness coefficient in complex channel conditions and provide valuable insights for future research and practical applications in the management of flood events and waterway analysis. [ABSTRACT FROM AUTHOR]

Grade control structure (GCS) can be used to reduce erosion in river beds. They decrease the river bed scour by changing the flow regime and reducing its velocity. It is required to maintain the stability of these structures against the scour hole that generates downstream of them, so investigating the scour hole characteristics downstream of the GCS is inevitable. In the present research, the equilibrium scour holes downstream of GCS were investigated under three discharges (q=0.00467, 0.00583, 0.00700 m3/s.m) and two different sedimentation conditions (d50=0.082, 1.6 mm). The results show that in the constant GCS geometry and finer sediment, the maximum scour depth (ds) and maximum scour hole length (ls) increase. In the same sedimentary conditions and different geometry, when the slope of the GCS downstream face varied from 90° to 60°, ds increases, but ls decreases. Also, the hydraulic jump forms on the scour hole at high flow intensity, which has an essential influence on the geometry of the equilibrium scour hole. Comparison of ds/Hc between the present study and Ben Meftah and Mossa (2020) has R2=0.891 and RE=10.66%, which reveals acceptable compatibility between the present study results and previous ones. [ABSTRACT FROM AUTHOR]

The alarming degradation of soils, particularly in the Moroccan Rif region, is the result of various forms of water erosion processes, leading to significant environmental and economic damage in the area. The Oued Lebene watershed is a sub-basin of the Sebou River, located in the central part of the Pre-Rif. Using GIS, remote sensing, and the universal soil loss Equation modified for North African conditions and validated by field observations, this study aimed to measure soil losses, sediment delivery capacity, and sediment yield rates. The estimation of soil loss reveals that the watershed is exposed to a high degree of erosion, reflected by an estimated total annual loss of 6 379 314 t/yr, with an average annual rate of 46.17 t/ha/yr. The severe erosion class covers 52.25% of the study area, contributing to 90.67% of sediment production with an average of 80.11 t/ha/yr-1. The erosion class below the tolerance threshold according to Wischmeier represents 48 108 hectares, or 34.82% of the total watershed area. Analysis of the synthetic sediment delivery ratio (SDR) map shows that the sediment delivery capacity is approximately 0.17, and the sediment yield (SY) in the Oued Lebene watershed is estimated at 770 440.32 t/yr. This is the outcome of the interaction between multiple causative factors, including steep slopes, friable substrates, severely degraded vegetation cover, etc., which increasingly accelerate the degradation of water resources in the downstream Oued Sebou, a source of irrigation for agricultural lands. [ABSTRACT FROM AUTHOR]

The present study discusses flood hazard characteristics in the lower reaches of the West Rapti River based on the results obtained from field surveys and numerical computations using depth averaged 2-D numerical models for flood flow and associated sediment transportation. To evaluate the inundation process with sediment erosion and deposition in the floodplain, a new erosion term was introduced into the mass conservation equations for suspended sediment and bed sediment. The results obtained from numerical computations indicated that field data on the spatial distributions of depths for inundation, and sediment erosion and deposition can be evaluated by the numerical model. Thus, numerical predictions were performed for the inundated areas, and the accumulated volumes of sediment erosion/deposition for floods with return periods of 50, 100, and 200 years, as a step towards damage assessment and risk assessment due to floods with active sediment transportation in the floodplains. [ABSTRACT FROM AUTHOR]

Naumure Multipurpose Project (NMP) featuring a 169 m high Concrete Face Rock Filled Dam (CFRD) is the proposed reservoir project in the West Rapti River with an installed capacity of 218.34 MW. Most of the rivers in Nepal carry significant sediment loads that will consequently catalyze reservoir sedimentation. This phenomenon prevails as the primary factor in reducing reservoirs useful life, making ineffective for both flood control and hydroelectricity generation. Ultimately, such process of sedimentation has adverse impacts on projects economic feasibility and long-term sustainability. Therefore, the objective of this research was to examine the expected sediment deposition pattern in the NMP reservoir throughout its operational period by employing 1D HEC-RAS model to simulate the sedimentation process. The model was simulated for 10, 20, 30, 40 and 50 years. Yang's equation as a sediment transport function, Active layer as a bed sorting method and Toffaleti as a fall velocity method were best suited for the river reach. The delta deposition was formed between 11 km and 22 km upstream of the dam region in the Jhimruk river, with the sediment deposition depth reaching peaks of about 23 m, 38 m, 39 m, 41 m and 49 m in 10, 20, 30, 40 and 50 years, respectively. Similarly, the delta deposition was formed between 13 km and 33 km upstream of dam region in the Madi river, with the sediment deposition depth reaching peaks of about 47 m, 62 m, 60 m, 68 m and 75 m in 10, 20, 30, 40 and 50 years respectively. Headcutting of delta deposition occurred between 20 and 30 year due to high flood during low stage of reservoir. Furthermore, the study revealed that about 6.22%, 11.61%, 15.94%, 22.96% and 25.65% of the storage capacity of NMP reservoir will be depleted in 10, 20, 30, 40 and 50 years respectively. [ABSTRACT FROM AUTHOR]

While the Cretaceous Normal Polarity Superchron has documented instances of brief reversed polarity intervals, the absence of accurate age determinations for such abrupt shifts poses a challenge in leveraging them as reliable reference tiepoints. This study presents a cyclostratigraphic analysis of gamma‐ray data from the DSDP Site 402A. The identification of Milankovitch cycles allowed us to construct a 405‐kyr astronomically‐tuned age model for two reversed events that occurred in the Aptian. Our results estimate an age of 117.03 ± 0.14 Ma for the Chron M"‐1r" or ISEA and 116.17 ± 0.14 Ma for reversal "2," with timespans of ∼20 and ∼10 kyr, respectively. Sedimentation patterns are influenced by orbital eccentricity cycles with an average sedimentation rate of 5 cm/kyr. The short time intervals related to these reversals exposes the difficulty in their detection in cores through paleomagnetic analysis as well as in deep‐tow surveys. Plain Language Summary: The Cretaceous Normal Polarity Superchron (CNPS) was characterized as a "quiet zone," which includes no geomagnetic reversals during ∼38 Myr. A number of studies propose significant fluctuations in geomagnetic intensity, with distinct features observed in paleosecular variations, including periods of reversal events, and the actual occurrence, timespan and ages for these rapid magnetozones have been under debate in literature. This paper provides the age and constrains the timespan of two of these debated reversals (i.e., M"‐1r" or ISEA, and "2") during the CNPS. The determination of the age of the reversals during the CNPS is a fundamental support for global correlations. Key Points: Orbital tuning for M‐1r (ISEA) has an age of 117.03 ± 0.14 Ma and a timespan of 20 kyrThe reversal "2" has an age of 116.16 ± 0.14 Ma and a minimum timespan of 10 kyrDSDP Site 402A has an average 5 cm/kyr sedimentation rate and eccentricity Milankovitch cycles rules sedimentation patterns [ABSTRACT FROM AUTHOR]

While the biogeochemical properties of the Israeli coastal shelf (ICS) are similar to adjacent pelagic waters, the external sources of inorganic nitrogen (N) are very different. The main source of 'new' N to the pelagic zone is deep winter mixing, with minor contributions from atmospheric deposition and eddy diffusion across the nutricline. For the ICS, major N sources include offshore water advection (260 × 10⁶ mol N y−¹), atmospheric input (115 × 10⁶ mol N y−¹), and riverine input (138 × 10⁶ mol N y−¹), which primarily consists of treated wastewater and stormwater runoff. Direct pollutant discharge from sewage outfalls and submarine groundwater discharge are relatively minor. Key N sinks are new production (420 × 10⁶ mol N y−¹) and sediment deposition and uptake (145 × 10⁶ mol N y−¹). Inputs of nitrate and ammonium were similar and dominant in winter. Unlike temperate shelves, where riverine input is dominant, here it was only slightly higher than atmospheric input, with net N advection onto the shelf being significant. External N inputs did not change net primary production (NPP) by more than ~30% or affect dominant pico and nanophytoplankton genera, except in localized patches. This study offers baseline values for future climate and environmental change assessments. [ABSTRACT FROM AUTHOR]

Submarine fan reservoirs are important accumulation zones for oil, gas, and natural gas hydrates, offering significant potential for hydrocarbon exploration. During the deposition period of the Sanya Formation in the southern part of the Changchang Sag of the Qiongdongnan Basin, a large submarine fan developed. However, the internal structure, source-sink system, and formation mechanism of this fan remain poorly understood, posing significant challenges to exploration in this area. This paper examines the source-to-sink sedimentary processes and deposition of submarine fans, using the Changchang Sag, in the Qiongdongnan Basin in the Northern South China Sea, as an example, which will provide valuable general guidance for deep water oil and gas exploration. Based on the theories of seismic stratigraphy and seismic sedimentology, this paper utilizes techniques such as seismic facies analysis, seismic attribute optimization, paleogeomorphology reconstruction, and source-to-sink sedimentary systemanalysis to analyze the 3D seismic data of the study area. Research indicates that the Sanya Formation in the Changchang Sag of the Qiongdongnan Basin comprises three depositional units: submarine fan, feeder channel, and Semi-deep marine to deep marine mudstone. The submarine fan is a fan formed by the coupling and convergence of submarine fans sourced from the southwest and southeast. Internally, it is divided into three sub-facies: the proximal fan of the sand-rich submarine fan, the main body of the sand-rich submarine fan lobes, and the distal lobes of the sand-rich submarine fan. The submarine fan sourced from the southwest extends nearly north-south and is primarily fed by sediment transported through three large, banded ancient valleys. The sedimentary filling is characterized by three-phase progradation. The submarine fan sourced from the southeast extends nearly east-west and is primarily fed by sediment transported through a single large, banded ancient valley. The sedimentary filling is characterized by two-phase lateral accumulation. During the deposition period of the Sanya Formation, certain areas of the southern uplift belt were exposed for extended periods and subjected to weathering and erosion. Sediments are transported to large ancient valleys through small supply channels. A large number of sediments were transported to the southern slope of the Changchang sag through the provenance channel system such as large ancient valleys and slope belts and deposited in the center of the sag. These make up a complete system of large ancient uplifts and submarine fan source-to-sink sedimentary systems. The sedimentary model is a lobed submarine fan controlled by semi-restricted ancient valleys and expansive basins. [ABSTRACT FROM AUTHOR]

The northwestern continental margin of the South China Sea, extending from the broad shelf and canyon-growth slope across the Xisha Trough, represents a relic crustal rift that eventually connects to the abyssal plain. However, the provenance and source-to-sink process of sediments in this special topography remains unclear. In this study, we present the detrital zircon U-Pb geochronology of surface sediments from the northwestern margin of the South China Sea to identify the sediment provenance, track the transport pathway, and understand the source-to-sink process in this margin. The results showed that detrital zircons exhibit a wide range of U-Pb ages from 3,062.9 to 41.5 Ma and are characterized by peaks centered on 140–154 Ma, 240–258 Ma, 425–452 Ma, and 738–991 Ma. Statistical analysis indicated that the clastic sediments on the shelf closely resemble those sourced from the Pearl River system. Conversely, sediments on the slope and abyssal plain demonstrated characteristics indicative of multiple sources, primarily originating from the Pearl River, with a minor contribution from the Red River. Further quantitative study revealed a progressive increase (from 8.2% to 43.2%) in the prevalence of Red River-derived sediments with ascending water depth on the shelf and slope, whereas sediment influx in the deepest sector remains predominantly sourced from the Pearl River. This study emphasizes the controls of topography and currents in modulating the transportation of coarse-grained and fine-grained sediments within the sourceto- sink system and provides a favorable solution for reconstructing the sedimentary process in continental margins. [ABSTRACT FROM AUTHOR]

Controlled sediment flushing operations (CSFOs) allow to recover reservoirs storage loss while rebalancing the sediment flux interrupted by dams but, at the same time, may cause unacceptable ecological impact. In this study, we investigated the responses of the food web of an upland stream to a CSFO, focusing on the effects of fine sediment deposition detected in three different mesohabitats, i.e., a pool, a riffle, and a step-pool. The field campaign lasted two years and included repeated measurements of fine sediment deposits, and sampling of periphyton, benthic macroinvertebrates and fishes. A moderate and patchy deposition occurred due to the CSFO with short and medium-term ecological impact on the lower trophic levels of the food web, which may affect the whole ecosystem functioning. The monitoring of all available mesohabitats in the investigated stream allowed to detect variations in the ecological response to CSFO, providing a more adequate assessment of the impact. As expected, sedimentation was larger in the pool but, in contrast to our hypotheses, the impact was lower and the recovery was longer for the benthic organisms inhabiting the riffle. In the case of fishes, no lethal impact of both brown trout and bullhead was recorded in the short term but the occurrence of longer lasting effects could not be excluded. To date, this is one of the few studies dealing with a detailed integrative assessment of the downstream impact of sediment management from reservoir on both abiotic and biotic components of stream ecosystem. [ABSTRACT FROM AUTHOR]

High-latitude ecosystems have been overlooked in carbon budgets, which traditionally focus on mangroves, salt marshes, and seagrasses. The benthic assemblages and their Nature Contributions to People in Namuncurá – Burdwood Bank I and II, two offshore sub-Antarctic Marine Protected Areas (MPAs), are the conservation values. Here we show that the carbon reservoirs of these MPAs can be greater than those of their Antarctic counterparts, which, together with their extension, emphasize the need to maintain their protected status. Considering their total area, these MPAs stored in biomass 52,085.78 Mg C, corresponding 34,964.16 Mg to organic carbon (OC) and 17,121.62 Mg to inorganic carbon (IC). Surficial sediments stored 933,258,336 Mg C with 188,089,629 Mg of OC and 745,168,707 Mg of IC. However, when accounting for CO2 production through CaCO3 precipitation, the IC fractions decrease to 3,150.37 Mg C and 137,111,042 Mg C for biomass and sediments, respectively. We assume low sediment deposition due to the oceanic location, as direct sedimentation rates for these areas are unavailable. Most blue carbon assessments have focused solely on OC, despite the formation of CaCO3 releases CO2, decreasing net carbon storage. We compared various approaches for incorporating carbonates into carbon estimations. These results underscore the importance of including IC into carbon assessments and highlights the importance of sub-Antarctic benthic ecosystems as nature-based solutions to climate change. [ABSTRACT FROM AUTHOR]

The occurrence and abundance of Astrospartus mediterraneus (Risso, 1826) have significantly increased in the last three decades in several areas of the Mediterranean Sea. In the Tavolara–Punta Coda Cavallo Marine Protected Area (NE Sardinia, Tyrrhenian Sea, Mediterranean Sea), 60 specimens were observed mainly on the granitic shoals of the Tavolara Channel, an area characterized by very intense currents and high sedimentation. The basket stars were mainly found living as epibionts of gorgonians (Eunicella verrucosa, Paramuricea clavata and Leptogorgia sarmentosa) and massive sponges (Spongia officinalis, S. lamella, Sarcotragus foetidus). We also documented 21 small specimens (3–20 mm in diameter of the oral disc) observed in June 2024 between 27 and 52 m depth on E. verrucosa and P. clavata colonies. The bimodal size-frequency distribution of these specimens suggested that, probably, specimens belong to two different reproductive events occurring in spring 2023 and 2024. [ABSTRACT FROM AUTHOR]

This paper focuses on the numerical study of spherical particle sedimentation, taking into account hydrodynamic interactions. Infinite impulse response (IIR) digital filters, specially tailored to solve the sedimentation dynamics, were used in the present study to numerically solve the coupled ordinary differential equations with the time-dependent coefficients of the problem. Hydrodynamic interactions are modeled using the Rotne–Prager–Yamakawa (RPY) approximation, to which a correction is made to better account for short-range interactions. In order to validate both the proposed numerical resolution method and the RPY correction, this paper begins with the study of two interacting spherical particle sedimentation methods. Comparisons with previously published analytical or numerical results confirm the relevance of the present approach. [ABSTRACT FROM AUTHOR]

Flocculation sedimentation state observation could be used to facilitate interaction visualization in laboratories and establish theories for industrial manufacture. Herein, kaolinite was obtained from different sources and labeled as K1 and K2. Those characteristic characterizations indicated that silica sand was difficult to remove from refined commercial kaolinite with different sources. Some biosafe and removable surfactants have been used to evaluate the flocculation sedimentation state of kaolinite-surfactant slurry for a long time, indicating those surfactants could accelerate the settling velocities within a certain range, which could be attributed to sufficient surfactant-kaolinite interactions, but decelerate the settling velocities with the excess surfactant addition, which could be attributed to the surfactant-water colloidal characteristic. Then, the flocculation sedimentation mechanism was illustrated in detail based on the kaolinite-surfactants interaction, indicating that the excellent flocculation sedimentation state was beneficial to silica removal with sedimentation method, but the difficult flocculation sedimentation state was beneficial to size classification with differential centrifugation. [ABSTRACT FROM AUTHOR]

Soil erosion and sediment yield is a global problem that increasingly contributes to soil degradation. Although erosion analysis requires the availability of erosion and sedimentation data, the lack of sediment monitoring stations and the resulting limitations in collecting sediment measurements have necessitated the use of experimental models in many areas. The present study aimed to compare Factorial Scoring Model (FSM) and Modified Pacific South-West Inter-Agency Committee (MPSIAC) model for estimating erosion in the Mazdaran Basin (Firoozkuh, Iran). For this purpose, the required maps were prepared for both models, and the sediment rate was estimated using the two models to compare their efficiency using the corresponding maximum error (ME) and coefficient of determination (R2) values. The results showed that considering sediment based on the FSM model, the studied catchment consisted of regions with a high and very high sediment yield, while the MPSIAC model identified regions with low, medium, and high sediment yield. With an R2 value of 0.62 and an ME value of 2.24, the MPSIAC model provided more accurate estimates of the sediment yield in the studied area. Using the MPSIAC model, sediment yield was 6687.86 tons per year or the equivalent of 2.64 tons/ha per year. [ABSTRACT FROM AUTHOR]

Submarine conduits are features responsible for transporting clastic debris from continents to the deep ocean. While the architecture of conduits has been extensively studied, the process of their inception remains unclear. This study highlights the possibility that some conduits are initiated by depositional processes involving turbidity currents. Here, we present the results of eight experiments where gravity currents were allowed to develop their own pathways. The simulation tank represented natural scales of continental shelves, slopes, and basins. The initial experiments involved sediment-laden flows with low density (1–10% in volume). In first experiment runs (Series I), sediment deposition occurred primarily on the shelf and slope, resulting in an asymmetric transverse profile. This asymmetry facilitated subsequent conservative currents (1034 to 1070 kg/m3 due to salt dissolution) flowing alongside during the second series, resulting in the formation of a constructive submarine conduit. This feature is analogous to gully formations observed in various locations. This study correlates these findings with gully-like features and proposes a model where non-confined density flows can evolve into confined flows through the construction of asymmetric topography. An evolutionary model is proposed to explain the mechanism, which potentially elucidates the formation of many submarine conduits. [ABSTRACT FROM AUTHOR]

Hydraulic fracturing is the primary method used for oilfield stimulation, and the migration and settlement pattern of proppant plays a crucial role in the formation of high conductivity propping fractures in the reservoir. This study summarizes two growth modes of sand dune: the ‘overall longitudinal growth’ mode and the ‘push growth along fracture length direction’ mode. To investigate these modes, a two-phase velocity test is conducted using PIV, and the exposure difference is utilized to separate the tracer and track the single-phase velocity. By analyzing the slickwater flow field and proppant velocity field, the micro-motion mechanism behind the two dune growth modes is quantitatively examined. The results indicate that mode 1 growth of the sand dune occurs when a pump with a large mesh number, high polymer viscosity, and large displacement is used. On the other hand, mode 2 growth is observed when a pump with a small mesh number, low polymer viscosity, and small displacement is employed. It is important to note that there is no clear boundary for the migration and sedimentation mode of proppant, as they can transition into each other under certain conditions. These modes only exist during specific stages of sand dune growth. In the case of the ‘backflow’ pattern, the settlement of proppant is primarily influenced by the vortex structure of slickwater. Conversely, in the ‘direct’ pattern, the proppant is propelled forward by the drag of the fluid and settles due to its own gravity. Once the proppant placement reaches equilibrium, the direction of proppant velocity follows a normal distribution within 0°. This approach establishes a connection between the overall placement of the sand dune and the microscopic movement of the proppant and slickwater. Optimizing construction parameters during fracturing construction can enhance the effectiveness of distal proppant placement in fractures. [ABSTRACT FROM AUTHOR]

This paper presents the construction of a numerical three-dimensional model of the area of the Żelazny Most Mining Waste Storage Facility (MWSF). In the study area, the difficult geological conditions associated with glaciotectonics are accompanied by a complex hydrotechnical system of sediment deposition and sedimentary water drainage. In order to effectively reflect the water flow paths, a detailed schematization was carried out, using 700,000 boreholes and more than 300 hydrogeological cross-sections. In addition, numerous drainage sections, streams, and ditches were included to reliably assess the amount of saline water entering the underlying aquifers. This research was supported by magnetic resonance sounding (MRS) studies of the reservoir's sediments. The MWSF is currently being expanded, so the work primarily focuses on illustrating changes in the hydrodynamic field resulting from the inclusion of the new southern section. Models of similar facilities have been implemented before, but in the current one, the combination of meticulous analysis of the hydro-structural system, the water balance, a significant amount of data, the size of the facility, and the use of an unstructured discretization grid in the calculations is undoubtedly innovative and will be an important contribution to the development of analogous solutions around the world. [ABSTRACT FROM AUTHOR]

Sediment deposition is critical in maintaining riparian plant communities by providing essential nutrients and posing growth challenges. This study focuses on Cynodon dactylon, a dominant clonal species in the riparian zones of the Three Gorges Reservoir, and its interaction with sediment deposition over three years. Results indicated an average sediment deposition depth of 2.85 cm in the lower riparian regions. Observations revealed that C. dactylon coverage increased progressively at lower elevations despite its dominance diminishing with rising elevation levels. Additionally, positive linear correlations between C. dactylon coverage and sediment deposition depths were identified during flood periods, underscoring the species' role in enhancing sediment deposition. These findings suggest that C. dactylon plays a significant role in sediment accumulation, which may bolster its growth and survival prospects during subsequent growing cycles. The study highlights the importance of riparian vegetation, mainly perennial clonal species like C. dactylon, in promoting sediment accumulation and contributing to the stability and functionality of riparian ecosystems. [ABSTRACT FROM AUTHOR]

Study Design: Retrospective Upright MRI Study. Objectives: Determine the relationship between lumbar disc herniation and presence of the nerve root sedimentation sign on upright kinematic MRI patients. Methods: T2-weighted axial upright kMRI images of 100 patients with the presence of disc herniation in at least 1 lumbar disc between L1/L2 and L5/S1 were obtained. Sedimentation sign, spinal canal anterior-posterior (AP) diameter, disc height, disc herniation size, type of herniation, and zone of herniation were evaluated. A positive sedimentation sign was defined as having either the majority of nerve roots running ventrally or centrally in the canal or conglomeration of the nerve roots at the mid-disc level. Herniation types were defined as either no herniation, disc bulge, protrusion, extrusion, or sequestration. Zones of herniation were categorized as either central, lateral, or far lateral. Results: The kappa value of intra-observer reliability was.915. The kappa value of disc levels with a negative sedimentation sign were seen more frequently (n = 326, 65.2%) than those with a positive sedimentation sign (n = 174, 34.8%). The spinal canal AP diameter was significantly decreased at the L3/L4 and L4/L5 level in patients with a positive sedimentation sign. Discs with a positive sedimentation sign had a larger average size of disc herniation compared to those with a negative sign at all levels. A relationship between positivity of the sedimentation sign and disc herniation type was significant at L2/L3, L3/L4, and L4/L5. Conclusions: Patients with a positive sedimentation sign were seen to have larger disc herniations and more severely degenerated discs. [ABSTRACT FROM AUTHOR]

This article studies the migration and settlement laws of backflow proppants after fracturing tight sandstone. This paper proposes a fitting method based on a multi-task learning network to address the issue of interference from multiple physical parameters during the transport and settlement processes of proppants. This method can effectively handle multi-dimensional interference factors and fit the mapping logic of multiple engineering parameters to transport patterns through the continuous correction of multi-layer networks. We first introduce the characteristics of tight sandstone reservoirs and their important value in mining, as well as the status of current research on the migration and settlement laws of proppants at home and abroad. Based on this, we then deeply analyze the sedimentation rate model of proppants in tight sandstone backflow and the equilibrium height of proppants under multiple factors of interference while considering the distribution characteristics of proppants. In order to more accurately simulate the transport and settlement laws of proppants, this paper introduces a multi-task learning network. This network can comprehensively consider multi-dimensional parameters, learn the inherent laws of data through training, and achieve accurate fitting of the transport and settlement laws of proppants. This study trained and tested the model using actual production data, and the results showed that the proposed model can fit the input–output relationship well, thus effectively supporting the study of proppant transport and settlement laws. [ABSTRACT FROM AUTHOR]

Flash floods can carry substantial sediment, posing significant sedimentation hazards in hilly cities. The sedimentation hazard map can reproduce the sediment thickness and extent of an extreme events scenario, playing an important role in sediment risk management. However, current research primarily focuses on modeling the inundation area and depth of floods, while studying sedimentation hazard caused by flash floods in urban areas remains insufficient. This paper aims to address this gap by utilizing a numerical model that simulates hyperconcentrated flow in hilly urban areas using the two‐dimensional hydro‐sediment‐morphological model to compile the cumulative sedimentation hazard map. The model, built upon the open‐source TELEMAC‐MASCARET framework, incorporates Zhang Hongwu's formula to simulate sediment‐carrying capacity, particularly suitable for hyper‐sediment concentration near the riverbed. This paper uses the data of extreme flash flood events in the Wuding River basin in 2017 to simulate and compile the cumulative sedimentation hazard map. The hazard map delineates the sedimentation hazard extent and level attributable to overbank floodplain sedimentation. Notably, the sediment thickness is highest in areas near the levees on both sides of the Dali River. Moreover, the map illustrates the extent of channel erosion resulting from hyperconcentrated floods, which could jeopardize bank stability. [ABSTRACT FROM AUTHOR]

Many tidal marshes have been lost by past land use changes, but are nowadays increasingly restored and created to provide valuable ecosystem services such as nature‐based flood and erosion protection along estuarine shorelines. To be functional for flood and shoreline erosion protection, restored and created tidal marshes should develop erosion resistant sediment beds. Here, we investigated which factors drive the spatial variations in sediment strength and erosion resistance in a developing tidal marsh restoration site. Our results show that decreasing tidal inundation frequency, decreasing sedimentation rate, and better drainage led to stronger consolidation in deeper sediment layers. This consolidation resulted in greater sediment strength, quantified here by shear strength and penetration resistance. Generally, sediment strength was greater when sediment had higher bulk density, while a higher water and fine fraction (= clay and silt) content decreased sediment strength. Overall, all measurement locations were relatively erosion resistant, likely caused by the dense root network and cohesive sediment. To restore or create resilient tidal marshes for nature‐based flood and shoreline erosion protection, we should thus aim for sites with relatively low tidal inundation frequency, moderate sedimentation rates, and cohesive sediment mixtures of clay, silt, and sand, which are well drained and have potential for vegetation establishment. These conditions have a high likelihood of resulting in restored or created tidal marshes that contribute to nature‐based flood and shoreline erosion protection. [ABSTRACT FROM AUTHOR]

Sedimentary landforms on Earth and other planetary bodies are built through scour, transport, and deposition of sediment. Sediment connectivity refers to the hypothesis that pathways of sediment transport do not occur in isolation, but rather are mechanistically linked. In dryland river systems, one such example of sediment connectivity is the transport of fluvially deposited sediment by wind. However, predictive tools that can forecast fluvial‐aeolian sediment connectivity at meaningful scales are rare. Here we develop a suite of models for quantifying the availability of river‐sourced sediment for aeolian transport as a function of river flow, wind regime, and land cover across 168 km of the Colorado River in Grand Canyon, USA. We compare and validate these models using topographic changes observed over 10 years in a coupled river sandbar‐aeolian dunefield setting. The models provide a path forward for directly linking fluvial hydrology with the management and understanding of aeolian landscapes. Plain Language Summary: Landscapes on Earth are built from sediment, which is deposited by a variety of processes, especially water and wind. In rivers located in dry regions, sediment is deposited by flowing water during river floods. Once this sediment dries, it is often then moved by wind across the landscape. Although we frequently observe this sediment connectivity between water and wind, we are not currently able to predict when and where windblown transport of river‐deposited sediment may occur. We used maps of sand in Grand Canyon along 168 km of the Colorado River, along with records of river flow, wind speed, and vegetation cover, to develop four models that predict how much sediment is available for wind to move. We compared the results of these models to actual windblown sediment transport at a study site in Grand Canyon, finding that when models predicted more sand was available at the site, we also observed more landscape changes there which were due to wind. Our research makes it possible to understand how changes in river flows affect the amount of sediment moved by wind. Key Points: We developed four methods for modeling the extent of exposed, bare sand available for windblown transport in river valleysOur models employ data on river flow, land cover, wind velocity, and vegetation to predict exposed, bare sand extent at corridor scalesWhere models predict increased areal extent of bare sand, we also observe a greater volume of topographic changes driven by wind [ABSTRACT FROM AUTHOR]

Hydrological drought is a pervasive and reoccurring challenge in managing water resources. Reservoirs are critical for lessening the impacts of drought on water available for many uses. We use a novel and generalized approach to identify periods of unusually low reservoir storage—via comparisons to operational rule curves and historical patterns—to investigate how droughts affect storage in 250 reservoirs across the conterminous U.S. (CONUS). We find that the maximum amount of water stored in reservoirs is decreasing, and that periods of unusually low storage are becoming longer, more severe, and more variable in (a) western and central CONUS reservoirs, and (b) reservoirs with primarily over‐year storage. Results suggest that reservoir storage has become less reliable and more vulnerable to larger deviations from desired storage patterns. These changes have coincided with ongoing shifts to the hydroclimate of CONUS, and with sedimentation further reducing available reservoir storage. Plain Language Summary: Drought in water systems is a major challenge in managing water resources. Reservoirs are important as they can lessen the impacts of drought on water availability for many users. However, they are impacted by drought as well. We use a novel and generally applicable method to identify when reservoir storage is unusually low, potentially from drought, at 250 reservoirs across the conterminous U.S. We find that the maximum amount of water stored in reservoirs is decreasing across the U.S. We also find that periods of unusually low storage are becoming longer and more severe in western and central U.S. regions as well as for certain types of reservoirs. This suggests that reservoir storage may be less reliable and more vulnerable to extreme conditions and may be further impacted by changing climate and hydrology across the U.S. and by sediment building up behind reservoirs. Key Points: Low‐storage periods are longer, more severe, and more variable in over‐year storage reservoirs and in the western and central CONUSLonger periods of low storage for some regions in recent years suggests decreased reservoir reliability in a changing hydroclimateMaximum annual storage is also declining across CONUS, furthered by storage losses from sedimentation [ABSTRACT FROM AUTHOR]

The Zhongsha Platform is the largest modern isolated carbonate platform of around 8600 km2 in the South China Sea, providing a unique case study for sedimentary processes in pure carbonate settings. High-resolution multibeam bathymetric data, two-dimensional seismic profiles, and surface sediment cores are utilizes to reveal the initiation and evolution of submarine canyons on the northeastern slope of the Zhongsha Platform. Three submarine canyons are revealed within the survey area that incise the slope at water depths between 600 and 4100 m. C1 presents a linear pattern, whereas C2 and C3 exhibit dendritic morphologies. A large-scale scalloped collapse has deeply excavated the platform margin and slope. Within this catastrophic failure, C2 originated in a northeastward orientation and subsequently converted to an eastward direction with a length of 54.8 km. It is distinguished by the erosion of numerous tributaries in the upper course, the transition of flow direction in the middle course, and the presence of retrogressive landslides in the lower course. Slope landslides extend eastward from middle-lower slope towards the oceanic basin at water depths ranging from 2300 to 4200 m. A series of scarps and immature canyons have developed with escarpments showing pronounced relief at the landslide heads. The triggering mechanisms of platform margin collapses and slope landslides are attributed to sediment aggradation, slope oversteepening, gravity flows, relative sea-level changes, surface monsoon currents, and deep cyclonic circulation. The canyon evolution is explained through four stages: Inception stage, sediment instability on platform margin and slope-toe; Expansion stage, the presence of platformmargin collapses and slope landslides; Development stage, the initiation of submarine canyons eroded by gravity flows with downslope and retrogressive erosion; Present stage, the upper slope canyon incised into the landslide area and ultimately integrated with the lower slope canyon, creating an elongated modern canyon. This work contributes to enhance our understanding of the detailed morphology, transport processes, and triggering mechanisms of submarine canyons in the pure carbonate systems. [ABSTRACT FROM AUTHOR]

In order to explore the sediment deposition characteristic of ecological riverbanks associated with vegetation restoration in the deep waterway regulation scheme of Yangtze River, two kinds of typical ecological riverbanks and a traditional riprap riverbank (TRR) in engineering areas were investigated. The vegetation community characteristics, sediment aggregate compositions, nutrient contents, total organic carbon (TOC), sediment microbial biomass carbon (MBC), sediment microbial biomass nitrogen (MBN), and sediment microbial biomass phosphorus (MBP) were determined. The results indicated that the ecological restoration effect of the lattice gabion ballasted vegetation mat riverbank (LGBVR) was best, followed by the mesh grid riverbank (MGR), and that of the TRR was relatively poor. In different ecological riverbanks, the sediment aggregated compositions were not significantly varied. The sediment contents of NH4+-N, available phosphorus (AP), and TOC in ecological riverbank areas were relatively higher than those of the TRR. In the LGBVR, the sediment contents of MBC were relatively higher than those of the others. The sediment deposition characteristics and ecological restoration effects in the study area should be monitored for a long time. [ABSTRACT FROM AUTHOR]

Tidal flats, crucial for biodiversity and ecosystem services, are facing significant alterations due to human activities such as reclamation. In South Korea, over 65% of tidal flats have been reclaimed since the 1970s, resulting in morphological changes and altered sediment transport dynamics. This study investigates sediment transport processes in the artificial Aam tidal channel, created as part of the megacity development project in Incheon, Korea. Using data from Acoustic Doppler Current Profiler and Vector instruments deployed in 2019 and 2021, we analyzed tidal asymmetry, current velocities, shear stress, and suspended sediment concentration. Our results reveal a pronounced tidal asymmetry influencing sediment transport, with ebb-dominant currents near the channel entrance and flood-dominant currents in the interior. We observed significant sediment deposition in the landward section of the channel, driven by tidal mixing asymmetry and rainfall events. These findings highlight the complex interactions between artificial structures and natural sediment dynamics, informing future coastal development and management strategies. [ABSTRACT FROM AUTHOR]

Spaceborne spectroscopic imaging offers the potential to improve our understanding of biodiversity and ecosystem services, particularly for challenging and rich environments like mangroves. Understanding the signals present in large volumes of high-dimensional spectroscopic observations of vegetation communities requires the characterization of seasonal phenology and response to environmental conditions. This analysis leverages both spectroscopic and phenological information to characterize vegetation communities in the Sundarban riverine mangrove forest of the Ganges–Brahmaputra delta. Parallel analyses of surface reflectance spectra from NASA's EMIT imaging spectrometer and MODIS vegetation abundance time series (2000–2022) reveal the spectroscopic and phenological diversity of the Sundarban mangrove communities. A comparison of spectral and temporal feature spaces rendered with low-order principal components and 3D embeddings from Uniform Manifold Approximation and Projection (UMAP) reveals similar structures with multiple spectral and temporal endmembers and multiple internal amplitude continua for both EMIT reflectance and MODIS Enhanced Vegetation Index (EVI) phenology. The spectral and temporal feature spaces of the Sundarban represent independent observations sharing a common structure that is driven by the physical processes controlling tree canopy spectral properties and their temporal evolution. Spectral and phenological endmembers reside at the peripheries of the mangrove forest with multiple outward gradients in amplitude of reflectance and phenology within the forest. Longitudinal gradients of both phenology and reflectance amplitude coincide with LiDAR-derived gradients in tree canopy height and sub-canopy ground elevation, suggesting the influence of surface hydrology and sediment deposition. RGB composite maps of both linear (PC) and nonlinear (UMAP) 3D feature spaces reveal a strong contrast between the phenological and spectroscopic diversity of the eastern Sundarban and the less diverse western Sundarban. [ABSTRACT FROM AUTHOR]

The concentrations and composition of hydrocarbons (aliphatic, AHCs, and polycyclic aromatic, PAHs) are determined using molecular markers in bottom sediments of the Greenland–Norwegian basin and the Barents Sea (during the 84th cruise of the R/V Akademik Mstislav Keldysh in 2021). The research covered the deep-sea part of the Greenland Basin, the northern part of the East Greenland Ridge, the near-fault zone in the area of the junction of the Mohns and Knipovich ridges, the Western and Northwestern extremities of the Svalbard continental shelf (the Vestnes Ridge, the Ermak Plateau, the Sofia Basin, and the Hinlopen Trough), the Fram Strait, the Orly trough area with the intersection of the Erik-Eriksen trough, and the central part of the Barents Sea. The surface bottom sediments are found to contain a wide range of concentrations of Corg (0.25%–2.71%), AHCs (7–182 μg/g), and PAHs (23–1918 ng/g). The distribution of HCs is determined by the processes occurring in the sedimentary stratum (changes in Eh and fluid flows), and, to a lesser extent, by the lithotype of sediments. Therefore, in the sedimentary stratum, autochthonous components form in the composition of alkanes and naphthalenes form in the composition of PAHs. [ABSTRACT FROM AUTHOR]

• A novel three-equation two-phase flow model is proposed for sedimentation and consolidation. • Fluid pressure increases with initial sediment concentration, necessitating incorporation of non-hydrostatic pressure. • Inertial effects become significant with larger grains, indicating the need to incorporate inertial forces. Sedimentation and consolidation, a multi-physical phenomenon of great significance in aquatic environments, usually involves dynamic pore pressure, inertial effects, fluid-particle interphase interaction and solid stress. However, simplified models for sedimentation and consolidation typically assume hydrostatic mixture pressure and neglect inertial effects without proper justifications. Here, a one-dimensional three-equation two-phase flow model (TTP) is proposed for sedimentation and consolidation, which directly resolves dynamic fluid pressure and inertial terms. The present TTP model is benchmarked against a series of experimental cases and two existing four-equation two-phase flow (FTP) models. It features encouraging performance as compared to measured data and computed results of the existing FTP model. Furthermore, the present TTP model shows superior computing efficiency over the FTP models. To investigate the influences of inertial effects and non-hydrostatic mixture pressure, two simplified versions of the TTP model are constructed and compared with the TTP model. It is shown that incorporating inertial effects and non-hydrostatic fluid pressure are important for accurately predicting the sedimentation-consolidation process. The present study facilitates a promising framework for modelling sedimentation and consolidation, thereby supporting effective sediment management. [ABSTRACT FROM AUTHOR]

Reactive transport modeling (RTM) is an emerging method used to address geological issues in diagenesis research. However, the extrapolation of RTM results to practical reservoir prediction is not sufficiently understood. This paper presents a case study of the Eocene Qaidam Basin that combines RTM results with petrological and mineralogical evidence. The results show that the Eocene Xiaganchaigou Formation is characterized by mixed siliciclastic-carbonate-evaporite sedimentation in a semiclosed saline lacustrine environment. Periodic evaporation and salinization processes during the syngeneticpenecontemporaneous stage gave rise to the replacive genesis of dolomites and the cyclic enrichment of dolomite in the middle-upper parts of the meter-scale depositional sequences. The successive change in mineral paragenesis from terrigenous clastics to carbonates to evaporites was reconstructed using RTM simulations. Parametric uncertainty analyses further suggest that the evaporation intensity (brine salinity) and particle size of sediments (reactive surface area) were important rate-determining factors in the dolomitization, as shown by the relatively higher reaction rates under conditions of higher brine salinity and fine-grained sediments. Combining the simulation results with measured mineralogical and reservoir physical property data indicates that the preservation of original intergranular pores and the generation of porosity via replacive dolomitization were the major formation mechanisms of the distinctive lacustrine dolomite reservoirs (widespread submicron intercrystalline micropores) in the Eocene Qaidam Basin. The results confirm that RTM can be effectively used in geological studies, can provide a better general understanding of the dolomitizing fluid-rock interactions, and can shed light on the spatiotemporal evolution of mineralogy and porosity during dolomitization and the formation of lacustrine dolomite reservoirs. [ABSTRACT FROM AUTHOR]

The impacts of the growth and linkage of fault segments on sedimentation in a lacustrine rift basin, the Weixinan Depression, the Beibuwan Basin, in the northern South China Sea, which has been demonstrated to have huge petroleum potential, are elucidated on the basis of well-constrained 3D seismic data. Two main fault systems, the No. 1 boundary fault system and the No. 2 fault system, were developed in the Weixinan Depression. The evolution of the lower basement is based on the No. 1 fault system, which controls the distribution of depocenters (ranging from 450–800 m) within the lower structural layer. It includes the five fault segments isolated at the initial stage, the interaction and propagation stage, the linkage stage, and the decline stage. The No. 2 fault system governs the deposition of the upper structural layer with a series of discrete depocenters in the hangingwall. Initially, it comprises several right-order echelon branching faults. Each branch fault rapidly reached the existing length and maintained a constant length while establishing soft links with each other in the subsequent displacement accrual. The development of topographic slopes, transition zones, transverse anticlines, and related fault troughs and gullies related to the activity of the No. 1 boundary fault system is the main controlling factor that induces the differential development of the western, middle, and eastern sections of steep slope fans. The differential subsidence effect along the No. 2 fault system is responsible for the multiple 'rising-stable' stage changes in the relative lake level during the development of axial delta deposits. This study will help elucidate the different controls of extensional fault systems on associated sedimentation, as well as rift basin development in the South China Sea and similar areas throughout the world. [ABSTRACT FROM AUTHOR]

Vegetation plays a key role in trapping sediments and further controlling pollutants. However, few studies were conducted to clarify the erosion and deposition laws of sediments and the influence factors caused by vegetation patch properties, which is not conducive to the revelation of riverbank protection and erosion prevention. Therefore, this study investigated the change in scouring and deposition characteristics around submerged vegetation patches of nine kinds of typical configurations and their influencing factors. Vegetation patches were assembled from three vegetation densities (G/d = 0.83, 1.3, and 1.77, representing dense, medium, and sparse, respectively), and three vegetation patch thicknesses (dn = 170, 400, and 630, representing narrow, usual, and wide, respectively), to measure vegetation patch property influences. Flow velocity, scouring, and deposition characteristics under nine patches were determined by a hydraulic flume experiment, three-dimensional acoustic Doppler velocimetry (ADV), and three-dimensional laser scanner, and then ten geometry and morphology indices were measured and calculated based on the results of laser scanning. Results showed that both vegetation patch density and thickness were positively related to the turbulence kinetic energy (TKE) above the vegetation canopy, and only vegetation patch density was negatively related to the flow velocity above the vegetation canopy. The relation between the product of density and vegetation patch thickness and erosion area in planform (EA) showed a power function (R2 = 0.644). Both density and vegetation patch thickness determined the scouring degree, but deposition location and amount did not rely on each one simply. On average, medium density showed the smallest maximum erosion length (MEL), EA, deposition area in planform (DA), and average deposition length (ADL) and a minimum of the above parameters also occurred at narrow vegetation patch thickness. The shape factor of the erosion volume (SFEV), the shape factor of the deposition volume (SFDV), ADL, and MEL of medium density and narrow thickness vegetation patch (G/d = 1.3, dn = 170) were significantly smaller than that of other types of patches. DA and equivalent prismatic erosion depth on the erosion area (EPED) were significantly linearly related (R2 = 0.766). Consequently, most sediment was deposited close to the vegetation patch edge. It is suggested that vegetation patch thickness and density should be given to control sediment transport. In particular, natural vegetation growth changes vegetation patch density and then alters vegetation patch thickness. Management and repair need to be first considered. The results of this study shed light on riparian zone recovery and vegetation filter strip mechanism. [ABSTRACT FROM AUTHOR]

Engineering construction disturbs the Earth's surface and exacerbates soil erosion, resulting in sediment contributions at the watershed scale, the spatiotemporal variation of which remains to be clarified. Based on a typically disturbed catchment, soil samples were collected from sources such as forests, grasslands, spoil heaps, and exposed slopes. Sediment deposition was sampled in 2022 and 2023 along the main channel and fingerprinting technology was employed to calculate the relative contributions of different sources. The results indicated that the optimal composite fingerprints comprising Na₂O, Li, Sr, and Ce could effectively resolve the contributions of different sources. Natural sources were the main sediment contributors, but the average contribution decreased from 72.96% to 58.73% over two periods. In contrast, the contribution of spoil heaps and exposed slopes increased from 27.04% to 41.27% and the area percentage increased from 0.18% to 0.30%. The spoil heap represents the relatively large area of disturbance and its contact length with the river determines the sediment contribution rates, which varied spatially in a quadratic trend along the channel. Meanwhile, the sediment contribution of relatively small and dispersed exposed slopes could be quantified using a linear equation of the disturbance weighting indicator (DWI) composed of disturbed area and flow distance. These results would be helpful in assessing the environmental impact of engineering disturbances and optimizing mitigation measures. [ABSTRACT FROM AUTHOR]

This study presents the historical sequence of the inter-relationship between climate, sea-level change, hydromorphology, and the society in the "Delta of Neretva", Croatia. This study aims to support future-oriented planning, since the cumulative impact of climate and mean sea-level changes on the delta hydromorphology and socio-economy is very uncertain and difficult to predict. In particular, the sustainability development of the Delta of Neretva requires a long-range strategy that is complicated to outline. In the proposed approach, hydromorphology is used as a sustainability indicator since it considers both the physical character and water content of the delta and looks at how nature and human activities influence the biophysical system and economy. The direction of delta progression and persistence of socio-hydromorphology are evaluated with the assessment of system entropy generation considering the simple system state function. Such a method overcomes the difficulties posed by top–down and bottom–up approaches, making future scenarios and cumulative impacts visible and understandable to stakeholders. The historical co-evolution results indicate that the delta in the future could become a submerged estuary (rias), that is, a sea bay as a result of the subsequent delta progradation caused by an MSL rise, similar to the progradation during the Holocene, and decreasing sediment deposition due to anthropologic processes in their watershed. Technology (policy) assessment suggests that adaptation measures that gradually support environmental security and sustainable livelihoods, i.e., increase natural order at a society-acceptable cost, are preferable. [ABSTRACT FROM AUTHOR]

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Wetlands formed by natural sediment deposition account for a large proportion of new coastal lands, and these new wetlands usually have active ecosystems and obvious ecological effects. However, previous studies largely overlooked this sediment‐caused wetland expansion, and the spatiotemporal variation in these wetlands and future response to sea‐level rise (SLR) have not been determined. Here, we employed satellite observations to quantify the seaward expansion of coastal lands in China over the past two decades. A total land expansion of 6,651 km2 was found, and wetlands and artificial surfaces dominated, accounting for 32% and 25%, respectively. Subsequently, we utilized an integrated model to estimate the response of these new wetlands to SLR in the 21st century, that is, we estimated the wetland gain from sediment deposition and loss due to SLR. The results indicate that under the current condition of sediment availability, the area of China's new coastal wetlands is projected to increase by 200%–261% compared to that in 2020 based on four SLR scenarios, despite the unavoidable impact of SLR. These increases are accompanied by the continuous enhancement of carbon accumulation. Wetland changes are influenced by factors such as sediment deposition, SLR and storm surges, as well as the continued effect of local natural and anthropogenic factors. These results show the importance of understanding the ecological effects of new wetlands and constructing specific protection measures for sustainable development. Plain Language Summary: Compared to anthropogenic reclamation, sediment deposition represents an alternative mechanism for the formation of coastal lands. These newly formed lands possess highly dynamic ecosystems and offer additional land resources, making them immensely important for ecological environments and societal development. This study focused on the spatiotemporal changes in newly formed lands in China's coastal regions over the past two decades, and an examination of the land use status was conducted. The results show that wetlands constitute the predominant component of these new lands, rather than artificial surfaces. Using an integrated model, we estimated the future response of these new wetlands to sea‐level rise and the corresponding carbon accumulation trend. Additionally, the factors influencing the area of new wetlands was analyzed to provide valuable insights and recommendations for future wetland conservation policies. Key Points: A total of 6,651 km2 of newly formed coastal lands were found in China in the past 20 years, and wetlands were the predominant componentCarbon accumulation in China's new coastal wetlands is projected to increase by 200%–261% by 2100 under various sea‐level scenariosOur results show that wetland change is primarily driven by sediment availability and that wetland loss is maintained with sea‐level rise [ABSTRACT FROM AUTHOR]

A sudden angle change between the Y-shaped diversion channel and the inlet tank of the circular pump station often leads to boundary layer separation and large vortex formation. These flow patterns can cause significant sediment deposition in sediment-laden rivers, reducing pump efficiency. A mixture model is introduced to describe water-sediment two-phase flows. Simulation results analyze vortex characteristics and formation mechanisms, and evaluate potential sediment deposition areas. Without rectification, vortex areas cause significant sediment migration towards the sidewalls of the Y-shaped diversion channel and pump inlet. Diversion measures like sills and pressure plates are introduced to reduce flow vortices. Results show that sills generally optimize flow structures. Sills in the main Y-shaped diversion channel outperform those in other channels in terms of optimization. Pressure plates also optimize flow structures. Vortex structure and position are closely related to the distance between the pressure plate and the circular intake tank. Optimized measures with pressure plates significantly reduce the flow deviation angle and improve flow velocity uniformity. Numerical simulation accuracy is validated through experiments. Results reveal the formation mechanism of adverse vortices and their sedimentation effects, which are detrimental to pump stations. The proposed rectification scheme provides theoretical support for optimizing pump station operation. [ABSTRACT FROM AUTHOR]

The Devonian-Carboniferous (D-C; 359 Ma) boundary is marked by widespread deposition of organic-matter-rich black shales associated with the Hangenberg mass extinction event. The Exshaw Formation spans the D-C boundary in the Western Canada Sedimentary Basin (WCSB) and includes the basal Exshaw Shale deposited under broadly anoxic waters. The sediments at the base of the Exshaw Shale were deposited synchronously during a transgressive event across the WCSB, spanning the geographic variability of the basin. The variable Corg content of the shale was affected by local nutrient upwelling and paleotectonic features impacting water depth and circulation. To characterize the link between paleogeography and nutrient cycling, geographic (N = 20 locations) and stratigraphic (N = 6 locations) trends of δ13^^ and δ15^^ were examined throughout the WCSB, representing a range of depositional settings. The δ15^^ values range between 0.0 and 6.3%" and δ13^^ from -29.5 to -26.8%. Phytoplankton production in focused upwelling zones acquired a relatively 15N-depleted signature through isotopic fractionation during nutrient assimilation, and the residual nutrient pool was 15N-enriched. The advection of surface waters away from the location of upwelling supported additional phytoplankton growth and the deposition of sediments with higher δ1^ values. The stratigraphic sections include black laminated and burrowed mudrock sequences that record changes in paleoredox conditions, water depth, and tectonism over time. Up-core from the base of the Exshaw, the Corg content decreases and simultaneously δ15^^ increases, suggesting a decrease in eutrophic conditions. Variable δ13^^ and δ15^^ trends demonstrate that there is no "type" isotopic profile spanning the D-C boundary in the WCSB. [ABSTRACT FROM AUTHOR]

The Skagerrak basin represents the main sink area for fine-grained sediment in the North Sea region and constitutes a natural deposition center for sediments that are supplied from the Atlantic, the Baltic Sea and the surrounding continental margins and coasts. However, the exact sources and their proportional contributions to the North Sea sediments and to the Skagerrak deposits are not well understood. To trace the predominant sources of the sediment and to gain a better understanding of the sedimentary processes in the North Sea and the Skagerrak basin, radiogenic Sr, Nd, and Hf isotope signatures and clay mineral compositions of the detrital clay fraction of surface sediment samples from the North Sea, the Scandinavian margins and the Baltic Sea were measured. The results indicate that the major source for Skagerrak clay-size sediments is the northern North Sea but Scandinavia as well as the southern North Sea including the southern England coast also contribute material. Seabed and coastal erosion in the northern North Sea are enhanced by the inflowing Atlantic Currents, which provide the Skagerrak with high amounts of clay size sediments. In contrast, the southern North Sea, the Baltic Sea and mid-European rivers such as Weser, Elbe and Ems are only minor contributors. As Skagerrak deposits are dominated by clay sized material (up to 60%), the reconstructed sediment processes in this study deviate from findings in previous sediment budget studies, which were based on both clay and silt fraction and indicated predominant influences from the southern North Sea. These results highlight that coastal and seabed erosion in the North Sea is a previously underestimated source of fine-grained sediments for depocenters in the entire North Sea. With regard to climate change, the global sea-level rise will likely enhance erosional processes and can therefore significantly influence the sediment budget of the entire North Sea. [ABSTRACT FROM AUTHOR]

Considering currently operative European and worldwide regulations, preserving and/or improving the state of remnant alluvial floodplains is a high-priority goal for experts. One of the threats is the decrease of lateral connectivity: due to the erosion in the mainstem riverbed and the sedimentation of the floodplain and its channels, the bed elevation gap slowly increases between the main channel and the side branches and oxbows of the floodplain. Without revitalization measures, this progress predicts severe ecological consequences. As an example, and as a continuation of our earlier work, we considered the Gemenc floodplain forest along the Danube, in Hungary. We set up a two-dimensional coupled hydrodynamic and sediment transport computational model to describe floodplain deposition dynamics. Model validation was carried out with historical data, i.e., two ground elevation sets measured in 1990 and in 2009, respectively. Our aim was 1. to show, how coarse resolution measured data can be used for validating a large-scale model in terms of sediment deposition processes, and 2. to interpret the first results on some areas exposed to strong deposition, after validation. Showing good agreements in three pillars: magnitude of estimation, spatial tendencies and spatial patterns, the model was deemed valid. We were also able to observe a clear gradient, along which areas could be categorized with high, medium and small extent of sediment deposition. With this model, the sediment dynamics in the Gemenc floodplain forest can be assessed, with special attention to the impact analysis of restoration measures to improve lateral connectivity conditions. [ABSTRACT FROM AUTHOR]

A prospective study was conducted from September 2022 to March 2023 to examine the occurrence and contamination rates of different parasitic stages on fresh edible fruits and vegetables in local markets of Erbil city. Eight different types of fruits and vegetables were selected from eight markets, and 144 samples were analyzed for parasites using direct sedimentation, indirect floatation (ZnSO4), Kinyoun, and trichrome staining methods. The highest total frequencies of parasites were detected using the direct sedimentation method (18.75%), followed by the indirect floatation method (6.25%), Kinyoun technique (5.55%), and modified trichrome staining (4.16%). A. lumbricoides (Ova) was detected with 4.16% using direct sedimentation, while no positive detections were observed with other techniques. Kinyoun technique identified Cryptosporidium spp. oocysts. For E. histolytica 1.3% were positive using the direct sedimentation method, while the other three methods showed no positive detections. Similar results were observed for G. lamblia where only the modified trichrome staining technique detected 0.69% with trophozoites and 1.3% with cysts. Additionally, the direct sedimentation method revealed the presence of nematodes at 2.77%, but no positive detections were made with other methods. Concerning Taeniid eggs, the indirect floatation identified 0.69% with ova, while other methods showed no positive detections. Lastly, the direct sedimentation method yielded 6.25% with unidentified flagellate protozoa, but no positive detections were found using the indirect floatation method, Kinyoun technique, or modified trichrome staining technique. The study concluded that Kinyoun and trichrome techniques are the gold standard for detecting different parasite stages. [ABSTRACT FROM AUTHOR]

The sustainability of social–ecological systems within river deltas globally is in question as rapid development and environmental change trigger "negative" or "positive" tipping points depending on actors' perspectives, e.g. regime shift from abundant sediment deposition to sediment shortage, agricultural sustainability to agricultural collapse or shift from rural to urban land use. Using a systematic review of the literature, we show how cascading effects across anthropogenic, ecological, and geophysical processes have triggered numerous tipping points in the governance, hydrological, and land-use management of the world's river deltas. Crossing tipping points had both positive and negative effects that generally enhanced economic development to the detriment of the environment. Assessment of deltas that featured prominently in the review revealed how outcomes of tipping points can inform the long-term trajectory of deltas towards sustainability or collapse. Management of key drivers at the delta scale can trigger positive tipping points to place social–ecological systems on a pathway towards sustainable development. [ABSTRACT FROM AUTHOR]