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The densely populated coast of the Gulf of Guinea (GoG) is experiencing escalating erosion from climate change (CC). To assess Longshore Sediment Transport (LST) changes in the past and future, an empirical formula was used to model the GoG's LST. Nearshore wave conditions, crucial for LST estimation, were derived by projecting significant wave height, mean wave period, and mean wave direction from deep water to the breaker zone. These wave conditions were used as input for LST computation. Analysing three time slices: Past (1979–2005), mid-century (2026–2045), and end-century (2081–2100) under RCPs 4.5 and 8.5, results indicate continuous increase in LST in most locations, with local and seasonal variations. LST magnitudes range from 104 to 105 m3y−1 in the GoG, with the Cameroonian coast having the least. This aligns with the rising wave energy from CC. LST directions are predominantly eastward, though some locations, like off Lagos and Cameroon-Gabon coasts, show westward trend, correlating with coastal orientation influenced by southward wave directions. RCP 8.5 projections suggest mid-century increase, intensifying by end of century, with yearly rates of change around 103 m3y−1 and future LST changes up to 105 m3y−1. This situation implies accelerated sediment removal, heightening erosion. [ABSTRACT FROM AUTHOR]

Suspended sediment load (SSL) and discharge are closely related concepts that characterise the sediment movement and quantity within water bodies and play a crucial role in evaluating the impact of erosion, sedimentation, and land management practices on riverine ecosystems. Despite numerous studies on SSL and discharge assessments, a site-specific understanding remains essential for effective riverine ecosystem protection. This study integrates daily sediment and discharge data from the Koelwar station spanning June 2010 to May 2015, with a primary focus on analysing SSL variability relative to Sone River discharge in Bihar. SSL–discharge rating curves were computed to assess concentration shifts during low flow season (LFS), high flow season (HFS), and the annual period. Results indicate a nearly linear dependence of SSL on discharge, with r2 values of 0.72, 0.94, and 0.84 for LFS, HFS, and the annual period, respectively. The study unveils the underlying mechanics driving catchment erosion and sediment transport during lean and peak flows through hysteresis loops. Findings reveal that 50% of events are influenced by shear stress and hydraulic forces from the channel bed, 20% by sediment depletion in the channel bed due to repeated peak flows, and the remaining 30% by a combination of shear stress and sediment reduction. Additionally, MATLAB-utilized wavelet analysis explains the time-frequency variability of discharge and SSL. Cross-wavelet analysis shows the outflow of SSL closely following discharge, indicating synchronisation across all scales. The study underscores the importance of effectively managing runoff events to mitigate SSL. The proposed methodology and results offer valuable insights for water management and policymakers, aiding in the formulation of guidelines to minimise anthropogenic activities and sustain aquatic ecosystems. [ABSTRACT FROM AUTHOR]

Erosion of banks and channel migrations are usually common phenomenon and recurring geo-hazardous problem in the Brahmaputra-Jamuna river system of Bangladesh. The present study intensively analysed multi-temporal Landsat satellite imageries (Landsat MSS, Landsat TM, Landsat ETM+, Landsat OLI TIRS), historical documents (Hunter maps), and literature information employing Remote Sensing and Geographic Information System techniques, and estimation of braiding and sinuosity indices especially emphasizing channel bar development, braiding, and bank-line migration of the river. The computed braiding indices of the river were 1.5, 10.3, 13.4, 11.0, 10.6 and 14.6 for the year of 1853–1857, 1977, 1989, 2000, 2014 and 2018, respectively (overall deciphering increasing trend). Similar to the braiding indices, the sinuosity indices (2.58, 7.02, 9.92, 8.31, 7.42 and 11.25 for the same selected years) of the river have also been changed over time. During 1853–1857 to 2018, 766.7 and 1624.2 km2 of lands extensively eroded on the east and west bank, respectively at a rate of 4.8 and 10.1 km2 yr−1. However, from 1977 to 2018, the erosion rates were 14.4 and 12.5 km2 yr−1, respectively. High discharges, sediment transport associated with random bars formation related braiding expansion, and weak bank materials are presumably the governing factors for causing such simultaneous severe bank erosion and remarkable bank-line migration phenomenon. Although, from 1853–1857 to 1977 the erosion of the river followed the river flow direction. It is expected that the outcomes of this research can contribute further research on morphodynamic characteristics of the braided river for better understanding the river characteristics, the river hydromorphology, water and sediment transport, its bank erosion, and formulating protective measurement plan for their sustainable current flow path maintenance. [ABSTRACT FROM AUTHOR]

This article reviews research on sediment flux impacts on the receiving estuary, ports, and society in Cartagena, Colombia. The city hosts both the country's largest touristic and coastal industrial sectors and is home to vulnerable coastal communities whose health and livelihoods are impacted by pollution. These marginalized artisanal fishing communities lack basic water and health services but have finally been recognized in a new intersectoral committee for Cartagena Bay's environmental management. To support the governance of these complex socioenvironmental challenges, the Cartagena Bay Observatory has been developed as a scientific tool to monitor the bay's conditions and forecast the effects of future sediment remediation plans. Cartagena Bay receives large freshwater discharges from the Dique Canal, draining from the 260,000 km2 Magdalena River watershed where 80% of the national population resides. This runoff transports sediment loads of 2.3 Mt/year, dispersing large plumes that affect the marine ecosystems and tourism and make the bay one of the Caribbean's largest sediment‐receiving estuaries. Following decades of watershed deforestation and erosion, the upward trending sediment inputs and accretion of the Dique delta have resulted in deposition rates of 1.8 cm/year, and the need for frequent dredging. Mercury dumped by a chemical industry in the 1970s can be found in concentrations as high as 18.8 μg/g buried below the bay's bottom. Mercury has also been found in the bay's biota and human populations, and so the dredging needed for the port's sustainability thereby presents a health risk by allowing this trapped mercury to surface. This article is categorized under:Science of Water > Hydrological ProcessesScience of Water > Water QualityScience of Water > Water and Environmental Change [ABSTRACT FROM AUTHOR]

Mount Meager is a deeply eroded quaternary volcanic complex located in southwestern British Columbia (BC) and is known for its frequent large landslides. In 2010, the south face of Mount Meager collapsed, generating a long-runout debris avalanche that was one of the largest landslides (50 × 106 m3) in Canadian history. Over the past 14 years, the landslide deposit has been reworked by stream action, delivering large amounts of sediment to Lillooet River, just downstream. In this study, we investigate 10 years of geomorphic evolution of the landslide deposit using orthophotos and digital elevation models (DEMs) generated using Structure from Motion (SfM) photogrammetry on aerial photographs acquired during unmanned aerial vehicle (UAV) and Global Navigation Satellite System (GNSS) surveys. The SfM products were used to produce a series of precise maps that highlight the geomorphological changes along the lower Meager Creek within the runout area of the landslide. Comparison of DEMs produced from 2010, 2012, 2015, and 2019 imagery allowed us to calculate deposit volume changes related to erosion, transport, and redeposition of landslide material. We estimate that about 1.1 × 106 m3 of sediment was eroded from the landslide deposit over the period 2015–2019. About 5.2 × 105 m3 of that sediment was redeposited inside the study area. About 5.8 × 105 m3 of sediment, mainly sand, silt, and clay, were exported from the study area and are being carried by Lillooet River towards Pemberton, 40 km from Mount Meager, and farther downstream. These remobilized sediments likely reduce the Lillooet River channel capacity and thus increase flood hazards to the communities of Pemberton and Mount Currie. Our study indicates a landslide persistence in the landscape, with an estimated 47-year half-life decay, suggesting that higher flood hazard conditions related to increased sediment supply may last longer than previously estimated. This study shows the value of using SfM in tandem with historic aerial photographs, UAV photos, and high-resolution satellite imagery for determining sediment budgets in fluvial systems. [ABSTRACT FROM AUTHOR]

The Laurentide Ice Sheet's (LIS) interior had a dynamic polythermal base, but the spatiotemporal variations of subglacial processes related to ice divide migration and other transient changes remain largely unknown, limiting our understanding of regional glacial dynamics. Previous studies focused on the regional glacial landform record, while ice sheet models lacked detailed parameterization within these regions, leading to an overestimation of cold-based subglacial conditions' extent and duration. In this study, glacial sediment dispersal patterns as identified by heavy minerals, clasts, and multivariate statistics of till matrix geochemistry were used to assess ice sheet dynamics within the Quebec–Labrador sector of the LIS. The earliest ice-flow phase produced and transported till across the study area (>175 km). However, major oxide data from till matrix geochemistry show a correlation with underlying bedrock, and this relationship is relatively common in areas of thin till cover and resistant bedrock lithologies. These results suggest a switch from an early phase of widespread erosion and long, sustained sediment transport to one of more limited erosion, perhaps abrasion dominant and shorter transport. Till compositional data and related dispersal patterns add supporting evidence to earlier ice sheet reconstructions based on ice-flow indicators and 10Be data together suggesting a transition from widespread uniform warm-based conditions during the earliest ice flow, followed by the development of an ice divide, its migration, and more sporadic warm-based conditions. Consequently, a thorough understanding of ice-flow history is essential for ice sheet modelling and future mineral exploration programs in inner ice sheet regions of the LIS. [ABSTRACT FROM AUTHOR]

This study identifies and summarizes potential risks to operations, regulatory compliance, supply chains, and infrastructure of the electric power industry from changing surface water conditions resulting from global climate change. The results help inform companies/utilities seeking to incorporate climate change risk in their planning and decision‐making processes by ranking risk severity and likelihood of occurrence on both a regional basis and by risk receptor. The assessment includes identification of potential risks to: (1) thermal generating, (2) hydroelectric, (3) land‐based renewable generating, and (4) transmission and distribution assets. These risks may result from such projected changes as reduced water availability (e.g., for hydroelectric or once‐through cooling), increased water temperatures (e.g., decrease in cooling efficiency, inability to meet discharge permit conditions), increased flood severity (e.g., increased streambank erosion and/or damage to river‐adjacent infrastructure), and decreased water quality (e.g., from increased transport of sediment and dissolved solids). The potential risks identified from this qualitative risk‐assessment are documented in a graphical format depicting both severity and likelihood. This approach allows for comparison of risks across a portfolio and for future prioritization of adaptation strategies. A total of 32 risks were identified in the study, including nine risks to infrastructure, six risks to operations, four risks to supply chain, and 13 environmental/regulatory risks. [ABSTRACT FROM AUTHOR]

Human-induced shoreline instability is a widespread issue among the world's Mega Deltas. Out of 120 million tons/year of sediment, 30 million tons/year reached Damietta promontory before the entire operation of Aswan High Dam (AHD), which blocks most of that sediment. This study uses remote sensing techniques to investigate the Land Use Land Cover Changes (LULCC) and the shoreline dynamics around Damietta promontory. In addition, more attention was devoted to the challenges of Damietta Harbour, which regularly suffers from inlet closure using a filed validated morpho-dynamic model addressing sediment transport and erosion problem at the eastern part. The LULCC based Maximum Likelihood approach shows that the developed areas were doubled from 1984 to 2018. Besides, within the Area of Interest (AoI), 8.961 km2 were eroded during the period (1984–2000), while 2.7046 km2 were eroded during (2000–2018). Change detection technique showed that accretion area was 1.8991 and 2.4909 km2 for the periods 1984–2000 and 2000–2018, respectively. Six scenarios were tested to investigate the best combinations of interventions to mitigate the challenge of siltation inside the harbour entrance and the erosion at the eastern side. Morphodynamical results showed that scenario 4 (two groins each 1000 m length at the west side of the western jetty combined with two groins each 500 m length at the east side of the existing eastern jetty of the harbour) has considered the best scenario. [ABSTRACT FROM AUTHOR]

Estuarine sediment transport is driven by the combined action of a multitude of influencing factors, including astronomical tides, waves dynamics, and river discharges. This study focuses on the effects of wave forces on sediment transport patterns in micro-tidal estuaries near Wanbao Beach, China. Numerical simulations are carried out using Delft3D. Modeling scenarios are configured using different wave characteristics, spanning from typical waves to those with a return period of 50 years. Results show that waves have a positive effect on landward sediment transport, resulting a larger active range of sediment. By comparing the spatial geomorphic variations under varying wave conditions, we find that modifications in significant wave height (Hs) primarily impact the position of erosion and deposition zones, whereas alterations in spectral peak period (Tp) predominantly influence the magnitude of these changes. The finding is further demonstrated by a comparison of residual currents under different wave intensities. Analysis of sediment transport rates in different transects indicates that the sediment transport rate is highest at the mouth transects and lowest at the alongshore transects. Moreover, variations in sediment transport rates exhibit distinctive patterns between the two outlet transects, even when subjected to identical wave conditions. The disparities are attributed to differences in runoff and the topographical features in proximity to the estuaries. Additionally, we find the sediment transport rate becomes insensitive to the variations in Hs when Hs is larger than a threshold value. The threshold decreases with increasing Tp. [ABSTRACT FROM AUTHOR]

Mass‐transport deposits are products of resedimentation phenomena involving a broad spectrum of gravity‐driven processes, and commonly have a high preservation potential in deep‐marine environments. This study documents various types of mass‐transport deposits that are interbedded with intensely bioturbated shallow‐marine calciclastic sediments deposited along a reflective coast during the middle and late Eocene. The sedimentary succession, located in the vicinity of Novigrad in northern Dalmatia, Croatia, comprises sediments deposited in a range of nearshore and carbonate ramp environments, and represents the infill of a thrust‐top (piggyback) basin of the North Dalmatian foreland basin. Five types of mass‐transport deposits, ranging in thickness from 13 cm to 6 m, have been identified: (i) calcilutite and calcarenite slumps; (ii) conglomeratic slump‐debrites with a 'dough‐like' appearance; (iii) blocky‐flow deposits bearing large blocks of beachface and/or shoreface deposits; (iv) rockfall deposits comprising scattered blocks of beachface conglomerates and shoreface calcarenites; and (v) 'classical' matrix‐supported debrites. Calciturbidites are rare and mainly comprise Ta and Tb divisions. Conglomeratic slump‐debrites are mostly found in association with offshore‐transition deposits, suggesting that mass flows were triggered above the storm‐wave base likely due to a combined effect of: (i) strong earthquakes related to the tectonic development of the basin; (ii) sediment destabilization due to pore‐water overpressure during forced regressions; and (iii) storm‐wave loading affecting the shallow seabed. Progressive deepening likely favoured mass‐flow transformations, although the overall paucity of turbidites suggests relatively short mass‐flow transport distance and turbidity current bypass to deeper realms. Multiple erosion phases and resedimentation processes from the Cretaceous to the late Eocene contributed to the diverse suite of extraformational clasts in the mass‐transport deposits studied. The mass‐transport deposits may be triggered and emplaced in shallow‐marine settings mainly during regressive stages of basin development, as the diverse gravel clast composition suggests significant tectonic influence. Although the mass‐transport deposits reported herein are relatively small, some of their peculiar sedimentary features and occurrence within shallow‐marine calciclastic deposits render them rather unique and suitable for a re‐assessment of the nature and evolutionary continuum of processes involved in subaqueous sediment mass transport, as well as the preservation potential of sedimentary features in high‐energy wave‐reworked environments. [ABSTRACT FROM AUTHOR]

The 2021 Navalacruz wildfire occurred in a mountainous area in the Sistema Central (Spain). Despite having an average low severity index (dNBR), the loss of vegetation cover associated with the fire was responsible for a high rate of sedimentation in the rivers and streams. Additionally, the burned area affected up to 60 cultural heritage sites, including archaeological and ethnological sites, and damage ranged from burnt pieces of wood to the burial of archaeological sites. In the present work, we document and analyze the post-fire evolution in several rivers and streams. This is based on a field survey of infiltration rates, hydrodynamic modeling, and the study of channel morphological changes. Our analysis revealed how the first post-fire rains caused the mobilization and transport of ashes. This created hydrophobicity in the soils, resulting in large amounts of materials being transported to rivers and streams by subsequent medium- and low-magnitude storms. A hydrological and hydraulic model of the study catchments under pre- and post-fire conditions suggests that these trends are a consequence of a post-fire increase in flow rates for similar rainfall scenarios. In this respect, our estimates point at a significant increase in sediment transport capacities associated with this post-fire increase in flow rates. The combination of locally steep slopes with high-severity fire patches, and a considerable regolith (derived from pre-fire weathering), resulted in a series of cascading responses, such as an exacerbated supply of sand to the drainage network and the triggering of debris flows, followed by erosion and entrenchment. [ABSTRACT FROM AUTHOR]

In this study, a new remote sensing tool was used in conjunction with sampling of river bank sediments to map channel migration patterns and estimate the net contribution of bank erosion to the sediment and phosphorus (P) budget of the Nishnabotna River in southwestern Iowa. Between the years 2009 and 2018, we found that at least 1.81 ± 0.57 × 107 Mg of sediment and 8.26 ± 2.5 × 103 Mg of P entered the Nishnabotna River due to channel migration. This equates to 0.87 Mg of sediment per meter of channel per year and 0.40 kg of P per meter of channel per year. Barring additional deposition elsewhere in the river corridor, these values represent as much as 77% of annual suspended sediment and 46% of the annual P export from the watershed. Our results also indicate that the contribution of net sediment and P volume loss by stream order increases sharply from third to sixth order, even though the total channel length is much smaller in the higher orders. These results suggest that bank erosion is an important source of sediment and P within the watershed and that future attempts to decrease riparian exports of sediment and P should focus on high‐order reaches. [ABSTRACT FROM AUTHOR]

Reliable descriptions of erosion events are foundational to effective frameworks relevant to the fate of tidal landscape evolution. Besides the rhythmic, predictable action of tidal currents, erosion in shallow tidal environments is strongly influenced by the stochastic wave-induced bottom shear stress (BSS), mainly responsible for sediment resuspension on tidal flats. However, the absence of sufficiently long, measured time series of BSS prevents a direct analysis of the combined tide- and wave-driven erosion dynamics and its proper representation in long-term morphodynamic models. Here we test the hypothesis of describing erosion dynamics in shallow tidal environments as a Poisson process by analysing, with the peak-over-threshold theory, the BSS time series computed using a fully coupled, bi-dimensional numerical model. We perform this analysis on the Venice Lagoon, Italy, taking advantage of several historical surveys done in the last 4 centuries, which allow us to investigate the effects of morphological modifications on spatial and temporal erosion patterns. Our analysis suggests that erosion events on intertidal flats can effectively be modelled as a marked Poisson process in different morphological configurations because the interarrival times, durations, and intensities of the over-threshold exceedances are always well described by exponentially distributed random variables. The resulting statistical characterization allows a straightforward computation of morphological indicators, such as the erosion work, and paves the way for a novel synthetic, yet reliable, approach for the long-term morphodynamic modelling of tidal environments. [ABSTRACT FROM AUTHOR]

A proper understanding of sediment resuspension and transport processes is key to the morphodynamics of shallow tidal environments. However, a complete spatial and temporal coverage of suspended sediment concentration (SSC) to describe these processes is hardly available, preventing the effective representation of depositional dynamics in long-term modelling approaches. Through aiming to couple erosion and deposition dynamics in a unique synthetic theoretical framework, we here investigate SSC dynamics, following a similar approach to that adopted for erosion. The analysis with the peak-over-threshold theory of SSC time series computed using a fully coupled, bi-dimensional model allows us to identify interarrival times, intensities, and durations of over-threshold events and test the hypothesis of modelling SSC dynamics as a Poisson process. The effects of morphological modifications on spatial and temporal SSC patterns are investigated in the Venice Lagoon, for which several historical configurations in the last 4 centuries are available. Our results show that, similar to erosion events, SSC can be modelled as a marked Poisson process in the intertidal flats for all the analysed morphological lagoon configurations because exponentially distributed random variables describe over-threshold events well. Although erosion and resuspension are intimately intertwined, erosion alone does not suffice to describe also SSC because of the non-local dynamics due to advection and dispersion processes. The statistical characterization of SSC events completes the framework introduced for erosion mechanics, and together, they represent a promising tool to generate synthetic, yet realistic, time series of shear stress and SSC for the long-term modelling of tidal environments. [ABSTRACT FROM AUTHOR]

The measurement of cosmogenic nuclide (CN) concentrations in riverine sediment has provided breakthroughs in our understanding of landscape evolution. Yet, linking this detrital CN signal and relief evolution is based on hypotheses that are not easy to verify in the field. Models can be used to explore the statistics of CN concentrations in sediment grains. In this work, we present a coupling between the landscape evolution model Cidre and a model of the CN concentration in distinct grains. These grains are exhumed and detached from the bedrock and then transported in the sediment to the catchment outlet with temporary burials and travel according to the erosion–deposition rates calculated spatially in Cidre. The concentrations of various CNs can be tracked in these grains. Because the CN concentrations are calculated in a limited number of grains, they provide an approximation of the whole CN flux. Therefore, this approach is limited by the number of grains that can be handled in a reasonable computing time. Conversely, it becomes possible to record part of the variability in the erosion–deposition processes by tracking the CN concentrations in distinct grains using a Lagrangian approach. We illustrate the robustness and limitations of this approach by deriving the catchment-average erosion rates from the mean 10Be concentration of grains leaving a synthetic catchment and comparing them with the erosion rates calculated from sediment flux, for different uplift scenarios. We show that the catchment-average erosion rates are approximated to within 5 % uncertainty in most of the cases with a limited number of grains. [ABSTRACT FROM AUTHOR]

To investigate the influence of bedrock fragmentation by intensive tillage on the hydrological characteristics and soil erosion processes on slopes, two experimental treatments (soil–bedrock mixtures, WB, and pure soil, CK) in steel tanks were subjected to simulated rainfall under five rainfall patterns (constant, increasing, decreasing, decreasing–increasing, and increasing–decreasing) with the same total rainfall of 90 mm. For each rainfall event, runoff and sediment concentration were sampled at regular intervals. The flow velocity (v), effective/critical shear stress (τ/τc), Darcy–Weisbach resistance coefficient (f), unit stream power (p), and soil erodibility factor (Kr) were calculated to analyze the differences in hydrodynamic characteristics between the WB and CK. Our experimental findings show that significant differences in runoff volume and sediment yield were observed among different rainfall patterns and stages. Bedrock fragmenting significantly promoted runoff and sediment production under different rainfall patterns, with runoff volume and sediment yield increasing by averages of 59.29% and 71.62%, respectively. An increasing trend in average contribution rate of bedrock to runoff volume and sediment yield was observed across three distinct intensities: 6.37% and 4.61% for 30 mm h−1, 12.53% and 7.53% for 90 mm h−1, as well as 14.79% and 36.98% for 150 mm h−1, respectively. The v and p values under various rainfall patterns exhibited an increasing trend from the upper to the bottom slope positions, whereas the f and τ values showed an opposite trend, regardless of the WB and CK. Compared with the CK, the v, f, and p values for the WB increased by 23.34% to 48.94%, 1.59% to 53.16%, and 3.86% to 27.86%, respectively, whereas the τ value decreased by 1.52% to 22.19% for varying-intensity rainfall patterns. Among the variable rainfall patterns, the WB significantly increased sediment yield and also had a promoting effect on runoff generation. However, the WB displayed better erosion resistance compared to the CK under constant rainfall patterns. Therefore, varied-intensity patterns had a profound impact on bedrock-induced runoff and sediment transport processes. [ABSTRACT FROM AUTHOR]

Canyons in carbonate depositional settings, as important elements of the source-to-sink system, remain poorly studied compared to those in siliciclastic depositional environments. The latest high-resolution three-dimensional seismic data, well logs, and core data at the eastern edge of the Precaspian Basin are used to investigate the geomorphology, infillings, and depositional process of a unique carbonate-filled canyon in the Carboniferous KT-II formation parallel to the carbonate platform, which is distinct from other slope-perpendicular canyons. The canyon has a total length of more than 52.3 km with a nearly N-S orientation and an S-shaped geometry, and the whole canyon can be divided into three segments by two knickpoints. The slope-parallel orientation of the canyon is mainly controlled by the palaeogeomorphology and reverse faults. Due to the collision of the Kazakh and European plates in the early-middle Visean (early Carboniferous), the canyon was formed in a northern tilted, elongated, and restricted palaeotopographic feature between uplifts. The development of reverse faults related to tectonic movement controlled the variations in the width of the canyon and the positions of the knickpoints. Tectonics controlled the orientation and formation of the canyon, while sedimentary processes contributed to its infilling. The well-seismic tie analysis indicated two distinct periods of the canyon fillings, Ss1 and Ss2, which were separated by a second-order sequence boundary. The lower part contained sediments supplied by both sides of the canyon through channels or gullies, and the upper part was dominated by a carbonate platform that prograded from the eastern side of the canyon. The evolution of the canyon can be subdivided into three stages. The increasing stage was mainly characterized by significant upslope erosion through headward retrogressive mass failures in the slope-parallel confined negative relief to form the canyon during the lowstand system tract of Ss1. Subsequently, in the early filling stage, the carbonate factory was productive during the highstand, and massive excess carbonate sediments were transported into the adjacent canyon by channels or gullies on both sides and deposited. The canyon was basically filled, and the morphology became much gentler. During the subsequent late filling stage, the carbonate platform was flooded again during the highstand, and the production rates of the carbonate factory greatly increased. The lateral progradation of carbonate platforms accelerated on the canyon of the early filling stage and further into the inner sag. [ABSTRACT FROM AUTHOR]

This review paper reports on the state-of-the-art concerning observations of surface winds, waves, and currents from space and their use for scientific research and subsequent applications. The development of observations of sea state parameters from space dates back to the 1970s, with a significant increase in the number and diversity of space missions since the 1990s. Sensors used to monitor the sea-state parameters from space are mainly based on microwave techniques. They are either specifically designed to monitor surface parameters or are used for their abilities to provide opportunistic measurements complementary to their primary purpose. The principles on which is based on the estimation of the sea surface parameters are first described, including the performance and limitations of each method. Numerous examples and references on the use of these observations for scientific and operational applications are then given. The richness and diversity of these applications are linked to the importance of knowledge of the sea state in many fields. Firstly, surface wind, waves, and currents are significant factors influencing exchanges at the air/sea interface, impacting oceanic and atmospheric boundary layers, contributing to sea level rise at the coasts, and interacting with the sea-ice formation or destruction in the polar zones. Secondly, ocean surface currents combined with wind- and wave- induced drift contribute to the transport of heat, salt, and pollutants. Waves and surface currents also impact sediment transport and erosion in coastal areas. For operational applications, observations of surface parameters are necessary on the one hand to constrain the numerical solutions of predictive models (numerical wave, oceanic, or atmospheric models), and on the other hand to validate their results. In turn, these predictive models are used to guarantee safe, efficient, and successful offshore operations, including the commercial shipping and energy sector, as well as tourism and coastal activities. Long-time series of global sea-state observations are also becoming increasingly important to analyze the impact of climate change on our environment. All these aspects are recalled in the article, relating to both historical and contemporary activities in these fields. [ABSTRACT FROM AUTHOR]

In this study, we assess charcoal records from eolian deposits within the Cooloola Sand Mass, a subtropical coastal dune system in eastern Australia, to determine whether they can be used as a proxy for Holocene fire history. We excavate four profiles in depositional wedges at the base of dune slipfaces (footslope deposits) and calculate charcoal concentrations for three size classes (180-250 μm, 250-355 μm, and 355 μm-2 mm) at predetermined depth intervals. Age--depth models are constructed for each profile using radiocarbon measurements (n = 46) and basal optically stimulated luminescence ages (n = 4). All records appear intact with little evidence of postdepositional mixing as demonstrated by minimal age reversals and consistent trends in charcoal concentration and accumulation rates (CHAR) among size classes. Combining all four records, we generate a ca. 7 cal ka BP terrestrial fire history that depicts distinct peaks representing periods of increased local fire activity at <0.3, 1.1-0.4, 2.2-1.6, 3.4-2.6, and 6.7-5.3 cal ka BP. Our findings parallel regional records and highlight the utility of dune footslopes as ecological and sedimentary archives. As dune fields are much more common than wetlands and lakes in semiarid and arid areas, these deposits have the potential to increase the spatial resolution of fire records globally. [ABSTRACT FROM AUTHOR]

By incorporating horizontal sediment transport and bed erosion into the two-layer depth-averaged shallow water system, one can construct a hydro-sediment-morphodynamic mathematical model in which a variable sediment concentration in a denser layer and interaction between underflows and ambient water are taken into account. Numerically solving such a promising system presents challenges due to its inherent mathematical properties of being conditionally hyperbolic and nonconservative. These properties may result in instability and incorrect results near sharp hydraulic gradients in numerical solutions. The major contribution of this paper is to develop a novel numerical scheme to overcome these issues and to allow the system to be extended to a wider range of engineering applications. To this end, for a one-dimensional two-layer hydro-sediment-morphodynamic system, (1) its mathematical model is first reformulated to a novel relaxation format, which is mathematically equivalent and unconditionally hyperbolic, by relaxing interlayer surface level, and (2) this relaxation system is then solved using a novel path-conservative numerical algorithm with new discrete formulas for the fluxes and nonconservative terms. Thus, the proposed numerical scheme ensures the well-balanced property, and has a major advantage in its ability to accurately and stably handle sharp hydraulic/density gradients with second-order accuracy. Several numerical and laboratory tests are conducted to demonstrate the performance of the proposed new scheme. [ABSTRACT FROM AUTHOR]

Due to the active sediment movement in sandy coasts, great changes may develop in the shoreline near the building after it is built into the sea. The downstream erosion problems and protective measures of buildings in sandy coast are reviewed and summarized based on the results of previous studies to facilitate further studies. On the basis of several typical cases such as that in the Friendship Harbor in Mauritania, the law of coastal changes in the downstream of sandy coastal buildings is analyzed from the aspects of coastline variation and sectional variation. The mechanism of water and sediment movement near protective measures such as groins, offshore breakwaters and offshore submerged breakwaters, is discussed, and soft protective measures such as artificial beach cultivation and by-pass sediment transport are summarized. Finally, the prospects for future research on coastal erosion of downstream sandy coastal structures and corresponding protective measures are given. [ABSTRACT FROM AUTHOR]

Suspended sediment (SS) is a natural component of rivers, but elevated SS concentrations (SSCs) can impact aquatic ecosystems and engineering infrastructures. However, a significant gap remains in predicting SSC dynamics, which are influenced by catchment and climate factors that control sediment erosion, transport and deposition. The research aim is to develop and apply new SS transport dynamics indicators to determine how SSC varies spatially and temporally at a continental scale. Daily SSC data (mg/l) from 1,425 gauging stations in the US were used to calculate indicators of magnitude, frequency and timing (MFT). A filtering approach was applied to calculate frequency indicators that capture SSC events of differing durations. Spatial patterns in indicators were examined and integrated using K-means clustering. High SSC was identified at sites in dry and mountainous regions, but longer-duration SSC events were found in the northern US. The western coastal region and Puerto Rico had consistent timings of high SSC (winter and autumn, respectively). SSC magnitude had a decreasing trend over time across most of the US, but increasing trends were identified for the duration of SSC events. The use of MFT indicators is recommended for future studies to support prediction of climate change impacts on SSC. [ABSTRACT FROM AUTHOR]

This study aims to document and to elucidate the Jeneberang River delta evolution during 1922 -2022 by analyzing the transport of sediment in and out of the river through erosion and sedimentation. The method used is a geospatial analysis of the delta and river evolution using the Dutch map of 1922 and Landsat long-term data from 1972, 1981, 1991, 2000, 2010, 2020, and 2022 by dividing once every fifty to two years, so the delta pattern changes. The data collection was done by downloading data via Landsat, the data processing was simulated using ArcGIS software, and sedimentation and erosion were estimated. This study shows that the lowest sedimentation occurred in 2002 - 2004 with an area of 6.21 ha, and the highest one in 2004 - 2006 with an area of 34.99 ha. The lowest erosion occurred in 2014-2016 with an area of 1.08 ha, and the highest in 2006 - 2008 with an area of 22.64 ha. The evolution of the delta occurred due to landform and river migrations. Landform migration occurs gradually starting with the direction of migration relative to the north to relative to the west resulting in the formation of a delta landform with an area of 5349.42 ha. Furthermore, the development of the landform no longer leads relatively north to west, but there is still sediment migration due to tides and sediment supply from rivers resulting in a delta landform with an area of 5586.56 ha. Then landform migration is derived from the river sedimentary supply stalled to the north because of water gate construction which caused the concentration of migration lead to the southern estuary. Tides then became a major factor in the migration, but were not as intensive as before with additional formation with an area of 5655.79 ha. The meandering changes or evolution of rivers occur naturally and are influenced by human activities. The emergence of changes is divided into five periods ranging from changes in the meandering direction to the south to the sedimentation and control of erosion with the construction of sluices and reclamation. Based on the study and by using the Galloway classification, Jeneberang delta is classified as an estuarine delta that is predominantly influenced by tides (tide-dominated) during its formation. [ABSTRACT FROM AUTHOR]

The interaction of sedimentary systems with oceanographic processes in deep‐water environments is not well understood yet, despite its importance for palaeoenvironmental reconstructions, and for a full understanding of source‐to‐sink sediment transport. The aim of this study is to improve the understanding of how contourite moats, elongated depressions formed by bottom currents associated with contourite drifts, develop and of the link between moat‐drift system morphology and bottom current dynamics. This study provides a systematic comparison of 185 cross‐sections of moat‐drift systems distributed at 39 different locations worldwide, and a detailed analysis of the morphology of six moats that cover a wide range of typical geological and hydrodynamic settings. Additionally, in situ measured current data were analysed to better link hydrodynamics to moat morphology. The median of all profiles across all moat‐drift systems reveals a 50 m relief, a width of 2.3 km, a relief to width ratio of 0.022, a slope angle of 6°, a drift angle of 3° and a concave‐up shaped morphology. Moats can be over 100 km long. Some moats are driven by sediment erosion while others are depositional and primarily exist due to differential sedimentation inside the moat compared to the drift alongside the moat. A new sub‐classification of moat‐drift systems based on their stratigraphy is proposed. This classification distinguishes moats depending on the degree of erosion versus deposition. No relation is found between latitude and moat‐drift morphology or stratigraphy in the analysed examples. The combined data indicate that a steeper slope focuses the current more than a gentle slope, resulting in an increase of the relief–width ratio and drift angle. Thus, this study provides new insights into the interaction of ocean currents with sedimentary morphology, which thereby affects the evolution of a poorly understood deep‐water sedimentary system. [ABSTRACT FROM AUTHOR]

Hyperpycnal flow deposits, one of the most important deep‐water gravity‐flow deposits in lacustrine basins, have become the research focus in recent years. However, the sedimentary characteristics and depositional model of hyperpycnal flow deposits in lacustrine basins remain unclear due to the differences of depositional settings between lacustrine and marine environments. Hyperpycnal flow deposits observed in the middle of the third member of the Shahejie Formation (Es3z) in the Bonan Sag, Bohai Bay Basin, Eastern China, provide a rare case study to reveal the characteristics and depositional model in lacustrine basins. For the first time, detailed core analysis, high‐resolution 3D seismic data, petrology and grain size analysis were used to unravel the characteristics and depositional model of hyperpycnal flow deposits in this study. Twelve lithofacies, six bed types and four bedsets (corresponding to feeder channel, distributary channel, levee and lobe) were recognized from detailed facies analysis. Plant fragment, an important identification mark for hyperpycnal flow deposits, can be classified into three types: completely broken plant fragments, partially broken plant fragments and complete leaves. The proximal part of the deposit develops a small amount of scattered and completely broken plant fragments in massive or spaced stratified pebbly sandstone and massive sandstone due to strong erosion of sustained high‐density turbidity current. The medial part of the deposit is dominated by laminated partially broken plant fragments in planar laminated or rippled sandstone due to suspended settling of sustained high‐density turbidity current and quasi‐steady low‐density turbidity current. Layered partially broken plant fragments with some complete leaves are common in the upper part mud rich division of hybrid event bed and laminated siltstone in the distal part of the deposit. The distribution pattern of hyperpycnites is controlled comprehensively by palaeogeomorphy and sediment supply. Palaeogullies determine the provenance direction of hyperpycnal flow. The formation of synsedimentary faults and troughs control the transport routing patterns. Local micro‐palaeogeomorphy and depression areas further restrict the distribution of sand bodies. During the early stage of deposition with insufficient sediment supply, sediments are transported to the deep basin along confined faulted troughs forming elongated sandy bodies. During the late stage of deposition with sufficient sediment supply, sediments are transported to the deep basin without confinement accumulating fan‐shaped sandy bodies. This study offers insight for enhancing the recognition criteria of hyperpycnites, as well as their depositional model in lacustrine basins. [ABSTRACT FROM AUTHOR]

The rate of deformation of the longitudinal profile for a period of half a century in the sediment flow and riverbed morphology has been assessed by comparison of the leveling survey data on the longitudinal profile of a number of lowland rivers in Russia. This problem remains relevant in both the theoretical and practical aspects, especially for rivers in which a range of in-stream mines occupies kilometers and tens of kilometers and they have operated for decades. The removal of a large amount of alluvial material from the sediment transport and changes in the riverbed morphometric characteristics have given impetus to the leveling process of the sediment transport capacity along the river due to scouring. The result is lowering of the bottom and water surface. The scouring reaches 3–8 cm in rate and spreads 400–700 m/yr along the river. Retrogressive erosion (headcutting) is well-defined, whereas progressive erosion is less pronounced, because it is partially replaced by the mechanical removal of alluvial material. Under these deformations, the longitudinal profile has changed from convex or straight to concave, and there are no signs of recovery over the past decades, despite the fact that the mining has been relatively moderate for the past 30 years or has been completed in the rivers under consideration. [ABSTRACT FROM AUTHOR]

Glaciers expel sediment as they melt, in addition to ice and water. As a result, changing glacier dynamics and melt produce changes to glacier erosion and sediment discharge, which can impact the landscape surrounding retreating glaciers, as well as communities and ecosystems downstream. Currently, numerical models that transport subglacial sediment on sub-hourly to decadal scales are one-dimensional, usually along a glacier's flow line. Such models have proven useful in describing the formation of glacial landforms, the impact of sediment transport on glacier dynamics, and the interactions among climate, glacier dynamics, and erosion. However, these models omit the two-dimensional spatial distribution of sediment and its impact on sediment connectivity – the movement of sediment between its detachment in source areas and its deposition in sinks. Here, we present a numerical model that fulfills a need for predictive frameworks that describe subglacial sediment discharge in two spatial dimensions (x and y) over time. SUGSET_2D evolves a two-dimensional subglacial till layer in response to bedrock erosion and changing sediment transport conditions. Numerical experiments performed using an idealized alpine glacier illustrate the heterogeneity in sediment transport and bedrock erosion below the glacier. An increase in sediment discharge follows increased glacier melt, as has been documented in field observations and other numerical experiments. We also apply the model to a real alpine glacier, Griesgletscher in the Swiss Alps, where we compare outputs with annual measurements of sediment discharge. SUGSET_2D accurately reproduces the general quantities of sediment discharge and the year-to-year sediment discharge pattern measured at the glacier terminus. The model's ability to match the measured data depends on the tunable sediment grain size parameter, which controls subglacial sediment transport capacity. Smaller grain sizes allow sediment transport to occur in regions of the bed with reduced water flow and channel size, effectively increasing sediment connectivity into the main channels. The model provides the essential components of modeling subglacial sediment discharge on seasonal to decadal timescales and reveals the importance of including spatial heterogeneities in water discharge and sediment transport in both the x and y dimensions in evaluating sediment discharge. [ABSTRACT FROM AUTHOR]

Submarine channels conveying sediment gravity flows are often topographically confined, but the effect of confinement width on channel morphodynamics is incompletely understood. We use physical experiments and a reduced-complexity model to investigate the effects of confinement width (B) and the inflow-to-sediment discharge ratio (Qin/Qs) on the evolution of submarine braided channels. The results show that a larger confinement width results in increased active braiding intensity (BIA) and that BIA takes longer to stabilize (i.e., a longer critical time; tc). At a fixed confinement width, a higher Qin/Qs slightly decreases the BIA. Digital elevation models of difference (DoD) of the experiments allow measurement of the morphological active width (Wa) of the submarine channels and the bulk morphological change (Vbulk) within an experiment, defined as the sum of total erosion and deposition. We find that Wa and Vbulk are proportional to B. We further confirm that BIA is proportional to both dimensionless sediment–stream power (ω**) and dimensionless stream power (ω*). These trends are consistent for submarine braided channels both with and without confinement width effects. Furthermore, we built a reduced-complexity model (RCM) that can simulate flow bifurcation and confluence of submarine braided channels. The simulated flow distribution provides reliable predictions of flow depth and sediment transport rate in the experiments. Using kernel density estimation (KDE) to forecast the probability and trends of cross-sectional flow distribution and corresponding BIA under extreme events, we find that skewness of the flow distribution decreases as discharge increases. The development of braided submarine channels, shown here to extend to conditions of topographic confinement, suggests that factors not modeled here (e.g., fine sediment) may be necessary to explain the abundance of single-thread submarine channels in nature. [ABSTRACT FROM AUTHOR]

In the development of water resources projects with large hydraulic infrastructures, alterations to the natural flow regime will increase the erosive processes on the discharge structures due to variability of the turbulent velocities and the particle transport. We analyzed the case of the Mazar dam, a project designed to regulate the solid and liquid flows that come from the Paute river basin. Erosive processes of great magnitude are generated in the stilling basin of Mazar dam, due to the intensity of turbulent velocities produced in extreme events. We applied the Delft3D numerical model to simulate the hydrodynamic and sediment transport conditions to evaluate the stability conditions of the Mazar dam stilling basin. With the results obtained, vulnerable zones have been identified in the stilling basin. We recommended mitigation measures with the installation of a geomembrane to reduce the erosive processes in the vulnerable zones. [ABSTRACT FROM AUTHOR]

Coherence change detection (CCD) is a remote sensing technique used to map phenomena that, under certain conditions, can be directly related to changes in Interferometric SAR (InSAR) coherence. Mapping the areas affected by sediment transport events in arid environments is one of the most common applications of CCD. However, the reliability of these maps remains an unsolved issue. This paper focuses on verifying that InSAR coherence is indeed able to detect all the fluvial sediment transport events that have actually mobilised sediments in arid environments by building a classification model and validating its results. The proposed methodology is tested in three study areas in Salar de Atacama, Chile, using three years of Sentinel data plus a fourth year for validation, and meteorological records of rainfall, the relative humidity of the air and snow cover. The results prove that InSAR coherence can be used to remotely detect sediment transport events related to flash floods in arid environments, that it might have a greater detection ability than meteorological records and that the perpendicular baseline does have a relevant effect on the InSAR coherence that needs to be considered. All these findings will increase the reliability of maps based on InSAR coherence. In addition, the proposed method will allow focusing the mapping tasks only on the relevant dates and, once calibrated, the classification model will enable the automatised remote detection of new events. [ABSTRACT FROM AUTHOR]

The scour induced by wall jets may cause serious bed erosion and thus damage to hydraulic structures. Previous studies are largely empirical, providing only correlations of experimental data. At present, it is not clear what difference exists in the physical mechanisms of two-dimensional (2D) and three-dimensional (3D) wall jet scour. This study first summarizes previous efforts for predicting wall jet scour depths. Then, a scaling analysis is presented for investigating scour depths by applying the phenomenological theory of turbulence. It is shown that for wall jet cases, the dimensionless equilibrium scour depth can generally be expressed as a power function of the densimetric Froude number and relative roughness height, with the power index depending on jet configurations. The predictions of scour depth using the resulting formulas agree well with published data. The present analysis provides new insights into the understanding of the underlying physical mechanisms of wall jet scour as well as the difference between 2D and 3D configurations. [ABSTRACT FROM AUTHOR]

We describe a framework for the simultaneous estimation of model parameters in a partial differential equation using sparse observations. Markov Chain Monte Carlo sampling is used in a Bayesian framework to estimate posterior probability distributions for each parameter. We describe the necessary components of this approach and its broad potential for application in models of unsteady processes. The framework is applied to three case studies, of increasing complexity, from the field of cohesive sediment transport. We demonstrate that the framework can be used to recover posterior distributions for all parameters of interest and the results agree well with independent estimates (where available). We also demonstrate how the framework can be used to compare different model parameterizations and provide information on the covariance between model parameters. Plain Language Summary: We describe a framework for the simultaneous estimation of multiple unobserved parameters by combining observations of a tracer with a numerical model. This framework uses Bayesian inference techniques established in statistical literature to estimate the unobserved parameters of interest used in the model with uncertainty quantification. We explain the key components of this framework in simple terms to encourage its use for analyzing other unsteady processes and performing quantitative inference on parameters that are difficult or impossible to measure directly. We then demonstrate the framework's efficacy by applying it to three case studies from the field of cohesive sediment transport that all use the transport equation (advection‐diffusion). Inferred parameter values show good agreement with independent estimates, where available. Key Points: Probabilistic framework to estimate unobserved erosion model parameters using sparse measurements collected above the seabedGeneral approach can be updated with any model parameterization and quantitatively comparedThe framework is applicable to many similar data sets with both unsteady or quasi‐steady forcing and response [ABSTRACT FROM AUTHOR]

Infragravity waves are key components of the hydro‐sedimentary processes in coastal areas, especially during extreme storms. Accurate modeling of coastal erosion and breaching requires consideration of the effects of infragravity waves. Here, we present InWave, a new infragravity wave driver of the Coupled Ocean‐Atmopshere‐Waves‐Sediment Transport (COAWST) modeling system. InWave computes the spatial and temporal variation of wave energy at the wave group scale and the associated incoming bound infragravity wave. Wave group‐varying forces drive free infragravity wave growth and propagation within the hydrodynamic model of the coupled modeling system, which is the Regional Ocean Modeling System (ROMS) in this work. Since ROMS is a three‐dimensional model, this coupling allows for the combined formation of undertow currents and infragravity waves. We verified the coupled InWave‐ROMS with one idealized test case, one laboratory experiment, and one field experiment. The coupled modeling system correctly reproduced the propagation of gravity wave energy with acceptable numerical dissipation. It also captured the transfer of energy from the gravity band to the infragravity band, and within the different infragravity bands in the surf zone, the measured three‐dimensional flow structure, and dune morphological evolution satisfactorily. The idealized case demonstrated that the infragravity wave variance depends on the directional resolution and horizontal grid resolution, which are known challenges with the approach taken here. The addition of InWave to COAWST enables novel investigation of nearshore hydro‐sedimentary dynamics driven by infragravity waves using the strengths of the other modeling components, namely the three‐dimensional nature of ROMS and the sediment transport routines. Plain Language Summary: Infragravity waves have periods between 25 and 250 s and are the result of wind‐wave groups, or "sets." When wind‐waves of similar periods travel together, they group, resulting in varying wave heights within the groups. This wave height variation at the group scale forces ocean surface infragravity waves. Coastal circulation, flooding, sand transport, and erosion are strongly influenced by these infragravity waves, especially during extreme storms. Therefore, it is important that we are able to model infragravity waves. We present a novel infragravity wave component of the Coupled‐Ocean‐Atmosphere‐Wave‐Sediment Transport (COAWST) modeling system: InWave. By coupling InWave and a circulation model, COAWST is now able to account for the main processes needed to predict coastal hazards due to extreme storms. This new coupled system is verified by reproducing observations from idealized numerical cases, a laboratory experiment on dune erosion, and a field experiment. Results show a good agreement with observations. Key Points: InWave is a new infragravity wave driver of the Coupled Ocean‐Atmosphere‐Wave Sediment Transport (COAWST) modeling systemCoupling InWave with the Regional Ocean Modeling System within COAWST enables the modeling of infragravity waves and three‐dimensional flowsThe coupled system is verified by reproducing laboratory and field observations, with good hydrodynamic and morphodynamic performance [ABSTRACT FROM AUTHOR]

The transport of suspended sediment in estuaries affects the erosion and deposition of estuaries and changes in landform patterns, and it has a profound impact on primary productivity and ecosystem regulation in estuaries. It is of great value for coastal construction and environmental monitoring to study the surface suspended sediment concentration (SSC) in estuaries and adjacent waters. Using 2355 Landsat 5/7/8 satellite images from the Google Earth Engine, the SSC in the surface layer of the Yellow River Estuary from 1984 to 2021 was studied. The results showed that from 1984 to 2021, the SSC declined by more than 30%. The Xiaolangdi Dam and Water and Sediment Regulation Scheme have affected the sediment transport and runoff of the Yellow River, which can explain more than 40% of the SSC in the buffer area of the estuary and have a close relationship with the inter-monthly changes in SSC. The diversion of estuaries and circulation to the transport of suspended sediment have largely affected the changes in nearshore SSC, including the spatial patterns and temporal variations in SSC. Wave changes caused by wind speed on the sea surface can explain the inner-annual changes in SSC in Laizhou Bay and southern Bohai Bay. From January to February, the area of high concentration zones (100 mg L−1≤SSC) accounts for more than 10%, higher than in other months, and re-suspension of sediment caused by wind is the main reason for the increase in SSC. [ABSTRACT FROM AUTHOR]

Alpine rivers have experienced considerable changes in channel morphology over the last century. Natural factors and human disturbance are the main drivers of changes in channel morphology that modify natural sediment and flow regimes at local, catchment, and regional scales. In glaciated catchments, river sediment loads are likely to increase due to increasing snowmelt and glacier melt runoff, facilitated by climate change. Additionally, channel erosion and depositional dynamics and patterns are influenced by sediment delivery from hillslopes and sediment in the forefields of retreating glaciers. In order to reliably assess the magnitudes of the channel-changing processes and their frequencies due to recent climate change, the investigation period needs to be extended to the last century, ideally back to the end of the Little Ice Age. Moreover, a high temporal resolution is required to account for the history of changes in channel morphology and for better detection and interpretation of related processes. The increasing availability of digitised historical aerial images and advancements in digital photogrammetry provide the basis for reconstructing and assessing the long-term evolution of the surface, in terms of both planimetric mapping and the generation of historical digital elevation models (DEMs). The main issue of current studies is the lack of information over a longer period. Therefore, this study contributes to research on fluvial sediment changes by estimating the sediment balance of a main Alpine river (Fagge) in a glaciated catchment (Kaunertal, Austria) over 19 survey periods from 1953 to 2019. Exploiting the potential of historical multi-temporal DEMs combined with recent topographic data, we quantify 66 years of geomorphic change within the active floodplain, including erosion, deposition, and the amounts of mobilised sediment. Our study focuses on a proglacial river that is undergoing a transition phase, resulting from an extensive glacier retreat of approximately 1.8 km. This has led to the formation of new channel networks and an overall negative cumulative sediment balance for the entire study area. We found that high-magnitude meteorological and hydrological events associated with local glacier retreats have a significant impact on the sediment balance. The gauge record indicates an increase in such events, as well as in runoff and probably in sediment transport capacity. Despite this, the sediment supply has declined in the last decade, which can be attributed to a lower contribution of the lateral moraines coupled to the channel network and less sediment sourced from the melting Gepatsch Glacier as evidenced by roches moutonnées exposed in the current/most recent forefield. Nonetheless, we observed significant erosion in the tributary, leading to the transport of sediment downstream. Overall, this study enhances our understanding of the complexity of sediment dynamics in proglacial rivers across various spatial and temporal scales and their relationship to climate change factors. [ABSTRACT FROM AUTHOR]

Resuspension and redistribution of sediments induced by propeller wash may significantly influence aquatic ecosystems at contaminated sediment sites. This study describes a numerical modeling method developed to predict the sediment resuspension and subsequent transport processes resulting from ship traffic, with a fully coupled simulation of hydrodynamics, sediment transport, and propeller wash. By including propeller momentum effects in the flow field computation, the advection and dispersion of resuspended sediments are better represented than in previously available methods. To achieve this improvement, a computational algorithm was first developed to calculate the propeller wash effects from one or more ships (e.g., erosion rate and momentum flux); these results were then dynamically linked to a hydrodynamic and sediment transport computation using Environmental Fluid Dynamics Code Plus (EFDC+). This modeling framework was evaluated using a field experiment conducted by the US Navy. The model was calibrated with flow velocities and sediment erosion depths, and then validated with resuspended sediment concentrations in the water column. The model results reproduced the horizontal and vertical distributions of resuspended sediments better when the propeller-induced momentum was incorporated into the flow field computation. The sensitivity test indicated that the increased flow energy from propeller momentum resulted in significant dispersion of resuspended sediments in both longitudinal and lateral directions. The maximum scour was dependent on the propeller revolution speed, the ship engine power, and the distance between the propellers and the sediment bed. [ABSTRACT FROM AUTHOR]

The influence of land use/cover patterns on soil erosion and sediment transport can be one of the most important indicators to optimize the soil and water conservation measures in a watershed. However, it is still lacking in the quantitative evaluation of the land use/cover pattern and their impacts on soil erosion and sediment yield at the watershed scale. This study aims to explore the long-term changes in the sediment yield on the interannual and intermonthly temporal scales from 1982 to 2020, together with their responses to the land and use/cover pattern. A typical watershed was selected in the Loess Plateau, and the Lyuergou watershed. The M-K trend analysis was employed to elucidate the long-term temporal trends of annual rainfall, runoff, and sediment yield in the study area. An investigation was explored on the changes in the runoff and sediment under different vegetation patterns using the land use/cover pattern. The index of connectivity was chosen to characterize the impacts of the land use/cover pattern on soil erosion and sediment yield. Accordingly, quantitative relationships were also established between the index of connectivity and sediment yield. In addition, the monthly rainfall amount, the maximum daily rainfall amount, and erosive rainfall days were selected as the indices to classify the rainfall types. The results indicated that the Lyuergou watershed experienced cropland abandonment and vegetation restoration, where the index of connectivity decreased significantly during 1982-2020. Consequently, the whole study period was divided into four stages: 1982-1985, 1986-1990, 1991-2000, and 2001-2020, corresponding to the land use/cover pattern Ⅰ, Ⅱ, Ⅲ, and Ⅳ, respectively. The average annual sediment yield varied consistently, as the land use/cover pattern changed. Significantly downward trends were found in the average annual sediment yield and runoff depth, whereas, the annual rainfall amount showed no significant changing trend. Specifically, the annual runoff depth and sediment yield of land use/cover pattern Ⅳ decreased by 74.5% and 68.1%, respectively, compared with the land use/cover pattern Ⅰ, respectively. The average monthly runoff depth and sediment yield in the flood season were 11.7, 5.9, 1.8, 4.0 mm and 713.4, 377.4, 112.0, 317.9 t/km² in the land use/cover pattern Ⅰ, Ⅱ, Ⅲ, and Ⅳ, respectively. The runoff depth and sediment yield under the later land use/cover pattern (Ⅲ and Ⅳ) were significantly lower as opposed to those in the early land use/cover pattern Ⅰ. The erosive rainfall in the flood season was classified into four types: type A (minor rainfall amount, and weaker rainfall erosivity), type B (medium rainfall amount, and weaker rainfall erosivity), type C (great rainfall amount, and medium rainfall erosivity), and type D (great rainfall amount, and larger rainfall erosivity). Type A, B and C contributed to the most sediment yield on the small watershed. However, there was no significant difference in the monthly runoff depth and sediment yield among different land use/cover patterns under type C. The sediment yield on both interannual and intermonthly scales increased exponentially with index of connectivity, whereas the relationships were weaker under type C. The finding can provide a strong reference to the optimal allocation of land use/cover patterns and soil and water conservation measures in arid and semi-arid areas. [ABSTRACT FROM AUTHOR]

As sea-level rise (SLR) and human-made interventions affect coastal currents and sediment transport, coastal barriers have become more vulnerable to the effect of storms, hurricanes, and climate variability. The response of each barrier is unique and depends on wave regime, coastline orientation, weather conditions, bathymetry, and type of human-made interventions, among other factors. In the Magdalena River deltaic barrier, located on the Colombian Caribbean coast, coastal erosion has caused the loss of hundreds of square kilometers of critical ecosystems, such as wetlands and lagoons, since the 1960s. This work aims to analyze the short-term drivers behind the observed loss of lagoons, particularly the drivers of lagoon breaching events and subsequent healing along the deltaic barrier. Lagoon breaching events and healings were detected using satellite imagery, and the timing of these events was related to prior local atmospheric, oceanographic, and fluvial conditions. The findings reveal that the dynamics of the lagoons are driven by extreme river discharges and energetic wave conditions associated with storms or hurricanes. Healing is driven by the sediment supplied by littoral currents and average waves punctuated by energetic events. The cumulative effect of breaching and healing has resulted in a deltaic barrier that has rolled over the lagoons, reducing their size over time. These findings provide a better understanding of the forces of coastal retreat and will help inform future management decisions of the coastal zone. [ABSTRACT FROM AUTHOR]

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Splash erosion plays a vital role in the loss of eroded materials. Unlike those in slope central areas, laterally ejected splashed materials in slope border areas cannot be replenished easily because slope edges prevent splash erosion particles from entering the slope. Thus, splashed materials in slope border areas are less than those in slope central areas because of the lack of source areas for splash‐eroded materials. However, this phenomenon, called the slope border effect, has received minimal attention by researchers. The partially missing splash erosion induced by the slope border effect on sediment transport was investigated to understand the slope erosion mechanism further in this paper. A modified soil pan divided into four areas, namely, central erosion test area (length = 100 cm, width = 35 cm, depth = 45 cm), border erosion test area (length = 100 cm, width = 35 cm, depth = 45 cm), splash compensate border area (length = 110 cm, width = 30 cm, depth = 45 cm) and splash collection area (length = 100 cm, width = 2.5 cm, depth = 45 cm) was used to monitor diffusion and splash erosion under simulated rainfall. Results showed that the splash detachment rate increased with the increase in slope but initially decreased and then increased with the increase in rainfall intensity. The runoff rate and diffuse erosion rates for complete splash erosion (SE) treatments were higher than those without partial splash erosion (SEL). Under low rainfall erosive power and runoff transport capacity (e.g., 5° slope and 60 mm h−1), the transported clay in SE treatments was approximately 2% more than that in SEL treatments. This amount changed to more than 2% sand under high rainfall and runoff erosive power. However, the mass fraction accounted for by silt particles in the sediments of the SEL treatments was more than that in the SE treatments. Thus, the partially missing splash erosion can weaken the selective transport ability of runoff for sediments. The effect of missing partial splash erosion on diffuse erosion was enhanced with an increase in erosive power. The results of our paper will provide insights into the effect of the boundary effect zone of slope on soil erosion and its related mechanisms. [ABSTRACT FROM AUTHOR]

Model-based soil erosion studies have increased in number, given the availability of geodata and the recent technological advances. However, their accuracy remains rather questionable since the scarcity of field records hinders the validation of simulated values. In this context, this study aims to present a method for measuring sediment deposition at a typical Mediterranean catchment (870 ha) in Greece through high spatial resolution field measurements acquired by an Unmanned Aerial Vehicle (UAV) survey. Three-dimensional modeling is considered to be an emerging technique for surface change detection. The UAV-derived point cloud comparison, applying the Structure-from-Motion (SfM) technique at the Platana sediment retention dam test site, quantified annual topsoil change in cm-scale accuracy (0.02–0.03 m), delivering mean sediment yield of 1620 m3 ± 180 m3 or 6.05 t ha−1yr−1 and 3500 m3 ± 194 m3 or 13 t ha−1yr−1 for the 2020–2021 and 2021–2022 estimation. Moreover, the widely applied PESERA and RUSLE models estimated the 2020–2021 mean sediment yield at 1.12 t ha−1yr−1 and 3.51 t ha−1yr−1, respectively, while an increase was evident during the 2021–2022 simulation (2.49 t ha−1yr−1 and 3.56 t ha−1yr−1, respectively). Both applications appear to underestimate the net soil loss rate, with RUSLE being closer to the measured results. The difference is mostly attributed to the model's limitation to simulate gully erosion or to a C-factor misinterpretation. To the authors' better knowledge, this study is among the few UAV applications employed to acquire high-accuracy soil loss measurements. The results proved extremely useful in our attempt to measure sediment yield at the cm scale through UAV-SfM and decipher the regional soil erosion and sediment transport pattern, also offering a direct assessment of the retention dams' life expectancy. [ABSTRACT FROM AUTHOR]

Suspended sediment is an integral part of riverine transport and functioning that has been strongly altered during the Anthropocene due to the overwhelming human pressure on soils, sediments, and the water cycle. Understanding the controls of changing suspended sediment in rivers is therefore vital for effective management strategies. Here we present results from a trend analysis of suspended sediments covering 62 monitoring stations along the German waterways (catchment sizes range between 2000 and 160 000 km 2) with more than 440 000 water samples taken between 1990 and 2010. Based on daily monitoring of suspended sediment concentration (SSC), we found significant declines in mean annual SSC and annual suspended sediment loads (SSLs) at 49 of 62 monitoring stations totaling - 0.92 mg L -1 yr -1. At some stations decreases during the 20 years represent up to 50 % of the long-term average SSC. Significant decreases in SSC are associated with declining SSL despite an increase in sheet and rill erosion by almost 150 % derived from modeling due to changes in land use and management as well as rainfall erosivity. The contemporary suspended sediment loads of the Rhine at the German–Dutch border are approaching the natural base level of ∼1 Mt yr -1 , which was reached by the Rhine during the mid-Holocene when the suspended sediment load was adjusted to the Holocene climatic conditions and before the onset of increased loads due to human-induced land use changes in the Rhine catchment. At this point we can only speculate regarding potential reasons for a decline in sediment transport in larger rivers despite erosion increase. We argue that increased sediment retention in upstream headwaters is presumably the major reason for declining SSC in the large river channels studied. [ABSTRACT FROM AUTHOR]

Detrital 10Be from continental river sands or submarine sediments has been extensively used to determine the average long-term denudation rates of terrestrial catchments, based on the assumption that the rate of cosmogenic nuclide production by the interaction of source rocks with cosmic radiation balances out the loss of these nuclides by surface denudation. However, the 10Be signal recorded in sediments may be affected at the source by the response time of mountainous catchments to high-frequency forcings. In addition, transient sediment storage in piedmonts, alluvial plains and lakes or near the coast may also induce a difference between the erosive signal and its record in the sedimentary sink. Consequently, a significant part of the signal recorded in shallow-water sediments can be lost, as deep marine sediments may simultaneously record a signal coming from newly eroded source rocks along with one coming from the destabilization of previously deposited sediments. In this paper, we use the landscape evolution model Badlands to simulate erosion, deposition and detrital 10Be transfer from a source-to-sink sedimentary system (the Var River catchment, southern French Alps) over the last 100 kyr. We first compare model-based denudation rates with the ones that would be extracted from the 10Be record of local continental sediments (equivalent to river sands) and from sediments deposited offshore over time in order to examine if this record provides an accurate estimate of continental denudation rates. Then, we examine which conditions (precipitation rate, flexure, ice cover) satisfy published measured river incision rates and 10Be concentration in submarine sediments. Our results, based on the Var catchment cosmic ray exposure dating and modelling indicate that, while river sands do accurately estimate the average denudation rate of continental catchments, this is much less the case for deep submarine sediments. We find that deep-sea sediments have a different and often much smoother 10Be signature than continental ones and record a significant time lag with respect to imposed precipitation rate changes, representing the geomorphological response of the margin. A model which allows us to fit both measured 10Be concentration in marine sediments and river incision rates on land involves an increase in precipitation rates from 0.3 to 0.7 m yr -1 after 20 ka, suggesting more intense precipitation starting at the end of the Last Glacial Maximum. [ABSTRACT FROM AUTHOR]

The tectono-sedimentary history of Gippsland Basin from the Early Cretaceous to present was modelled using Badlands landscape software constrained by a 3D structural and stratigraphic Petrel model. The aim is to assess the theoretical sedimentary models using empirical data to better understand the sedimentary history for this rift basin. The models measure the relative effects and most significant variables for basin evolution, including climate, deposition and erosion with extension, subsidence, uplift and eustacy. They show how the detailed basin landscapes evolved and provide new insights to understand facies development in the basin. Early Cretaceous paleotopography ca 137 Ma had extensive highland areas to north, east and south of a rapidly subsiding intracratonic rift with sediment transport east to west. The simulated paleoenvironments are alluvial and fluvial with floodplain lakes developing into extensive lake systems further west. The mid-Cretaceous uplift changed basin architecture, initiating the Strzelecki Ranges and regional erosion. Tasman Sea rifting in early Late Cretaceous formed the Central Deep further east and flipped the paleodrainage eastwards. Latrobe Group sediments filled this smaller depocentre to the east starting with rapidly deposited very thick intracratonic fluvial and lacustrine sediments becoming more coastal plain and shallow marine up section, with Emperor, Golden Beach and Halibut subgroups containing reservoirs and potential source rocks for petroleum. Rising sea-levels in the Late Cretaceous transgressed most of the Latrobe Group by the Oligocene. Simulations from Oligocene to Holocene show less extensive non-marine deposition onshore with incised valleys and very thick coals, while a widespread carbonate shelf built and prograded offshore, periodically cut by submarine canyons. Scenario analysis for 13 variables shows that no single factor is the main control on rift basin evolution; rather basin history is shaped by interactions between climate, uplift, erosion, subsidence and deposition. These controls usually balance sea-level except where it changes rapidly. Numerical tectono-sedimentary basin history reconstruction constrained by empirical data requires a balance of uplift, sediment supply and subsidence. Paleolandscape simulation in the Gippsland Basin from Early Cretaceous to present-day shows how the detailed facies distribution changed with time. New potential reservoirs and source rocks are recognised within the Cretaceous Strzelecki Group, Emperor and Golden Beach subgroups. Organic-rich Turonian source rocks were deposited in restricted lacustrine intra-rift settings. [ABSTRACT FROM AUTHOR]

A landslide dam in most cases fails due to overtopping within a year of its formation, triggering a massive outburst flood. Although landslide dam material has a wide grain size distribution, the effects of coarse particles, which are immovable under normal river flow, on dam erosion processes and outflow discharge remain unknown. In this study, flume experiments on landslide dam failure caused by overtopping were conducted to reveal the effects of coarse particles on dam erosion processes and outflow discharge. In addition, this study developed a two-dimensional shallow water hydrodynamic model for predicting outflow discharge of a landslide dam with coarse particles. Our experiments demonstrated that an increase in the coarse particle fraction of dam material can increase the peak outflow discharge. This is because it can cause more rapid lowering of the maximum dam height due to the changes in erosion patterns. The numerical model proposed in this study successfully reproduced the experimental results showing temporal changes in outflow discharge of a landslide dam with and without coarse particles. Such a numerical model that can explain the transport of the non-uniform sediment particles could be an effective tool for predicting outburst floods of a landslide dam with a wide grain size distribution. [ABSTRACT FROM AUTHOR]

The drawdown of reservoirs behind dams is an important management strategy (e.g., for removal of aging infrastructure, flushing of sediment), and an opportunity to study erosional processes. A numerical model was developed to examine retrogressive bank erosion across reservoir drawdown scenarios and to evaluate factors controlling the rate, volume, and mechanisms of lateral erosion. Modeled processes included dynamic drawdown of groundwater, sequential slope failures via limit equilibrium analysis, and retrogression considering stress interaction between failing blocks. Field measurements were coupled with Staged, Slow, and Rapid drawdown scenarios. Results highlight the importance of including retrogression as an avenue for lateral erosion, as sequential block failures were found to occur in all scenarios except Slow drawdown. This result indicates that bank stability models without some means of characterizing the evolution of slope failure during drawdown are likely underestimating bank failure rates and volumes. In contrast, dynamic groundwater was not found to be a dominant control for any drawdown scenario. Model results also demonstrate that the drawdown increment is a first‐order control on slope instability via the development of drained or undrained conditions. A majority of failures occurred under undrained conditions. To maximize slope stability, using slow drawdown to activate internal friction under drained conditions is essential. The design of the drawdown rate created a tradeoff between the amount of impact created and when the impact is produced. The study also articulated the need for coupling models and field observations for rapidly changing systems. [ABSTRACT FROM AUTHOR]

Arc-shaped bank erosion is a common type of bank erosion in the middle and lower reaches of the Yangtze River. It has the characteristics of complex three- dimensional (3-D) flow structures, rapid expansion, and strong destructive capacity. The general and pocket types of arc-shaped bank erosion models were designed on the basis of actual bank erosion events. 3-D flow fields in general and pocket-type bank erosion zones were obtained from generalized tests by using particle image velocimetry technology. Flow structure and turbulence characteristics were analyzed. Results showed the following: ① The arc-shaped bank erosion zone can be divided into the main flow, mixing, and backflow zones in accordance with the flow structures and distributions of turbulent intensity. ② In the mixing zone, the velocity gradient and turbulence intensity were large, and the width of the mixing zone gradually increased along the main flow direction. The maximum values of the flow velocity at the backflow zone of the general and pocket types were approximately 0.19 and 0.27 times the average velocity of the mainstream, respectively. ③ The vertical average flow velocity at the backflow region of the general bank erosion zone was 48% —76% larger than that in the pocket-type bank erosion zone. The backflow center of the general bank erosion type was closer to the outer side of the bank erosion zone than that of the pocket- type bank erosion zone, thus facilitating the transport of sediment from the bank erosion zone to the main flow area. ④ Under the condition of high mainstream flow velocity, the exchange rate between the water in the general-type bank erosion zone and the main flow was higher than that in the pocket-type bank erosion zone, and the opposite was true under low mainstream flow velocity. [ABSTRACT FROM AUTHOR]

Soil may be a carbon source or sink under the effect of sediment and soil organic carbon (SOC) erosion, transport and deposition. Partial SOC processes to determine whether soil subjected to water erosion is a carbon sink or source have not been clarified but are essential for increasing and predicting SOC storage. In this review, the associations between SOC mineralization, stability and stock at erosion sites, in transported sediments and at deposition sites are clarified. An overview is given for possible determination standards that define soil carbon sinks and sources. Methods for enhancing SOC sequestration and suggestions for improving SOC prediction are also presented. Particle transport is an important intermediate process that determines the material base for SOC stability and sequestration in each erosion and deposition element. When subject to water erosion, a high probability of SOC physical stabilization and a thick soil layer are essential for soil to function as a SOC sink. Sediment transport weakens SOC physical protection in eroded areas but can promote aggregation factors at deposition sites in some cases while increasing the depth of SOC in the soil. In this circumstance, a good soil environment for plant growth facilitates the occurrence of carbon sinks. A concept for critical erosion intensity is proposed to understand SOC sink determination; the concept is presented as the volume of soil erosion per square kilometre (m3 km−2) for which the maximum reduction in vegetation cover or plant biomass still permits plants to provide enough organic matter to compensate for erosion‐induced SOC loss. If erosion intensity is higher than critical erosion intensity at the erosion site, soil degradation is obvious, and soil is presented as an OC source, and vice versa. Finally, the SOC burial method for increasing the soil carbon storage amounts in regions with thick soil layers is presented to explore the SOC sequestration potential in deep soil. The factors considered for SOC prediction should vary with research scale. We hope our review will have direct implications for the modelling of SOC dynamics under water erosion on both slopes and at large scales. Highlights: Changes in soil texture and soil thickness greatly affect the amount of SOC storage at erosion and deposition sites.Selective transport of soil materials or chemical elements promotes soil aggregation.Possible standards that define soil carbon sinks and sources and suggestions for improving SOC prediction are presented.SOC burial may be a good method for increasing C storage amounts in regions with thick layers of fine soil. [ABSTRACT FROM AUTHOR]