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The Tibetan Plateau (TP) is suffering from a substantial decline in terrestrial water storage (TWS) in exorheic basins, threatening water resources that are critical for ∼2 billion people downstream. TWS changes are commonly estimated using gravity satellites through observations of the total terrestrial mass storage (TMS) change, with an implicit assumption of a negligible contribution from sediment transport. Through long‐term (2002–2017) sediment flux observations in seven headwater basins on the TP, we reveal that the gravity satellite‐derived TMS has decreased at a rate of 3.85 ± 0.23 Gt yr−1 in the seven basins, of which 0.35 ± 0.04 Gt yr−1 is contributed by sediment transport. Neglecting this contribution leads to an overestimation of the TWS loss by 10.1 ± 1.3%, equivalent to the annual water demand of an additional 0.62 million people in the surrounding nations. Regionally, the overestimation is surprisingly high in the Indus River and Yarkant River basins, reaching up to 50.8%–77.6%. Plain Language Summary: Accurate quantification of the change in the terrestrial water storage (TWS) on the Tibetan Plateau (TP) is imperative to improve the assessment of water availability that are critical for ∼2 billion people downstream. Through long‐term sediment flux observations, here we find that sediment transport makes a substantial contribution to gravity satellite‐derived TWS change in regions with a high erosion rate such as the TP, which has never been taken into consideration in previous studies. Neglecting this contribution leads to an overestimation of the TWS loss by about 10% on average for the seven headwater basins on the TP. The contribution is especially high in the Indus River and Yarkant River basins. Our findings improve the regional estimation of water availability and thus support climate adaptation and sustainable water resource management. Key Points: For the first time, we quantify the contribution of sediment transport to gravity satellite‐based estimation of TWS change on the TPNeglecting the contribution of sediment transport leads to an overestimation of the TWS loss by 10.1% on averageThe overestimated TWS loss is equivalent to the annual water demand of an additional 0.62 million people in surrounding nations [ABSTRACT FROM AUTHOR]

Soil erosion poses a significant problem in the Mediterranean region, posing serious threats to the environment and natural resources. The objective of this study is to identify and evaluate the risks associated with gully erosion in the Medjerda watershed in the northeastern part of Algeria. To accomplish this goal, two models were utilized: the fuzzy analytic hierarchy process (F-AHP) and the frequency ratio (FR). Twelve factors that contribute to soil erosion were considered in the study: slope, elevation, distance to streams, land use and land cover, drainage density (DD), topographic wetness index (TWI), rainfall, soil groups, lineament density, soil power index (SPI), sediment transport index (STI), and plan curvature. The results indicate that sediment transport index (STI), rainfall, and slope are the most influential factors in predicting erosion in the Medjerda Basin. To validate the models used, the area under the receiver operating characteristics curve (AUC) was employed. The AUC values obtained for the FR and F-AHP models were 75.5 and 73.7%, respectively, indicating their excellent accuracy in identifying the erosion susceptibility area. The accuracy ratings of both models demonstrate their outstanding predictive capabilities. Thus, the results of soil erosion susceptibility maps with a better success rate and forecast could be beneficial and effective for implementing various policy measures to safeguard soil. They could be useful for managing gully erosion risks in different parts of the river basin. [ABSTRACT FROM AUTHOR]

The battering of bedrock by bedload collisions is the primary mechanism by which bedrock rivers erode and landscapes evolve. The energy imparted via impacts acts to detach bedrock via the growth and intersection of surface fractures. We present impact experiments designed to test the influence of particle impact energy on bedrock erosion rates. We found that erosional efficiency increased with increasing impact energy. Notably, these increases in efficiency are not captured by a widely‐used mechanistic bedrock erosion model. Observed increases in erosional efficiency were linked with enhanced elastic energy dissipation captured by differences in the coefficient of restitution. We suggest that this increase in energy dissipation is indicative of enhanced crack extension for high velocity impacts. Our experiments indicate a clear energy‐dependence for bedrock detachment processes that is not yet captured by bedrock incision models but may be integrated into long‐term erosion rates and landscape evolution. Plain Language Summary: Bouncing sediment grains batter the bedrock beds of rivers during floods. As these impacts collide with the bed, they slowly chip away at the riverbed bedrock. It's perhaps intuitive that a grain with more energy when it collides with the riverbed is able to chip away more bedrock. But, how much more destructive are these high energy impacts? We designed an experiment where we hit a bedrock sample with a steel ball at a range of impact energies, over and over again, up to 30,000 times, and measured how much material was chipped away. High energy impacts eroded more material, but this increased efficiency of erosion is not fully captured by impact‐based erosion models. We hypothesize that for higher energy impacts, a larger fraction of the incoming energy is used to crack the bedrock, more easily eroding material. We liken the relative influence of these high energy impacts to a battering ram, where only a few strikes can easily break down a door, whereas lower energy impacts, similar to a simple knock, are unlikely to achieve the same result. We suggest that this effect may be important in determining the influence of extreme events on bedrock erosion over long timescales. Key Points: Impact experiments demonstrate that bedrock erosional efficiency is enhanced with increasing impact energyExperimentally‐derived coefficients of restitution and rock resistance coefficients indicate enhanced elastic energy dissipation with increasing impact energyResults suggest that more energetic impacts enhance crack extension, increasing erosional efficiency [ABSTRACT FROM AUTHOR]

Previous studies have demonstrated that vegetation‐generated turbulence can enhance erosion rate and reduce the velocity threshold for erosion of non‐cohesive sediment. This study considered whether vegetation‐generated turbulence had a similar influence on natural cohesive sediment. Cores were collected from a black mangrove forest with aboveground biomass and exposed to stepwise increases in velocity. Erosion was recorded through suspended sediment concentration. For the same velocity, cores with pneumatophores had elevated turbulent kinetic energy compared to bare cores without pneumatophores. However, the vegetation‐generated turbulence did not increase bed stress or the rate of resuspension, relative to bare cores. It was hypothesized that the short time‐scale fluctuations associated with vegetation‐generated turbulence were not of sufficient duration to break cohesion between grains, explaining why elevated levels of turbulence associated with the pneumatophores had no impact on the erosion threshold or rate. Plain Language Summary: Mangrove habitat grows by retaining sediment. To restore these systems, it is necessary to understand how vegetation influences the transport and retention of sediment. This study used sediment cores collected from the interior of a mangrove forest to study how the aboveground roots, called pneumatophores, influence hydrodynamic conditions and sediment transport, and in particular the onset and rate of sediment erosion. Individual pneumatophores generate eddies that enhance turbulence, compared to conditions without pneumatophores. In sandy soil, vegetation‐generated turbulence can enhance erosion. However, in this study, vegetation‐generated turbulence did not increase the rate of erosion for natural cohesive (muddy) sediment, suggesting that the mangrove forest interior has naturally greater resistance to erosion and sediment loss. Key Points: For the same velocity, cores with pneumatophores had higher turbulent kinetic energy (TKE) compared to cores without pneumatophoresUnlike sands, the inception of erosion and erosion rates for cohesive sediment were better predicted by bed shear stress than by TKEModelers should parameterize erosion within vegetation differently for cohesive and non‐cohesive sediment [ABSTRACT FROM AUTHOR]

Guru Prasath, J.; Sannasiraj, S.A., and Chandramohan, P., 2024. Nearshore morphological changes due to severe cyclonic storm activity along the east coast of India. Journal of Coastal Research, 40(4), 696–713. Charlotte (North Carolina), ISSN 0749-0208. Nearshore waves, wind, and tidal current mobilize seabed sediments; sort, transport, and redistribute the sediments; and modify the nearshore seabed morphology. Waves play a dominant role in morphological changes among winds, waves, and tidal currents. The nearshore wave breaking induces the initiation of sediment movement, and the associated alongshore current transports a large volume of sediments that tend to either accrete toward or erode from the beach face and seabed. Sediment transport rate in the nearshore waters during cyclones is higher than that under normal conditions. The measured changes due to Cyclone Nivar in November 2020 in the nearshore morphology along the Mahabalipuram coast are examined to understand the response of nearshore morphology to cyclonic wave-induced forcing. The beach-profile measurements across 10 transects at 100 m spacing covering about 1000 m along the coast were measured before and after the passage of Cyclone Nivar as a part of the present field study. The evolving beach profiles during Cyclone Nivar were simulated using the storm-induced beach change (SBEACH) model, which is a cross-shore profile evolution model. The changes due to berm erosion and deposition of nearshore sand bars have been compared from field measurements data and model prediction. The calibrated model was then used to simulate the beach profile response at two other locations along the cyclone-affected coastline to examine the shoreline impact. The calibrated model can be used along the coast to understand the poststorm profiles of the beach with reasonable accuracy. [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]

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]

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]

Soil erosion rates after wildfire are strongly controlled by intrinsic properties such as topography, weather, climate, soil, and vegetation. These landscape and hydroclimatic properties are important in determining post-fire erosion rates; however, their influence on post-fire erosion and their interaction with the intensity of a wildfire remains uncertain. A key limitation in resolving this uncertainty is the lack of conceptual models and frameworks for organising data related to the geomorphic sensitivity of landscapes to wildfire. Our aim is to develop a framework for consolidating understanding of post-fire erosion in the context of hydroclimatic conditions which contribute to system states, for example soil and vegetation properties, and wildfire regime. The framework is developed around a simple conceptual model where the change in erosion due to wildfire is a product of change in runoff generation and sediment supply, which is strongly related to landscape net primary productivity (NPP). We hypothesised that geomorphic sensitivity to wildfire should vary as a unimodal humped relationship across a gradient of NPP, peaking at an intermediate level. To develop this framework and to test the hypothesis, we first review intrinsic soil and vegetation properties related to the supply and transport of sediment from burned and unburned hillslopes. Net primary productivity is systematically related to these intrinsic properties because it integrates many processes involved in soil and vegetation development. Empirical data indicate a trend in the change in surface runoff generation with NPP after wildfire, peaking at an NPP of approximately 15 Mg C ha−1 y−1. A simple model of fuel availability and soil heating are correlated with a similar "humped" trend in sediment supply. These results are consistent with our conceptual model, which indicates that sediment supply and runoff contribute towards a distinct peak in wildfire effects on erosion at an intermediate level of NPP. We propose that landscapes of intermediate NPP typically have the highest quantity of fuel available to burn, which cause large changes to the soil surface properties. Landscapes at intermediate NPP also tend to produce intrinsic soil and vegetation properties that promote erosion after wildfire. The interplay between these short and long-term landscape characteristics is strongest at intermediate levels of NPP. Our proposed biogeographic model of geomorphic sensitivity to wildfire was supported by erosion data from burned hillslope and zero-order catchments studies from a range fire-prone landscapes in Australia and North America. Our proposed conceptual model will help identify areas most vulnerable to post-fire erosion changes. [ABSTRACT FROM AUTHOR]

We synthesize evidence suggesting a chain of global cause-effect relationships, linking population and economic development with cumulative effects on changes in landscape dynamics, including denudation and sediment transport/deposition. Temporal trends in global patterns of geomorphic processes or process combinations such as denudation, sedimentation, or frequency of geomorphic disasters, appear to reflect growing human pressure. Erosion rates, intensified by anthropogenic factors, are currently one to two orders of magnitude greater than prior to the 20th century, and are growing further. Per capita human transfer of Earth materials has increased tenfold. A considerable increase in the frequency of disasters related to geomorphic processes has also taken place in just over half a century, outpacing changes in other natural disasters. It is especially significant that the ratio between the frequency of geomorphic (implying water/land interaction, obviously influenced by climate change) disasters and frequency of purely climate-related disasters has increased more than ten-fold since the early 20th century. The changes described in geomorphic processes (global geomorphic change) appear to respond mainly to land surface modification, which reflects a "Great Geomorphic Acceleration" after the mid-twentieth century. However, these stressors, characteristic of the "Anthropocene", likely interact with climate change, increasing concerns about future implications for Earth surface dynamics and underscoring the need to not only reduce GHG emissions, but also improve land use practices, which modify the conditions of the terrain. [ABSTRACT FROM AUTHOR]

Water erosion poses a significant environmental threat in the Mediterranean region, with pronounced impacts observed throughout Morocco. It impairs soil quality and disrupts both sediment transport and water availability. Contributing factors range from natural (climate, topography, and geology) to anthropogenic (land use, vegetation cover, and management). This study introduces an improved Priority Actions Program/Regional Activity Centre (PAP/RAC) model, enriched with GIS and the Caesium-137 (137Cs) technique, to investigate erosion within Morocco's Raouz basin. Enhanced with additional variables including soil types, slope length, rainfall erosion potential, slope orientation, soil moisture, and land surface temperature, the model transcends the classical approach, promoting granularity and precision in predictions. In addition to the comprehensive model, the 137Cs method, which discerns long-term soil erosion and redistribution, provides a dual-faceted validation, bolstering the robustness of this project's erosion risk evaluation. This study's outcomes underscore the gravity of the erosion hazard with significant soil depletion rates ranging from 8.1 to 20 t ha−1 yr−1, demonstrating the model's alignment with empirical data, affirming its utility. The modified PAP/RAC model concurs with the 137Cs data, demonstrating its usefulness for water erosion assessment and management in similar areas. • The modified PAP/RAC model enhances erosion prediction. •Model validated with extensive 137Cs data. •GIS integration identifies erosion hotspots. •A comparative study with global erosion data. • The model adapts to diverse Mediterranean climates. [ABSTRACT FROM AUTHOR]

Sand waves are found on shallow, sandy seabeds throughout the world and their dynamics may pose an imminent threat to offshore construction. Therefore, there is a pressing need to understand bed level dynamics in sand wave areas. These bed level dynamics lead to variations in sand wave shape and migration rate over time. However, these variations cannot be explained with the present-day process-based sand wave models, which all include a purely periodic tidal forcing. To explain these fluctuations a more intricate description of the hydrodynamics is necessary. The aim of this study is to explore the importance of time-varying, non-tidal currents for sand wave dynamics in the North Sea. We adopted the three-dimensional Delft3D-Flexible Mesh model, and were able to reconstruct time-varying, non-tidal currents on top of the periodic tidal forcing, while significantly reducing computation times. The simulated currents and water levels showed a good agreement with in-situ measurements. Compared to the situation with only tidal forcing, the simulated sedimentation and erosion rates were amplified up to 15 times due to time-varying, non-tidal currents. Additionally, periods of net erosion were found at locations in the sand wave transect where tidally forced models only showed net-sedimentation. It is therefore important to consider time-varying, non-tidal currents when predicting future sand wave dynamics in the field. • The reproduction of observed hydrodynamics is improved significantly compared to previous sand wave modelling approaches. • Effects of time-varying, non-tidal currents on sediment transport in sand wave fields are quantified. • Net sedimentation rates due to time-varying, non-tidal currents are be up to 15 times larger than the tidally induced rates. • First application of Delft3D FM software to study sand wave dynamics leads to a significant decrease in computation time. • Excluding time-varying, non-tidal currents can lead to underestimation of sand wave migration and trench infill rates. [ABSTRACT FROM AUTHOR]

Secondary airflow occurs when the primary flow interacts with obstacles and other roughness elements such as dense vegetation. It is characterised by the deviation of the wind velocity and direction from the primary flow. Secondary airflow is often manifested as a reversing, separation, horseshoe, or deflection vortex flow, which is fully developed where the curvature of the topography changes abruptly, such as near the crest region of an aeolian dune, the edge of an escarpment, or around buildings. Secondary airflow has been proven to be one of the main driving forces for the formation of obstacle-related bedforms, such as echo dunes, climbing dunes, cliff-top dunes, falling dunes, shadow dunes, foredunes, blowouts, and parabolic dunes. Morphologies of these obstacle-related dunes have been extensively investigated, whereas the factors controlling secondary airflow and their effects on sediment erosion, transport, and deposition have been less mentioned. Here, we review the types and characteristics of secondary airflow and the controlling factors of their patterns, such as the shape and spatial alignment of obstacles and the incident flow angle. We also investigate the effects of these controlling factors on the morphodynamics of obstacle-related bedforms. As confirmed by field observations, the wind-blown sand hazards controlled by the secondary airflow are discussed. Finally, we summarize the scales of the secondary airflow, and highlight the possible focus for future investigation. • Secondary airflow has been proven to be one of the main driving forces for the formation of obstacle-related bedforms. • Secondary airflow patterns and occurrence of the associated landforms are scale-dependent. • Secondary airflow is the main driving force for wind-blown sand hazards for desert infrastructures. [ABSTRACT FROM AUTHOR]

Sediment associated carbon and nitrogen loss under rainfall, an important cause of soil quality degradation and water eutrophication, strongly depends on the intrinsic properties of original soil types. Relative to total loss, the transport behaviors of organic carbon and nitrogen among sediment size classes and response to soil types remain poorly understood. The concentrations of organic carbon (OC) and total nitrogen (TN) in different sediment size classes (>1, 0.25–1, 0.10–0.25, and <0.10 mm) and their contributions to total sediment load during rainfall erosion were determined under field plot rainfall simulation (at 90 mm h−1) on three contrasting soil types (Luvisol, Alisol and Ferralsol) with increased aggregate stability. During rainfall erosion, the concentrations of OC and TN in total and different sized sediments decreased first and then reached a steady state. The variability of OC and TN concentrations (coefficient of variations in 4.2–53.1% and 6.6–41.9%) among sediment size classes decreased from Luvisol to Ferralsol. Compared to original soils, sediments exhibited larger C/N ratios for Luvisol, and smaller values for Alisol, indicating the more selective transport of labile organic matter for weaker aggregated soils. Among sediment size classes, fine particles (<0.10 mm) accounted 69–88% of total OC and TN losses for Luvisol, and decreased to 30–39% for Ferralsol; and the main transport mechanisms of sediment associated OC and TN shifting from suspension-saltation (<0.10 mm) to rolling (>0.25 mm) with increased aggregate stability. Among original soil properties, inorganic cementing agents (including amorphous iron oxides and clay minerals) showed closer relationships with sediment OC and TN losses (|r| = 0.61–0.89, p < 0.001) than organic matter properties (|r| = 0.55–0.87, p < 0.001), further implying the important role of soil aggregate stability across soil types. This study provides an in-depth understanding on soil carbon and nitrogen losses and their divergent characteristics among soil types deserves consideration in the development of erosion model and land management in agricultural systems. • Variability of OC and TN concentrations among sediment sizes decreased from Luvisol to Ferralsol. • Suspension-saltation (<0.10 mm) dominated OC and TN losses for weak aggregated soils. • Contribution of coarse particles by rolling to OC and TN losses increased with aggregate stability. • Runoff rate, iron oxides and sediment size controlled the loss characteristics of OC and TN. [ABSTRACT FROM AUTHOR]

Storms and extremely energetic events may significantly impact the form and structure of beaches, and so cause erosive processes and coastal damages. Efficient management actions require an up-to-date and accurate knowledge of beach morphological changes, with the shoreline position being a good indicator of such changes. This work proposes the use of the open-source Shoreline Analysis and Extraction Tool (SAET) software for the definition of satellite-derived shorelines (SDSs) from L8 and Sentinel-2 imagery to reveal the shoreline position changes at the beaches of the Ebro Delta, NE Spain. Spatial-temporal models (STMs) of shoreline changes enable a characterisation of how the beaches responded to the storms of 2020. In conjunction with wave data, STMs enable an analysis of the erosive response to storm events, as well as a monitoring of subsequent beach recovery in the short and medium term (<1 year). Results show how Storm Gloria (January 2020, Hs max = 7.62 m) acted as a disruptive event and shifting point in the shoreline trend. As a response to that storm, major erosive processes occurred along the delta that caused an average shoreline retreat of 47 m. A progressive recovery during the spring and summer was mainly associated with periods of low wave energy. Nevertheless, by the end of the year a complete recovery had been achieved for about half of the coast, while the other half showed an average erosion of more than 10 m when compared to the pre-storm situation. Both the erosive and the recovery processes took place unevenly on different sections of the coast, probably dependent on factors such as the orientation of the beach and the pattern of longitudinal sediment transport along the coast. • Automatic shoreline extraction from Sentinel 2 and Landsat 8 imagery using SAET. • Pre and post-storm characterisation of SDS position in time and space using STMs. • Storm Gloria (January 2020) caused an unprecedented and heterogeneous impact on the Ebro Delta. • Slow recovery occurred in the months following the event conditioned by orientation and wave patterns. • About half of the delta showed a significant shoreline retreat by the end of 2020. [ABSTRACT FROM AUTHOR]

Quantitative predictions of marine and aeolian sediment transport in the nearshore–beach–dune system are important for designing Nature-Based Solutions (NBS) in coastal environments. To quantify the impact of the marine-aeolian interactions on shaping NBS, we present a framework coupling three existing process-based models: Delft3D Flexible Mesh, SWAN and AeoLiS. This framework facilitates the continuous exchange of bed levels, water levels and wave properties between numerical models focussing on the aeolian and marine domain. The coupled model is used to simulate the morphodynamic evolution of the Sand Engine mega-nourishment. Results display good agreement with the observed aeolian and marine volumetric developments, showing similar marine-driven erosion from the main peninsula and aeolian-driven infilling of the dune lake. To estimate the magnitude of the interactions between aeolian and marine processes, a comparison between the simulated morphological development by the coupled and stand-alone models was made. This comparison shows that aeolian sediment transport to the foredune, i.e. 214,000 m3 over 5 years, extracts sediment from the marine domain. As a result, the alongshore redistribution of sediment from the main peninsula by marine-driven processes decreased by 70,000 m3, representing 1.7% of the total marine-driven dispersion. From the aeolian perspective, marine-driven deposition and erosion reshape the cross-shore profile, controlling the supply-limited aeolian sediment transport and the magnitude of sediment deposition in the foredunes. In the region with persistent accretion along the Sand Engine's southern flank, a higher than average foredune deposition was predicted due to morphological development of the region where sediment is picked up by aeolian transport. Including these marine processes in the coupled model resulted in an increase of 1.3% in foredune growth in year 1 and up to 6.7% in year 5 along this accretive section. At the northern flank, where the developing lagoon and tidal channel provided increased shelter to the supratidal beach, predicted foredune deposition reduced up to −11.5% over the evaluation period. Our findings show that both aeolian and marine transports impact reshaping the nourished sand, where developments in one domain affect the other. The study findings echo that the interplay between aeolian- and marine-driven morphodynamics could play a relevant role when predicting sandy NBS. • Predicting nearshore–dune morphodynamics is enabled with a new 2D coupling framework. • The model reproduces the Sand Engine's dynamics in both marine and aeolian domains. • Alongshore varying marine sediment transport influences foredune growth patterns. • Marine alongshore transport is slightly reduced by aeolian transport into the dunes. [ABSTRACT FROM AUTHOR]

Vegetation and biological soil crust (biocrust) cover can have a stabilizing effect on dunes by fixing sediment in-place and increasing surface roughness, thus limiting dune mobility, sediment transport, and erosion. These biological effects influence rates of aeolian activity and thus surficial changes, though variability in wind and sediment supply may obscure these topographic effects. In this study, we compare monthly measures of sediment transport and decadal estimates of dune mobility to repeat topographic changes measured as a net volume change in sediment storage (difference in volume between all positive and negative topographic changes) and total volume change (absolute summed volume of all positive and negative changes) for areas of bare, vegetated, and biocrusted sand within a dunefield with limited sediment supply and unimodal winds. We found that monthly net volume changes normalized by area were similar between bare sand and sand with at least 20 % vegetation cover. However, total volume change was significantly greater for bare sand and correlated with monthly sediment flux estimates (R2 = 0.46), though the relationship was significantly improved by including monthly changes in surface roughness (R2 = 0.8). Longer-term decadal trends in topographic change showed larger total volume changes with the greatest decreases in vegetation canopy cover. Additionally, decadal total volume changes strongly correlated with estimates of dune mobility (R2 = 0.99). We also found that increased total volume changes did not necessarily signal increased net volume changes for all land cover types. Specifically, increases in total volume change for bare sand resulted in near equal or lower net volume changes, as both positive (deposition) and negative (erosion) change increased with sediment transport. Conversely, less mobile land covers, such as biocrust covered sand, increased in erosion without significant increases in total volume change, demonstrating that more stable surfaces might exhibit a larger topographic change imbalance than mobile sediment surfaces under the same conditions. This study highlights the importance of considering multiple measures of topographic change for interpreting sediment mobility, transport, and availability. Additionally, we hypothesize a novel framework for remote sensing-based empirical studies aimed at interpreting aeolian landscape evolution resulting from climate change effects on weather as well as biological controls such as vegetation and biocrusts. • Total and net volume changes demonstrate complexity of partially stable dunefields. • Total volume changes were highest for bare sand, correlating with sand transport. • Biological cover reduced correlations between surface changes and transport. • Net volume changes related to sediment availability but not transport or mobility. [ABSTRACT FROM AUTHOR]

• The runoff, sediment load and runoff erosion power decreased significantly. • Compared with runoff, runoff erosion power-sediment relationship is better. • The power function of runoff erosion power and sediment is better than linear. • Erosion in particular geographic locations responds strongly to runoff erosion power. In recent years, the acceleration of urbanization in the Yangtze River Economic Belt (YREB) has brought about problems such as soil erosion, ecosystem degradation and decline in ecological service functions. Therefore, this paper selects the Fujiang River Basin (FRB) in Upper Yangtze River (UYR), and analyzes the relationship between runoff erosion power (REP) and sediment transport (ST) on the basis of analyzing the variation characteristics of hydrological elements. Based on SWAT model, a variety of scenarios are set up to quantitatively analyze the impact of different land use changes on runoff and ST and REP in the basin. The results indicated that: (1) The annual precipitation in FRB from 1960 to 2018 did not change significantly, while the annual runoff, annual ST and annual REP decreased significantly. Compared with runoff and runoff depth, the relationship between sediment transport modulus (STM) and REP is the best, especially the power function between them is better than the linear function. (2) The results of the evaluation indexes of the simulation results of the SWAT model based on the measured runoff and sediment data from 2008 to 2018 are pass and above, that is, the simulation results are considered reliable. (3) Under the five scenarios of conversion of sloping farmland to forest, conversion of dry land to paddy field and conversion of grassland to bushland and forest land, the runoff and ST in the basin decreased but the overall range was small. The simulation results of SWAT model show that the erosion of specific areas in the basin shows the greatest degree of weakening with the decrease of REP. [ABSTRACT FROM AUTHOR]

The implementation of check dams serves as a crucial measure in mitigating debris flow events, effectively stabilizing sediments and diminishing the magnitude of such occurrences. However, less attention has been paid to the fact that intact check dams also promote the release of sediment downstream, and the sediment control mechanism of the check dam during debris flow has not been clearly elucidated. In this study, according to the field survey data of the typical check dam and its surrounding sediment in Chutou Gully, several numerical flume models are built to explore the variation of the fluid kinetic energy and sediment alteration under the different channel gradients and different check dam setting patterns. An improved evaluation index for sediment transport of the check dam, DEI total , is put forward to evaluate the sediment control efficiency of the established flume models. The results show the influence range of the check dam can be generally divided into positive and negative regions. The positive regions effectively intercept sediment, while the negative regions enhance the fluid erosion on sediment and promote the release of sediment. Both the positive and negative regions of the check dam are affected by the channel gradient and dam height. In addition, with the increase in sediment diameter, the resistance of sediment to fluid erosion is significantly improved. • A detail investigation of the typical check dam and the surrounding sediment are presented. • An improved evaluation index is constructed and used to assess the check dam effect on sediment. • The control mechanism of the check dam on sediment during the debris flows were revealed. • We discussed the arrangement suggestion of the check dam resisting debris flows in gullies. [ABSTRACT FROM AUTHOR]

Literature review reveals that many erosion models have limitations for application to constructed landforms. The new EroCA model aims to address this gap. The model uses established erosion and sediment transport models applied to multiple particle size classes at fine spatial and temporal resolutions, covering both suspended load and bedload. Using data from an experimental plot in Northern Australia, global sensitivity analysis was used to investigate the sources of uncertainty, limitations of the model, and priorities for data collection. Further analysis explored sensitivity to model grid size. The results showed that the Manning roughness, erodibility parameters and particle size are the most important parameters. Results also showed low parameter identifiability and hence the difficulty of calibration, even when using high quality experimental data. EroCA has the capacity to be a powerful landform modelling tool at appropriate scales of application; however ideally its data needs would be considered during monitoring design. • In-depth attempt to develop and assess a high spatial resolution process-based erosion model for a mined landform. • Improved understanding of the effects of various parameters on soil erosion process and modelling. • New insight into the limitations of experimental plot data sets for supporting high resolution erosion models. [ABSTRACT FROM AUTHOR]

Storm surge, a major disaster in coastal areas, is generated by tropical cyclones. Strong currents and waves during storm surges often cause sediment transport and beach erosion, significantly damaging the coastal ecosystem. This paper presents a flow-wave-sediment-morphodynamic coupled model to predict morphodynamic changes caused by overwash during storm surges. In the model, the flow field is calculated using the generalized shallow water equations coupled with the Simulating Waves Nearshore (SWAN) model, while sediment transport and bed changes are computed using a non-equilibrium total-load sediment transport model. The model solves the governing equations by employing the explicit finite-volume approach based on a rectangular mesh. The Godunov-type central upwind scheme is adopted to calculate the interface fluxes, thereby solving the complex Riemann problem. A series of numerical experiments considering wave-induced longshore current and short-term bed erosion are conducted to validate the established model and demonstrate its ability to simulate waves, flow fields, and bed changes during storm surge. Specifically, we used the model to simulate the morphological evolution of the Santa Rosa barrier island caused by Hurricane Ivan's storm surge, and the results indicate that the model accurately predicts the real-case erosion process caused by storm surge and overwash during the hurricane. The simulated results clearly explain overwash development, including washover fans, foredune erosion, and back-barrier deposition. It demonstrates that the front dune significantly eroded with the Santa Rosa barrier island coastline retreating by a maximum of about 80 m during the storm surge. More than three breaches with a width of up to 135 m were formed on the sandy barrier due to wave overwash, while the topography at the breach changed significantly. • A new flow-wave-sediment-morphodynamic coupled model is developed to predict morphodynamic changes caused by overwash during storm surges. • A series of numerical experiments conducted using the new model demonstrates its ability and it successfully predicts the overwash erosion of the Santa Rosa barrier island during Hurricane Ivan's storm surge. [ABSTRACT FROM AUTHOR]