Abstract The timing, stratigraphic development, and mechanisms of late Paleogene loess deposition remain poorly understood, yet they are critical to understanding how tectonics, fluvial reworking, and eolian transport interacted during a key interval of western North American landscape evolution. Here we combine lithofacies analysis with high‐resolution grain‐size analysis, quartz surface morphology, and detrital zircon U–Pb geochronology to refine the onset and depositional context of lower Eocene loess in western Wyoming and northeastern Colorado. In Wyoming, our data documents a transition from a fluvial to eolian dominant deposition. Loess‐like bimodal grain‐size distributions with characteristic eolian quartz surface features first emerged at 39.7 ± 0.4 Ma, ∼4 Myr earlier than previously recognized. This is the oldest and coarsest reported Paleogene loess in the western U.S.A. In Colorado, the earliest loess appeared by at least 35.1 ± 0.3 Ma and lasted at least into 31.1 ± 0.4 Ma. This study establishes a previously unrecognized fluvial–eolian transition zone in western Wyoming and supports an eastward younging and fining trend for the loess system. Comparison with coeval global loess records shows that loess systems consistently formed adjacent to major mountains during global cooling, suggesting that rivers originating at high topography supplied the necessary sediment, while concurrent global cooling promoted aridification for wind transport. Furthermore, a comparison to Asian loess shows that similar boundary conditions can produce comparable loess records via different atmospheric processes, implicating that synoptic‐scale climate variability may have played a major role in western U.S.A. loess formation.
Abstract Plant roots stabilize sediment in engineered and natural landscapes, but we lack a general understanding of how root architecture affects anchoring forces. Existing models can accurately simulate root breakage and soil failure, but such models primarily rely on experimentally calibrated empirical relations between root geometry characteristics and the peak force required for uprooting. To address this knowledge gap, we conducted physical experiments uprooting rigid root geometries via pullout from noncohesive sediment. We found that peak pullout force primarily increased with rooting depth and the volume of sediment mobilized during uprooting. We calculated the peak uprooting force for arbitrary rigid root geometries using an anchoring force balance and nondimensionalization and validated this theory with our experimental data. The work required for uprooting increased more than linearly with respect to peak force because both peak force and total displacement increased with root length and depth. To determine which root architectures maximized anchoring forces while minimizing energetic costs for root growth and maintenance, we developed a simple model in which the energetic cost increases linearly with overburden. Model results indicate that branching and growing laterally to increase the sediment overburden at shallow depths are the most energy‐efficient anchoring strategies for plants. Our results yield a general theory for peak pullout force, provide insight into root stabilization of minimally cohesive materials, and could inform erosion prevention strategies and numerical models of plant resource optimization.
Abstract Fjords are globally significant sedimentary archives that record the relationship between glacial, tectonic, and marine processes. Fiordland, on the southwest coast of New Zealand, hosts one of the most extensive temperate fjord provinces in the Southern Hemisphere, yet its postglacial evolution has remained poorly constrained. This study integrates high‐resolution seismic reflection data with existing geomorphic mapping across 15 fjords to reconstruct the regional deglaciation and sedimentary history following the Last Glacial Maximum. The resulting seismostratigraphic framework provides the first region‐wide chronology of marine inundation and sediment accumulation across Fiordland. Two principal depositional phases are identified: a basin‐confined unit representing pre‐marine infill deposited during and immediately following early glacier retreat, and an overlying marine unit that drapes the fjord floors following marine inundation. Uplift‐corrected sill depths combined with global and regional sea‐level curves reveal that marine inundation progressed asynchronously across Fiordland, with first inundation occurring as early as ∼16.9 ka and final fjords becoming marine by >8.7 ka, coincident with rapid sea‐level rise during Meltwater Pulses 1A and 1B. Post‐inundation sedimentation reflects a transition from high‐energy glacial deposition to low‐energy marine accumulation controlled by catchment size, fjord geometry, and tectonic setting. This reconstruction highlights Fiordland's role as efficient sediment and carbon traps, while preserving records of postglacial environmental change in temperate fjord systems. The integrated approach presented here offers a template for evaluating how tectonic, climatic, and eustatic processes collectively shape fjord evolution.
Abstract Non‐linear relationships between catchment‐wide erosion rate and normalized channel steepness within fluvial basins are commonly interpreted to indicate that river erosion is proportional to river slope raised to a power greater than one. This interpretation has crucial implications for the inferred erosion model and for our ability to extract information about past tectonic history from river topography. Here we show that the apparent non‐linearity between catchment‐wide average erosion rates and average channel steepness may be due in part to non‐linear hillslope and debris‐flow processes that bias the calculation of normalized, catchment‐averaged channel steepness in some landscapes. More specifically, when non‐linear hillslopes dominate the high elevation landscape close to the divide, then the transition to the fluvial domain becomes a function of the rock uplift rate, with faster rock uplift dictating longer hillslopes. If the minimum drainage area used for calculating average steepness is not scaled with the rock uplift rate, hillslopes may be included in the fluvial channel steepness analysis. In such cases, the inferred non‐linearity between erosion rate and catchment‐averaged steepness may be an artifact of the analysis procedure rather than a signature of the erosion process itself.
Abstract Lateral erosion of salt marshes via cliff retreat is a primary cause of global marsh loss, driven by interactions between hydrodynamics, sediment, and vegetation. While previous studies show a linear relationship between wave power and cliff retreat, models based on this relationship are largely unvalidated for short‐term (sub‐yearly) and spatially variable predictions, limiting their practical application. This study addresses this gap by integrating a process‐based subgrid cliff erosion model into a 2DH hydrodynamic model, validated using high‐resolution UAV‐derived DEMs over 9 months in a Dutch Wadden Sea marsh. The site featured 20–60 cm high cliffs retreating at ∼0.9 m/yr. Once calibrated, the model captured overall erosion trends and volumes, confirming the linear wave power‐retreat relationship when averaged across the marsh. However, it did not account for local effects, like artificial structures, cliff undercutting, or mass failure, highlighting the need for site‐specific calibration and better understanding of underlying processes. Simulations under varying hydrodynamic conditions assessed marsh cliff vulnerability. Water levels determine the location and timing of cliff exposure, while wave energy dictates retreat magnitude. Yearly storm surges caused the most significant erosion, whereas more extreme surges (5–10 years return‐period) submerged the marsh edge, limiting further erosion. This research shows that the linear wave‐power relationship is scale‐dependent: it can be calibrated for longer‐term, marsh‐averaged erosion volumes when sufficient local data support a linear relationship, but its applicability is limited for within‐marsh, shorter‐term forecasting. Accurate simulation and effective coastal management require further understanding of the processes and implementation of non‐linear erosion mechanisms.
Abstract Accurate estimation of bedload fluxes is critical to understanding sediment transport processes and associated channel evolution in gravel‐bed rivers, however, traditional direct measurements using samplers are time‐consuming and complex. To overcome these limitations, new indirect methods have been developed to estimate fluxes from bedload self‐generated noise recorded by hydrophones, but results from acoustic monitoring have generally been compared with discrete bedload samples or long‐term sediment budgets, offering limited insight into their performance over short timescales. To address this gap, this study compares bedload discharge estimated from continuous acoustic monitoring with those derived from two‐dimensional hydro‐sedimentary modeling and evaluates the reliability of both approaches to improve understanding of sediment transport dynamics at the flood scale. Acoustic power was continuously recorded by a hydrophone fixed at the bank, related to cross‐sectional acoustic power using acoustic maps, and converted into bedload fluxes using a calibration curve. In parallel, a high‐resolution and well‐calibrated two‐dimensional hydro‐sedimentary model was used to compute grain shear stress and estimate fluxes using transport capacity formulas, parameterized with particle tracing and bedload measurements. Both methods provided reliable estimates of cross‐sectional bedload discharge when compared with in situ samples, and resulted in similar event‐integrated bedload discharge, but instantaneous values differed significantly: acoustic monitoring revealed a clockwise hysteresis, while the model exhibited a discharge‐dependent response. Comparison of both approaches revealed that acoustic measurement captured an early mobilization of recent local sediment deposits and a subsequent sediment‐limited regime due to insufficient upstream supply, which the model was intrinsically unable to reproduce.
Abstract Extreme geophysical flows, such as granular and debris flows, can significantly shape the landscape in steep lands and generate seismic signals that can be recorded over long distances. However, direct field measurements needed to constrain the granular physics remain difficult due to the damage potential of those flows. Here, we investigate how the granular flows impact the bedrock channel using a computational fluid dynamics model coupled with the discrete‐element method, systematically varying the grain size, discharge, and water content for two flow regimes: unsteady and steady flows. These numerical experiments allow us to quantify the basal forces as probability density functions (PDFs). We test those PDFs based on several evaluation metrics, such as determination coefficient, residual sum of squares, Wasserstein distance, and information entropy for 12 selected probability distributions. We find that the t Location‐Scale and lognormal distributions are best‐performing among the tested distributions for unsteady and steady flows, respectively, rather than the exponential and generalized Pareto distributions in previous studies. Our results demonstrate that grain size, discharge, and water content strongly influence the basal‐force distribution. Furthermore, we established the relationships between flow kinematics and basal force statistics. Results indicate that compared to effective friction coefficient and volume fraction, the fitted parameters of the probability distributions exhibit monotonic relationships with Froude number, granular temperature, and dimensionless velocity. These results provide empirical constraints for modeling extreme geophysical flow incision and inversion of seismic signals generated by such flows.
Abstract Long‐distance aeolian dust transport represents one of the largest sediment fluxes on Earth, with North Africa being a dominant source. The island of Crete in the Eastern Mediterranean lies within major transport pathways but remains underexplored regarding multi‐proxy fingerprinting of deposited dust. Here, we evaluate the contribution of long‐range dust, sorting effects caused by the regional topography, and the contributions of different source areas on dust deposited in Crete over 15 months (03–2023 to 06–2024). We analyzed the bulk mineral, grain‐size, and radiogenic (Nd, Pb, and Sr) isotope composition of monthly deposition samples at seven sites across western Crete as well as local surface material and reference aerosols from Libya. The deposited material is dominated by long‐range transported dust originating from northern Africa, as indicated by the presence of palygorskite and distinct mineral and isotopic signatures from local surface sediments. Grain‐size distributions are largely uniform across measurement sites and dominated by silts, with temporal rather than spatial variability controlling compositional changes. Isotopic data suggest major contributions from source areas in northeastern Algeria and north Libya to northwestern Egypt. The absence of gypsum and the variability of clay mineral proportions suggest transport related fractionation and mixing of multiple source regions. Shifts in mineral assemblages suggest changes in provenance from northeastern Algeria in winter to northeastern Libya and northwestern Egypt in summer. These results highlight the dynamic and seasonally variable nature of dust provenance in the Eastern Mediterranean and emphasize the value of integrating mineralogical and isotope approaches for robust source attribution.
Abstract The Yilan impact crater in northeastern China is generally well preserved, except for a ∼2 km gap along its southern rim. To investigate the structural disturbances recorded beneath the remnant southern crater wall, we conducted a shallow‐seismic survey in the southern part of the Yilan crater. We constructed the S‐wave and P‐wave velocity models by inverting the surface‐wave dispersion curves and first‐arrival travel times individually. K‐means clustering was applied to the multi‐parameter velocity models to transform the geophysical attributes into a zonation of the shallow subsurface that shows lithological variations. By comparing the clustered model with the extrapolated rim topography estimated by its preserved part on the Earth's surface, we found that the fractured bedrock of the remnant southern crater wall lies buried beneath more than 10 m of loose sediments. This indicates that the southern part of the crater wall has been significantly eroded and covered by sediments but still exists. It also shows that the farther away the rim is from its surface pinching point, the stronger the erosion and sedimentation have been. Overall, this study demonstrates the effectiveness of combining multiple seismic approaches with statistical clustering for structural delineation of the remnant southern crater wall buried below the Earth's surface and provides new geophysical evidence on the deformation of the Yilan crater.
Quartz grain surface microtextures serve as robust records of sedimentary history and depositional environment, yet a coherent framework quantitatively linking specific microtextures to stream power remains underexplored. This study integrates scanning electron microscopy (SEM) with quantitative hydrodynamic analysis along the Kinu River, Japan, to elucidate the sensitivity of quartz microtextures to unit stream power (omega). Analysis reveals that microtexture frequencies vary distinctly along the river, yet correlations with unit stream power (omega) are insignificant at the overall catchment scale. However, within low-gradient reaches (S < 0.001), we identified a strong positive correlation between unit stream power (omega) and the frequency of crescentic percussion marks. As crescentic percussion marks require high-magnitude impacts to fracture the crystal lattice, they function as sensitive, high-threshold indicators of local collisional energy. In contrast, chemical microtextures show no significant relationship with the unit stream power (omega) in the Kinu River data set, consistent with previous interpretations that they primarily reflect cumulative residence in low-energy or organic-rich zones rather than instantaneous flow intensity. Furthermore, comparative analysis between a channel deposit and an adjacent dune deposit formed directly by wind action suggests that warm-humid riverine dunes can retain strong microtextural inheritance from their fluvial source, distinguishable mainly by incipient aeolian overprinting (e.g., bulbous edges and flat cleavage surfaces). Ultimately, building upon qualitative discrimination, this study establishes a framework relating grain-scale surface microtextures to fluvial energy heterogeneity.
A wide range of functions are currently available for simulating the calving of marine-terminating glaciers, but there is no consensus on the best approach to represent the calving process in glacier and ice-sheet models. Current assessments of calving functions are often crudely done by fitting functions to observed changes in terminus positions, neglecting the physical processes that drive changes in calving dynamics. Here, we use 3D simulations of synthetic tidewater glacier domains in Elmer/Ice, to determine whether natural behaviors emerge from the crevasse-depth and von Mises calving functions, and to provide a basis for more robust assessments of the potential capabilities of calving functions. The crevasse-depth calving function is shown to be able to simulate both serac and full-thickness calving events and simulates how their relative proportion is altered by changing the ice freeboard or submarine melting. A clear distinction between rate- and position-based calving is shown, with the von Mises calving function unable to respond to imposed changes in topography or freeboard ice. By comparing the two calving functions, it is apparent that the position-based crevasse-depth function more faithfully represents the calving behaviors observed in the natural world. Consequently, future projections should be made using position-based calving functions. Using a position function, calving rates vary with time and glacier state, so cannot be assumed to be a constant function of stress. In essence, a calving function must be able to capture the key physical processes that drive calving. If so, the transitions in calving dynamics will inherently emerge.
Abstract The Editors of the Journal of Geophysical Research: Earth Surface would like to express our thanks and appreciation to everyone who served as manuscript reviewers for this journal during 2025. We extend our thanks to the 921 reviewers who provided 1,240 reviews of manuscripts for JGR: Earth Surface . Finding the time to provide good quality and detailed peer reviews can be challenging, and requires individuals to take time from their own research to contribute to the progress of our field more widely. Providing peer review can also be a mentoring practice for early career colleagues, both through providing constructive feedback on their work and through co‐reviewing as a means of training the next generation of peer reviewers. We greatly appreciate the large community of geomorphologists who have taken the time to write reviews, and particularly for providing constructive and critical feedback that guides authors to write the best possible paper about their research.
Abstract Mud builds coastal landscapes and carries pollutants and carbon, yet predicting its transport is difficult because mud aggregates into flocs that control settling rates. Flocs are typically characterized using fractal theory with a constant fractal dimension , inferred from aggregated size–settling velocity data, despite diverse fractal structures. We conducted experiments on freshwater flocs under varied shear stress and organic concentration to characterize this diversity. Rather than the conventional approach of aggregating settling data to infer , we grouped measurements by the two‐dimensional (2D) box‐counting dimension from particle tracking, partially resolving structural variability. This stratified method reveals that increases with shear velocity and decreases with organic matter (OM) content, trends obscured by aggregation. The stratified analysis resolves variations of 0.2–0.35 units across experimental conditions, whereas conventional aggregation reduces this range roughly fivefold. The inferred primary particle diameter co‐varies with these conditions, and the concurrent variation of , , and floc size introduces competing effects on settling velocity. Our approach yields lower values (1.6–2.1) than the canonical range, which propagates nonlinearly into settling rates, implying that mud flocs are more porous and settle more slowly than expected. We also find that the 2D‐to‐3D relationship can be described by a nonlinear model, consistent with empirical conversions for synthetic aggregates. Overall, our results indicate that mud retention in floodplains and deltas is less efficient than current floc models assume, at least in the freshwater conditions we analyzed, with implications for sediment budgets, contaminant dispersal, and coastal landscape evolution.
Abstract Forward and inverse modeling techniques are often applied to paleotsunamis to reconstruct inundation parameters. The accuracy of both types of models can be influenced by geomorphology, particularly in areas such as northern Cascadia, where rocky headlands and fjords influence tsunami flow and the preservation of sedimentary deposits. Furthermore, the degree of agreement between these models remains unclear, particularly because inverse modeling is often one of the only viable approaches for reconstructing paleoflow characteristics of older tsunamis lacking instrumental records. We address this uncertainty by using the TSUFLIND inverse model and apply it to a series of cores that contain the 1964 Alaska tsunami deposit from Port Alberni, Canada, situated at the landward terminus of a 38 km fjord. A concurrent forward model, constrained by observational records, was developed using GeoClaw software, and estimated inundation depths were ∼1.40 m higher than those estimated by TSUFLIND at the same locations. This discrepancy suggests that regional conditions, such as the uniquely restricted geomorphology and post‐depositional changes to the tsunami deposit, exert a strong influence on inverse modeling results in northern Cascadia. When applied to paleotsunami deposits lacking observational records, the potential for both models to overestimate flow depth becomes more significant. Accordingly, TSUFLIND‐derived flow depths can provide important minimum constraints for forward inundation models.
Abstract A 7‐year coastal cliff erosion record, developed from 320 ∼weekly LiDAR surveys of a 2.3 km‐long cliff in southern California, is used to examine the cliff geomorphological response to the variability of environmental forcing (water level, waves, rain, and groundwater) from weekly to interannual timescales at different cliff elevations. When the environmental factors were considered independently, the erosion of the lower‐cliff within the wave exposure zone best correlated with wave forcing ( r 2 = 0.38) at weekly scales, while the upper‐cliff correlated best with rain ( r 2 = 0.36) and groundwater ( r 2 = 0.15). Higher correlations were found when considering combined environmental forcing, with the greatest lower/upper‐cliff geomorphological response to combined environmental changes at semiannual/monthly timescales, respectively ( R 2 = 0.66/ R 2 = 0.58). A wave‐forcing increase of 36% relative to the monthly climatology was observed during El Niño, coinciding with increased cliff‐erosion activity. Multi‐variable seasonal cliff erosion models accounting for the combined effects of environmental forcing captured the interannual variability in cliff erosion but presented limitations in capturing episodic cliff failure events. The results indicate that large‐scale interannual climate patterns, such as ENSO influence on wave forcing on cliffs at the study site, should be considered in rock coast evolution modeling.
Abstract Understanding the basal conditions of East Antarctica's outlet glaciers is critical for accurately modeling future ice‐sheet evolution. Denman Glacier, one of the continent's fastest‐flowing glaciers, has been identified in bed‐topography models as occupying the deepest continental trough on Earth, potentially acting as a major outlet of the East Antarctic Ice Sheet. Here we present a land‐based magnetotelluric transect across Denman Glacier, acquired approximately 50 km upstream from its grounding line. These measurements provide the first in situ, ground‐based geophysical constraints on the glacier's subglacial structure, enabling evaluation of existing airborne‐derived models and reducing uncertainty and non‐uniqueness in inferred bed topography. The resistivity model images a laterally continuous, highly resistive unit (–), interpreted as glacial ice. This ice overlies lower‐resistivity regions (–) interpreted to be unconsolidated sediments and rock. Along the glacier flanks, the boundary between ice and underlying material aligns closely with radar‐derived trough depths. In contrast, beneath the glacier center, the model indicates a trough depth of m below sea level, more than 1000 m shallower than previous estimates, indicating that the extreme depths predicted by earlier models are not observed. Basement resistivity is consistent with magnetic source depths and regional geological constraints. A low‐resistivity feature () near the center of the glacier is interpreted as a sedimentary topographic high. Low‐resistivity anomalies beneath the glacier are attributed to saline porewater within till or sedimentary rocks. The inferred bed geometry and basal conditions provide improved constraints for modeling Denman Glacier's stability and future evolution.
The Indus Fan, located in the Arabian Sea, is the second-largest submarine fan on Earth. Understanding its fan morphology and Channel-Levee System (CLS) is crucial because of its role in transporting sediment, organic carbon, nutrients, and contaminants to the deep-sea. However, accurate mapping of upper Indus Fan channels remains incomplete due to inadequate seabed bathymetric data. This study presents high-resolution multibeam bathymetry of the upper Indus Fan to unveil its complex morphology and CLS. The data reveal a truly vast, highly meandered, and deeply incised active CLS with an extensive network of abandoned CLS. The fan exhibits highly diverse geomorphology, characterized by channel-wall failures, sediment waves, and mass transport deposits. Only one channel is active, with others abandoned through avulsion processes. Outer levees of abandoned CLSs locally exhibit collapse, erosion, and interaction with adjacent CLSs, altering CLS morphology and reducing its preservation potential. Channel sinuosity is mostly achieved through preferential preservation of inner bend deposition and outer bend erosion, possibly favored by the muddy nature of the deposits. Meander bend cutoffs are widespread in the channel-levee belts, with neck cutoffs being more common along the channel path. The presence of multiple knickpoints, plunge pools, and neck cutoffs, along with compound asymmetrical meandering bends, highlights the role of autogenic processes in governing flow dynamics, terrace formation, and channel evolution. This study improves the understanding of the Indus Fan channel network through the mapping of one of the largest CLSs on Earth and showcases its morphological complexities.
This is the second of two papers aimed to investigate grain sorting patterns associated with the formation of steady alternate bars in gravel-bed rivers. Part 1 presented the analysis of a series of tailored experiments, performed in a mobile bed laboratory flume with fixed, straight banks. The results showed that a consistent pattern of grain size distribution emerges in conjunction with the bed topography upon reaching the final equilibrium configuration, nearly independent of the flow discharge and channel width. In this second part, a two-dimensional morphodynamic model is formulated to interpret the experimental observations. The model is solved through a linear analysis, which allows the description of the spatial structure of the flow field, channel bed, and bed surface texture at equilibrium. The model accurately reproduces the sorting pattern associated with bar development, as it captures the gradual coarsening upstream of the bar head and finer particles accumulating on the lee side. The sorting pattern is governed by the balance between the selective transport of sediment grains in the streamwise direction and the gravitational effect due to lateral bed slope. The model's outcomes crucially depend on the formulation adopted to describe the effect of lateral bed slope on the direction of sediment transport. Specifically, the good agreement between theory and laboratory data is verified when the effect of lateral hiding on particle direction is neglected. The results suggest the need for a general formulation, supported by dedicated laboratory and numerical experiments, to better understand grain mechanics on arbitrarily sloping beds.
Surface grain size in gravel-bed rivers is inherently heterogeneous, with marked spatial variability that remains challenging to predict, even in the presence of regular bedforms. This study investigates surface grain size variability on self-formed alternate bars at the scale of a single bar unit, and is divided in two parts. In Part 1, controlled laboratory experiments were conducted in a straight flume with fixed banks under steady water discharge and sediment supply conditions. High-resolution maps of bed topography and surface grain size were created using close-range photogrammetry and automated image analysis, while numerical simulations provided estimates of the flow field and bed shear stress distribution. Experiments show the formation of initially migrating bars, which gradually slow down, eventually leading to a steady configuration. Analysis of this equilibrium state reveals recurring periodic patterns in bed topography, shear stress, and grain size. Coarser sediment patches predominantly occur on the stoss side, upstream of the bar crest, while finer sediments concentrate near the bar front, upstream of pools. Grain size distribution is not directly correlated with bed elevation or bed shear stress but displays a systematic upstream shift with a consistent phase lag across all experiments. These patterns were unaffected by changes in discharge or channel width. Moreover, our analysis shows that the flow deflection induced by bars limits sediment transport on bar tops, which explains the lack of migration and the relatively long bar wavelength. In Part 2, a theoretical model is formulated to provide a mechanistic interpretation of the experimental results.
Tidal asymmetry and river flow are key drivers of residual sediment transport. Here, we provide a generalized formulation, applicable to non-cohesive transport, of how tide and river flow interactions influence tidal asymmetry of bed stress in mixed-tide estuaries. Existing analytical relationships for bed stress and tidal asymmetry are extended to include the effects of multiple tidal constituents and residual velocity into a single, one-dimensional framework. The framework includes asymmetry caused by the phase relationships between tidal constituents at diurnal, semidiurnal, terdiurnal, and quarterdiurnal frequencies, and is summarized by three non-dimensional numbers that scale and classify the dynamics of bed stress asymmetry in semidiurnal, diurnal, and mixed-tide estuaries. Comparison of these numbers to different sediment transport metrics shows that even modest residual velocities ( of the tidal current amplitude in semidiurnal systems) can reverse the asymmetry in bed stress and sediment transport that is induced by tidally asymmetric currents. Moreover, because sediment transport is a time integrated process, we show that flood dominant sediment transport can prevail in ebb dominant velocity fields (and vice versa). Particles with low thresholds for erosion/transport can also exhibit different and even opposing transport to those with higher thresholds. Application of the framework to observations in San Francisco Bay shows how bed-stress asymmetry can be diurnal-dominant in estuaries traditionally classified as semidiurnal. Many estuaries such as the San Francisco Bay exhibit tidal asymmetry and residual velocities large enough to alter or reverse transport patterns; thus, the framework described herein is widely applicable.
