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The aim of this study was to provide a broader view of the transport and mobilization of metal(loid)s in sediments from the Yellow Pine Mill site in Goodsprings, Nevada. This mine was principally a lead ore operation located in the township of Goodspring, Nevada. From the two wash systems originating from processed tailing piles of the mill the contaminant migration was evaluated. Concentrations of metal(loid)s in sediments were up to 10 times higher in the south wash than in the north. Maximum levels of As and Pb in surficial south wash sediments were 103 and 1351 mg kg−1, respectively. Similarly, the enrichment factors of Cd, Cu, and Pb were far lower in north wash tailing than those obtained for south wash. Principal component analysis (PCA) data from the south wash shows PC2 explained 13.98% of the total variance and loadings on Zn (0.982), Cu (0.875), Pb (0.778), and Cd (0.690), which can be considered anthropogenic component associated with mine tailing. Evaluation of the transport mechanism of sediments indicates that metal(loid)s in sediments were found to have been derived from anthropogenic activities and migrated at least 1050 m beyond source materials in the south wash. Sediment transport from source areas to the wider environment during storm events. [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]

Earth's terrestrial topography evolves in response to the interaction of tectonics, climate, and lithology. Recent discoveries suggest that the grain size of sediments produced on hillslopes and transported through river networks is key to understanding these interactions. Hillslope grain size varies systematically with erosion rate and residence time, the degree of chemical and physical weathering, and the fracture density and susceptibility to weathering of rock. Variations in initial grain size strongly influence the spatial evolution of grain size distributions as particles mix and wear during downstream transport through channel networks. In rivers, the size and flux of the coarse fraction of the sediment load control the rate of incision into bedrock and thus govern channel slope and ultimately the relief of actively eroding landscapes. These relationships suggest that a primary way that tectonics, climate, and lithology influence landscape evolution is through their controls on sediment grain size. Recent research reveals the central role of sediment grain size in controlling bedrock river morphodynamics, linking grain size to channel slope and topographic relief. Tectonics, climate, and lithology govern the size of sediments produced on hillslopes; hence, grain size mediates their influence on landscape evolution. Feedbacks linking sediment grain size, topography, weathering, erosion, and sediment transport provide new opportunities for advances in Earth surface science. [ABSTRACT FROM AUTHOR]

The concession of the Peruvian Amazon Waterway (PAW) project seeks to strengthen commercial transport between Brazil and Peru by using four rivers: Amazon, Ucayali, Marañón, and Huallaga, in which the Peruvian Ministry of Transportation and Communications (MTC) was in charge of developing the Terms of Reference (TOR). At the end, the TOR did not specify the methodology for the hydrogeomorphic characterization of rivers. The PAW project was designed to meet specific geometric characteristics to ensure navigable conditions: minimum water depth of 2.44 m (8 ft) and channel width ranging from 44 to 56 m, approximately. The zones where the river bottom limits the layout and dimensions of the navigation channel are called shallow zones (SZs). Based on the PAW project's TOR, the EIA-d (Detailed Environmental Impact Assessment) study was carried out using 14 SZs that required dredging 3.87 million m3 of sediments. In 2019, the EDI (Definitive Engineering Study) described 24 SZs with a total dredging volume of 4.39 million m3 of sediments. The number and locations of SZs and the volume of required dredging changed significantly, revealing a lack of understanding of meandering (i.e., Ucayali and Huallaga) and anabranching (i.e., Marañón and Amazon) river processes. This study presents an integral methodology for the hydrogeomorphic characterization of the meandering Huallaga River (the river with 56% of the total estimated volume to dredge) by using remote sensing and field measurements (hydrodynamic, sediment transport, and bathymetry). Geological confinement of river dynamics, together with the presence of anabranching structures, promote stable SZs. In regions where meandering rivers tend to develop ancient and modern geomorphic structures, SZs are temporarily and highly dependent of river dynamics. The present hydrogeomorphic characterization of the Huallaga River will support the Peruvian government to inform their technical guidelines (TOR), especially for infrastructure projects (e.g., PAW) in Amazonian rivers. Several river-related engineering projects lack a broad and comprehensive view to understand a river's spatial and temporal dynamics. One of these projects is the Amazon Waterway (Hidrovía Amazónica in Spanish) which sought to strengthen commercial transport between Brazil and Peru using four rivers: Amazon, Ucayali, Marañón, and Huallaga. The Terms of Reference (TOR) for the Environmental Impact Study (EIA) did not specify the methodology for understanding river dynamics; however, the focus was mainly concentrated on the need to develop dredging activities. During the EIA evaluation stage, more than 400 technical observations were presented, several related to fluvial geomorphology. This article presents a synthesis of how proper river studies should be carried out and how river dynamics is related to aquatic biodiversity, highlighting the importance of understanding rivers before developing infrastructure projects. [ABSTRACT FROM AUTHOR]

Perennial rivers in desert regions are relevant environments that tend to concentrate most ecosystem services and values, but are not as studied as much as intermittent and ephemeral rivers. This article reports on the main morphological and ecological features of the Silala River, a narrow permanent river in the arid region of Antofagasta, in the north of Chile. The study was motivated by the dispute between Chile and Bolivia concerning the status of the Silala as an international watercourse. Field surveys of sediment transport using traps and marked sediments (colored and tagged clasts) revealed that finer sediments are moved in higher percentages and for longer distances than coarser sediment fractions, which corroborates the size‐selective nature of sediment dynamics in the river. The stream features the typical step/pool‐plane bed morphology that is to be expected in an alluvial river with the given boundary conditions of slope, grain size of sediments, and lateral confinement. Furthermore, the Morphological Quality Index (MQI) classifies the river as featuring overall good morphological conditions and the river hosts an abundant population of rainbow trout (Oncorhynchus mykiss). Although this is a non‐native species, their presence shows that the general conditions of the river (availability of food and presence of aquatic habitats) are able to sustain a population of resident fish. Overall, the morphological forms, geomorphic processes, and ecological features of the Silala River are typical of an alluvial stream with a permanent flow regime. This article is categorized under:Science of Water > Water and Environmental ChangeHuman Water > Rights to WaterScience of Water > Hydrological ProcessesWater and Life > Nature of Freshwater Ecosystems [ABSTRACT FROM AUTHOR]

Despite geomorphic processes being increasingly recognized as a vital component of river management projects, evidence suggests that they may not be adequately captured in common river assessment procedures. We reviewed 91 river assessment procedures from around the world to evaluate their effectiveness in capturing geomorphic processes relevant for river management goals. Our objectives were to summarize which common geomorphic indicators are measured and how in different types of river assessments categorized based on their main focus: geomorphic, physical habitat, mixed geomorphic and habitat, and hydromorphology. Our analysis identified differences in the types of geomorphic indicators included and measurement methodologies between the types of assessment procedures. Some geomorphic processes, such as sediment transport, are nearly completely absent from all assessments, despite their importance for geomorphic processes. The variability among assessment procedures suggests that a single procedure is unlikely to capture all geomorphic components required to support every river management programs. Here, we discuss how the strengths and limitations of different assessment types can be used to guide decisions around how to select assessments and geomorphic indicators to support management project goals. A companion paper expands the discussion of how to plan effective river assessment procedures to support unique management goals. [ABSTRACT FROM AUTHOR]

Natural channel design (NCD) and analytical channel design (ACD) are two competing approaches to stable channel design that share fundamental similarities in accounting for sediment transport processes with designs based on hybrid fluvial geomorphology and hydraulic engineering methods. In this paper, we highlight the linkage between ACD's capacity/supply ratio (CSR) and NCD's sediment capacity models (FLOWSED/POWERSED), illustrating how ACD and NCD have reached a point of convergent evolution within the stream restoration toolbox. We modified an existing CSR analytical spreadsheet tool which enabled us to predict relative channel stability using both conventional bed load transport equations and regional sediment regression curves. The stable channel design solutions based on measured data most closely matched the Parker (ACD) and/or Pagosa good/fair (NCD) relationships, which also showed the greatest CSR sensitivity in response to channel alterations. We found that CSR differences among the transport relationships became more extreme the further the design width deviated from the supply reach, suggesting that a stable upstream supply reach may serve as the best design analog. With this paper, we take a step toward resolving lingering controversy in the field of stream restoration, advancing the science and practice by reconciling key differences between ACD and NCD in the context of reach scale morphodynamics. [ABSTRACT FROM AUTHOR]

Fluvial fans are large, low-gradient depositional systems that occur in sedimentary basins worldwide. Fluvial fans can represent much of the geologic record of foreland basins, create hazards, and record paleoclimate and tectonic signals. However, we lack an understanding of how fluvial fans grow into the variety of shapes observed around the world. We explored this aspect using a cellular model of foreland basin landscape evolution with rules for sediment transport, river avulsion, and floodplain processes. We tested the hypothesis that avulsion dynamics, namely, avulsion trigger period and abandoned channel dynamics, are a primary control on fluvial fan development. We found that shorter trigger periods lead to rounder planform fluvial fan shapes because, between avulsions, channel aggradation (and thus avulsion setup) propagates shorter distances from the upstream boundary along channel pathways. This prioritizes lateral sediment dispersion, creating shorter, rounder fans, over sediment delivery further into the basin, which would create elongated fans. Modeled fans with abandoned channel attraction (but not repulsion) generated a commonly observed abrupt fan boundary marked by a transition from distributary to tributary channel patterns. While fluvial fans are thought to be linked to climate, they can occur anywhere that rivers aggrade, lose lateral confinement, and preserve alluvial topography. Instead, fluvial fans might be more recognizable in environments that frequently trigger avulsions and preserve abandoned channels that capture future avulsions. [ABSTRACT FROM AUTHOR]

Although rivers are inherently dynamic systems that are susceptible to change, human impact on rivers in the last century is considered to have been so significant that it has caused an unprecedented intensity of geomorphological change in river channels and floodplains. As these changes often lead to deterioration of ecological conditions as well as increased flood risks, the approach to river management has changed over the past twenty years. There is an increasing emphasis on a holistic approach based on the understanding of river system processes, for which studies of geomorphological change in rivers represent a very important source of information. The aim of this review is to present the basic methods used in studies of geomorphological change in rivers, including the spatio-hierarchical delineation of the river system, data sources, and the most commonly analysed geomorphological characteristics and factors of change. The results of previous research are presented for the period of the last 150 years. The most important geomorphological changes include channel narrowing, incision, and reduction in the complexity of fluvial landforms and processes due to channelization and the construction of numerous barriers that disrupt the connectivity in water flow and sediment transport. Explaining the cumulative impacts and predicting future changes are the major research challenges. These challenges are related to the complexity of the river system, i.e. a large number of causal factors, connections, and interactions in the river system, and to the nonlinearity of the evolutionary trajectory of changes in rivers. [ABSTRACT FROM AUTHOR]

This study aimed to characterize the sedimentary facies and understand the morphodynamics of the study area, and their results were correlated with various analytical methods. Different analyses such as depositional environmental, statistical, shoreline change, and grain size illustrated the temporal and spatial distribution of sediments. It has previously been claimed that current research locations are locii to fluvial landforms and are affected by fluvial processes. However, there are currently no rivers in the study region. This study was done to better understand the presence of fluvial landforms and to evaluate the previous findings. The dynamic behavior of the coast was revealed through shoreline analysis, which was done using satellite images from various years. Oceanographic parameters and longshore sediment transport play a vital role in geomorphological changes in coastal zones. According to the grain size analysis results, mean values showed that the deposits predominantlyare medium grained. The outcome discussed the spatiotemporal variations in geomorphology, sedimentation, and the function of coastal and fluvial processes on the beach of an island and a sand spit. Also highlighted was the role that wave action, fluvial currents, and tidal currents had in the long-term evolution of coastal geomorphological features such as spits, beaches, open coasts, and islands. The standard deviation signifies that the sediments are very well sorted to poorly sorted. Skewness ranges from fine skewed to strongly fine skewed and the kurtosis values show that the sediments are predominately very platykurtic which implies a low-energy environment of deposition. Four sedimentary facies (Facies A, B, C, D) have been found and facies A, B, and C may be wave-influenced deposits, but facies D may be formed by fluvial processes and contain medium to sand-sized particles. The direction of the tip area is also pointing to the south and this result concluded that the tip area is continuously growing. Thus, the results of this study revealed that sediment transport and coastal geomorphology evolution may be governed by two main processes such as the present ocean hydrodynamics and paleo fluvial processes of the study regions. [ABSTRACT FROM AUTHOR]

Alluvial rivers aggrade, incise, and adjust their sediment‐transport rates in response to changing sediment and water supply. Fluvial landforms, such as river terraces, and downstream stratigraphic archives may therefore record information about past environmental change. Using a physically based model describing sediment transport and long‐profile evolution of alluvial rivers, we explore how their responses to environmental change depend on distance downstream, forcing timescales, and whether sediment or water supply is varied. We show that amplitudes of aggradation and incision, and therefore the likelihood of terrace formation, are greater upstream and in shorter and/or wetter catchments. Aggradation and incision, and therefore terrace ages, may also lag behind environmental change. How sediment‐transport rates evolve depends strongly on whether water or sediment supply is varied. Diverse responses to environmental change could arise in natural alluvial valleys, controlled by their geometry and hydrology, with important implications for paleo‐environmental interpretations of fluvial archives. Plain Language Summary: Rivers carry sediment from upland regions, where it is produced by weathering and erosion, to low‐lying areas where it is deposited and stored. This process is sensitive to climate: for example, wetter conditions enhance rivers' capacity to transport sediment, causing rivers to cut into their beds, which in turn remobilizes sediment that is transported downstream. Changing climate may also lead to enhanced sediment production and supply to rivers, causing them to accumulate sediment in their beds. Climate cycles can therefore produce alternating periods of sediment accumulation and removal, resulting in ancient floodplains being abandoned and preserved alongside modern rivers ("terraces"), and in variations in the amounts of sediment delivered downstream. Terraces and patterns of sediment accumulation downstream could therefore provide valuable records of past climatic change. We develop a mathematical model that describes the effects of climatic change on river‐bed height and sediment‐transport rates. We show how the amount and timing of river in‐filling and down‐cutting, and the timescales over which they occur, depend on the rate of climatic change, on river length and associated drainage‐basin area, and on the amount of water it carries. These predictions will facilitate more detailed interpretations of terrace records along rivers and of the sedimentary deposits that they leave behind. Key Points: Alluvial rivers respond in diverse ways to cyclical climatic change depending on their geometry and hydrology and on the forcing frequencyTerrace formation is favored upstream and in shorter and wetter catchments and may lag appreciably behind environmental changeVariation in sediment output lags variation in sediment supply but can lead and be amplified with respect to variation in water supply [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]

Fluvial cross strata are depositional products of bedform migration that record formative flow and sediment transport conditions on planetary bodies. Bedform evolution varies with transport stage even under constant flow depths, but our understanding of how prevailing sediment transport conditions affect preserved cross strata is limited. Here, we analyzed experimental bedform evolution and preserved set thickness spanning threshold‐of‐motion to suspension‐dominated transport conditions at multiple equilibrium flow depths. Results show that bedform trough depth and mean preserved set thickness have a parabolic dependence on transport stage, with maximum values observed at intermediate transport stages. Our results indicate that transport stage is a key control on the flow‐depth‐normalized set thickness but set thickness is a poor indicator of flow depth. Thus, the dependence of bedform dimensions on transport stage should be considered in paleohydraulic reconstruction, and the analysis of set thickness may aid in the estimation of ancient fluvial sediment flux. Plain Language Summary: Alluvial rivers have ripples and dunes (i.e., bedforms) that migrate across the riverbed, resulting in characteristic signatures called cross strata found in river deposits on Earth and Mars. Cross strata encode information about the flow and sediment transport conditions under which bedforms evolved. For over a century, the relation between cross strata thickness and formative flow conditions has been studied. However, we do not understand how prevailing sediment transport conditions control set thickness distributions. We used high‐resolution topography of bedform evolution from controlled physical experiments where transport stage—a parameter that quantifies sediment transport intensity—was systematically changed across multiple flow depths. We discovered that preserved cross set thickness is primarily controlled by transport stage, and that the mean set thickness of preserved deposits is a poor indicator of flow depth. We develop a new mathematical function that describes the dependence of mean set thickness on the formative transport stage. Our work indicates that the transport‐stage dependence of set thickness should be a primary consideration in paleohydraulic reconstruction, and that analysis of cross strata may aid the estimation of paleo‐sediment‐transport conditions. Key Points: Mean bedform trough depths and set thickness show a parabolic dependence on transport stage peaking under mixed‐load transport conditionsMean set thickness is a poor indicator of flow depth, but depth‐normalized mean set thickness is strongly influenced by transport stageTransport stage exerts a key control on preserved fluvial strata and should be considered in paleo‐hydraulic reconstructions [ABSTRACT FROM AUTHOR]

Large wood (LW) and log jams have important implications for sediment dynamics within river systems. Although many case studies explore this topic, far fewer synthesize these results at the reach and basin scales. In this paper, we present a conceptual model that relates valley setting and landscape history of forested, mountain streams to spatiotemporal patterns of sediment storage and transport via the formation and decay processes of logjams. This conceptual model explores the function of logjams as sediment transport moderators, significantly influencing sediment retention, channel morphology, and lateral and longitudinal connectivity. Detailed wood inventories, channel topographic surveys, and channel morphology from four case studies are used to illustrate the range of channel responses to logjam formation, evolution, and decay in different valley contexts. Valley setting is shown to influence logjam formation and dynamics by determining the mechanisms and timing of sediment and wood recruitment. In steep and narrow (and thus coupled, confined) reaches, colluvial processes are the dominant mechanisms of wood and sediment delivery, and logjams grow vertically as sediment is stored in a wedge behind the jam (longitudinal disconnectivity). In contrast, in unconfined reaches (decoupled hillslopes), wood and sediment recruitment occurs primarily through fluvial processes, and logjams grow laterally as the channel shifts across the valley bottom. These logjams have long lifespans, often over a century, and gradually release sediment as the logjam decomposes. Sediment deposits stabilized by riparian vegetation behind these structures may persist long after logjam decay. This conceptual model is a testable framework and practical tool that offers insight into wood-sediment interaction mechanisms within steep, forested basins. [ABSTRACT FROM AUTHOR]

The Holocene sedimentary history of the Turbio River valley in semi-arid north-central Chile and its relationship to climate variability is presented in this study. Fluvial landforms and sedimentary deposits serve as essential records for studying the long-term dynamics of fluvial systems in response to external factors such as tectonic and climatic influences. The study area, located in the Andean Mountain range, is highly sensitive to hydrodynamic changes and sediment transport processes, making it suitable for studying fluvial dynamics and their relationship to climate fluctuations over millennia. In particular, the transitional semi-arid conditions of this region provide an opportunity to link Holocene fluvial sediments to climatic shifts. This study presents the analysis of well-preserved sedimentary deposits that outcrop along the valley walls, including grain-size distribution, stratigraphy, geochemical composition and radiocarbon dating to establish the chronological context. Facies association analysis, along with geochemical data, allowed the interpretation of depositional sub-environments and their evolution through time. We interpret the Holocene sedimentary evolution for the Turbio River valley as six time periods that reflect shifts in sediment source, energy regime, flow types, and sedimentary processes linked to fluctuations between wet and dry climatic conditions. The sedimentary sequence is interpreted as reflecting an initial high-energy period with continuous surface runoff followed by two periods of formation of extensive lakes, likely separated by periods of runoff intensification. The later part of the sequence reflects a more stable fluvial landscape that led to the excavation of the sedimentary fill. This sedimentary record provides valuable insights into past climate variations and their impact on the hydrodynamic conditions of the fluvial system in the region. Comparisons with other regional records support a broader understanding of climate change in the semi-arid Andes of Chile. • Rio Turbio sedimentary record is studied to reconstruct Holocene river dynamics. • Fluctuations in fluvial processes are related to alternating wet and dry periods. • A new model explains how the river evolved in response to Holocene climate variations. • Fluvial record provide valuable insights into past climates. [ABSTRACT FROM AUTHOR]

The structure and function of riparian ecosystems generally result from feedbacks between plant dynamics and fluvial processes and landforms, i.e., river morphodynamics. Taxonomic approaches do not allow direct identification and quantification of the mechanisms involved in the interaction between plant communities and the geomorphological environment. Although riparian ecosystems show enormous taxonomic variations, comparable patterns of plant response traits across different taxa may evolve in response to the exposure to similar hydrogeomorphological processes in relation to flow dynamics, sediment transport, and nutrient and water availability. Biogeomorphological functional classifications for plant responses to, and effects on, river morphodynamics at the levels of individual plants, populations, and communities have been proposed in the literature. They serve herein as a basis for identifying and quantifying, within a presented standardized functional trait framework, key plant response and effect traits that can help to explain feedbacks between plants and morphodynamics. In particular, functional guilds and functional diversity metrics can be applied at the population and community levels for exploring feedbacks between vegetation and river morphodynamics worldwide. In this framework, the variability in plant effects across different environments and spatiotemporal scales, related to the biological characteristics of the plants (i.e., morphological reconfiguration of plants into the flow, seasonal phenology, phenotypic plasticity, and vegetation succession), can be explored. New opportunities including remote sensing and numerical modelling approaches, coupled with the inclusion of plant traits through our original framework, will improve our understanding of feedbacks between vegetation and morphodynamics and contribute to an improved prediction of biogeomorphological river trajectories. • Taxonomical approaches do not permit the analysis of plant-geomorphology feedbacks. • Functional traits links hydrological, geomorphological and biological drivers and processes which shape river systems. • Riparian plant traits converge despite taxonomic variation. • The functional trait approach is an opportunity for quantifying riparian vegetation-river interactions worldwide. • The functional trait approach can be supported by remote sensing and numerical modelling of river trajectories of change. [ABSTRACT FROM AUTHOR]

Modeling the dynamics of alluvial rivers is theoretically and numerically more challenging than modeling erosion of bedrock channels in active mountain ranges. As a consequence, the majority of the approaches developed in the context of alluvial rivers are one-dimensional. However, recent advances in the numerics of fluvial landform evolution models allow for two-dimensional simulations of erosion and sediment transport over time spans of several million years. This study aims at finding out fundamental properties of rivers in a tectonically inactive foreland of a mountain range by investigating a simple reference scenario theoretically and numerically. This scenario consists of a mountain range and a foreland in a quasi-steady state wherein the material eroded in the mountain range is routed through the foreland. In order to understand the properties of foreland rivers, a subdivision into two classes – carriers and redistributors – is introduced. Carriers originate in the mountain range and are thus responsible for the large-scale sediment transport to the ocean. In turn, redistributors are rivers whose entire catchment is located in the foreland. Using the concept of carriers and redistributors, it is shown that the drainage network in the foreland permanently reorganizes so that a steady state in the strict sense is impossible. However, the longitudinal profiles of carriers are described well by a steady-state approximation. Their concavity index is considerably greater than that of rivers in the mountain range. Carriers predominantly deposit sediment at high rates, while redistributors erode at much lower rates. Despite the low erosion rates, the sediment flux from redistributors into carriers is a major component of the overall sediment budget and finally the main driver of the highly dynamic behavior of the carriers. [ABSTRACT FROM AUTHOR]

The Cenozoic history of the Tibetan Plateau topography is critical for understanding the evolution of the Indian‐Eurasian collision, climate, and biodiversity. However, the long‐term growth and landscape evolution of the Tibetan Plateau remain ambiguous, it remains unclear if plateau uplift occurred soon after the India‐Asia collision in the Paleogene (∼50–25 Ma) or later in the Neogene (∼20–5 Ma). Here, we reproduce the uplift history of the southeastern Tibetan Plateau using a 2D landscape evolution model, which simultaneously solves fluvial erosion and sediment transport processes in the drainage basins of the Three Rivers region (Yangtze, Mekong, and Salween Rivers). Our model was optimized through a formal inverse analysis with 20,000 forward simulations, which aims to reconcile the transient states of the present‐day river profiles. The results, compared to existing paleoelevation and thermochronologic data, suggest initially low elevations (∼300–500 m) during the Paleogene, followed by a gradual southeastward propagation of topographic uplift of the plateau margin. Plain Language Summary: When and how was formed the Tibetan Plateau which includes the highest mountains in the world? The answer is critical to decipher between competing models trying to explain how the Indian and Asian tectonic plates behaved when they collided. It is also a major constraint on the evolution of Asian mountain biodiversity, Asian monsoons, and even global climate. However, current estimates of past Tibetan elevation are contradictory, some arguing for a high plateau since the onset of the India‐Asia collision over 50 million years ago, while others favor the region remained low until a sudden rise 25 million years ago. Here, we use a numerical model of landscape evolution to test various hypothesis focusing on the southeastern Tibetan Plateau. We compared the results to see how they fit with the observed river profiles of the Three Rivers. The best fits were obtained with low elevations between 50 and 25 million years ago, and a more gradual growth toward the southeast of the high‐elevated plateau until present day. Key Points: We constrained the uplift history of the southeastern (SE) Tibetan Plateau by performing inversion of the Three Rivers profilesThe inversion suggests that SE Tibet was at a low elevation until 50–25 Ma, followed by gradual outward growth until 0 MaOur modeling does not support Paleogene formation of the SE Tibetan Plateau with a major subsequent degradation via upstream fluvial erosion [ABSTRACT FROM AUTHOR]

With the ongoing climate change and the prolongation of the summer melting season and increasing air temperature that this entails, fluvial transport is likely to become a more important process shaping the deglaciated areas of Antarctica. Quantification of suspended sediment transport in the deglaciated catchment of the Bohemian Stream is presented in this study. It was shown that a large amount of fine-grained material is being transported even in the relatively small catchment during the short period of the Antarctic summer. The average calculated suspended sediment concentration during the 2018 austral summer reached 274.6 mg l−1, which corresponded to an average suspended sediment load of 3662 kg day−1 and suspended sediment yield of 68 t km−2 year−1 when considering the flow season to be approximately 4 months per year. Such values are considerably higher than those reported from continental Antarctica; however, they are lower compared to most of the Arctic catchments. [ABSTRACT FROM AUTHOR]

Bedrock river-gorge incision represents a fundamental landscape-shaping process, but a dearth of observational data at >10 yr timescales impedes understanding of gorge formation. I quantify 102 yr rates and processes of gorge incision using historical records, field observations, and topographic and image analysis of a human-caused bedrock meander cutoff along the North Fork Fortymile River in Alaska (USA). Miners cut off the meander in 1900 CE, abruptly lowering local base level by 6 m and forcing narrowing and steepening of the channel across a knickpoint that rapidly incised upstream. Tectonic quiescence, consistent rock erosivity, and low millennial erosion rates provide ideal boundary conditions for this 102 yr gorge-formation experiment. Initial fast knickpoint propagation (23 m/yr; 1900-1903 CE) slowed (4 m/yr; 1903-1981 CE) to diffusion (1981-2019 CE) as knickpoint slope decreased, yielding an ~350-m-long, 6-m-deep gorge within the pre-1900 CE channel. Today, diffusion dominates incision of a 500-m-long knickzone upstream of the gorge, where sediment transport likely limits ongoing adjustments to the anthropogenic cutoff. Results elucidate channel width, slope, discharge, and sediment dynamics consistent with a gradual transition from detachment- to transport-limited incision in fluvial adjustment to local base-level lowering. [ABSTRACT FROM AUTHOR]

The grain size of sediment delivered to a river by hillslope processes is an important factor which could impact fluvial erosion, sediment transport, and associated geomorphic changes. Grain size distribution (GSD) is increasingly recognised as an important factor for the impact of landslides on sediment pulses and long-term erosion rates. Therefore a better comprehension of grain size control on landslide-generated sediment transport and dynamics will help with understanding post-seismic fluvial processes and landscape evolution. In this study, we modelled the recovery of the Hongxi River basin affected by the Wenchuan earthquake under different landslide GSD scenarios. The CAESAR-Lisflood (CL) model was first modified to enable the spatial input of sediment GSD, which allows the model to distinguish the grain size composition of landslide sediment and the background sediment sourced from other areas. Using the modified CL model, we simulated three different landslide GSD scenarios (Original, Coarser, Finer) by altering the original landslide sediment GSD observed from a post-earthquake basin. In particular, we analysed the fate of landslide-generated sediment using a new sediment tracing function embedded in CL. This enabled us to evaluate the role of landslide GSD variation on the spatio-temporal heterogeneity of sediment transport. Our results show that the GSD of landslide material exerts a clear control on both sediment yield and channel deposition, the sediment transport of landslides disconnected to the fluvial system is more sensitive to grain size variation, while the GSD of landslides connected to the fluvial system has less impact on sediment dynamics. The duration of landslide disturbances on basin sediment dynamics can largely be dependent on the period of time (e.g., 20 years in this study basin) taken for grain coarsening (the grain size is increasing upward), which is dominated by the evacuation of fine sediments. The modelling results and findings highlight the importance of grain size distribution of landslide material and provide information to support basin sediment management and environmental risk mitigation. [ABSTRACT FROM AUTHOR]

• New geomorphological and geochemical records from the southern Mu Us Desert (MUD), northern China. • The sources of southern MUD sediments have evident temporal variation. • Early–Mid-Holocene southern MUD sediments are mainly derived from a local source. • The maximum CIA occurs at 8.4–6.4 ka BP and is related to enhanced monsoonal rainfall. • Late-Holocene mixed sources in the southern MUD are associated with an enhanced winter monsoon. • Summer and winter monsoons alternate in controlling the sediment source and geomorphic evolution in the southern MUD. Identifying the sources and weathering degree of sediments in the northern deserts of China is crucial to understand the evolution of the Asian monsoon system and corresponding induced changes in surface processes. Great progress has been made in the reconstruction of paleoclimate and paleoenvironment from the Early Holocene onwards based on chronostratigraphy and proxies of aeolian sedimentary sequences in the Mu Us Desert (MUD). However, previous studies have given rise to some controversial over the timing of the Holocene optimum period, and there is a scarcity of studies on the sediment provenance evolution of the desert during the Holocene and its internal relationship with the East Asian summer (EASM) and winter (EAWM) monsoons. Here, we provide new elemental geochemical data from a fluvial–aeolian sedimentary sequence in the southern MUD; we then combine these data with other available elemental data and hydroclimatology information to investigate the characteristics of sediment source evolution and their possible connection with the EASM and EAWM on the southern margin of the MUD-desert/loess transition zone since the latter part of the Early-Holocene. The elemental composition and geochemical characteristics of the studied sedimentary sequence differed markedly in the periods before and after 6.4 ka BP, suggesting a change in the source of the sediments across this boundary. From the late Early-Holocene (10.6 cal. ka BP), sediments were dominated by the chemical weathering products of local source material, with a gradual increase in chemical weathering over time, indicating a gradual strengthening of the EASM; the EASM reached its peak Holocene strength at 8.4–6.4 ka BP, accompanied by a moderate level of chemical weathering. After 6.4 ka BP, with the weakening of monsoon precipitation, the EAWM began to strengthen, and long-distance transport of source material from the west and northwest increased; however, chemical weathering of local source material driven by the EASM remained dominant until 4.0 ka BP. After 4.0 ka BP, the EAWM became dominant, and sediments showed strong sedimentary cycles, mainly transported from long-distance sources by aeolian activity, and the MUD became an important sedimentary sink for the northern-central deserts. After 0.7 ka BP, the sediments in the MUD became a mixture of different-age sediments due to river scouring and the transport of pre-existing sediments along the shoreline. Collectively, the elemental geochemical and other proxy data from Holocene sediments on the southern margin of the MUD record an inverse relationship between the EASM and EAWM; these two monsoonal circulations have alternated in their control of the sedimentary source characteristics and geomorphological environmental evolution processes across the southern margin of the MUD during the Holocene. [ABSTRACT FROM AUTHOR]

The depositional history of alluvial fans on Mars provides insight into the climatic conditions during the time of fan formation in the late Hesperian to early Amazonian. However, traditional stratigraphic analysis of the alluvial fan deposits is not possible across most of Mars. This study assesses the use of thermal inertia data as a tool for sedimentologic interpretation of 437 Mars alluvial fans. Based on previous work demonstrating the relationship between depositional style, grain size, and thermophysical properties, this study uses analysis of the thermal inertia of alluvial fan surfaces across the global population of fans on Mars to make an assessment of depositional styles that built the alluvial fans. The thermal inertia values across the global population of fans are indicative of sand- to pebble-sized sediment. The variability of grain sizes across the global population is more homogenous than expected based on comparisons to terrestrial alluvial fans. Nearly all Mars alluvial fans have an average thermal inertia that corresponds to pebble and smaller grain size, and < 1% of Mars alluvial fans have an average thermal inertia that corresponds to cobble-sized grains. Spatial patterns of thermal inertia variability on alluvial fan surfaces show a small number of fans with evidence for either downslope fining or channelization, but the majority of fans show no recognizable geologic patterns in surface thermal inertia. The interpretation of the thermal inertia-derived grain size suggests that either there is widespread mantling of unconsolidated sand across the surface, or that Mars alluvial fans were built by primarily sand-sized sediment, which may be indicative of lower energy sediment transport events. • Thermal inertia of alluvial fan surfaces indicates primarily sand-sized sediment. • Thermal inertia of Mars alluvial fan surfaces is surprisingly homogeneous globally. • Alluvial fans built by sand-sized sediment suggest low energy fluvial processes. • Fluvial depositional processes may correlate to lack of clay in catchments. [ABSTRACT FROM AUTHOR]

• A strong signal of reduced winter conditions i.e. duration, snow accumulation and frost days. • Hydroclimatic regime shift alters the sediment flux seasonality in near future. • Thaw-seasons have important role controlling the annual sediment flux. Climate change alters high latitude hydrological cycle by diminishing the snow accumulation and spring flood magnitude, and by altering temperature and rainfall finally leading to hydroclimatic regime shift from snow-dominated to rain-dominated. These changes in temperature, precipitation patterns, and discharge strongly influence geomorphological processes in fluvial environments, leading to alterations in sediment transport, erosion, accumulation, and landscape changes. We conducted comprehensive analysis of hydroclimatic trends and shifts on boreal Oulanka River system, spanning over the past five decades. A strong signal of warming temperatures (+0.61 Celsius/decade), reduced winter conditions and warmer summers (+0.41 Celsius/decade) was detected. The spring flood magnitude diminished 7 %, but high discharge peaks (Q > annual p90m3/s) during other seasons increased 22 % together with 28 % increase of annual minimum discharge. Simultaneously, precipitation intensity increased during summer. The meander migration rate (mean 0.89 or 2.55 m/year) and bank erosion volume were interconnected to ground frost, high snow sum, high discharge, and high-water level during spring flood, but no significant long-term trends were observed. Our findings underscore that climate is the first-order control on fluvial geomorphology and emphasizes the complex interplay between various hydrological and climatic factors that shape the dynamics of river systems. Based on the results, we expect to see changes in the spatial–temporal distribution of high latitude rivers sediment flux in future. In addition, more attention should be addressed to the thaw seasons controlling the sediment transport, as majority of the observed shifts took place in these months. [ABSTRACT FROM AUTHOR]

Up to several meters thick fine-grained Holocene overbank deposits are ubiquitously found in most Western and Central European lowland floodplains. However, despite their large importance for the geomorphological and geoecological floodplain properties, the interplay of different possible causes for their formation are not well understood yet. Most authors suggest human-induced deforestation as the main precondition for sediment mobilization and transport from the slopes to the floodplain, whereas others suggest a stronger influence of climatic factors. This current research gap is caused by often missing well-resolved fluvial chronostratigraphies and spatio-temporal information about former human activity within the studied catchments. To fill this gap we exemplarily studied Holocene overbank sedimentation and possible human or natural drivers in the meso-scale Weiße Elster catchment in Central Germany. To do so, we applied numerical dating as well as sedimentological and micromorphological analyses to Holocene fluvial sediments along three floodplain transects. Furthermore, we built up an unprecedented systematic spatio-temporal database of former human activity within the catchment from the Neolithic until the Early Modern Ages. Together with published paleoclimatic data, this database allowed an unprecedented, systematic comparison of Holocene overbank sedimentation phases with possible external controls. Our data show that some overbank sedimentation phases were directly linked with human activities in the affected site sub-catchments, whereas others were not. Instead, all phases seemed to be linked with natural factors. This difference with most former studies could possibly be explained by previously often limited numerical dating of the fluvial sediments and by largely missing spatio-temporally well-resolved regional settlement records, hindering a precise temporal link of fluvial sedimentation with former human settlement. Furthermore, this difference could possibly also be explained by a relatively high natural sensitivity of the landscape dynamics in the Central German lowlands, showing a subcontinental climate, towards climatic external controls. [Display omitted] [ABSTRACT FROM AUTHOR]

Sediment management is currently limited by uncertainties in the applicability of existing radionuclide tracers and the effects of urbanization. Here, we use plutonium isotopes (239+240Pu) from weapons‐testing fallout to trace sediment transport across five watersheds in an urbanizing landscape in Kansas, USA. Historic flooding in the region provided an opportunity to assess extreme connectivity of sediment sources. 239+240Pu activity of transported sediment decreased as catchments urbanized, indicating a greater contribution from subsurface bank sediment; Bayesian modeling predicted 50% (8%–80%) bank sourcing in the most rural watershed, which rose to 93% (73%–100%) in the most urban catchment. 239+240Pu activity provides explanatory information on the superposition of sediment sources, which is beyond that given by traditional organic and geochemical tracers that primarily infer vegetative and geologic sourcing, respectively. Our study demonstrates the utility of 239+240Pu as a sediment tracer for managing erosion under anthropogenic change. Plain Language Summary: Sediment is one of the most common contaminants in rivers around the globe. The susceptibility of soil to erosion increases as humans convert natural landscapes into rural and urban systems. Uncertainties remain regarding how urbanization alters sediment pathways and what tools are appropriate for quantifying this alteration. Radioactive isotopes, generated from nuclear weapons testing in the 1950s, have proven useful in this regard, although the most prominent tracer, for example, cesium, is losing some utility due to a short half‐life and extensive radioactive decay. We suggest that plutonium isotopes, which have longer half‐lives, are a viable option for tracing sediment in modern landscapes. Plutonium results suggest that in rural basins the source of sediment transitions from upland soil during low‐flows to bank material at high‐flows. On the other hand, urban streams always deliver bank sediment, regardless of storm intensity. Our study demonstrates the utility of plutonium as an alternate sediment tracer and highlights how urbanization changes the pathways and mechanisms of fluvial sediment transport. Key Points: 239+240Pu activity is a robust tracer for describing sediment sources and fluvial mixtures in a rapidly urbanizing landscapeFrequentist and Bayesian models were consistent in estimating increased bank erosion with increasing urban land useSediment sourcing is dependent on discharge in rural watersheds whereas it is independent of discharge in urban watersheds [ABSTRACT FROM AUTHOR]

Background: Rainfall and other climatic agents are the main triggers of soil erosion in the Mediterranean region, where they have the potential to increase discharge and sediment transport and cause long-term changes in the river system. For the Magra River Basin (MRB), located in the upper Tyrrhenian coast of Italy, we estimated changes in net erosion as a function of the geographical characteristics of the basin, the seasonal distribution of precipitation, and the vegetation cover. Methods and findings: Based on rainfall erosivity and surface flow and transport sub-models, we developed a simplified model to assess basin-wide sediment yields on a monthly basis by upscaling the point rainfall input. Our calibration dataset of monthly data (Mg km-2 month-1, available for the years 1961 and 1963–1969) revealed that our model satisfactorily reproduces the net soil erosion in the study area (R2 = 0.81). For the period 1950–2020, the reconstruction of an annually aggregated time-series of monthly net erosion data (297 Mg km-2 yr-1 on average) indicated a moderate decline in sediment yield after 1999. This is part of a long-term downward trend, which highlights the role played by land-use changes and reforestation of the mountainous areas of the basin. Conclusion: This study shows the environmental history and dynamics of the basin, and thus the varying sensitivity of hydrological processes and their perturbations. Relying on a few climatic variables as reported from a single representative basin location, it provides an interpretation of empirically determined factors that shape active erosional landscapes. In particular, we showed that the most recent extreme storms associated with sediment yield have been characterised by lower cumulative rainfall, indicating a greater propensity for the basin to produce sediment more discontinuously over time. [ABSTRACT FROM AUTHOR]

The Paleocene-Eocene thermal maximum (PETM) was the most extreme example of an abrupt global warming event in the Cenozoic, and it is widely discussed as a past analog for contemporary climate change. Anomalous accumulation of terrigenous mud in marginal shelf environments and concentration of sand in terrestrial deposits during the PETM have both been inferred to represent an increase in fluvial sediment flux. A corresponding increase in water discharge or river slope would have been required to transport this additional sediment. However, in many locations, evidence for changes in fluvial slope is weak, and geochemical proxies and climate models indicate that while runoff variability may have increased, mean annual precipitation was unaffected or potentially decreased. Here, we explored whether changes in river morphodynamics under variable-discharge conditions could have contributed to increased fluvial sand concentration during the PETM. Using field observations, we reconstructed channel paleohydraulics, mobility, and avulsion behavior for the Wasatch Formation (Piceance Basin, Colorado, USA). Our data provide no evidence for changes in fluvial slope during the PETM, and thus no evidence for enhanced sediment discharge. However, our data do show evidence of increased fluvial bar reworking and advection of sediment to floodplains during channel avulsion, consistent with experimental studies of alluvial systems subjected to variable discharge. High discharge variability increases channel mobility and floodplain reworking, which retains coarse sediment while remobilizing and exporting fine sediment through the alluvial system. This mechanism can explain anomalous fine sediment accumulation on continental shelves without invoking sustained increases in fluvial sediment and water discharge. [ABSTRACT FROM AUTHOR]

Modeling glacial landform evolution is more challenging than modeling fluvial landform evolution. While several numerical models of large-scale fluvial erosion are available, there are only a few models of glacial erosion, and their application over long time spans requires a high numerical effort. In this paper, a simple formulation of glacial erosion which is similar to the fluvial stream-power model is presented. The model reproduces the occurrence of overdeepenings, hanging valleys, and steps at confluences at least qualitatively. Beyond this, it allows for a seamless coupling to fluvial erosion and sediment transport. The recently published direct numerical scheme for fluvial erosion and sediment transport can be applied to the entire domain, where the numerical effort is only moderately higher than for a purely fluvial system. Simulations over several million years on lattices of several million nodes can be performed on standard PCs. An open-source implementation is freely available as a part of the landform evolution model OpenLEM. [ABSTRACT FROM AUTHOR]

Invertebrates are important sediment engineers, making up for their small body size with abundance and behavioral diversity. However, despite the recognized importance of invertebrates as sediment engineers in terrestrial and marine environments, zoogeomorphology in rivers has primarily considered larger taxa, such as fish and beaver. This article reviews the zoogeomorphic effects of invertebrates in freshwater habitats, with a focus on rivers. To better synthesize current zoogeomorphic research and to help guide future studies we build a conceptual model considering biotic (behavior, abundance, body size, life history, and species invasions) and abiotic (geophysical energy and sediment grain size) controls on the direction and magnitude of zoogeomorphology. We also incorporate invertebrate engineers into conceptual sediment entrainment models, to understand their geomorphic role in the context of hydraulic power and sediment size. We structure our review around invertebrate behavior as a key control on whether invertebrates have a sediment destabilizing or stabilizing impact. Invertebrate zoogeomorphic behavior are diverse; the majority of research concerns bioturbation, a result of locomotion, foraging, and burrowing behaviors by many taxa. Similarly, burrowing into bedrock by a caddisfly and non‐biting midge larvae promotes bioerosion. Attachment to the substrate, (e.g., silk nets by caddisfly larvae or byssal threads by some mussels) can stabilize sediment, providing bioprotection. Bioconstructions (e.g., caddisfly cases and mussel shells) may have either stabilizing or destabilizing effects depending on their density and abiotic context. Interactions between lotic invertebrates and fluvial processes are complex and understudied, requiring further research across a greater range of taxa, behaviors, and spatiotemporal scales. This article is categorized under:Water and Life > Nature of Freshwater EcosystemsWater and Life > Conservation, Management, and Awareness [ABSTRACT FROM AUTHOR]

The timespan recorded in deposits from fluvial activity is a key gap in our understanding of ancient environments on Earth and Mars. Because riverine sediment transport occurs under time‐variable water discharge, common models that represent sediment transport with a single bankfull discharge require an intermittency factor. For this reason, the ability to predict intermittency factor values based on environmental factors would improve estimates of time from fluvial deposits. To address this knowledge gap, we calculated intermittency factors from 201 modern rivers and six fans and deltas with depositional timespans of months to millions of years. Intermittency factors range from 0.0064–0.73; they are uncorrelated with averaging timescale, bed‐material grainsize, or climate aridity, but are larger in river catchments with greater rates of denudation relative to precipitation. Application to ancient fluvial systems on Mars indicates long‐lived depositional river systems for up to 104–106 years. Plain Language Summary: To estimate the lifespan of ancient river courses, geologists estimate the time it took to transport and deposit all of the sediment within a landform, such as an alluvial fan or delta. This method relies on sediment‐transport calculations, which often assume a single reoccurring flood event that fills the river channel, even though river discharge varies in time from low flows to large floods. While the discharge of the channel‐filling flood event can be constrained from channel geometry or deposit characteristics, flow variability is unknown, and an intermittency factor is needed to adjust the sediment transport calculation. In this work, we calculated intermittency factors for 201 rivers and six river deposits on Earth. We also examined correlations between intermittency factor and environmental variables, and found no correlation with averaging timescale, bed‐material grainsize, or climate aridity. However, intermittency factors are larger in catchments that receive a large supply of sediment. Applying the new intermittency factor values to river deposits on Mars suggests that some of those rivers persisted for millions of years. Key Points: Rivers transport sediment intermittently; intermittency factor relates river duration to deposit volume and bankfull river characteristicsIntermittency factors we calculated have a 5–95 percentile range of 0.0064–0.73, independent of timescale, grainsize, and climateApplication to Mars implies fluvial activity over thousands to millions of years [ABSTRACT FROM AUTHOR]

Riverbanks undergo changes caused not only by river hydraulics, mainly sediment erosion and deposition processes, but also by the possible landslides that eventually change the channel bank profiles. Those failures are an important form of alluvial channel adjustments but are usually difficult to include during morphodynamic modeling. This paper proposes a novel approach combining a 2D depth-averaged hydrodynamic, sediment transport and mobile-bed model, SRH-2D, a limit equilibrium slope-stability model, BISHOP, and a bank failure sediment redistribution submodel, REDISSED, into a fully automatic and continuous dynamic simulation to predict vertical bed and lateral bank changes for a river reach undergoing exceptional flooding. The in-stream vertical fluvial changes predicted with the SRH-2D model will be automatically used to update the riverbank geometry profile by profile and assess their geotechnical stability to rotational slip failures with a developed slope-stability model based on Bishop's simplified method. A cone-shaped sliding area is defined in case the driving forces exceed the stabilizing forces. All mesh nodes located within the mass wasting zone will be automatically updated, allowing a new bank face form. The failed materials will be redistributed in the transect according to the geometry of the landslides observed at the study site. The Outaouais River at Notre-Dame-Du Nord, Quebec, is used to test the coupling procedure. Up to 100 m of bank retreat was predicted, and more than 20 cross-sections were reshaped. Typical results showing the effectiveness of the developed framework are presented and discussed. [ABSTRACT FROM AUTHOR]

There is as yet no consensus as to the dominant source of sediment transported to the oceans: the steep tectonically active highlands, or the gently sloping lowlands? In this study, new Pb isotopic analyses of detrital K‐feldspar have been combined with published data to constrain sand supply in the Yangtze River, one of the largest fluvial sediment transport systems on Earth. Tributaries draining southeastern Tibet have predominantly unradiogenic K‐feldspar sand grains. K‐feldspar in the middle Yangtze comprises c. 50% of grains of this kind, confirming that the southeastern Tibetan tributaries are the dominant sediment contributors. K‐feldspars characteristic of tributaries of the middle‐lower reaches are not strongly represented in the trunk Yangtze, indicating that they contribute little sediment. Our study demonstrates that tectonic uplift in southeastern Tibet is the primary control on sand supply. This is consistent with quartz 10Be data and with bulk‐sand petrography, indicating a major contribution of detritus from steep mountainous terrain. [ABSTRACT FROM AUTHOR]

Sediment transport (bedload and suspension) plays a relevant role in the morphological response of river channels to large floods. Sediment load controls erosion and aggradation patterns during high flows, drives the migration of macroforms and contributes to the definition of thresholds for bank erosion and channel instability. Given this influence on channel morphology, it is clear that sediment transport influences both the channel geometry and water stage reached during floods and should therefore be considered in flood hazard analysis. So far, however, legislation on flood hazard and flood management plans still continues to typically disregard sediment transport. This is due mainly to the paucity of available data on sediment transport and the lack of standardized approaches for its integration into flood hazard analysis. The present work, which aims to provide some guidance on how to advance in this issue, has undertaken a bibliometric study and thorough review of the published scientific literature that had previously addressed the implications of sediment transport on flood hazards assessment. This review showed that: i) most studies on the influence of sediment transport on flood risk have focused on mountain streams, as they are highly sensitive systems to changes in sediment supply; ii) research has also focused on explaining historical changes in channel-conveyance capacity and flood frequency based on long-term trends in sediment supply; and iii) recent developments in hydrodynamic and morphodynamic numerical models provide opportunities to explicitly incorporate sediment transport in flood hazard analysis. However, despite the recent advances, we have identified important challenges and discussed needs to better consider sediment transport in flood hazards at different spatial and temporal scales. [ABSTRACT FROM AUTHOR]

• Overlapping crater populations constrain the total era of martian valley formation. • Martian valleys may have formed intermittently over hundreds of millions of years. • Long-term erosion rates would have been similar to the modern Atacama Desert. A number of studies have constrained the cessation of martian valley network activity to around the Noachian-Hesperian boundary, but the total time period over which these features formed remains poorly constrained. Most attempts to ascertain valley network formative timescales rely on an intermittency factor that varies widely for terrestrial rivers and is unknown for Mars. In this contribution, superposition relationships are used to identify crater populations that pre- and postdate valley network incision, resulting in maximum cumulative valley formation times of ∼108 years. These timescales correspond with long-term erosion rates of ∼0.25 m/Myr, similar to those calculated for the Middle to Late Noachian as well as the central Atacama Desert since the Late Miocene. Assuming sediment transport rates previously calculated for other martian valley networks, this implies a minimum fluvial intermittency of ∼10−5, several orders of magnitude lower than modern day Earth rivers but similar to values independently calculated for some martian fluvial deposits. This low intermittency suggests that martian valley incision may have been significantly hindered by erosion into existing bedrock or by boulder armoring of the valley floor. Alternatively, unlike river valleys on Earth, runoff events driving martian valley network activity may have been non-seasonal, Milankovitch-like cycles, with long eras of quiescence between periods of intensified fluvial activity. [ABSTRACT FROM AUTHOR]

The volume and grain‐size of sediment supplied from catchments fundamentally control basin stratigraphy. Despite their importance, few studies have constrained sediment budgets and grain‐size exported into an active rift at the basin scale. Here, we used the Corinth Rift as a natural laboratory to quantify the controls on sediment export within an active rift. In the field, we measured the hydraulic geometries, surface grain‐sizes of channel bars and full‐weighted grain‐size distributions of river sediment at the mouths of 47 catchments draining the rift (constituting 83% of the areal extent). Results show that the sediment grain‐size increases westward along the southern coast of the Gulf of Corinth, with the coarse‐fraction grain‐sizes (84th percentile of weighted grain‐size distribution) ranging from approximately 19 to 91 mm. We find that the median and coarse‐fraction of the sieved grain‐size distribution are primarily controlled by bedrock lithology, with late Quaternary uplift rates exerting a secondary control. Our results indicate that grain‐size export is primarily controlled by the input grain‐size within the catchment and subsequent abrasion during fluvial transport, both quantities that are sensitive to catchment lithology. We also demonstrate that the median and coarse‐fraction of the grain‐size distribution are predominantly transported in bedload; however, typical sand‐grade particles are transported as suspended load at bankfull conditions, suggesting disparate source‐to‐sink transit timescales for sand and gravel. Finally, we derive both a full Holocene sediment budget and a grain‐size‐specific bedload discharged into the Gulf of Corinth using the grain‐size measurements and previously published estimates of sediment fluxes and volumes. Results show that the bedload sediment budget is primarily comprised (~79%) of pebble to cobble grade (0.475–16 cm). Our results suggest that the grain‐size of sediment export at the rift scale is particularly sensitive to catchment lithology and fluvial mophodynamics, which complicates our ability to make direct inferences of tectonic and palaeoenvironmental forcing from local stratigraphic characteristics. [ABSTRACT FROM AUTHOR]

Uranium (U) isotopes can be used to estimate the comminution age of sediments , i.e. the time elapsed from sediment production on continents, via weathering and physical erosion, to deposition in the sedimentary record. The calculation of this comminution age is based on measured (234U/238U) activity ratios in river sediments, and inferred time-dependent recoil effect, which leads to the preferential release of 234U from mineral lattices during erosion processes. In this study, we report on a large-scale (234U/238U) investigation of modern river sediments worldwide, with the aim to determine the extent to which parameters such as grain size, lithology, weathering, climate and geomorphology may influence the distribution of U isotopes in fine-grained sediments. Our extensive dataset (N = 64) includes U isotopic measurements for many of the world's largest rivers, but also rivers draining particular climatic and geological settings. Our results indicate that sediments collected from river basins draining mostly igneous, metamorphic or volcanic rocks often display (234U/238U) ratios > 1, with clay-size fractions (<4 µm) being less depleted in 234U (higher 234U/238U) than corresponding silt-size fractions (4–63 µm). In contrast, sediments derived from multi-lithological basins or draining sedimentary rocks are typically characterized by (234U/238U) ratios <1, with clays generally exhibiting more depleted 234U signatures than silts. Taken together, these observations suggest that the formation of secondary clay minerals in soils from basins draining mostly igneous, metamorphic is accompanied by partial incorporation by recoil injection of 234U initially released during weathering processes, possibly from U-rich minerals, such as sphene or apatite. Instead, in multi-lithological catchments draining sedimentary rocks, we propose that the erosion of recycled sediments having experienced several cycles of weathering, possibly over glacial-interglacial timescales, could explain the much lower (234U/238U) ratios observed in clay-size fractions. While no direct relationships can be identified between sediment (234U/238U) ratios and lithology, weathering intensity, climatic or geomorphic parameters in corresponding river basins, we show that the catchment size probably plays an important role in controlling the distribution of (234U/238U) in river sediments, through its direct influence on the sediment residence time. Finally, a multiple regression analysis of our data, combining various environmental parameters for the lithology, climate and geomorphology of studied river basins, indicates predicted (234U/238U) values that are very similar to measured values (with R2 ∼ 0.8). This finding provides further support for the usefulness of (234U/238U) ratios in the sedimentary record for reconstructing past landscape changes and their effect on sediment transport and residence time in river basins. [ABSTRACT FROM AUTHOR]

Landslides are the main source of sediment in most mountain ranges. Rivers then act as conveyor belts, evacuating landslide-derived sediment. Sediment dynamics are known to influence landscape evolution through interactions among landslide sediment delivery, fluvial transport and river incision into bedrock. Sediment delivery and its interaction with river incision therefore control the pace of landscape evolution and mediate relationships among tectonics, climate and erosion. Numerical landscape evolution models (LEMs) are well suited to study the interactions among these surface processes. They enable evaluation of a range of hypotheses at varying temporal and spatial scales. While many models have been used to study the dynamic interplay between tectonics, erosion and climate, the role of interactions between landslide-derived sediment and river incision has received much less attention. Here, we present HyLands, a hybrid landscape evolution model integrated within the TopoToolbox Landscape Evolution Model (TTLEM) framework. The hybrid nature of the model lies in its capacity to simulate both erosion and deposition at any place in the landscape due to fluvial bedrock incision, sediment transport, and rapid, stochastic mass wasting through landsliding. Fluvial sediment transport and bedrock incision are calculated using the recently developed Stream Power with Alluvium Conservation and Entrainment (SPACE) model. Therefore, rivers can dynamically transition from detachment-limited to transport-limited and from bedrock to bedrock–alluvial to fully alluviated states. Erosion and sediment production by landsliding are calculated using a Mohr–Coulomb stability analysis, while landslide-derived sediment is routed and deposited using a multiple-flow-direction, nonlinear deposition method. We describe and evaluate the HyLands 1.0 model using analytical solutions and observations. We first illustrate the functionality of HyLands to capture river dynamics ranging from detachment-limited to transport-limited conditions. Second, we apply the model to a portion of the Namche Barwa massif in eastern Tibet and compare simulated and observed landslide magnitude–frequency and area–volume scaling relationships. Finally, we illustrate the relevance of explicitly simulating landsliding and sediment dynamics over longer timescales for landscape evolution in general and river dynamics in particular. With HyLands we provide a new tool to understand both the long- and short-term coupling between stochastic hillslope processes, river incision and source-to-sink sediment dynamics. [ABSTRACT FROM AUTHOR]

Currently, the use of numerical models for reproducing the evolution of river systems and landscapes is part of the day-by-day research activities of fluvial engineers and geomorphologists. However, despite landscape evolution modelling is based on a rather long tradition, and scientists and practitioners are studying how to schematize the processes involved in the evolution of a landscape since decades, there is still the need for improving the knowledge of the physical mechanisms and their numerical coding. Updating past review papers, the present work focuses on the first aspect, discussing six main components of a landscape evolution model, namely continuity of mass, hillslope processes, water flow, erosion and sediment transport, soil properties, vegetation dynamics. The more common schematizations are discussed in a plain language, pointing out the current knowledge and possible open questions to be addressed in the future, towards an improvement of the reliability of such kind of models in describing the evolution of fluvial landscapes and river networks. [ABSTRACT FROM AUTHOR]

In fluvio‐tidal settings, the sediment is dominantly derived from the river systems. However, the importance of landward tidal transport of sediment in tidally influenced sedimentary environments is difficult to assess, particularly in the rock record. This problem is addressed using two intervals within the Lower Cretaceous McMurray Formation, each representing a distinct inclined heterolithic stratification motif. The ichnological variation between the heterolithic intervals is analyzed to determine which lithosomes are associated with brackish‐water (tidally influenced) colonization windows. From this, the relative fluvial influence responsible for the deposition of the fine and coarse members can be determined. Both of the inclined heterolithic stratification fabrics studied record the deposition of fluvio‐tidal point bars wherein the heterolithic bedding represents variations in river discharge. The first fabric comprises inclined heterolithic stratification in which bioturbation only occurs in mudstone beds. This fabric indicates that deposition occurred in more proximal positions within a fluvio‐tidal system (i.e. the outermost inner to middle estuary or distributary channels). In this example sand deposition is interpreted to represent high‐energy, freshwater dune migration within a fluvial‐dominated setting, whereas mud beds reflect brackish‐water suspension deposition during times of low river discharge. The second fabric, which is interpreted to have developed in more distal depositional positions (i.e. the middle estuary or seaward of the turbidity maximum in deltas), consists of inclined heterolithic stratification with laminated mudstone and bioturbated sandstone. In these inclined heterolithic stratification successions the mudstone beds were deposited under the influence of freshwater and heightened sedimentation rates, whereas bioturbated sandstone was colonized under brackish‐water conditions and in the presence of tidally facilitated sediment transport. In both examples, the bioturbated lithosomes are related to colonization windows that indicate the predominance at that time of marine or tidally influenced processes over fluvial processes. [ABSTRACT FROM AUTHOR]

Sequence stratigraphic models emphasize changes in accommodation driven by relative sea level as a principal control on continental-margin development. Therefore, it has been hypothesized that there are differences in the volume and distribution of sand delivered to deep-water during the high-amplitude sea-level changes of icehouse settings versus the low-amplitude sea-level changes of greenhouse settings. Previous numerical modeling and field studies suggest an alternative hypothesis: that there would be minimal differences between each setting. Here, we used a three-dimensional numerical stratigraphic forward model to test the impact of greenhouse and icehouse sea-level changes on sand distribution in a passive margin setting. Model results were analyzed to evaluate the impacts of the rate and amplitude of relative sea-level changes on individual deep-water sand delivery events, total deep-water sand volumes, and sand distribution. Model results show that total deep-water sand volume is almost independent of the rate of relative sea-level change, which we attribute to the interaction of this sea-level change rate and the time required by the delta to reach a dynamic equilibrium state as a result of avulsion processes. However, there are major differences in the large-scale spatial distribution of sand between the icehouse and greenhouse conditions. The high amplitude sea-level changes in the icehouse model caused significant shelfal incision, which minimized deltaic avulsion processes and localized deep-water sedimentation. The relatively low amplitude sea-level changes in the greenhouse model allowed avulsion of the fluvial-deltaic system, thus causing more laterally extensive deep-water deposits. Our experimental results demonstrate that the rate of deep-water sand delivery is largest during periods of low sea level in both icehouse and greenhouse conditions, but show that there is a poor relationship between the rate of deep-water sediment delivery and the rate of sea-level change. We attribute both of these results to the nature of avulsion processes on the delta: more frequent avulsions of greenhouse deltas spread sediment across the shelf and limit sediment delivery to deep water until a dynamic equilibrium state is achieved, whereas the development of an icehouse incised valley locks the fluvial-deltaic system in place and localizes deep-water sedimentation. Moreover, our results indicate that the total volume of deep-water sand is controlled by the total sediment supply to the basin. These results provide a framework for the timing and quantity of continental-margin sedimentation and deep-water sediment delivery, with applications to sequence-stratigraphic interpretations. • Numerical stratigraphic forward models show icehouse and greenhouse settings deliver similar total deep-water sand volumes. • The equilibrium state of the delta influences deep-water sand delivery rates. • Model results show sea-level change can modulate fluvio-deltaic avulsion. • Icehouse setting limited fluvio-deltaic avulsion compared to the greenhouse setting. • Icehouse setting resulted in areally restricted deep-water sand deposition. [ABSTRACT FROM AUTHOR]

While the grain-sorting morphodynamics of gravel- and sand-bed rivers has been intensively studied, sand-silt bed rivers such as the Lower Yellow River (LYR), China and the Pilcomayo River, Paraguay/Argentina have received much less attention. As a first step, we use a database from the LYR in the 1980s to develop a grain size specific extended Engelund–Hansen total bed material load relation. We then use this relation in two morphodynamic calculations. First, we "spin-up" the calculation from an arbitrary bed slope over 600 years to reproduce the downstream fining observed before the closing of Xiaolangdi Dam in 2000. We then cut off the sediment supply, and reproduce the observed pattern of bed coarsening as the bed armours in response to degradation. We argue that our model is likely not site-specific, but applies to other sand-silt bed rivers, basic data for which is as yet lacking. [ABSTRACT FROM AUTHOR]

Although general trends in transgressive to highstand sedimentary evolution of river‐mouth coastlines are well‐known, the details of the turnaround from retrogradational (typically estuarine) to aggradational–progradational (typically coastal/deltaic) stacking patterns are not fully resolved. This paper examines the middle to late Holocene eustatic highstand succession of the Po Delta: its stratigraphic architecture records a complex pattern of delta outbuilding and coastal progradation that followed eustatic stabilization, since around 7·7 cal kyr bp. Sedimentological, palaeoecological (benthic foraminifera, ostracods and molluscs) and compositional criteria were used to characterize depositional conditions and sediment‐dispersal pathways within a radiocarbon‐dated chronological framework. A three‐stage progradation history was reconstructed. First, as soon as eustasy stabilized (7·7 to 7·0 cal kyr bp), rapid bay‐head delta progradation (ca 5 m year−1), fed mostly by the Po River, took place in a mixed, freshwater and brackish estuarine environment. Second, a dominantly aggradational parasequence set of beach‐barrier deposits in the lower highstand systems tract (7·0 to 2·0 cal kyr bp) records the development of a shallow, wave‐dominated coastal system fed alongshore, with elongated, modestly crescent beaches (ca 2·5 m year−1). Third, in the last 2000 years, the development of faster accreting and more rapidly prograding (up to ca 15 m year−1) Po delta lobes occurred into 30 m deep waters (upper highstand systems tract). This study documents the close correspondence of sediment character with stratal distribution patterns within the highstand systems tract. Remarkable changes in sediment characteristics, palaeoenvironments and direction of sediment transport occur across a surface named the 'A–P surface'. This surface demarcates a major shift from dominantly aggradational (lower highstand systems tract) to fully progradational (upper highstand systems tract) parasequence stacking. In the Po system, this surface also reflects evolution from a wave‐dominated to river‐dominated deltaic system. Identifying the A–P surface through detailed palaeoecological and compositional data can help guide interpretation of highstand systems tracts in the rock record, especially where facies assemblages and their characteristic geometries are difficult to discern from physical sedimentary structures alone. [ABSTRACT FROM AUTHOR]

Rivers (on land) and turbidity currents (in the ocean) are the most important sediment transport processes on Earth. Yet how rivers generate turbidity currents as they enter the coastal ocean remains poorly understood. The current paradigm, based on laboratory experiments, is that turbidity currents are triggered when river plumes exceed a threshold sediment concentration of ~1 kg/m3. Here we present direct observations of an exceptionally dilute river plume, with sediment concentrations 1 order of magnitude below this threshold (0.07 kg/m3), which generated a fast (1.5 m/s), erosive, short‐lived (6 min) turbidity current. However, no turbidity current occurred during subsequent river plumes. We infer that turbidity currents are generated when fine sediment, accumulating in a tidal turbidity maximum, is released during spring tide. This means that very dilute river plumes can generate turbidity currents more frequently and in a wider range of locations than previously thought. Key Points: Here we document for the first time how very dilute (up to 0.07 kg/m3) river plumes can generate powerful turbidity currentsSuch low sediment concentrations are 20 times lower than those predicted by past theory and experimentsTherefore, turbidity currents are likely to be much more frequent and occur at a far wider range of locations than previously thought [ABSTRACT FROM AUTHOR]

Hydrodynamic sorting has been shown to strongly influence the composition and age of organic carbon (OC) during sediment transport and burial in the marine environment, yet sorting effects on terrestrial OC (OC terr) in fluvial systems remain poorly understood. We conducted size fractionation of suspended particle samples from the lower Yellow River, China, and examined variations in mass distribution and carbon isotopic (δ13C and Δ14C) composition of bulk OC and specific biomarkers among grain size fractions in order to investigate the influence of hydrodynamic sorting and selective transport on organic matter export. In general, the 16–32 μm and 32–63 μm fractions contributed the most of sediment mass while the majority of the OC resided in the 16–32 μm fraction. Over 80% of OC and n -fatty acids (FAs) were concentrated in <32 μm fractions. Significant differences in OC%, surface area (SA), Δ14C OC , n -FAs contents, and compound-specific 13C and 14C compositions were found among size fractions. Of particular note was a progressive decrease of Δ14C values (i.e., increase in 14C age) of long-chain (C 26+28+30) FAs with decreasing grain size. Taken together, the bulk and molecular characteristics imply two distinct types of selective OC terr transport in the Yellow River. Coarser particles (>32 μm), characterized by relatively low SA, OC%, and Δ14C OC values, but higher Δ14C values of C 26+28+30 FAs, are inferred to reflect a combination of bedrock-derived detrital sediment and fresh vascular-plant material (e.g., plant fragments). In contrast, finer particles (<32 μm), exhibiting higher SA, OC%, and lower Δ14C 26+28+30FAs values, reflect preferential transport of pre-aged, mineral soil-derived OC that is susceptible to repeated mobilization, as well as widespread dispersal in marginal seas. The latter, once buried in marine sediments, could account for the high burial efficiency of OC terr in the adjacent Bohai Sea and Yellow Sea. Thus, hydrodynamic sorting processes induce heterogeneity of composition and selective transport of OC. Bulk and molecular 14C measurements of size-fractionated particles facilitate both elucidation of these processes and assessment of their impact on OC cycling in (and export from) rivers. [ABSTRACT FROM AUTHOR]

Fluvial sediment fingerprinting employs various methods, directly link sink and source. However, the identification and quantification of the transformation that sediments experience during fluvial transport remain unclear. The luminescence properties of quartz and K-feldspar change during the burial/exposure to sunlight cycles undergone by fluvial sediments, potentially allow scientists to trace fluvial sediment transport. Here, we report on changes in luminescence properties in active river bars from source to sink along the Yarlung Tsangpo-Brahmaputra River system. Optically stimulated luminescence (OSL) sensitivities and residual doses of quartz and K-feldspar within the fluvial sediments are used for the fingerprint method. Source rock is identified as the primary determinant of regional variations in quartz OSL sensitivities within fluvial sediments along the Yarlung Tsangpo River, while transportation distance governs local changes. Samples from narrower river channels with higher normalized channel steepnesses (Ksn) along the Yarlung Tsangpo River exhibit higher residual doses. Furthermore, the Brahmaputra River exhibits higher residual dose values compared to the Old Brahmaputra River. The sediments' residual doses are therefore employed to fingerprint fluvial erosion ability. Our luminescence fingerprint results indicate that coarse-grained fractions experience a "dilution" effect due to the input of new sediments after traveling approximately 50-200 km along the Yarlung Tsangpo River and about 50-100 km along the Brahmaputra-Old Brahmaputra River course. The comparison of luminescence (quartz and feldspar) and detrital zircon fingerprinting within the fluvial sediment holds the potential to trace weathering and erosion cycles during transportation in large river contexts. • Luminescence fingerprints fluvial sediment transport along the Yarlung Tsangpo River. • Source rock determine regional variations in quartz sensitivities. • Transportation distance governs local changes in quartz sensitivities. • The residual doses are employed to fingerprint fluvial erosion capabilities. • Coarse-grained fractions would likely be "diluted" by the input of local sediments. [ABSTRACT FROM AUTHOR]

Topographic relief and bedrock fractures caused by fault activity can accelerate surface erosion, suggesting that erosion rates increase with decreasing distance to the fault core. To test this hypothesis, we used 10Be cosmogenic nuclides to quantify catchment-wide erosion rates at various distances from a fault in the footwall of the Daqing Shan fault system, a 200-km-long active normal fault in Inner Mongolia, northern China. In addition, in order to examine the influence of topography and bedrock fractures on the surface erosion processes in the fault-weakened zone, their relationships with hillslope erosion, fluvial sediment grain size and transport efficiency, erosion rates, and erosion coefficients were studied. The resulting catchment-wide erosion rates ranged from 0.01 ± 0.00–0.13 ± 0.01 mm yr−1. These erosion rates and coefficients were unaffected by distance from the fault. The analysis of topography, bedrock fractures, and hillslope erosion yielded distinct hillslope erosion processes at different distances from the fault. Rapid mass wasting events, such as landslides, occurred at <15 km from the fault in steep, rocky hillslopes with abundant bedrock fractures. In contrast, at >15 km from the fault, hillslopes gradually become more gentle and soil-mantled. These spatial-slope configuration differences result in a decrease in sediment grain size delivered to river channels with increasing distance from the fault. Once sediments enter river channels, they impact fluvial transport capacity by influencing the initial motion threshold of sediment. Correlation analyses revealed that sediment transport efficiency in channels directly controls the catchment-averaged erosion rate and coefficient. This mechanism explains why the erosion rate remains insensitive to variations in topography and bedrock fractures in fault-weakened zones. • Study of patterns and controls on erosion rate across Daqing Shan fault zone. • Cosmogenic nuclide 10Be used to derive catchment-averaged erosion rate. • Erosion rates do not vary with distance from the fault. • Erosion rate remains insensitive to variations in topography and bedrock fractures. • Sediment transport efficiency in channels controls erosion rate. [ABSTRACT FROM AUTHOR]

The gross morphology of a free face and talus rampart occurs in a range of landscape settings. Semi-arid mesas, river gorges and coastal cliffs all share this geometry, but differ in how the components respond to their respective environments, to each other and to the capacity to export material from the talus rampart. Differences are reflected in the rates and processes of cliff retreat, and in the boundary conditions for rampart growth and removal. For mesas and buttes, export from the talus is controlled by the rate at which coarse material weathers to a size that can be readily washed away, leading to a stable proportional height for the rampart, which then consists of a boulder controlled slope at the angle of repose. For river gorges, a high incremental increase in fluvial sediment transport allows incision to accompany cliff retreat, while low rates lead to valley widening and rampart formation. Coastal cliffs may either lack ramparts, with supply limited development controlled by wave attack on cliffs; or be limited by the transport capacity of transverse offshore sediment processes, allowing development of a persistent rampart. In all contexts, the transport term should not be ignored in understanding both the rates of retreat and the morphology of cliffed landforms. [Display omitted] • Cliffs with a talus rampart occur in diverse settings. • Mesas, river gorges and steep coasts. • Boundary conditions depend on the process setting and geometry. • Evolution may be driven by supply- or transport-limited removal. • The rate of material transport from rampart base is always important. [ABSTRACT FROM AUTHOR]