Articles | Volume 6, issue 3
Research article 25 Jul 2018
Research article | 25 Jul 2018
Evidence of, and a proposed explanation for, bimodal transport states in alluvial rivers
Kieran B. J. Dunne and Douglas J. Jerolmack
No articles found.
Sophie Bodek and Douglas J. Jerolmack
Earth Surf. Dynam. Discuss.,
Revised manuscript under review for ESurfShort summary
As rocks are transported, they undergo two attrition mechanisms: chipping, shallow cracking at low collision energies, and fragmentation, significant fracture growth from high-energy impacts. We examine the mass and shape evolution of concrete particles in a rotating drum to experimentally delineate the boundary between chipping and fragmentation. By connecting the mechanics of these attrition processes to resulting shape evolution, we can use particle shape to infer past transport conditions.
Dylan B. Lee and Douglas Jerolmack
Earth Surf. Dynam., 6, 1089–1099,Short summary
The transport of pebbles in a river is smooth and continuous under high flow conditions but under typical flows becomes erratic and unpredictable. We perform experiments to learn more about the origins of this unpredictable, intermittent behavior. Our results show that this unpredictability is similar to how infrequent avalanches occur in a sandpile. Transport events are similar in size but become more infrequent and erratic as the river transports less and less sediment.
C. B. Phillips and D. J. Jerolmack
Earth Surf. Dynam., 2, 513–530,Short summary
This study tracked the episodic motion of coarse sediment cobbles over 2 years to unravel how floods in mountain rivers move sediment. Despite large fluctuations in river discharge and natural variability in climate and topography, observed sediment dynamics agree well with theory and small-scale laboratory experiments; results demonstrate that sediment particle motion can be predicted from a record of river flow depth, providing a direct link between climate and sediment transport.
Related subject area
Physical: Geomorphology (including all aspects of fluvial, coastal, aeolian, hillslope and glacial geomorphology)Relationship between meteoric 10Be and NO3− concentrations in soils along Shackleton Glacier, AntarcticaSediment shell-content diminishes current-driven sand ripple development and migrationSand mining far outpaces natural supply in a large alluvial riverThe formation and geometry characteristics of boulder bars due to outburst floods triggered by overtopped landslide dam failureLandslide-lake outburst floods accelerate downstream hillslope slippageThe relative influence of dune aspect ratio and beach width on dune erosion as a function of storm duration and surge levelA temperature-dependent mechanical model to assess the stability of degrading permafrost rock slopesThe effects of storms and a transient sandy veneer on the interannual planform evolution of a low-relief coastal cliff and shore platform at Sargent Beach, Texas, USAIdentification of rock and fracture kinematics in high alpine rockwalls under the influence of elevationControls on the grain size distribution of landslides in Taiwan: the influence of drop height, scar depth and bedrock strengthAssessing the effect of topography on Cs-137 concentrations within forested soils due to the Fukushima Daiichi Nuclear Power Plant accident, JapanClimatic controls on mountain glacier basal thermal regimes dictate spatial patterns of glacial erosionTectonically and climatically driven mountain-hopping erosion in central Guatemala from detrital 10Be and river profile analysisStochastic alluvial fan and terrace formation triggered by a high-magnitude Holocene landslide in the Klados Gorge, CreteControls on the rates and products of particle attrition by bed-load collisionsBedrock river erosion through dipping layered rocks: quantifying erodibility through kinematic wave speedParticle energy partitioning and transverse diffusion during rarefied travel on an experimental hillslopeShort communication: Runout of rock avalanches limited by basal friction but controlled by fragmentationSedimentary architecture and landforms of the Late Saalian (MIS 6) ice sheet margin, offshore the NetherlandsRarefied particle motions on hillslopes – Part 1: TheoryRarefied particle motions on hillslopes – Part 2: AnalysisRarefied particle motions on hillslopes – Part 3: EntropyRarefied particle motions on hillslopes – Part 4: PhilosophyImplications of the ongoing rock uplift in NW Himalayan interiorsInteractions between deforestation, landscape rejuvenation, and shallow landslides in the North Tanganyika–Kivu rift region, AfricaRelevance of acoustic methods to quantify bedload transport and bedform dynamics in a large sandy-gravel-bed riverTemporal changes in the debris flow threshold under the effects of ground freezing and sediment storage on Mt. FujiEarthquake-induced debris flows at Popocatépetl Volcano, MexicoControls on the hydraulic geometry of alluvial channels: bank stability to gravitational failure, the critical-flow hypothesis, and conservation of mass and energyGenesis and propagation of exogenous sediment pulses in mountain channels: insights from flume experiments with seismic monitoringEffect of stress history on sediment transport and channel adjustment in graded gravel-bed riversHack distributions of rill networks and nonlinear slope length–soil loss relationshipsDevelopment of smart boulders to monitor mass movements via the Internet of Things: a pilot study in NepalLaboratory observations on meltwater meandering rivulets on iceQuantifying thresholds of barrier geomorphic change in a cross-shore sediment-partitioning modelThe enigma of relict large sorted stone stripes in the tropical Ethiopian HighlandsGrowing topography due to contrasting rock types in a tectonically dead landscapeHow do modeling choices and erosion zone locations impact the representation of connectivity and the dynamics of suspended sediments in a multi-source soil erosion model?Different coastal marsh sites reflect similar topographic conditions under which bare patches and vegetation recovery occurCoupling threshold theory and satellite-derived channel width to estimate the formative discharge of Himalayan foreland riversInertial drag and lift forces for coarse grains on rough alluvial beds measured using in-grain accelerometersGERALDINE (Google Earth Engine supRaglAciaL Debris INput dEtector): a new tool for identifying and monitoring supraglacial landslide inputsShort communication: Multiscalar roughness length decomposition in fluvial systems using a transform-roughness correlation (TRC) approachEvolution of events before and after the 17 June 2017 rock avalanche at Karrat Fjord, West Greenland – a multidisciplinary approach to detecting and locating unstable rock slopes in a remote Arctic areaComplementing scale experiments of rivers and estuaries with numerically modelled hydrodynamicsCharacterization of morphological units in a small, forested stream using close-range remotely piloted aircraft imageryTopographic controls on divide migration, stream capture, and diversification in riverine lifeIce sheet and palaeoclimate controls on drainage network evolution: an example from Dogger Bank, North SeaExperimental study of sediment supply control on step formation, evolution, and stabilityA bed load transport equation based on the spatial distribution of shear stress – Oak Creek revisited
Melisa A. Diaz, Lee B. Corbett, Paul R. Bierman, Byron J. Adams, Diana H. Wall, Ian D. Hogg, Noah Fierer, and W. Berry Lyons
Earth Surf. Dynam., 9, 1363–1380,Short summary
We collected soil surface samples and depth profiles every 5 cm (up to 30 cm) from 11 ice-free areas along the Shackleton Glacier, a major outlet glacier of the East Antarctic Ice Sheet (EAIS), and measured meteoric beryllium-10 and nitrate concentrations to understand the relationship between salts and beryllium-10. This relationship can help inform wetting history, landscape disturbance, and exposure duration.
Chiu H. Cheng, Jaco C. de Smit, Greg S. Fivash, Suzanne J. M. H. Hulscher, Bas W. Borsje, and Karline Soetaert
Earth Surf. Dynam., 9, 1335–1346,Short summary
Shells are biogenic particles that are widespread throughout natural sandy environments and can affect the bed roughness and seabed erodibility. As studies are presently lacking, we experimentally measured ripple formation and migration using natural sand with increasing volumes of shell material under unidirectional flow in a racetrack flume. We show that shells expedite the onset of sediment transport, reduce ripple dimensions and slow their migration rate.
Christopher R. Hackney, Grigorios Vasilopoulos, Sokchhay Heng, Vasudha Darbari, Samuel Walker, and Daniel R. Parsons
Earth Surf. Dynam., 9, 1323–1334,Short summary
Unsustainable sand mining poses a threat to the stability of river channels. We use satellite imagery to estimate volumes of material removed from the Mekong River, Cambodia, over the period 2016–2020. We demonstrate that current rates of extraction now exceed previous estimates for the entire Mekong Basin and significantly exceed the volume of sand naturally transported by the river. Our work highlights the importance of satellite imagery in monitoring sand mining activity over large areas.
Xiangang Jiang, Haiguang Cheng, Lei Gao, and Weiming Liu
Earth Surf. Dynam., 9, 1263–1277,Short summary
Boulder bars are a common form of riverbed morphology which can be affected by outburst flood. However, few studies have focused on boulder bars' formation process and development characteristics during landslide dam failure. In this paper, eight groups of dam failure experiments were carried out to study the development and geometry characteristics of boulder bars during and after dam failure. Moreover, the relationships between geometry parameters of boulder bars are investigated.
Wentao Yang, Jian Fang, and Jing Liu-Zeng
Earth Surf. Dynam., 9, 1251–1262,Short summary
The eastern Tibetan Plateau is an ideal place to study interactions among different geomorphic drivers. We report the impacts of two 2018 landslide-lake outburst floods up to 100 km distance downstream of the Jinsha River. By using remote sensing images, we found that the 2018 floods caused many hillslopes to slump during the prolonged period afterwards. The finding could help us to obtain a holistic picture of LLF impacts and improve geomorphic models of landscape evolution.
Michael Itzkin, Laura J. Moore, Peter Ruggiero, Sally D. Hacker, and Reuben G. Biel
Earth Surf. Dynam., 9, 1223–1237,Short summary
Studies of the impact of storms on dunes typically focus on the importance of dune elevation, here we analyze the protective services offered by the dune height and width, the morphology of the beach fronting the dune, and artificial dune construction via the use of sand fences. We find that dune volume loss most strongly correlates to beach width rather than dune shape, although when beach width is controlled for low and wide dunes offer greater protection than tall and narrow dunes.
Philipp Mamot, Samuel Weber, Saskia Eppinger, and Michael Krautblatter
Earth Surf. Dynam., 9, 1125–1151,Short summary
The mechanical response of permafrost degradation on high-mountain rock slope stability has not been calculated in a numerical model yet. We present the first approach for a model with thermal and mechanical input data derived from laboratory and field work, and existing concepts. This is applied to a test site at the Zugspitze, Germany. A numerical sensitivity analysis provides the first critical stability thresholds related to the rock temperature, slope angle and fracture network orientation.
Rose V. Palermo, Anastasia Piliouras, Travis E. Swanson, Andrew D. Ashton, and David Mohrig
Earth Surf. Dynam., 9, 1111–1123,Short summary
At Sargent Beach, Texas, USA, a rapidly eroding soft-sediment cliff system, we study the planform evolution of the cliff face in response to storms and sediment cover. Through this analysis, we characterize the feedbacks between morphology and retreat rate of a cliff face. We find that after a storm event, the roughness and sinuosity of the cliff face increase, which sustains higher retreat rates for years following.
Earth Surf. Dynam., 9, 977–994,Short summary
Alpine rockwalls are affected by weathering processes that result in rock and fracture deformation. This deformation decreases rockwall stability with time. I installed crackmeters along a topographic gradient to identify the spatial and temporal variation of weathering processes. My data show that elevation-dependent snow cover, topographic factors and fracture dipping control the frequency and magnitude of weathering processes and resulting rock kinematics.
Odin Marc, Jens M. Turowski, and Patrick Meunier
Earth Surf. Dynam., 9, 995–1011,Short summary
The size of grains delivered to rivers is an essential parameter for understanding erosion and sediment transport and their related hazards. In mountains, landslides deliver these rock fragments, but few studies have analyzed the landslide properties that control the resulting sizes. We present measurements on 17 landslides from Taiwan and show that their grain sizes depend on rock strength, landslide depth and drop height, thereby validating and updating a previous theory on fragmentation.
Misa Yasumiishi, Taku Nishimura, Jared Aldstadt, Sean J. Bennett, and Thomas Bittner
Earth Surf. Dynam., 9, 861–893,Short summary
Topographic effects on radioactive contamination in a forested area were quantitatively examined using soil core samples collected in a village in Fukushima, Japan. The results confirmed that local topography influences the contamination patterns in soils, and its effects vary depending on the combinations of the topographic parameters. This finding suggests that topographic characteristics should be considered carefully in future environmental radioactive risk assessments.
Jingtao Lai and Alison M. Anders
Earth Surf. Dynam., 9, 845–859,Short summary
Glaciers are strong erosive agents, and they have created many unique landforms in mountain belts. Climate has been viewed as a primary control on glacial erosion, yet our understanding of the mechanism by which climate impacts glacial erosion remains limited. Using computer simulations, we find that climate controls glacial erosion by modulating the temperature of the basal ice. Our results suggest that a warm and/or wet climate can create warm basal ice and, therefore, enhance erosion.
Gilles Brocard, Jane Kathrin Willenbring, Tristan Salles, Michael Cosca, Axel Guttiérez-Orrego, Noé Cacao Chiquín, Sergio Morán-Ical, and Christian Teyssier
Earth Surf. Dynam., 9, 795–822,Short summary
The rise of a mountain affects the circulation of water, both in the atmosphere and over the land surface, thereby affecting the erosion of the land surface. We document how the rise of a mountain in central Guatemala has affected the erosion of an older range nearby. The new range intercepts precipitation formerly delivered to the older range. River response to the uplift of the new range has decreased incision across the older one. Both have reduced hillslope erosion over the old range.
Elena T. Bruni, Richard F. Ott, Vincenzo Picotti, Negar Haghipour, Karl W. Wegmann, and Sean F. Gallen
Earth Surf. Dynam., 9, 771–793,Short summary
The Klados River catchment contains seemingly overlarge, well-preserved alluvial terraces and fans. Unlike previous studies, we argue that the deposits formed in the Holocene based on their position relative to a paleoshoreline uplifted in 365 CE and seven radiocarbon dates. We also find that constant sediment supply from high-lying landslide deposits disconnected the valley from regional tectonics and climate controls, which resulted in fan and terrace formation guided by stochastic events.
Kimberly Litwin Miller and Douglas Jerolmack
Earth Surf. Dynam., 9, 755–770,Short summary
We conducted experiments to investigate the mechanics of sediment attrition due to collisions with the channel bed during downstream transport. During this process, the grains become rounder and smaller, changing the overall distribution of sediment in the river. In this work we examine how material properties play a role in the breakdown of sediment due to energetic collisions and the fine particles that are produced when chipped off of larger grains.
Nate A. Mitchell and Brian J. Yanites
Earth Surf. Dynam., 9, 723–753,Short summary
A landscape's appearance reflects the properties of the underlying bedrock. For example, strong bedrock can lead to steep slopes. Recent work has shown, however, that in areas with mixed rock types the stronger bedrock can have lower slopes. In this study, we use numerical models of bedrock river erosion to show why this change in behavior occurs. We also present a new approach for estimating bedrock erodibility. This new approach can allow for new opportunities in the field of geomorphology.
Sarah G. W. Williams and David J. Furbish
Earth Surf. Dynam., 9, 701–721,Short summary
Particle motions and travel distances prior to deposition on hillslope surfaces depend on a balance of gravitational and frictional forces. We elaborate how particle energy is partitioned and dissipated during travel using measurements of particle travel distances supplemented with high-speed imaging of drop–impact–rebound experiments. Results show that particle shape plays a dominant role in how energy is partitioned during impact with a surface and how far particles travel in two dimensions.
Øystein T. Haug, Matthias Rosenau, Michael Rudolf, Karen Leever, and Onno Oncken
Earth Surf. Dynam., 9, 665–672,Short summary
The runout of rock avalanches scales with their volume but also shows a considerable variation for avalanches with similar volumes. Here we show that besides size-dependent weakening mechanisms, fragmentation can account for the observed variability in runout. We use laboratory-scale experimental avalanches to simulate and analyse the role of fragmentation. We find that fragmentation consumes energy but also increases avalanche mobility. It does so systematically and predictably.
Víctor Cartelle, Natasha L. M. Barlow, David M. Hodgson, Freek S. Busschers, Kim M. Cohen, Bart M. L. Meijninger, and Wessel P. van Kesteren
Earth Surf. Dynam. Discuss.,
Revised manuscript accepted for ESurfShort summary
Reconstructing the growth and decay of past ice sheets is critical to understand the relationships between global climate and sea-level change. We take advantage of large windfarm datasets in the southern North Sea to investigate the buried landscapes left by ice sheet advance and retreat occurring ≈160,000 years ago. We demonstrate the utility of offshore windfarm data in refining palaeo ice sheet margin limits and providing insight into the processes influencing ice sheet dynamics.
David Jon Furbish, Joshua J. Roering, Tyler H. Doane, Danica L. Roth, Sarah G. W. Williams, and Angel M. Abbott
Earth Surf. Dynam., 9, 539–576,Short summary
Sediment particles skitter down steep hillslopes on Earth and Mars. Particles gain speed in going downhill but are slowed down and sometimes stop due to collisions with the rough surface. The likelihood of stopping depends on the energetics of speeding up (heating) versus slowing down (cooling). Statistical physics predicts that particle travel distances are described by a generalized Pareto distribution whose form varies with the Kirkby number – the ratio of heating to cooling.
David Jon Furbish, Sarah G. W. Williams, Danica L. Roth, Tyler H. Doane, and Joshua J. Roering
Earth Surf. Dynam., 9, 577–613,Short summary
The generalized Pareto distribution of particle travel distances on steep hillslopes, as described in a companion paper (Furbish et al., 2021a), is entirely consistent with measurements of travel distances obtained from laboratory and field-based experiments, supplemented with high-speed imaging and audio recordings that highlight the effects of bumpety-bump particle motions. Particle size and shape, in concert with surface roughness, strongly influence particle energetics and deposition.
David Jon Furbish, Sarah G. W. Williams, and Tyler H. Doane
Earth Surf. Dynam., 9, 615–628,Short summary
The generalized Pareto distribution of particle travel distances on steep hillslopes, as described in two companion papers (Furbish et al., 2021a, 2021b), is a maximum entropy distribution. This simply represents the most probable way that a great number of particles become distributed into distance states, subject to a fixed total energetic cost due to frictional effects of particle–surface collisions. The maximum entropy criterion is equivalent to a formal application of Occam's razor.
David Jon Furbish and Tyler H. Doane
Earth Surf. Dynam., 9, 629–664,Short summary
Using analyses of particle motions on steep hillslopes in three companion papers (Furbish et al., 2021a, 2021b, 2021c), we offer philosophical perspective on the merits of a statistical mechanics framework for describing sediment particle motions and transport, and the implications of rarefied versus continuum transport conditions. We highlight the mechanistic yet probabilistic nature of the approach, and the importance of tailoring the style of thinking to the process and scale of interest.
Saptarshi Dey, Rasmus C. Thiede, Arindam Biswas, Naveen Chauhan, Pritha Chakravarti, and Vikrant Jain
Earth Surf. Dynam., 9, 463–485,Short summary
Ongoing deformation of the Himalaya is not constrained to its southern extremity. With morphometric analysis using a high-resolution digital elevation model, satellite image analysis, luminescence chronology of fluvial terraces and field observations, we identify a zone of rapid rock uplift in the interior of the Kashmir Himalaya. Our results suggest active tectonic and structural control on the growth of topography in the Himalayan interiors over multi-millennial timescales.
Arthur Depicker, Gerard Govers, Liesbet Jacobs, Benjamin Campforts, Judith Uwihirwe, and Olivier Dewitte
Earth Surf. Dynam., 9, 445–462,Short summary
We investigated how shallow landslide occurrence is impacted by deforestation and rifting in the North Tanganyika–Kivu rift region (Africa). We developed a new approach to calculate landslide erosion rates based on an inventory compiled in biased © Google Earth imagery. We find that deforestation increases landslide erosion by a factor of 2–8 and for a period of roughly 15 years. However, the exact impact of deforestation depends on the geomorphic context of the landscape (rejuvenated/relict).
Jules Le Guern, Stéphane Rodrigues, Thomas Geay, Sébastien Zanker, Alexandre Hauet, Pablo Tassi, Nicolas Claude, Philippe Jugé, Antoine Duperray, and Louis Vervynck
Earth Surf. Dynam., 9, 423–444,Short summary
Despite the inherent difficulties in quantifying its value, sediment transport is essential to understanding fluvial systems. This study tries to improve the measurement by comparing several methods. Acoustic methods are compared to direct measurements with samplers. The hydrophone is well adapted to quantify sediment transport in mountain streams, but this study shows the potential and the efficiency of this device in large lowland rivers.
Fumitoshi Imaizumi, Atsushi Ikeda, Kazuki Yamamoto, and Okihiro Osaka
Earth Surf. Dynam. Discuss.,
Revised manuscript accepted for ESurfShort summary
The rainfall threshold for the debris flow occurrence was evaluated on Mt. Fuji, Japan. Debris flows during frozen periods were triggered by a smaller magnitude of rainfall than during unfrozen periods. During unfrozen periods, the rainfall threshold was higher when the volume of channel deposits was larger. The results suggest that the occurrence of frozen ground need to be monitored for better debris flow disaster mitigation in cold regions.
Velio Coviello, Lucia Capra, Gianluca Norini, Norma Dávila, Dolors Ferrés, Víctor Hugo Márquez-Ramírez, and Eduard Pico
Earth Surf. Dynam., 9, 393–412,Short summary
The Puebla–Morelos earthquake (19 September 2017) was the most damaging event in central Mexico since 1985. The seismic shaking produced hundreds of shallow landslides on the slopes of Popocatépetl Volcano. The larger landslides transformed into large debris flows that travelled for kilometers. We describe this exceptional mass wasting cascade and its predisposing factors, which have important implications for both the evolution of the volcanic edifice and hazard assessment.
Jon D. Pelletier
Earth Surf. Dynam., 9, 379–391,Short summary
The sizes and shapes of alluvial channels vary in a systematic way with the water flow they convey during large floods. It is demonstrated that the depth of alluvial channels is controlled by the resistance of channel bank material to slumping, which in turn is controlled by clay content. Deeper channels have faster water flow in a manner controlled by the critical hydraulic state to which channels tend to evolve. Channel width and slope can be further quantified using conservation principles.
Marco Piantini, Florent Gimbert, Hervé Bellot, and Alain Recking
Earth Surf. Dynam. Discuss.,
Revised manuscript accepted for ESurfShort summary
We carry out laboratory experiments to investigate the formation and propagation dynamics of exogenous sediment pulses in mountain rivers. We show that the ability of a self-formed deposit to destabilize and generate sediment pulses depends on the sand content of the mixture, while each pulse turns out to be formed by a front, a body, and a tail. Seismic measurements reveal a complex and non-unique dependency between seismic power and sediment pulses’ transport characteristics.
Chenge An, Marwan A. Hassan, Carles Ferrer-Boix, and Xudong Fu
Earth Surf. Dynam., 9, 333–350,Short summary
Mountain rivers are characterized by fluctuations of water flow, including both flood and inter-flood low flow. Recently, increasing attention has been paid to how inter-flood low flow affects the sediment transport in subsequent floods. Here we present a series of flume experiments. Results show that the existence of inter-flood low flow can reduce the sediment transport at the beginning of the subsequent flood. However, such an effect is gradually erased with the increase of flow intensity.
Tyler H. Doane, Jon D. Pelletier, and Mary H. Nichols
Earth Surf. Dynam., 9, 317–331,Short summary
This paper explores how the geometry of rill networks contributes to observed nonlinear relationships between soil loss and hillslope length. This work develops probability functions of geometrical quantities of the networks and then extends the theory to hydraulic variables by relying on well-known relationships. Theory is complemented by numerical modeling on numerical and natural surfaces. Results suggest that the particular arrangement of rill networks contributes to nonlinear relationships.
Benedetta Dini, Georgina L. Bennett, Aldina M. A. Franco, Michael R. Z. Whitworth, Kristen L. Cook, Andreas Senn, and John M. Reynolds
Earth Surf. Dynam., 9, 295–315,Short summary
We use long-range smart sensors connected to a network based on the Internet of Things to explore the possibility of detecting hazardous boulder movements in real time. Prior to the 2019 monsoon season we inserted the devices in 23 boulders spread over debris flow channels and a landslide in northeastern Nepal. The data obtained in this pilot study show the potential of this technology to be used in remote hazard-prone areas in future early warning systems.
Roberto Fernández and Gary Parker
Earth Surf. Dynam., 9, 253–269,Short summary
We present a set of observations from laboratory experiments on meltwater meandering rivulets on ice and compare them (qualitatively and quantitatively) to patterns commonly found in meandering channels flowing over different materials. Our channels display great similarities with real rivers in spite of being much smaller. Higher temperature differences between water and ice create deeper and less sinuous channels with bends that preferentially point downstream and are not as rounded.
Daniel J. Ciarletta, Jennifer L. Miselis, Justin L. Shawler, and Christopher J. Hein
Earth Surf. Dynam., 9, 183–203,Short summary
The world's sandy coastlines are increasingly altered by humans and sea-level rise, yet quantitative relationships between coastal landscapes and sediment availability remain poorly described. Using a novel modeling framework, we explore the evolution of coastal barrier islands under varying rates of sea-level rise and sediment availability. Our model results suggest that as sea levels increase, minor changes in sediment availability could result in rapid changes to barrier coasts.
Alexander R. Groos, Janik Niederhauser, Luise Wraase, Falk Hänsel, Thomas Nauss, Naki Akçar, and Heinz Veit
Earth Surf. Dynam., 9, 145–166,Short summary
Large sorted stone stripes have been discovered on the 4000 m high central Sanetti Plateau of the tropical Bale Mountains in Ethiopia. The stripes are a mystery as similar landforms have so far only been reported in the temperate zone and polar regions. Our investigations suggest that the stripes formed in the vicinity of a former ice cap on the plateau during a much colder climatic period. The distinct pattern is the result of a process related to cyclic freezing and thawing of the ground.
Daniel Peifer, Cristina Persano, Martin D. Hurst, Paul Bishop, and Derek Fabel
Earth Surf. Dynam., 9, 167–181,Short summary
Plate tectonics drive the formation of mountain ranges. Yet when tectonic forces cease, mountain ranges persist for hundreds of millions of years, forming major Earth surface features. This work presents denudation rate estimates from one such ancient mountain range that show that denudation is strongly tied to rock type. Resistant rocks denude more slowly despite having much steeper topography, and contrasts in rock type cause increasing relief in the absence of active tectonics.
Magdalena Uber, Guillaume Nord, Cédric Legout, and Luis Cea
Earth Surf. Dynam., 9, 123–144,Short summary
Understanding soil erosion and suspended sediment transport is an important issue in terms of soil and water resources management. This study analyzes the impact of choices made during numerical model setup on the modeled suspended sediment dynamics at the outlet of two mesoscale watersheds. While the modeled liquid and solid discharges were found to be sensitive to these choices, the actual location of sediment sources in each catchment was the most important feature.
Chen Wang, Lennert Schepers, Matthew L. Kirwan, Enrica Belluco, Andrea D'Alpaos, Qiao Wang, Shoujing Yin, and Stijn Temmerman
Earth Surf. Dynam., 9, 71–88,Short summary
Coastal marshes are valuable natural habitats with normally dense vegetation. The presence of bare patches is a symptom of habitat degradation. We found that the occurrence of bare patches and regrowth of vegetation is related to spatial variations in soil surface elevation and to the distance and connectivity to tidal creeks. These relations are similar in three marshes at very different geographical locations. Our results may help nature managers to conserve and restore coastal marshes.
Kumar Gaurav, François Métivier, A V Sreejith, Rajiv Sinha, Amit Kumar, and Sampat Kumar Tandon
Earth Surf. Dynam., 9, 47–70,Short summary
This study demonstrates an innovative methodology to estimate the formative discharge of alluvial rivers from remote sensing images. We have developed an automated algorithm in Python 3 to extract the width of a river channel from satellite images. Finally, this channel width is translated into discharge using a semi-empirical regime equation developed from field measurements and threshold channel theory that explains the first-order geometry of alluvial channels.
Georgios Maniatis, Trevor Hoey, Rebecca Hodge, Dieter Rickenmann, and Alexandre Badoux
Earth Surf. Dynam., 8, 1067–1099,Short summary
One of the most interesting problems in geomorphology concerns the conditions that mobilise sediments grains in rivers. Newly developed
smartpebbles allow for the measurement of those conditions directly if a suitable framework for analysis is followed. This paper connects such a framework with the physics used to described sediment motion and presents a series of laboratory and field smart-pebble deployments. Those quantify how grain shape affects the motion of coarse sediments in rivers.
William D. Smith, Stuart A. Dunning, Stephen Brough, Neil Ross, and Jon Telling
Earth Surf. Dynam., 8, 1053–1065,Short summary
Glacial landslides are difficult to detect and likely underestimated due to rapid covering or dispersal. Without improved detection rates we cannot constrain their impact on glacial dynamics or their potential climatically driven increases in occurrence. Here we present a new open-access tool (GERALDINE) that helps a user detect 92 % of these events over the past 38 years on a global scale. We demonstrate its ability by identifying two new, large glacial landslides in the Hayes Range, Alaska.
David L. Adams and Andrea Zampiron
Earth Surf. Dynam., 8, 1039–1051,Short summary
This paper presents a novel method of estimating the relative contribution of different physical scales of river bed topography to the total roughness length, based on thalweg elevation profiles. By providing more detailed information regarding the interaction between surface topography and fluid dynamics, the proposed technique may contribute to advances in hydraulics, channel morphodynamics, and bedload transport. Also, it may provide alternatives to existing representative roughness metrics.
Kristian Svennevig, Trine Dahl-Jensen, Marie Keiding, John Peter Merryman Boncori, Tine B. Larsen, Sara Salehi, Anne Munck Solgaard, and Peter H. Voss
Earth Surf. Dynam., 8, 1021–1038,Short summary
The 17 June 2017 Karrat landslide in Greenland caused a tsunami that killed four people. We apply a multidisciplinary workflow to reconstruct a timeline of events and find that three historic landslides occurred in 2009, 2016, and 2017. We also find evidence of much older periods of landslide activity. Three newly discovered active slopes might pose a future hazard. We speculate that the trigger for the recent events is melting permafrost due to a warming climate.
Steven A. H. Weisscher, Marcio Boechat-Albernaz, Jasper R. F. W. Leuven, Wout M. Van Dijk, Yasuyuki Shimizu, and Maarten G. Kleinhans
Earth Surf. Dynam., 8, 955–972,Short summary
Accurate and continuous data collection is challenging in physical scale experiments. A novel means to augment measurements is to numerically model flow over the experimental digital elevation maps. We tested this modelling approach for one tidal and two river scale experiments and showed that modelled water depth and flow velocity closely resemble the measurements. The implication is that conducting experiments requires fewer measurements and results in flow data of better overall quality.
Carina Helm, Marwan A. Hassan, and David Reid
Earth Surf. Dynam., 8, 913–929,Short summary
Forested, gravel-bed streams possess complex channel morphologies which are difficult to objectively characterize. This paper describes a novel technique using a remotely piloted aircraft (RPA) to characterize these systems below the forest canopy. The results demonstrate the accuracy and coverage of RPAs for objectively characterizing and classifying these systems relative to more traditional, time-consuming techniques that are generally used in these environments.
Nathan J. Lyons, Pedro Val, James S. Albert, Jane K. Willenbring, and Nicole M. Gasparini
Earth Surf. Dynam., 8, 893–912,Short summary
Organisms evolve in ever-changing environments under complex process interactions. We applied a new software modelling tool to assess how changes in river course impact the evolution of riverine species. Models illustrate the climatically and tectonically forced landscape changes that can drive riverine biodiversity, especially where topographic relief is low. This research demonstrates that river course changes can contribute to the high riverine biodiversity found in real-world lowland basins.
Andy R. Emery, David M. Hodgson, Natasha L. M. Barlow, Jonathan L. Carrivick, Carol J. Cotterill, Janet C. Richardson, Ruza F. Ivanovic, and Claire L. Mellett
Earth Surf. Dynam., 8, 869–891,Short summary
During the last ice age, sea level was lower, and the North Sea was land. The margin of a large ice sheet was at Dogger Bank in the North Sea. This ice sheet formed large rivers. After the ice sheet retreated down from the high point of Dogger Bank, the rivers had no water supply and dried out. Increased precipitation during the 15 000 years of land exposure at Dogger Bank formed a new drainage network. This study shows how glaciation and climate changes can control how drainage networks evolve.
Matteo Saletti and Marwan A. Hassan
Earth Surf. Dynam., 8, 855–868,Short summary
Mountain streams often display a stepped morphology but the conditions under which these steps form, remain stable, and eventually collapse are still not entirely clear. We run flume experiments to study how (a) the amount of sediment input and (b) channel width variations affect step dynamics in steep channels. Steps form preferentially in areas of flow convergence (channel narrowing) and their frequency is higher when sediment supply is larger than zero but smaller than the transport capacity.
Angel Monsalve, Catalina Segura, Nicole Hucke, and Scott Katz
Earth Surf. Dynam., 8, 825–839,Short summary
Part of the inaccuracies when estimating bed load transport in gravel-bed rivers is because we are not considering the wide distributions of shear stress in these systems. We modified a subsurface-based bed load transport equation to include these distributions. By doing so, our approach accurately predicts bed load transport rates when the pavement layer is still present, while the original one predicts zero transport. For high flows, our method had similar performance to the original equation.
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What controls the size and shape of a river – its width, depth, and slope? The cross-sectional channel geometry of gravel-bedded rivers is understood to be a function of the river's fluid shear stress and the weight of the average particle on its bed; however, there is no satisfactory explanation for sand-bedded rivers. We analyze global datasets and individual river profiles and propose that accounting for riverbank cohesion could allow for an explanation for sand-bedded river channel geometry.
What controls the size and shape of a river – its width, depth, and slope? The cross-sectional...