Articles | Volume 3, issue 4
Research article 20 Oct 2015
Research article | 20 Oct 2015
Spatial distributions of earthquake-induced landslides and hillslope preconditioning in the northwest South Island, New Zealand
R. N. Parker et al.
No articles found.
Mark C. Quigley, Wendy Saunders, Chris Massey, Russ Van Dissen, Pilar Villamor, Helen Jack, and Nicola Litchfield
Nat. Hazards Earth Syst. Sci., 20, 3361–3385,Short summary
This paper examines the roles of earth science information (data, knowledge, advice) in land-use decision-making in Christchurch, New Zealand, in response to the 2010–2011 Canterbury earthquake sequence. A detailed timeline of scientific activities and information provisions relative to key decision-making events is provided. We highlight the importance and challenges of the effective provision of science to decision makers in times of crisis.
Jonathan M. Carey, Chris I. Massey, Barbara Lyndsell, and David N. Petley
Earth Surf. Dynam., 7, 707–722,Short summary
Slow-moving landslides are a major hazard but their movement mechanisms during earthquakes and rainstorms are not fully understood. We collected samples from a slow-moving landslide complex in New Zealand and subjected them to a range of porewater pressure and dynamic stress scenarios in a dynamic back-pressured shear box. Our results show how the complex movement patterns, observed in many large slow-moving landslides, may be mobilized by strong earthquakes and significant rain events.
Louise Mary Vick, Valerie Zimmer, Christopher White, Chris Massey, and Tim Davies
Nat. Hazards Earth Syst. Sci., 19, 1105–1117,Short summary
Rockfall boulders can travel long distances downslope, and it is important to predict how far fatalities can be prevented. A comparison of earthquake data from New Zealand during summer and full-scale rockfall experiments in the same soil during winter shows that during dry seasons boulders travel further downslope because the soil is harder. When using predictive tools, engineers and geologists should take soil conditions (and seasonal variations thereof) into account.
David G. Milledge, Alexander L. Densmore, Dino Bellugi, Nick J. Rosser, Jack Watt, Gen Li, and Katie J. Oven
Nat. Hazards Earth Syst. Sci., 19, 837–856,Short summary
Mitigating landslide risk requires information on landslide hazards on a suitable scale to inform decisions. We develop simple rules to identify landslide hazards and the probability of being hit by a landslide, then test their performance using six existing landslide inventories from recent earthquakes. We find that the best rules are "minimize your maximum look angle to the skyline" and "avoid steep (> 10˚) channels with many steep (> 40˚) areas that are upslope".
Jack G. Williams, Nick J. Rosser, Richard J. Hardy, Matthew J. Brain, and Ashraf A. Afana
Earth Surf. Dynam., 6, 101–119,Short summary
We present a method to analyse surface change using 3-D data collected at hourly intervals. This is applied to 9000 surveys of a failing rock slope, acquired over 10 months. A higher proportion and frequency of small rockfall is observed than in less-frequent (e.g. monthly) monitoring. However, quantifying longer-term erosion rates may be more suited to less-frequent data collection, which contains lower accumulative errors due to the number of surveys and the lower proportion of small events.
Jack G. Williams, Nick J. Rosser, Mark E. Kincey, Jessica Benjamin, Katie J. Oven, Alexander L. Densmore, David G. Milledge, Tom R. Robinson, Colm A. Jordan, and Tom A. Dijkstra
Nat. Hazards Earth Syst. Sci., 18, 185–205,Short summary
There is currently no protocol for rapid humanitarian-facing landslide assessment and no published recognition of what is possible and useful to compile immediately after a triggering event. Drawing on the 2015 Gorkha earthquake (Nepal), we consider how quickly a landslide assessment based upon manual satellite-based emergency mapping (SEM) can be realistically achieved and review the decisions taken by analysts to ascertain the timeliness and type of useful information that can be generated.
Tom R. Robinson, Nicholas J. Rosser, Alexander L. Densmore, Jack G. Williams, Mark E. Kincey, Jessica Benjamin, and Heather J. A. Bell
Nat. Hazards Earth Syst. Sci., 17, 1521–1540,Short summary
Current methods to identify landslides after an earthquake are too slow to effectively inform emergency response operations. This study presents an empirical approach for modelling the spatial pattern and landslide density within hours to days of the earthquake. The approach uses small initial samples of landslides to identify locations where as yet unidentified landslides may have occurred. The model requires just 200 initial landslides, provided they have sufficiently wide spatial coverage.
Robert N. Parker, Nicholas J. Rosser, and Tristram C. Hales
Nat. Hazards Earth Syst. Sci. Discuss.,
Revised manuscript has not been submittedShort summary
In mountainous regions, large earthquakes often trigger widespread and destructive landslides. Understanding and predicting where these landslides occur is important for assessing hazards, as well as investigating their impact on the physical landscape. Based on correlations between landslides and different landscape and earthquake characteristics in nine past earthquakes, we developed a generalised algorithm for predicting and mapping the probability of earthquake-triggered landslides.
S. A. Sepúlveda and D. N. Petley
Nat. Hazards Earth Syst. Sci., 15, 1821–1833,Short summary
We compiled a data set of 611 fatal landslides in the 2004-2013 period in Latin America and the Caribbean, with 11631 fatalities recorded. Our analysis suggests that on a continental scale the mapped factors that best explain the observed distribution are topography, annual precipitation and population density. Analysis of research on countries affected by fatal landslides shows a landslide research deficit in Latin America and the Caribbean.
Related subject area
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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.
Marco Redolfi, Matilde Welber, Mattia Carlin, Marco Tubino, and Walter Bertoldi
Earth Surf. Dynam., 8, 789–808,Short summary
Alternate bars are large sediment deposits that tend to naturally form in rivers when the channel width is sufficiently large. Our laboratory experiments on a scaled model reveal that equilibrium properties of self-formed alternate bars highly depend on the water discharge with respect to the relevant theoretical thresholds. This work provides fundamental information for predicting the response of rivers to natural or human alterations of the flow regime.
Marius L. Huber, Maarten Lupker, Sean F. Gallen, Marcus Christl, and Ananta P. Gajurel
Earth Surf. Dynam., 8, 769–787,Short summary
Large boulders found in two Himalayan valleys show signs of long fluvial transport (>10 km). Paleo-discharges required to mobilize these boulders exceed typical monsoon discharges. Exposure dating shows that a cluster of these boulders was emplaced ca. 5 kyr ago. This period is coeval with a weakening of the Indian monsoon and glacier retreat in the area. We, therefore, suggest that glacier lake outburst floods are likely mechanisms that can explain these exceptional transport processes.
Ingo Hartmeyer, Markus Keuschnig, Robert Delleske, Michael Krautblatter, Andreas Lang, Lothar Schrott, Günther Prasicek, and Jan-Christoph Otto
Earth Surf. Dynam., 8, 753–768,Short summary
Rockfall size and frequency in two deglaciating cirques in the Central Alps, Austria, is analysed based on 6-year rockwall monitoring with terrestrial lidar (2011–2017). The erosion rates derived from this dataset are very high due to a frequent occurrence of large rockfalls in freshly deglaciated areas. The results obtained are important for rockfall hazard assessments, as, in rockwalls affected by glacier retreat, historical rockfall patterns are not good predictors of future events.
Fritz Schlunegger, Romain Delunel, and Philippos Garefalakis
Earth Surf. Dynam., 8, 717–728,Short summary
We calculated the probability of sediment transport in coarse-grained mountainous streams in the Alps and the Andes where data on water discharge is available. We find a positive correlation between the predicted probability of sediment transport and the grain size sorting of the bed material. We suggest that besides sediment discharge, the bedload sorting exerts a significant influence on the mobility of sediment and thus on the stability of gravel bars in mountainous streams.
Magdalena Uber, Guillaume Nord, Cédric Legout, and Luis Cea
Earth Surf. Dynam. Discuss.,
Revised manuscript accepted for ESurfShort summary
Soil erosion and suspended sediment transport understanding is an important issue in terms of soil and water resources management. This study analyzes the impact of choices made during numerical model set-up on the modelled suspended sediment dynamics at the outlet of two meso scale watersheds. While the modelled 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.
Jagriti Mishra and Takuya Inoue
Earth Surf. Dynam., 8, 695–716,Short summary
This study provides an extensive review of field- and laboratory-scale studies and mathematical models used for predicting the sediment processes in bedrock river channels. We tested the model capabilities by reproducing and comparing the results with laboratory-scale experiments. This study provides an insight into the strengths and shortcomings of various available models.
Thomas O. Hoffmann, Yannik Baulig, Helmut Fischer, and Jan Blöthe
Earth Surf. Dynam., 8, 661–678,Short summary
We study the dynamics of suspended matter and associated nutrients in large rivers in Germany. The relationship between suspended sediment concentration and discharge is diagnostic of the processes and sources of suspended matter. We show that suspended matter originates from organic growth within the river at low flow and from soil erosion at high flow. In a warmer climate with increased frequency of droughts, low flow states are likely to be more prolonged, affecting the behavior of rivers.
Kumar Gaurav, François Métivier, AV Sreejith, Rajiv Sinha, Amit Kumar, and Sampat Kumar Tandon
Earth Surf. Dynam. Discuss.,
Revised manuscript accepted for ESurfShort 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 to discharge by using a semi-empirical regime equation developed from field measurements and threshold channel theory, that explains the first-order geometry of alluvial channels.
Giulia Battista, Peter Molnar, and Paolo Burlando
Earth Surf. Dynam., 8, 619–635,Short summary
Suspended sediment load in rivers is highly uncertain because of spatial and temporal variability. By means of a hydrology and suspended sediment transport model, we investigated the effect of spatial variability in precipitation and surface erodibility on catchment sediment fluxes in a mesoscale river basin. We found that sediment load depends on the spatial variability in erosion drivers, as this affects erosion rates and the location and connectivity to the channel of the erosion areas.
Clare Wilkinson, Daniel C. H. Hikuroa, Angus H. Macfarlane, and Matthew W. Hughes
Earth Surf. Dynam., 8, 595–618,Short summary
This review highlights potential contributions that Indigenous knowledge can make to geomorphic research. We evaluate several frameworks and models for including Indigenous knowledge in geomorphic research and discuss how they can be adapted for use with Indigenous communities across the world. We propose that weaving Indigenous knowledge with geomorphic science has the potential to create new solutions and understandings that neither body of knowledge could produce in isolation.
Oliver R. Francis, Tristram C. Hales, Daniel E. J. Hobley, Xuanmei Fan, Alexander J. Horton, Gianvito Scaringi, and Runqiu Huang
Earth Surf. Dynam., 8, 579–593,Short summary
Large earthquakes can build mountains by uplifting bedrock, but they also erode them by triggering large volumes of coseismic landsliding. Using a zero-dimensional numerical model, we identify that the storage of sediment produced by earthquakes can affect surface uplift and exhumation rates across the mountain range. However, the storage also reduces the time span at which the impact of the earthquake can be measured, preventing the recognition of single earthquakes in many long-term records.
Chen Wang, Lennert Schepers, Matthew L. Kirwan, Enrica Belluco, Andrea D'Alpaos, Qiao Wang, Shoujing Yin, and Stijn Temmerman
Earth Surf. Dynam. Discuss.,
Revised manuscript accepted for ESurfShort 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 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.
Alexander R. Groos, Janik Niederhauser, Luise Wraase, Falk Hänsel, Thomas Nauss, Naki Akçar, and Heinz Veit
Earth Surf. Dynam. Discuss.,
Revised manuscript under review for ESurfShort summary
The magnitude of cooling in tropical high mountains during the last glacial period is controversially debated. Here, we report on enigmatic large sorted stone polygons and stripes from the ~ 4000 m high Sanetti Plateau in Ethiopia. Geomorphological features of that size are associated with seasonal or permanent frost and have yet only been described for few locations in the mid and high latitudes. The presence of these features implies a strong tropical cooling at high elevations in the past.
Maxime Mouyen, Philippe Steer, Kuo-Jen Chang, Nicolas Le Moigne, Cheinway Hwang, Wen-Chi Hsieh, Louise Jeandet, Laurent Longuevergne, Ching-Chung Cheng, Jean-Paul Boy, and Frédéric Masson
Earth Surf. Dynam., 8, 555–577,Short summary
Land erosion creates sediment particles that are redistributed from mountains to oceans through climatic, tectonic and human activities, but measuring the mass of redistributed sediment is difficult. Here we describe a new method combining gravity and photogrammetry measurements, which make it possible to weigh the mass of sediment redistributed by a landslide and a river in Taiwan from 2015 to 2017. Trying this method in other regions will help us to better understand the erosion process.
Benjamin Campforts, Veerle Vanacker, Frédéric Herman, Matthias Vanmaercke, Wolfgang Schwanghart, Gustavo E. Tenorio, Patrick Willems, and Gerard Govers
Earth Surf. Dynam., 8, 447–470,Short summary
In this contribution, we explore the spatial determinants of bedrock river incision in the tropical Andes. The model results illustrate the problem of confounding between climatic and lithological variables, such as rock strength. Incorporating rock strength explicitly into river incision models strongly improves the explanatory power of all tested models and enables us to clarify the role of rainfall variability in controlling river incision rates.
Timothée Jautzy, Pierre-Alexis Herrault, Valentin Chardon, Laurent Schmitt, and Gilles Rixhon
Earth Surf. Dynam., 8, 471–484,Short summary
Remote sensing is widely used to document historical fluvial dynamics. However, the geometric error affecting the inferred planform changes can result in undesired geomorphological misinterpretation. Here, we present a novel approach to quantify the uncertainty associated with eroded/deposited surfaces. Concluding that this uncertainty depends on the magnitude and the shape of the surficial changes, restoration programs targeting lateral mobility of streams can benefit from our approach.
Jan de Leeuw, Michael P. Lamb, Gary Parker, Andrew J. Moodie, Daniel Haught, Jeremy G. Venditti, and Jeffrey A. Nittrouer
Earth Surf. Dynam., 8, 485–504,
Arya P. Iwantoro, Maarten van der Vegt, and Maarten G. Kleinhans
Earth Surf. Dynam., 8, 413–429,Short summary
We investigated the effect of tides on the morphodynamic evolution of bifurcations in tide-influenced deltas. Using results from a numerical morphodynamic model (Delft3D), we found that tides cause less asymmetric bifurcations and thereby keep both downstream channels open. Our results explain why avulsion rarely occurs in tide-influenced deltas, whereas it occurs more often in river-dominated deltas.
Katherine R. Barnhart, Eric W. H. Hutton, Gregory E. Tucker, Nicole M. Gasparini, Erkan Istanbulluoglu, Daniel E. J. Hobley, Nathan J. Lyons, Margaux Mouchene, Sai Siddhartha Nudurupati, Jordan M. Adams, and Christina Bandaragoda
Earth Surf. Dynam., 8, 379–397,Short summary
Landlab is a Python package to support the creation of numerical models in Earth surface dynamics. Since the release of the 1.0 version in 2017, Landlab has grown and evolved: it contains 31 new process components, a refactored model grid, and additional utilities. This contribution describes the new elements of Landlab, discusses why certain backward-compatiblity-breaking changes were made, and reflects on the process of community open-source software development.
Filipe Galiforni-Silva, Kathelijne M. Wijnberg, and Suzanne J. M. H. Hulscher
Earth Surf. Dynam., 8, 335–350,Short summary
Storm surges are often related to coastal dune erosion. We found that, for specific coastal settings, storm surges may enhance dune growth rather than only undermine it. Using a computer model and elevation data, we noticed that storm surges could deposit sand onto the sand flat from sand previously deposited closer to the sea. As they move to areas farther from the sea, it becomes easier for the wind to move this sand to the dunes. These findings may help coastal managers and policymakers.
Giovanni Coco, Daniel Calvete, Francesca Ribas, Huib E. de Swart, and Albert Falqués
Earth Surf. Dynam., 8, 323–334,Short summary
Sandbars are ubiquitous features of the surf zone. They are rarely straight and often develop crescentic shapes. Double sandbar systems are also common, but the possibility of feedback between inner and outer sandbars has not been fully explored. The presence of double sandbar systems affects wave transformation and can result in a variety of spatial patterns. Here we model the conditions, waves and initial bathymetry that lead to the emergence of different patterns.
Léo Szewczyk, Jean-Louis Grimaud, and Isabelle Cojan
Earth Surf. Dynam., 8, 275–288,
Dana Ariel Lapides and Michael Manga
Earth Surf. Dynam., 8, 195–210,Short summary
Spring-fed streams throughout volcanic regions of the western United States are wider than runoff-fed streams with similar flow levels. We used high-resolution satellite imagery in combination with flow and climate data to examine the relationship between wood loading and stream width in 38 spring-fed and 20 runoff-fed streams. This study identifies distinct wood dynamics in spring-fed and runoff-fed streams and a strong correlation between stream width and wood length in spring-fed streams.
Alison R. Duvall, Sarah A. Harbert, Phaedra Upton, Gregory E. Tucker, Rebecca M. Flowers, and Camille Collett
Earth Surf. Dynam., 8, 177–194,Short summary
In this study, we examine river patterns and the evolution of the landscape within the Marlborough Fault System, South Island, New Zealand, where the Australian and Pacific tectonic plates collide. We find that faulting, uplift, river capture and the long-lived nature of the drainage network all dictate river patterns at this site. Based on these results and a wealth of previous geologic studies, we propose two broad stages of landscape evolution over the last 25 million years of orogenesis.
Kate C. P. Leary and Daniel Buscombe
Earth Surf. Dynam., 8, 161–172,
Jens Martin Turowski
Earth Surf. Dynam., 8, 103–122,Short summary
Bedrock channels are the conveyor belts of mountain regions, evacuating sediment produced by erosion. Bedrock channel morphology and dynamics affect sediment transport rates and local erosion and set the base level for hillslope response. Here, using mechanistic considerations of the processes of fluvial erosion and transport, and considerations of the mass balance of sediment and bedrock, I discuss the principles governing steady-state channel morphology and the dynamic paths to achieve it.
Jon Schwenk, Anastasia Piliouras, and Joel C. Rowland
Earth Surf. Dynam., 8, 87–102,Short summary
Standing on a riverbank, it is usually obvious which direction the river flows. However, when observing a river from space, we cannot see the flowing water and must use other clues to determine flow directions. For complicated river channel networks like those of deltas and braided rivers, determining the flow direction of each channel within the network is not trivial. We present and demonstrate a method to automatically determine flow directions for each link in aerially viewed river channels.
William H. Booker and Brett C. Eaton
Earth Surf. Dynam., 8, 51–67,Short summary
Using experiments, we found that the form and behaviour of a river depends on its ability to move the larger of its constituents. The manner in which all particles move depends upon the rate and calibre of the supplied material, as well as the rate of supplied water. This goes against the prevailing theory of a single important and representative grain size under depositing conditions, and these results may alter how we interpret river deposits to explain their formation.
Eli D. Lazarus, Kirstin L. Davenport, and Ana Matias
Earth Surf. Dynam., 8, 37–50,Short summary
Scaling relationships mathematically describe how two geometric traits of a geomorphic feature change relative to each other in a systematic way (how length changes with area in drainage basins and sedimentary deposits, for example). Here we demonstrate the emergence of scaling relationships in coastal overwash morphology. These findings may help to predict overwash deposition and offer insight into how spatial patterns in overwash morphology may self-organise.
Martin Jakobsson, Matt O'Regan, Carl-Magnus Mörth, Christian Stranne, Elizabeth Weidner, Jim Hansson, Richard Gyllencreutz, Christoph Humborg, Tina Elfwing, Alf Norkko, Joanna Norkko, Björn Nilsson, and Arne Sjöström
Earth Surf. Dynam., 8, 1–15,Short summary
We studied coastal sea floor terraces in parts of the Baltic Sea using various types of sonar data, sediment cores, and video. Terraces (~1 m high, > 100 m long) are widespread in depths < 15 m and are formed in glacial clay. Our study supports an origin from groundwater flow through silty layers, undermining overlying layers when discharged at the sea floor. Submarine groundwater discharge like this may be a significant source of freshwater to the Baltic Sea that needs to be studied further.
Timothée Sassolas-Serrayet, Rodolphe Cattin, Matthieu Ferry, Vincent Godard, and Martine Simoes
Earth Surf. Dynam., 7, 1041–1057,Short summary
The topographic steady-state assumption is often used in geomorphology. However, recent studies suggest that a drainage network is more mobile than previously thought. Using landscape evolution models, we show that those migrations have a significant impact on basin-wide denudation rates even if an overall topographic steady state is achieved at large scale. Our approach provides new tools to derive minimal uncertainties in basin-scale denudation rates due to this topographic disequilibrium.
Florence Magnin, Bernd Etzelmüller, Sebastian Westermann, Ketil Isaksen, Paula Hilger, and Reginald L. Hermanns
Earth Surf. Dynam., 7, 1019–1040,Short summary
This study proposes the first permafrost (i.e. ground with temperature permanently < 0 °C) map covering the steep rock slopes of Norway. It was created by using rock temperature data collected at the near surface of 25 rock walls spread across the country between 2010 and 2018. The map shows that permafrost mostly exists above 1300–1400 m a.s.l. in southern Norway and close to sea level in northern Norway. The results have strong potential for the study of rock wall sliding and failure.
Michele Delchiaro, Marta Della Seta, Salvatore Martino, Maryam Dehbozorgi, and Reza Nozaem
Earth Surf. Dynam., 7, 929–947,Short summary
This study provides insights into the causes and effects of the largest landslide and related damming that occurred on the emerged Earth surface. Understanding the hazard conditions is important for refining risk mitigation strategies for extreme landslide scenarios. We mapped and dated lacustrine and fluvial terrace sediments constraining the evolutionary model of the valley, thus providing the basis for future studies on the possible seismic trigger for such an extreme case study.
Roberto Fernández, Gary Parker, and Colin P. Stark
Earth Surf. Dynam., 7, 949–968,Short summary
This paper describes the case of a meandering bedrock river with loose sediment on the bed. In such rivers, the sediment hits and erodes the bed as it moves with the flow. We did experiments in a laboratory flume to identify the areas where the sediment moves and those where it deposits. We discovered that the size and location of those areas change with the amount of sediment in the channel and its curvature. The fluctuations of sediment cover over the bed drive the erosion potential.
Gerard Salter, Vaughan R. Voller, and Chris Paola
Earth Surf. Dynam., 7, 911–927,Short summary
Bifurcations are the switches that steer water and sediment in delta and multithread river networks, playing an important role in shaping the landscape. In lab experiments, we found that when the downstream branches grow through time, frequent switching in the water and sediment partitioning occurs. In contrast, once sediment freely exits the downstream boundary, long periods of time when one branch dominates occur; however, unlike our theoretical prediction, these are not permanent.
Noah J. Finnegan, Kiara N. Broudy, Alexander L. Nereson, Joshua J. Roering, Alexander L. Handwerger, and Georgina Bennett
Earth Surf. Dynam., 7, 879–894,Short summary
In some settings, landslides trigger valley blockages that impound huge volumes of sediment, often drastically changing river habitat and habitability. In other settings, landslides appear to have little effect on rivers. In this study, we explore what governs the different sensitivity of rivers to blocking from landslide debris. We accomplish this by comparing two sites in California with dramatic differences in blocking from otherwise similar slow-moving landslides.
Benjamin Purinton and Bodo Bookhagen
Earth Surf. Dynam., 7, 859–877,Short summary
We develop and test new methods for counting pebble-size distributions in photos of gravel-bed rivers. Our open-source algorithms provide good estimates in complex imagery from high-energy mountain rivers. We discuss methods of river cross-section photo collection and processing into seamless georeferenced imagery. Application of a semi-automated version of the algorithm in small patches can be used as validation data for upscaling to entire survey sites using a fully automated version.
Russell T. Bair, Catalina Segura, and Christopher M. Lorion
Earth Surf. Dynam., 7, 841–857,Short summary
Large wood (LW) pieces are often part of fish habitat restoration projects. We investigated reach-scale changes after the addition of LW that are relevant to juvenile coho salmon. A survivable habitat for juvenile coho was characterized in terms of critical swim speed and bed stability. Model predictions showed that survivable habitat increased by 86–128 % in terms of flow velocity and bed stability. Our findings are applicable to stream restoration efforts throughout the Pacific Northwest.
Claire Rault, Alexandra Robert, Odin Marc, Niels Hovius, and Patrick Meunier
Earth Surf. Dynam., 7, 829–839,Short summary
Large earthquakes trigger thousands of landslides in the area of their epicentre. For three earthquake cases, we have determined the position of these landslides along hillslopes. These co-seismic landslides tend to cluster at ridge crests and slope toes. We show that crest clustering is specific to seismic triggering. But although co-seismic landslides locate higher in the landscape than rainfall-induced landslides, geological features strongly modulate their position along the hillslopes.
He Zhang, Emilien Aldana-Jague, François Clapuyt, Florian Wilken, Veerle Vanacker, and Kristof Van Oost
Earth Surf. Dynam., 7, 807–827,Short summary
We evaluated the performance of a drone system to reconstruct 3-D topography. We used a direct georeferencing method to make the pictures have precise coordinates, which also improves the survey efficiency. With both consumer-grade and professional-grade camera and drone setups, we obtained centimetric accuracy, which provides a flexible application in topography remote sensing using drones.
Large earthquakes commonly trigger widespread and destructive landsliding. This paper tests the hypothesis that spatial distributions of earthquake-induced landslides are determined by both the conditions at the time of the triggering earthquake and the legacy of past events. Our findings emphasise that a lack of understanding of the legacy of damage in hillslopes potentially represents an important source of uncertainty when assessing regional landslide susceptibility.
Large earthquakes commonly trigger widespread and destructive landsliding. This paper tests the...