Earth Surface Dynamics最新文献

{"title":"Analysis of autogenic bifurcation processes resulting in river avulsion","authors":"Gabriele Barile, Marco Redolfi, Marco Tubino","doi":"10.5194/esurf-12-87-2024","DOIUrl":"https://doi.org/10.5194/esurf-12-87-2024","url":null,"abstract":"Abstract. River bifurcations are constituent components of multi-thread fluvial systems, playing a crucial role in their morphodynamic evolution and the partitioning of water and sediment. Although many studies have been directed at exploring bifurcation dynamics, the conditions under which avulsions occur, resulting in the complete abandonment of one branch, are still not well understood. To address this knowledge gap, we develop a novel 1D numerical model based on existing nodal point relations for sediment partitioning, which allows for the simulation of the morphodynamic evolution of a free bifurcation. Model results show that when the discharge asymmetry is so high that the shoaling branch does not transport sediments (partial avulsion conditions) the dominant branch undergoes significant degradation, leading to a higher inlet step between the bifurcates and further amplifying the discharge asymmetry. The degree of asymmetry is found to increase with the length of the downstream channels to the point that when they are sufficiently long, the shoaling branch is completely abandoned (full avulsion conditions). To complement our numerical findings, we also formulate a new analytical model that is able to reproduce the essential characteristics of the partial avulsion equilibrium, which enables us to identify the key parameters that control the transition between different configurations. In summary, this research sheds light on the fundamental processes that drive avulsion through the abandonment of river bifurcations. The insights gained from this study provide a foundation for further investigations and may offer valuable information for the design of sustainable river restoration projects.","PeriodicalId":48749,"journal":{"name":"Earth Surface Dynamics","volume":"6 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139422893","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evidence of slow millennial cliff retreat rates using cosmogenic nuclides in coastal colluvium","authors":"Rémi Bossis, Vincent Regard, Sébastien Carretier, Sandrine Choy","doi":"10.5194/egusphere-2023-3020","DOIUrl":"https://doi.org/10.5194/egusphere-2023-3020","url":null,"abstract":"<strong>Abstract.</strong> The erosion of rocky coasts contributes to global cycles of elements over geological times and also constitutes a major hazard that may potentially increase in the future. Yet, it remains a challenge to quantify rocky coast retreat rates over millennia; a time span that encompasses the stochasticity of the processes involved. Specifically, there are no available methods that can be used to quantify slow coastal erosion (&lt; 1 cm yr^-1) averaged over millennia. Here, we use the ¹⁰Be concentration in colluvium, corresponding to the by-product of aerial rocky coast erosion, to quantify the local coastal retreat rate averaged over millennia. We test this approach along the Mediterranean coast of the Eastern Pyrenees (n=8) and the desert coast in Southern Peru (n=3). We observe a consistent relationship between the inferred erosion rates, the geomorphic and climatic contexts. The retreat rates are similar, 0.3–0.5 mm yr^-1 for five samples taken on the Mediterranean coast, whereas one sample located on a cape and two samples from a vegetated colluvium have a lower rate of ~0.1 mm yr^-1. The coastal retreat rate of the drier Peruvian coast is slower at 0.05 mm yr^-1. Although the integration periods of these erosion rates may encompass pre-Holocene times, during which the sea-level and thus the retreat rate were much lower, we conclude here that the associated bias on the inferred retreat rate is less than 80 %. We anticipate that this new method of quantifying slow rocky coastal erosion will fill a major gap in the coastal erosion database and improve our understanding of both coastal erosion factors and hazards.","PeriodicalId":48749,"journal":{"name":"Earth Surface Dynamics","volume":"1 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139462749","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Introducing standardized field methods for fracture-focused surface process research","authors":"Martha Cary Eppes, Alex Rinehart, Jennifer Aldred, Samantha Berberich, Maxwell P. Dahlquist, Sarah G. Evans, Russell Keanini, Stephen E. Laubach, Faye Moser, Mehdi Morovati, Steven Porson, Monica Rasmussen, Uri Shaanan","doi":"10.5194/esurf-12-35-2024","DOIUrl":"https://doi.org/10.5194/esurf-12-35-2024","url":null,"abstract":"Abstract. Rock fractures are a key contributor to a broad array of Earth surface processes due to their direct control on rock strength as well as rock porosity and permeability. However, to date, there has been no standardization for the quantification of rock fractures in surface process research. In this work, the case is made for standardization within fracture-focused research, and prior work is reviewed to identify various key datasets and methodologies. Then, a suite of standardized methods is presented as a starting “baseline” for fracture-based research in surface process studies. These methods have been shown in pre-existing work from structural geology, geotechnical engineering, and surface process disciplines to comprise best practices for the characterization of fractures in clasts and outcrops. This practical, accessible, and detailed guide can be readily employed across all fracture-focused weathering and geomorphology applications. The wide adoption of a baseline of data collected using the same methods will enable comparison and compilation of datasets among studies globally and will ultimately lead to a better understanding of the links and feedbacks between rock fracture and landscape evolution.","PeriodicalId":48749,"journal":{"name":"Earth Surface Dynamics","volume":"48 3 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139102689","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Bedload transport fluctuations, flow conditions, and disequilibrium ratio at the Swiss Erlenbach stream: results from 27 years of high-resolution temporal measurements","authors":"Dieter Rickenmann","doi":"10.5194/esurf-12-11-2024","DOIUrl":"https://doi.org/10.5194/esurf-12-11-2024","url":null,"abstract":"Abstract. Based on measurements with the Swiss plate geophone system with a 1 min temporal resolution, bedload transport fluctuations were analysed as a function of the flow and transport conditions in the Swiss Erlenbach stream. The study confirms a finding from an earlier event-based analysis of the same bedload transport data, which showed that the disequilibrium ratio of measured to calculated transport rate (disequilibrium condition) influences the sediment transport behaviour. To analyse the transport conditions, the following elements were examined to characterise bedload transport fluctuations: (i) the autocorrelation coefficient of bedload transport rates as a function of lag time (memory effect), (ii) the critical discharge at the start and end of a transport event, (iii) the variability in the bedload transport rates, and (iv) a hysteresis index as a measure of the strength of bedload transport during the rising and falling limb of the hydrograph. This study underlines that above-average disequilibrium conditions, which are associated with a larger sediment availability on the streambed, generally have a stronger effect on subsequent transport conditions than below-average disequilibrium conditions, which are associated with comparatively less sediment availability on the streambed. The findings highlight the important roles of the sediment availability on the streambed, the disequilibrium ratio, and the hydraulic forcing in view of a better understanding of the bedload transport fluctuations in a steep mountain stream.","PeriodicalId":48749,"journal":{"name":"Earth Surface Dynamics","volume":"71 1 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139102842","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Stochastic properties of coastal flooding events – Part 1: convolutional-neural-network-based semantic segmentation for water detection","authors":"Byungho Kang, Rusty A. Feagin, Thomas Huff, Orencio Durán Vinent","doi":"10.5194/esurf-12-1-2024","DOIUrl":"https://doi.org/10.5194/esurf-12-1-2024","url":null,"abstract":"Abstract. The frequency and intensity of coastal flooding is expected to accelerate in low-elevation coastal areas due to sea level rise. Coastal flooding due to wave overtopping affects coastal communities and infrastructure; however, it can be difficult to monitor in remote and vulnerable areas. Here we use a camera-based system to measure beach and back-beach flooding as part of the after-storm recovery of an eroded beach on the Texas coast. We analyze high-temporal resolution images of the beach using convolutional neural network (CNN)-based semantic segmentation to study the stochastic properties of flooding events. In the first part of this work, we focus on the application of semantic segmentation to identify water and overtopping events. We train and validate a CNN with over 500 manually classified images and introduce a post-processing method to reduce false positives. We find that the accuracy of CNN predictions of water pixels is around 90 % and strongly depends on the number and diversity of images used for training.","PeriodicalId":48749,"journal":{"name":"Earth Surface Dynamics","volume":"15 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139084559","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Role of the forcing sources in morphodynamic modelling of an embayed beach","authors":"Nil Carrion-Bertran, Albert Falqués, Francesca Ribas, Daniel Calvete, Rinse de Swart, Ruth Durán, Candela Marco-Peretó, Marta Marcos, Angel Amores, Tim Toomey, Àngels Fernández-Mora, Jorge Guillén","doi":"10.5194/egusphere-2023-2721","DOIUrl":"https://doi.org/10.5194/egusphere-2023-2721","url":null,"abstract":"<strong>Abstract.</strong> The sensitivity of a 2DH coastal area (XBeach) and a reduced-complexity (Q2Dmorfo) morphodynamic models to using different forcing sources is studied. The models are tested by simulating the morphodynamic response of an embayed beach in the NW Mediterranean over a 6-month period. Wave and sea level forcing from in-situ data, propagated buoy measurements, hindcasts as well as combinations of these different data sources are used and the outputs are compared to in-situ bathymetric measurements. Results show that when the two models are calibrated with in-situ measurements, they accurately reproduce the morphodynamic evolution with a \"Good\" BSS (Brier Skill Score). The wave data propagated from the buoy also produces reliable morphodynamic simulations but with a slight decrease in BSS. Conversely, when the models are forced with hindcast wave data the mismatch between the modelled and observed beach evolution increases. This is attributed to a large extent to biased mean directions in hindcast waves. Interestingly, in this small tide site the accuracy of the simulations did not depend on the sea-level data source, and using filtered or non-filtered tides also yielded similar results. These results have implications for long-term morphodynamic studies, like those needed to validate models for climate change projections, emphasizing the need of using accurate forcing sources such as those obtained by propagating buoy data.","PeriodicalId":48749,"journal":{"name":"Earth Surface Dynamics","volume":"239 2 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2023-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138826723","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geomorphic risk maps for river migration using probabilistic modeling – a framework","authors":"Brayden Noh, Omar Wani, Kieran B. J. Dunne, Michael P. Lamb","doi":"10.5194/egusphere-2023-2190","DOIUrl":"https://doi.org/10.5194/egusphere-2023-2190","url":null,"abstract":"<strong>Abstract.</strong> Lateral migration of meandering rivers poses erosional risks to human settlements, roads, and infrastructure in alluvial floodplains. While there is a large body of scientific literature on the dominant mechanisms driving river migration, it is still not possible to accurately predict river meander evolution over multiple years. This is in part because we don't fully understand the relative contribution of each mechanism and because deterministic mathematical models are not equipped to account for stochasticity in the system. Besides, uncertainty due to model-structure deficits and unknown parameter values remains. For a more reliable assessment of risks, we, therefore, need probabilistic forecasts. Here, we present a workflow to generate geomorphic risk maps for river migration using probabilistic modeling. We start with a simple geometric model for river migration, where nominal migration rates increase with local and upstream curvature. We then account for model structure deficits using smooth random functions. Probabilistic forecasts for river channel position over time are generated by monte carlo runs using a distribution of model parameter values inferred from satellite data. We provide a recipe for parameter inference within the Bayesian framework. We demonstrate that such risk maps are relatively more informative in avoiding false negatives, which can be both detrimental and costly, in the context of assessing erosional hazards due to river migration. Our results show that with longer prediction time horizons, the spatial uncertainty of erosional hazard within the entire channel belt increases – with more geographical area falling within 25 % &lt; probability &lt; 75 %. However, forecasts also become more confident about erosion for regions immediately in the vicinity of the river, especially on its cut-bank side. Probabilistic modeling thus allows us to quantify our degree of confidence – which is spatially and temporally variable – in river migration forecasts. We also note that to increase the reliability of these risk maps, we need to describe the first-order dynamics in our model to a reasonable degree of accuracy, and simple geometric models do not always possess such accuracy.","PeriodicalId":48749,"journal":{"name":"Earth Surface Dynamics","volume":"1 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2023-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138579792","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Coexistence of two dune scales in a lowland river","authors":"Judith Y. Zomer, Bart Vermeulen, Antonius J. F. Hoitink","doi":"10.5194/esurf-11-1283-2023","DOIUrl":"https://doi.org/10.5194/esurf-11-1283-2023","url":null,"abstract":"Abstract. A secondary scale of bedforms, superimposed on larger, primary dunes, has been observed in fluvial systems worldwide. This notwithstanding, very little is known about the morphological behavior and characteristics of this secondary scale. This study aims to better characterize and understand how two dune scales coexist in fluvial systems and how both scales adapt over time and space, considering their interdependence. The study is based on analysis of a large biweekly multibeam echo sounding dataset from the river Waal, a lowland sand-bedded river. Results reveal that the secondary dune scale is ubiquitous across space and time and not limited to specific flow or transport conditions. Whereas primary dunes lengthen during low flows, secondary dune height, lee slope angle, and length correlate with discharge. Secondary dune size and migration strongly depend on the primary dune lee slope angle and height. Secondary dunes can migrate over the lee slope of low-angled primary dunes, and their height is inversely correlated to the upstream primary dune height and lee slope angle. In the Waal river, a lateral variation in bed grain size, attributed to shipping, largely affects dune morphology. Primary dunes are lower and less often present in the southern lane, where grain sizes are smaller. Here, secondary bedforms are more developed. At peak discharge, secondary bedforms even become the dominant scale, whereas primary dunes entirely disappear but are re-established during lower flows.","PeriodicalId":48749,"journal":{"name":"Earth Surface Dynamics","volume":"24 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2023-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138579796","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Short communication: Concentrated impacts by tree canopy drips – hotspots of soil erosion in forests","authors":"Ayumi Katayama, Kazuki Nanko, Seonghun Jeong, Tomonori Kume, Yoshinori Shinohara, Steffen Seitz","doi":"10.5194/esurf-11-1275-2023","DOIUrl":"https://doi.org/10.5194/esurf-11-1275-2023","url":null,"abstract":"Abstract. The degradation of ground vegetation cover caused by large grazing herbivores frequently results in enhanced erosion rates in forest ecosystems. Splash erosion can be caused by drop impacts with a high throughfall kinetic energy (TKE) from the tree canopy. Notably larger canopy drips from structurally mediated woody surface points appear to induce even higher TKE and generate concentrated impact locations causing severe focus points of soil erosion. However, TKE at these locations has rarely been reported. This pilot study investigated the intensity of TKE at a concentrated impact location and compared it with general TKE locations under the canopy and freefall kinetic energy (FKE) outside the forest. We measured precipitation, TKE and FKE using splash cups at seven locations under Japanese beech trees and five locations outside the forest during the leafless and leafed seasons in 2021 in a mixed forest with evergreen coniferous trees and deciduous broadleaved trees in Japan. The TKE at the concentrated impact location was 15.2 and 49.7 times higher than that at the general locations under the beech and FKE, respectively. This study confirmed that canopy drip from woody surfaces could be a hotspot of soil erosion in temperate forest ecosystems. Throughfall precipitation at the concentrated impact location was 11.4 and 8.1 times higher than that at general locations and freefall, respectively. TKE per 1 mm precipitation (here, “unit TKE”) at the concentrated impact location (39.2 ± 23.7 J m−2 mm−1) was much higher than that at general locations (22.0 ± 12.7 J m−2 mm−1) and unit FKE (4.5 ± 3.5 J m−2 mm−1). Unit TKE in the leafless season was significantly lower than in the leafed season because of fewer redistribution of canopy drips induced only by woody tissue. Nevertheless, unit TKE at the concentrated impact location in the leafless season (36.4 J m−2 mm−1) was still higher than at general locations in the leafed season. These results show that potentially high rates of sediment detachment can be induced not only by throughfall precipitation but also by larger throughfall drop size distributions at the concentrated impact location, even in the leafless season. Further studies with more replication building on this first report are necessary to investigate how many of these concentrated impact locations may occur on average with different tree species to better assess the extent of the erosion risk under forests.","PeriodicalId":48749,"journal":{"name":"Earth Surface Dynamics","volume":"27 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2023-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138568815","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"On the potential of a low-complexity model to decompose the temporal dynamics of soil erosion and sediment delivery","authors":"Francis Matthews, Panos Panagos, Arthur Fendrich, Gert Verstraeten","doi":"10.5194/egusphere-2023-2693","DOIUrl":"https://doi.org/10.5194/egusphere-2023-2693","url":null,"abstract":"<strong>Abstract.</strong> Testing and improving the capacity of soil erosion and sediment delivery models to simulate the intra-annual dynamics climatic drivers and disturbances (e.g. vegetation clearcutting, tillage events, wildfires) is critical to understand the drivers of the system variability. In seasonally changing agricultural catchments, explicit temporal dynamics are typically neglected within many soil erosion modelling approaches, in favour of a focus on the long-term annual average as the predictive target. Here, we approach the trade-off between the need for model simplicity and temporally-dynamic predictions by testing the ability of a low-complexity, spatially distributed model (WaTEM/SEDEM), to decompose the 15-day dynamics of soil erosion and sediment yield. A standardised parameterisation and implementation routine was applied to four well-studied catchments in North-West Europe with open-access validation data. Through the testing of several alternative model spatial and connectivity structures, including the addition of an empirical runoff coefficient, we show that a temporally-static calibration of transport capacity cannot adequately replicate the relative seasonal decoupling of gross (on-site) soil erosion and sediment delivery. Instead, embedding seasonality into the calibration routine significantly improved the model performance, revealing a negative relationship between gross (pixel-scale soil displacement) and net erosion (stream channel sediment load) throughout the year. By incorporating temporal dynamics, the relative net effect is a reduction in the magnitudes of the spatially-distributed sediment fluxes at aggregated timescales, compared to a temporally-lumped approach. Published catchment observations infer that the efficacy of sediment delivery via overland flow is strongly reduced in the summer by abundant vegetative boundaries and increased in the winter via soil crusting and its promotion of runoff. Models operating at temporally-aggregated timescales should account for the possibility of decoupling in time and space between gross erosion and sediment delivery in arable catchment systems, related to alternations between transport- and detachment-limited sediment transport capacity states. Despite the complexities involved in the temporal downscaling of WaTEM/SEDEM, we show the utility of this approach to: 1) identify key missing information components requiring attention to reduce error in gross erosion predictions (e.g. more consideration of antecedent soil conditions), 2) form a basis for strategically adding physical process-representation, with a focus on maintaining low model complexity while improving predictive skill, and 3) better understand the spatial and temporal interdependencies within soil erosion models when undertaking upscaling exercises.","PeriodicalId":48749,"journal":{"name":"Earth Surface Dynamics","volume":"108 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2023-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138568937","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}