Earth Surface Dynamics最新文献

{"title":"Optimization of passive acoustic bedload monitoring in rivers by signal inversion","authors":"Mohamad Nasr, Adele Johannot, Thomas Geay, Sebastien Zanker, Jules Le Guern, Alain Recking","doi":"10.5194/esurf-12-117-2024","DOIUrl":"https://doi.org/10.5194/esurf-12-117-2024","url":null,"abstract":"Abstract. Recent studies have shown that hydrophone sensors can monitor bedload flux in rivers by measuring the self-generated noise (SGN) emitted by bedload particles when they impact the riverbed. However, experimental and theoretical studies have shown that the measured SGN depends not only on bedload flux intensity but also the propagation environment, which differs between rivers. Moreover, the SGN can propagate far from the acoustic source and be well measured at distant river positions without bedload transport. It has been shown that this dependency of the measured SGN data on the propagation environment can significantly affect the performance of monitoring bedload flux by hydrophone techniques. In this article, we propose an inversion model to solve the problem of the SGN propagation and integration effect. In this model, we assume that the riverbed acts as SGN source areas with intensity proportional to the local bedload flux. The inversion model locates the SGN sources and calculates their corresponding acoustic power by solving a system of linear algebraic equations, accounting for the actual measured cross-sectional acoustic power (acoustic mapping) and attenuation properties. We tested the model using data from measured bedload SGN profiles (acoustic mapping with a drift boat) and bedload flux profiles (direct sampling with an Elwha sampler) acquired during two field campaigns conducted in 2018 and 2021 on the Giffre river in the French Alps. Results confirm that the bedload flux measured at different verticals on the river cross-section correlates more with the inversed acoustic power than measured acoustic power. Moreover, it was possible to fit data from the two field campaigns with a common curve after inversion, which was not possible with the measured acoustic data. The results of the inversion model, compared to measured data, show the importance of considering the propagation effect when using the hydrophone technique and offer new perspectives for the calibration of bedload flux with SGN in rivers.","PeriodicalId":48749,"journal":{"name":"Earth Surface Dynamics","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139462321","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 2: Probabilistic analysis","authors":"Byungho Kang, Rusty A. Feagin, Thomas Huff, Orencio Durán Vinent","doi":"10.5194/esurf-12-105-2024","DOIUrl":"https://doi.org/10.5194/esurf-12-105-2024","url":null,"abstract":"Abstract. Low-intensity but high-frequency coastal flooding, also known as nuisance flooding, can negatively affect low-lying coastal communities with potentially large socioeconomic effects. Partially driven by wave runup, this type of flooding is difficult to predict due to the complexity of the processes involved. Here, we present the results of a probabilistic analysis of flooding events measured on an eroded beach at the Texas coast. A high-resolution time series of the flooded area was obtained from pictures using convolutional neural network (CNN)-based semantic segmentation methods, as described in the first part of this contribution. After defining flooding events using a peak-over-threshold method, we found that their size follows an exponential distribution. Furthermore, consecutive flooding events were uncorrelated at daily timescales but correlated at hourly timescales, as expected from tidal and day–night cycles. Our measurements confirm the broader findings of a recent multi-site investigation of the probabilistic structure of high-water events that used a semi-empirical formulation for wave runup. Indeed, we found a relatively good statistical agreement between our CNN-based empirical flooding data and predictions using total-water-level estimations. As a consequence, our work supports the validity of a relatively simple probabilistic model of high-frequency coastal flooding driven by wave runup that can be used in coastal risk management and landscape evolution models.","PeriodicalId":48749,"journal":{"name":"Earth Surface Dynamics","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139420806","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":"Field monitoring of pore water pressure in fully and partly saturated debris flows at Ohya landslide scar, Japan","authors":"Shunsuke Oya, Fumitoshi Imaizumi, Shoki Takayama","doi":"10.5194/esurf-12-67-2024","DOIUrl":"https://doi.org/10.5194/esurf-12-67-2024","url":null,"abstract":"Abstract. The characteristics of debris flows (e.g., mobility, sediment concentration, erosion, and deposition of sediment) are dependent on the pore water pressure in the flows. Therefore, understanding the magnitude of pore water pressure in debris flows is essential for improving debris flow mitigation measures. Notably, the pore water pressure in a partly saturated flow, which contains an unsaturated layer in its upper part, has not been previously understood due to a lack of data. The monitoring performed in Ohya landslide scar, central Japan, allowed us to obtain the data on the pore water pressure in fully and partly saturated flows during four debris flow events. In some partly and fully saturated debris flows, the pore water pressure at the channel bed exceeded the hydrostatic pressure of clean water. The depth gradient of the pore water pressure in the lower part of the flow, monitored using water pressure sensors at multiple depths, was generally higher than the depth-averaged gradient of the pore water pressure from the channel bed to the surface of the flow. The low gradient of the pore water pressure in the upper part of partly saturated debris flows may be affected by the low hydrostatic pressure due to unsaturation of the flow. Bagnold number, Savage number, and friction number indicated that frictional force dominated in the partly saturated debris flows. Excess pore water pressure was observed in the lower part of partly saturated surges. The excess pore water pressure may have been generated by the contraction of interstitial water and have been maintained due to low hydraulic diffusivity in debris flows. The pore water pressure at the channel bed of fully saturated flow was generally similar to the hydrostatic pressure of clean water, while some saturated surges portrayed higher pore water pressure than the hydrostatic pressure. The travel distance of debris flows, investigated by the structure-from-motion technique using uncrewed aerial vehicle (UAV-SfM) and the monitoring of time-lapse cameras, was long during a rainfall event with high intensity even though the pore water pressure in the flow was not significantly high. We conclude that the excess pore water pressure is present in many debris flow surges and an important mechanism in debris flow surge behaviors.","PeriodicalId":48749,"journal":{"name":"Earth Surface Dynamics","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139411580","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":"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":null,"pages":null},"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":null,"pages":null},"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":null,"pages":null},"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":null,"pages":null},"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":null,"pages":null},"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":null,"pages":null},"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":null,"pages":null},"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}