Geomorphology最新文献_第4页

Drainage patterns in the Sudetes Mountains (Central Europe) – A clue to understanding polygenetic relief?

IF 3.1 2区地球科学 Q2 GEOGRAPHY, PHYSICAL

Geomorphology

Pub Date : 2025-01-27 DOI: 10.1016/j.geomorph.2025.109637

Piotr Migoń, Kacper Jancewicz, Milena Różycka, Mariusz Szymanowski

The Sudetes range is a topographic unit of protracted history that can be traced back to the Variscan orogeny in the Palaeozoic. After marine inundation in the Late Cretaceous and uplift at the turn of the Cenozoic, a phase of long-term denudation ensued and rock-controlled morphology began to evolve. Differential uplift and subsidence resumed in the Neogene, producing the contemporary horst-and-graben relief with altitude differences exceeding 1000 m. Thus, the present-day topographic diversity is the combined outcome of structure-controlled denudation, vertical displacements, and variable erosional response to uplift modulated by rock resistance, over a timescale of ~60 Ma. However, no systematic attempts were made to disentangle this complex topography and to evaluate the role of lithology and structure versus differential uplift. Here we demonstrate that an analysis of regional fluvial network versus topography may provide important clues, allowing to discriminate between drainage patterns which are well-adjusted to lithology and structure, implicitly of long history, and river reaches that reflect fluvial response to younger tectonic forcing. Three lines of inquiry are explored. First, morphometric properties of main rivers in respect to plan and profile, and of their drainage basins, are analysed. Second, relationships of drainage patterns to the surrounding relief, including analysis of water gaps, styles of fluvial incision, and possible water-divide migrations, are investigated. Third, peculiarities in geometric patterns of drainage networks are identified. We propose that despite an important relief-forming role of the Neogene uplift, tectonic perturbations imposed on the drainage pattern were comparatively minor, no major reorganizations occurred, and much of the present-day fluvial network is inherited from the more distant history. The predominant fluvial response to uplift was continuous valley downcutting, perhaps with minor lateral shifts, although ongoing water-divide migrations are hypothesized for the most elevated parts of the Sudetes, which experienced asymmetric uplift.

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引用次数: 0

Event-driven erosion of a glacial till cliff

IF 3.1 2区地球科学 Q2 GEOGRAPHY, PHYSICAL

Geomorphology

Pub Date : 2025-01-25 DOI: 10.1016/j.geomorph.2025.109626

Jan-Eike Rossius , Tanita Averes , Knut Krämer , Christian Winter

Soft-rock cliff coasts are eroded by various mechanisms. Marine erosion occurs during storm surges and is linked to increased water levels and wave heights while terrestrial erosion by mass movements is affected by precipitation. This study aims at improving the system understanding of soft-rock cliffs by quantifying observed erosion and the boundary conditions necessary for marine erosion and relating terrestrial erosion to certain prerequisites and weather conditions at a glacial till cliff at the German Baltic Sea coast. The changes at the cliff are quantified using digital elevation models obtained from about monthly drone surveys over a period of four years. Marine and terrestrial erosion both occur mostly in winter and set the mutual preconditions. For terrestrial erosion, precipitation is the main enabling factor, a clear quantification is however difficult. For marine erosion, a threshold based on water level and significant wave height is quantified. With a certain increase in water level, a single event is more likely to surpass that threshold than with the same increase in wave height. Moreover, the effects of the exceptionally severe storm Babet in October 2023 are quantified: It eroded more than all other storms during the study period combined and about as much as would be eroded within seven normal years. The findings exemplify a high vulnerability of soft-rock cliffs to sea-level rise and future storm events.

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引用次数: 0

A pre-Pliocene origin of the glacial trimline in the Ellsworth Mountains and the prevalence of old landscapes at high elevations in West Antarctica

IF 3.1 2区地球科学 Q2 GEOGRAPHY, PHYSICAL

Geomorphology

Pub Date : 2025-01-24 DOI: 10.1016/j.geomorph.2025.109634

David Small , Michael J. Bentley , Stewart P.H.T. Freeman , Angel Rodés , Sheng Xu

A glacial trimline at high elevations in West Antarctica informs on previous warm-based glaciation that occurred during an earlier stage of Antarctic Ice Sheet evolution. A multi-million-year history of theses landscapes has previously been evidenced in a few disparate locations. Here we present new cosmogenic nuclide analyses (¹⁰Be and ²⁶Al) from a total of 60 samples (clasts and bedrock) at high elevations in several hard-to-access locations across the interior of West Antarctica. In the Sentinel Range of the Ellsworth Mountains this trimline occurs at the highest elevations of any sites in West Antarctica (~3000 m asl). These new data reveal that clasts and bedrock, both above and below the trimline, have long exposure histories with minimum exposure-burial histories of 0.9–2.6 Ma. Accounting for low rates of erosion extends these exposure-burial histories to 2.7–4.8 Ma. Under the assumption of cyclical exposure-burial for proportions of glacial-interglacial cycles we show that some of our samples have exposure-burial histories extending back to the Miocene. We also present new data from the nearby Heritage Range where our new data supports previous work potentially extends the inferred persistence of the location of the West Antarctic ice sheet divide to >2.1 Ma. Finally, we present new data from two isolated nunataks (Mount Woollard and Mount Johns) located deep in the interior of the West Antarctic Ice Sheet near the main ice divide. Paired nuclide analyses of samples from these nunataks also shows long exposure histories and unambiguous evidence of past burial within the last ~100 ka. Such a thickening is not currently represented in ice-sheet models.

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引用次数: 0

An archaoseismological investigation of the footprints of human resilience to seismic shaking from the alluvial plains of Gujarat, Western India

IF 3.1 2区地球科学 Q2 GEOGRAPHY, PHYSICAL

Geomorphology

Pub Date : 2025-01-23 DOI: 10.1016/j.geomorph.2025.109631

Aashna Tandon , S.P. Prizomwala , Tarun Solanki , Abhijit Ambekar , Rakesh Nikam , Pradeep Srivastava , Sumer Chopra

The town of Vadnagar, located on a prominent geomorphic surface ∼ Gujarat Alluvial Plains (GAP) of western India, presents unabetted human occupation for the last 2754 years. An integrated archaeoseismological study (involving tectonogeomorphology, geophysical and geoarchaeological investigation) in the Cambay basin led to the identification of a previously un-noticed the reverse splay fault for the first time with the evidence of the surface rupture in the GAP region. The present study based on electrical resistivity tomography (ERT) and previous investigation of magnetotulleric geophysical surveys in the vicinity, demonstrates it to be the ruptured splay of the East Margin Cambay Basin Fault. The timing of the event is constrained ∼1200–2000 years Before Present (BP) using optical dating, whereas archaeological findings briefs it around 9th – 10th Century CE. Additionally, based on the various empirical relationships between magnitude and maximum displacement of 1.6 m observed in the trench, the magnitude of the event was constrained at M_w 7 ± 0.3. In addition to this, our investigation in the vicinity of the site reveals the tectono-geomorphic expressions of the identified Vadnagar Fault and associated archaeological seismic deformations (i.e. collapsed structures, tilted, and rotated wall fragments) along the hanging wall. The presence of timber-bondings in masonry walls (1st – 4th century CE) suggests earthquake resistant structural know-how in Vadnagar as one of the oldest in Asia. We invite more in-depth scrutiny by seismologists and geologists for assessing the realistic hazard of GAP in light of this new seismic source and the human resilience to earthquakes.

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引用次数: 0

Hillslope surface classification from elevation models by using normal vectors

IF 3.1 2区地球科学 Q2 GEOGRAPHY, PHYSICAL

Geomorphology

Pub Date : 2025-01-23 DOI: 10.1016/j.geomorph.2025.109614

Guanghui Hu , Sijin Li , Liyang Xiong , Guoan Tang

Hillslope surface classification via digital terrain analysis (DTA) is a current research focus in geomorphology and geographic information science (GIS) studies. However, traditional methods are generally based on raster digital elevation models (DEMs) and window difference methods, which suffer from terrain description and analysis scale mismatch issues. In this study, we propose a hillslope surface classification approach based on the vector structure. Triangulated irregular networks (TINs) are used as an example. Benefiting from free sampling with TINs, we apply terrain surface reconstruction to the original point cloud or DEM and then calculate the terrain derivatives based on the normal vectors of the optimized TINs. Finally, the fuzzy inference method is used to classify hillslope surface elements. We select two cases to evaluate the proposed method: a small watershed with dense point cloud data and a large region with complex landforms and a 30 m resolution Copernicus DEM. The results show that the proposed approach can effectively reduce the influence of DEM errors on classification and mitigate the scale mismatching problem in terrain generalization and analysis. A novel hillslope surface classification method with a new data structure is proposed to extend the application of vector methods and structures in DTA and GIS.

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引用次数: 0

Delineating individual alluvial fans and morphological analysis based on digital elevation models

IF 3.1 2区地球科学 Q2 GEOGRAPHY, PHYSICAL

Geomorphology

Pub Date : 2025-01-23 DOI: 10.1016/j.geomorph.2025.109629

Xingyu Zhou, Yang Chen, Wenjie Sun, Xin Yang, Yanxiang Wang, Chenrui Li, Guoan Tang

Alluvial fans are common landforms deposited by streams and/or debris flows. Multiple fans can overlap and connect with each other, developing a bajada. Currently, studies about the evolutionary process of alluvial landscapes and environmental changes in arid areas urgently need clear, detailed and object-based evaluation within bajadas. However, existing methods still struggle to divide these alluvial slopes into individual fans. Accordingly, we proposed a novel method for delineating individual alluvial fans based on free digital elevation models. This method incorporated multi-directional hillshades to accurately extract alluvial slopes, and two flow direction algorithms to support the delineation of individual fans. The method was tested in Death Valley, where a total of 89 individual fans were delineated for morphological analysis. Our result demonstrated high accuracy validated by a Landset-9 L2 satellite image, with an intersection over union (IoU) of 95.51 % for alluvial slopes and a mean IoU of 86.19 % for individual fans, and it also aligned well with the geological map. Additionally, based on the delineated individual fans, we computed morphological features, distinguished the surface differences of both sides and analyzed the feature correlations. Overall, this study accomplished the delineation of individual fans and provided a viable solution for the automated and large-scale mapping of arid alluvial landscapes. The delineated results can act as the foundation for research about the evolutionary process and genetic mechanisms of alluvial fans, and provide opportunities for understanding the tectonic activities, sediment deposition and erosion process and environmental changes in arid regions.

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引用次数: 0

Microscale fluvial landscape evolution and its impacts on early human settlement at the Shangshan cultural site in the upper Qiantang region, eastern China

IF 3.1 2区地球科学 Q2 GEOGRAPHY, PHYSICAL

Geomorphology

Pub Date : 2025-01-23 DOI: 10.1016/j.geomorph.2025.109630

Wenjia Zhang , Zhou Lin , Guoping Zhang , Leping Jiang , Meiling Chen , Shengchao Zhou , Yuchen Zhang , Xiang Zhao

Detailed reconstruction of the evolution of fluvial landscapes is important for understanding early human settlement where habitats may be influenced by local river processes. Based on high-resolution geomorphological mapping and sedimentological analyses from five trenches, we reconstructed the geomorphic processes before and after the Shangshan period (10–8.5 ka BP) at the Pujiang Shangshan site in the upper Qiantang region, home to the earliest known rice agricultural population in eastern China. Excavation of paleochannel sediments and analysis of geomorphological features revealed that a migrating river channel and floodplain began developing at least ca. 16 ka cal BP, following extensive eolian sedimentation. By this time, terraces (Q₂) formed by the accretion of middle Pleistocene alluvium, had been established, providing ideal Shangshan settlement locations. The Q₂ terrace at that time was 5–8 m above the riverbed. Moreover, the identification of later Holocene, small-scale (1–2 m) terraces (Q₄), and sedimentary evidence indicate that after the Shangshan occupation, the floodplain experienced prolonged aggradation and channel migration. These river activities greatly altered the fluvial landscapes, reducing both the dimensions of the occupied terrace and its height difference from the riverbed. Our reconstruction reveals that two major aggradations occurred during the late Pleistocene and middle to late Holocene, with dominant lateral accretion observed in the fluvial plain construction of the upper Qiantang region. The aggradational river systems, characterized by wide floodplains and elevated Q₂ terraces, provided favorable conditions for rice cultivation and living spaces for early humans, which likely contributed to the emergence of a sedentary agricultural society in eastern China. These results emphasize the importance of river processes in shaping human settlement patterns in the lower Yangtze region and offer insights into Holocene human-environmental relationships. We suggest that similar methodologies can be employed to reconstruct geomorphic processes at other riverine archaeological sites.

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引用次数: 0

Mitigating scour around bridge piers in alluvial channels using inclined collars

IF 3.1 2区地球科学 Q2 GEOGRAPHY, PHYSICAL

Geomorphology

Pub Date : 2025-01-21 DOI: 10.1016/j.geomorph.2025.109619

Hossein Hamidifar , Seyed Mohammad Amin Kowsar

Effective mitigation of scour around bridge piers is crucial not only for ensuring structural stability but also for managing the morphological changes in rivers. This study investigates the effectiveness of various collar configurations in mitigating local scour around a cylindrical bridge pier, focusing on the impact of collar inclination and position on scour reduction. Experiments were conducted in a laboratory flume, examining the effects of two collar positions including at the bed-level and buried, four orientations including horizontal, upward, downward, and sideward, and four collar vertical inclination angles including 0°(horizontal), 15°, 30°, and 45°. The maximum scour hole depth, volume, and area, and its longitudinal profile were compared with a baseline no-collar condition. The 15° downward inclined buried collar achieved the largest reductions, with maximum scour depth decreasing by approximately 47.14 % compared to the no-collar setup, 25.40 % compared to the horizontal collar at bed level, and 15.53 % compared to the horizontally buried collar. The 15° upward inclined collar was also effective, though slightly less so than the downward inclination. Results also indicate that the 15° upward and downward inclined buried collar provided the most substantial reductions in scour volume and scoured-bed area compared to the no-collar condition. These reductions underscore the ability of inclined collars to minimize both the depth and lateral spread of scour, providing a more comprehensive mitigation solution. The study also includes a comparative analysis with existing models and introduces a newly developed regression-based equation that outperforms previous models, providing a more reliable tool for practical applications. These findings highlight the potential of tailored collar designs to enhance scour protection around bridge piers, with implications for improved structural resilience in hydraulic engineering.

{"title":"Mitigating scour around bridge piers in alluvial channels using inclined collars","authors":"Hossein Hamidifar , Seyed Mohammad Amin Kowsar","doi":"10.1016/j.geomorph.2025.109619","DOIUrl":"10.1016/j.geomorph.2025.109619","url":null,"abstract":"<div><div>Effective mitigation of scour around bridge piers is crucial not only for ensuring structural stability but also for managing the morphological changes in rivers. This study investigates the effectiveness of various collar configurations in mitigating local scour around a cylindrical bridge pier, focusing on the impact of collar inclination and position on scour reduction. Experiments were conducted in a laboratory flume, examining the effects of two collar positions including at the bed-level and buried, four orientations including horizontal, upward, downward, and sideward, and four collar vertical inclination angles including 0°(horizontal), 15°, 30°, and 45°. The maximum scour hole depth, volume, and area, and its longitudinal profile were compared with a baseline no-collar condition. The 15° downward inclined buried collar achieved the largest reductions, with maximum scour depth decreasing by approximately 47.14 % compared to the no-collar setup, 25.40 % compared to the horizontal collar at bed level, and 15.53 % compared to the horizontally buried collar. The 15° upward inclined collar was also effective, though slightly less so than the downward inclination. Results also indicate that the 15° upward and downward inclined buried collar provided the most substantial reductions in scour volume and scoured-bed area compared to the no-collar condition. These reductions underscore the ability of inclined collars to minimize both the depth and lateral spread of scour, providing a more comprehensive mitigation solution. The study also includes a comparative analysis with existing models and introduces a newly developed regression-based equation that outperforms previous models, providing a more reliable tool for practical applications. These findings highlight the potential of tailored collar designs to enhance scour protection around bridge piers, with implications for improved structural resilience in hydraulic engineering.</div></div>","PeriodicalId":55115,"journal":{"name":"Geomorphology","volume":"473 ","pages":"Article 109619"},"PeriodicalIF":3.1,"publicationDate":"2025-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143137872","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}

引用次数: 0

Microstructural analysis of sandstone from Pravcicka brana, the largest rock arch in Europe

IF 3.1 2区地球科学 Q2 GEOGRAPHY, PHYSICAL

Geomorphology

Pub Date : 2025-01-21 DOI: 10.1016/j.geomorph.2025.109617

M. Maľa , V. Greif , M. Slavík , M. Lanzendörfer

This study uses a multi-method approach to perform a comprehensive microstructural analysis and to discuss the resistance to various weathering processes of sandstone from Pravčická brána, the largest sandstone arch in Europe. In addition to conventionally used methods of sample testing such as mercury intrusion porosimetry, we focused on experimental and non-destructive sample testing such as pore network modelling and permeability simulation based on post-processed μCT images or saturation flow experiments using non-Newtonian fluids - ANA method. These methods showed consistent pore size distribution (PSD) peaks at 18 μm (ANA), 22 μm (PNM) and 48 μm (MIP). The sandstone exhibited high total porosity (34–45 %) and effective porosity (30–42 %), with a network predominantly composed of macropores (>50 nm) that are readily accessible to water. Laboratory tests yielded a permeability of 3.1 × 10–⁵ m.s-¹, which is close to the simulated value of 2.21 × 10–⁵ m.s-¹. Scanning electron microscopy (SEM) analysis identified features such as quartz grain fractures that were attributed to past frost weathering processes. Analysis of the PSD indicated high resistance of the sandstone studied to freeze-thaw and salt weathering. However, when considering other factors, such as mechanical and hydraulic properties and tectonic predisposition in the arch body, the vulnerability of Pravčická brána becomes more evident. The susceptibility of Pravčická brána sandstone to weathering is increased by its low strength (as evident from previous studies), which is further reduced by ongoing weathering, while the presence of the observed macropores increases the likelihood of fracturing under deformation. This study highlights the need to integrate advanced techniques with traditional methods to provide a comprehensive assessment of sandstone durability.

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引用次数: 0

Characterizing barchan dune interactions based on high-resolution remote sensing imagery

IF 3.1 2区地球科学 Q2 GEOGRAPHY, PHYSICAL

Geomorphology

Pub Date : 2025-01-21 DOI: 10.1016/j.geomorph.2025.109608

Ning Jiang, Li Jiang, Xintong Wu, Dazhi Wang, Hong Cheng

Variations in the migration rates of barchan dunes of different sizes make dune merging and separation a prevalent phenomenon that is essential for controlling the scale of barchan dune swarms and regulating the evolutionary patterns of dune fields. However, existing research relies predominantly on numerical simulations or flume experiments. The morphology and migration characteristics of barchan dunes at various stages of merging or separation in natural settings and their responses to wind conditions still need to be explored. To examine the types and morphological and migratory characteristics of barchan dunes across different merging and separation phases while elucidating the impacts of wind conditions, dune morphology, and relative positions of barchan dunes on these processes, we used high-resolution remote sensing images and extended time series meteorological data. The main conclusions are as follows: (1) The mering types of barchan dunes include lateral, offset, and coaxial merging. The separation types include lateral splitting, separation from the leeward slope, and separation from the horn. (2) The barchan dune migration rate at different merging or separation stages was logarithmically negatively correlated with the dune basal area. The migration distance of a barchan dune under a specific wind force can be expressed by the ratio of the resultant wind force to the dune height, and their fitting parameters differed in the process of isolation → merging → separation. (3) Under a certain wind condition, when the migration distance of the upwind barchan is greater than the sum of the migration distance of the downwind barchan and the distance between the two dunes, two adjacent isolated dunes merge. According to the height and distance of adjacent isolated dunes, the wind force required for dune merging can be judged by Eq. (6). (4) There was a power function relationship between lateral spacing factor and dune size factor and a logarithmic positive correlation between longitudinal spacing factor and dune size factor of barchans in the merging state. However, the fitting parameters changed with dune coalescence and separation, which could be used to predict whether the merging dunes would separate again.

{"title":"Characterizing barchan dune interactions based on high-resolution remote sensing imagery","authors":"Ning Jiang, Li Jiang, Xintong Wu, Dazhi Wang, Hong Cheng","doi":"10.1016/j.geomorph.2025.109608","DOIUrl":"10.1016/j.geomorph.2025.109608","url":null,"abstract":"<div><div>Variations in the migration rates of barchan dunes of different sizes make dune merging and separation a prevalent phenomenon that is essential for controlling the scale of barchan dune swarms and regulating the evolutionary patterns of dune fields. However, existing research relies predominantly on numerical simulations or flume experiments. The morphology and migration characteristics of barchan dunes at various stages of merging or separation in natural settings and their responses to wind conditions still need to be explored. To examine the types and morphological and migratory characteristics of barchan dunes across different merging and separation phases while elucidating the impacts of wind conditions, dune morphology, and relative positions of barchan dunes on these processes, we used high-resolution remote sensing images and extended time series meteorological data. The main conclusions are as follows: (1) The mering types of barchan dunes include lateral, offset, and coaxial merging. The separation types include lateral splitting, separation from the leeward slope, and separation from the horn. (2) The barchan dune migration rate at different merging or separation stages was logarithmically negatively correlated with the dune basal area. The migration distance of a barchan dune under a specific wind force can be expressed by the ratio of the resultant wind force to the dune height, and their fitting parameters differed in the process of isolation → merging → separation. (3) Under a certain wind condition, when the migration distance of the upwind barchan is greater than the sum of the migration distance of the downwind barchan and the distance between the two dunes, two adjacent isolated dunes merge. According to the height and distance of adjacent isolated dunes, the wind force required for dune merging can be judged by Eq. <span><span>(6)</span></span>. (4) There was a power function relationship between lateral spacing factor and dune size factor and a logarithmic positive correlation between longitudinal spacing factor and dune size factor of barchans in the merging state. However, the fitting parameters changed with dune coalescence and separation, which could be used to predict whether the merging dunes would separate again.</div></div>","PeriodicalId":55115,"journal":{"name":"Geomorphology","volume":"473 ","pages":"Article 109608"},"PeriodicalIF":3.1,"publicationDate":"2025-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143137965","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}

引用次数: 0