Geomorphology最新文献_第6页

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.

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引用次数: 0

Impact of landslides activity on changes in the composition of alluvia and morphometric changes in stream beds on the example of the Polish Outer Carpathians

IF 3.1 2区地球科学 Q2 GEOGRAPHY, PHYSICAL

Geomorphology

Pub Date : 2025-01-21 DOI: 10.1016/j.geomorph.2025.109618

Jarosław Cebulski

An important aspect of the function of slope and fluvial processes is their interaction. Riverside landslides are more active than other landslides due to an additional activating factor in the form of fluvial erosion of landslide fronts. Another type of interaction is the change in particle size composition of the alluvium through colluvium supplied to riverbeds. This paper considers the effect of active landslides on the change in particle size composition in the alluvium below the landslides. The effect of active landslides on the change in channel morphometry at the site of the resulting landslides was also determined. Five sections of the channels of small streams were selected for the study: three were in low mountain areas - Rożnowskie Foothills, and two in middle mountain areas - Beskid Niski Mts. Material from the riverbeds and landslides was sampled twice, first immediately after a flood and second a year later after a period without a flood. The material was analysed using laser diffraction. The volume of colluvium supplied to the riverbed was measured using terrestrial laser scanning. The results show a significant effect of colluvium influx on the particle size composition of the alluvium by increasing the proportion of the very fine fraction: clay and silt. The highest proportion of material from landslides in the composition of alluvium was noted immediately below each given landslide. Further downstream this proportion decreased and then declined to zero after 190 to 450 m. Differences in the particle size composition of alluvium depending on the time of sampling were also observed. In the material sampled immediately after the landslide occurrence, significantly more of the fine fraction component was registered, i.e. the impact of landslides was higher.

{"title":"Impact of landslides activity on changes in the composition of alluvia and morphometric changes in stream beds on the example of the Polish Outer Carpathians","authors":"Jarosław Cebulski","doi":"10.1016/j.geomorph.2025.109618","DOIUrl":"10.1016/j.geomorph.2025.109618","url":null,"abstract":"<div><div>An important aspect of the function of slope and fluvial processes is their interaction. Riverside landslides are more active than other landslides due to an additional activating factor in the form of fluvial erosion of landslide fronts. Another type of interaction is the change in particle size composition of the alluvium through colluvium supplied to riverbeds. This paper considers the effect of active landslides on the change in particle size composition in the alluvium below the landslides. The effect of active landslides on the change in channel morphometry at the site of the resulting landslides was also determined. Five sections of the channels of small streams were selected for the study: three were in low mountain areas - Rożnowskie Foothills, and two in middle mountain areas - Beskid Niski Mts. Material from the riverbeds and landslides was sampled twice, first immediately after a flood and second a year later after a period without a flood. The material was analysed using laser diffraction. The volume of colluvium supplied to the riverbed was measured using terrestrial laser scanning. The results show a significant effect of colluvium influx on the particle size composition of the alluvium by increasing the proportion of the very fine fraction: clay and silt. The highest proportion of material from landslides in the composition of alluvium was noted immediately below each given landslide. Further downstream this proportion decreased and then declined to zero after 190 to 450 m. Differences in the particle size composition of alluvium depending on the time of sampling were also observed. In the material sampled immediately after the landslide occurrence, significantly more of the fine fraction component was registered, i.e. the impact of landslides was higher.</div></div>","PeriodicalId":55115,"journal":{"name":"Geomorphology","volume":"477 ","pages":"Article 109618"},"PeriodicalIF":3.1,"publicationDate":"2025-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143551131","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

Spatial distribution of landslides triggered by the 2022 Taitung Earthquakes in relation to active fault systems, topographic effects, and geological conditions

IF 3.1 2区地球科学 Q2 GEOGRAPHY, PHYSICAL

Geomorphology

Pub Date : 2025-01-20 DOI: 10.1016/j.geomorph.2025.109615

Chi-Wen Chen , Lun-Wei Wei , Ryuji Yamada , Tomoyuki Iida

In September 2022, eastern Taiwan was shaken by a series of earthquakes, known as the 2022 Taitung earthquakes. A total of 45 landslides were triggered by the earthquakes, and the frequency-area distribution revealed a scarcity of small- and large-scale landslides. Most of the landslides were moderate in scale, with areas ranging from 10³ to 10⁴ m². We examined the relationship between the landslide distribution and earthquake source faults. The distances between landslides and active faults ranged from 0.82 to 17.65 km. The results allowed us to infer parameters of the source faults and the magnitudes of the earthquakes using a model proposed in a previous study, which aligns with the real situation. Furthermore, we analyzed the topographic and geological conditions associated with landslide distribution. We found that most landslides occurred on mid-hillsides or in close proximity to streams, in contrast to the findings of previous studies that highlighted ridge areas as the primary locations of coseismic landslides. As the source fault in this study is situated in a valley, with a flat plain on both sides, only six landslides occurred within 3 km of the fault. Seismic waves transmitted to distant mountains were attenuated and lacked the strength to have amplification on ridges. Because the seismic waves failed to reach higher mountains, the landslides predominantly occurred at lower elevations on steep slopes with more fragile geological conditions. Based on the comprehensive conditions of fault type and surrounding topography and geology, the landslides mostly occurred on mid-hillsides rather than on ridges.

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引用次数: 0

Evolution of the proto-Weihe River system during the Eocene–Oligocene: Evidence from sediment provenance of the Weihe Basin

IF 3.1 2区地球科学 Q2 GEOGRAPHY, PHYSICAL

Geomorphology

Pub Date : 2025-01-20 DOI: 10.1016/j.geomorph.2025.109616

Zeyu Chen, Hanzhi Zhang, Huayu Lu, Fan Lyu, Hengzhi Lyu, Ruixue Gao, Yang Chen, Mengying Wu

The Weihe River, originating from the northeastern Tibetan Plateau, is one of the most important tributaries of the Yellow River. The Cenozoic evolution of the Weihe River provides critical insights into the geomorphologic uplift of the northeastern Tibetan Plateau, and the drainage evolution of the Yellow River. However, the Paleogene evolution of the Weihe River remains poorly understood. The Weihe Basin, located adjacent to the northeast of the Tibetan Plateau and at the lower reaches of the Weihe River, preserved continuous sediments record spanning from the middle Eocene to the Oligocene. Source to sink analysis offers valuable evidence for deciphering regional drainage evolution. This study investigates the sediment provenance of the Eocene-Oligocene sedimentary strata in the Weihe Basin and its temporal variations, employing detrital zircon UPb dating on 19 new samples alongside sedimentary analyses. We find that the regional river drainage underwent two evolutionary of stages during this period. During the Eocene (ca. 46–34 Ma), the Weihe Basin was characterized by a shallow lacustrine environment, receiving clastic materials primarily from the surrounding areas. By the early Oligocene (ca. 34–31.7 Ma), contributions from the modern upper reaches of the Weihe River increased. This suggested that the proto-Weihe River system began to form during the Oligocene, exhibiting a pattern that closely resembles its modern configuration. This drainage evolution was mainly controlled by tectonic deformation of the northeastern Tibetan Plateau, and enhancement in headwards erosion due to increased precipitation.

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引用次数: 0

New insights into geomorphological and tectonic processes in the Gulf of Tehuantepec and constraints on tsunami generation

IF 3.1 2区地球科学 Q2 GEOGRAPHY, PHYSICAL

Geomorphology

Pub Date : 2025-01-19 DOI: 10.1016/j.geomorph.2025.109612

Diego A. Aguilar-Anaya , Carlos A. Mortera-Gutiérrez , Christian Berndt , William L. Bandy

Earthquakes can cause tsunamis by rapidly deforming the seafloor or triggering submarine slope failures. The intraplate earthquake in the Gulf of Tehuantepec on September 8, 2017 generated a tsunami that did not match the predicted tsunami run-up heights and distributions, indicating a possible additional slope failure. An oceanographic expedition, TEHUANTEPEC19, was carried out between May and June 2019, onboard the El Puma vessel, during which bathymetric, magnetic, and high-resolution seismic data were gathered and evaluated together with pre-existing seismic data. The results document a wide range of erosion-deposition processes in the region including past submarine landslides. However, the mapped landslide deposits are already heavily overprinted by gully formation and sedimentation, ruling out that submarine slumping influenced the recent tsunami after the 2017 Tehuantepec earthquake. Other geological processes, such as subsidence and extension of the forearc, large numbers of faults, and the subduction of the Tehuantepec Ridge, suggest that the Tehuantepec shelf is dominated by subduction erosion. This process may have deformed the continental shelf more complexly than assumed for the earthquake-derived tsunami model, explaining the mismatch between modeled and observed tsunamis. Our findings indicate that slope failure-induced tsunamis can play a role on the coasts of Central America, but this was not the case for the 2017 Tehuantepec earthquake.

{"title":"New insights into geomorphological and tectonic processes in the Gulf of Tehuantepec and constraints on tsunami generation","authors":"Diego A. Aguilar-Anaya , Carlos A. Mortera-Gutiérrez , Christian Berndt , William L. Bandy","doi":"10.1016/j.geomorph.2025.109612","DOIUrl":"10.1016/j.geomorph.2025.109612","url":null,"abstract":"<div><div>Earthquakes can cause tsunamis by rapidly deforming the seafloor or triggering submarine slope failures. The intraplate earthquake in the Gulf of Tehuantepec on September 8, 2017 generated a tsunami that did not match the predicted tsunami run-up heights and distributions, indicating a possible additional slope failure. An oceanographic expedition, TEHUANTEPEC19, was carried out between May and June 2019, onboard the El Puma vessel, during which bathymetric, magnetic, and high-resolution seismic data were gathered and evaluated together with pre-existing seismic data. The results document a wide range of erosion-deposition processes in the region including past submarine landslides. However, the mapped landslide deposits are already heavily overprinted by gully formation and sedimentation, ruling out that submarine slumping influenced the recent tsunami after the 2017 Tehuantepec earthquake. Other geological processes, such as subsidence and extension of the forearc, large numbers of faults, and the subduction of the Tehuantepec Ridge, suggest that the Tehuantepec shelf is dominated by subduction erosion. This process may have deformed the continental shelf more complexly than assumed for the earthquake-derived tsunami model, explaining the mismatch between modeled and observed tsunamis. Our findings indicate that slope failure-induced tsunamis can play a role on the coasts of Central America, but this was not the case for the 2017 Tehuantepec earthquake.</div></div>","PeriodicalId":55115,"journal":{"name":"Geomorphology","volume":"473 ","pages":"Article 109612"},"PeriodicalIF":3.1,"publicationDate":"2025-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143137796","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

The topographic implications deduced from relationships between different river concavity indices

IF 3.1 2区地球科学 Q2 GEOGRAPHY, PHYSICAL

Geomorphology

Pub Date : 2025-01-19 DOI: 10.1016/j.geomorph.2025.109613

Yanzai Wang , Yongqiu Wu

River longitudinal profiles are often smoothly concave up. Normalized Concavity Index (NCI) and concavity index (

θ

) are usually used to quantify the degree of river concavity. These indices are calculated from distinct perspectives, and their interrelationships remain poorly understood. This study examines the relationships between NCI and

θ

in the Hulu River, a steady-state basin in the central Loess Plateau of China, using both all-channel and trunk-channel data. Landform evolution was modeled using Landlab to investigate changes in NCI and

θ

and their association. We find that (i) Due to the influence of tributary channels, NCI and

θ

are calculated using all channel data are larger than those for trunk channel data.

θ

calculated from all channels data may not effectively capture topographic implications, i.e., larger

θ

indicates more concave profiles. (ii) While NCI and

θ

derived from all-channel data show no significant correlation (P < 0.05), these concavity indices of trunk channels are significantly correlated (P < 0.05), indicating that tributary profiles may not be in a steady state even when trunk-channel profiles are in a steady state. (iii) Among model parameters, the drainage area exponent m in the stream power law strongly affects NCI and

θ

, and their correlations. However, it is important to note that the sensitivity analysis conducted in this study was relatively simple, and further in-depth analysis is needed to fully confirm the extent of the influence of m. Our results highlight the distinct behaviors of NCI and

θ

due to difference in their calculation methods and provide guidance for selecting suitable metrics for assessing river concavity.

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引用次数: 0

Analyzing topographic change profiles in coastal foredune systems: Methodological recommendations

IF 3.1 2区地球科学 Q2 GEOGRAPHY, PHYSICAL

Geomorphology

Pub Date : 2025-01-17 DOI: 10.1016/j.geomorph.2025.109610

Bernard O. Bauer , Jeff Ollerhead , Irene Delgado-Fernandez , Robin G.D. Davidson-Arnott

Estimates of total sand volume in foredunes are commonly made for purposes of predicting coastal erosion and inundation potential during major storms, which is of critical importance for resource management and engineering purposes. However, changes in dune volume through time are potentially of greater relevance to process geomorphologists because volume changes are diagnostic of the long-term evolution of beach-dune systems and can be related to drivers of change (e.g., storm climatology, sediment supply, human action). The methods by which dune volume change estimates are made vary widely in the literature because there are no established protocols that provide guidance on the horizontal distances over which volume integration should be performed. In addition, identifying a diagnostic geomorphic feature such as the dune toe as a limit on integration is fraught with subjective uncertainties. In this paper, an objective methodology for quantifying dune volume change directly (rather than absolute volume) is proposed that is simple, intuitive, and robust. The horizontal limits of integration are identified by zero-crossings in the topographic change profiles between two transect surveys taken at different times, and this avoids challenges associated with identification of the dune toe as a fixed profile feature. Instead, the proposed method focuses on locations of morphodynamic significance where there has been a transition from erosion to accretion in the time interval between surveys.

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引用次数: 0

Late Holocene sediment source changes in the Yellow River basin, China

IF 3.1 2区地球科学 Q2 GEOGRAPHY, PHYSICAL

Geomorphology

Pub Date : 2025-01-17 DOI: 10.1016/j.geomorph.2025.109611

Xiaoqing Ma , Changxing Shi , Huijuan Li , Wei Liu

Information on sediment sources in river basins is crucial for the rational distribution of soil and water conservation measures. The Yellow River in China has an overground channel in its downstream, which is prone to be breached during floods and has been elevated mainly by siltation of coarse particles in the river load. Soft sandstone strata underlaying an area in the middle reaches were found to be one of the principal coarse sediment sources of the river. Using a sediment fingerprinting mixing model with geochemical elements as tracers, we fingerprinted the changes in source apportionments from the region underlain by soft sandstone strata and the region with other substrata in the river basin in the past 2600 years. Source sediment samples were collected from the sediment deposits at the outlets of the main tributaries in the middle reaches, and target sediment samples were collected from alluvial fans in the lower reaches of the river. Geochemical properties of the samples were used as source fingerprints. Using the range test and Kruskal–Wallis H-test and considering the chemical reactivity of the tracer, five geochemical tracers were selected. The results showed that the sediment contribution (<63 μm) of the basins in the region underlain by soft sandstone strata was in the range of 4.2 %–56.0 %, 19.6 % on average. Combining the relative source contributions with the total river load in historical periods, the reconstructed sediment yields from both sources showed an increasing trend with time, but the increasing rate was lower in the region underlain by soft sandstone strata where human interference was weaker historically. This study can serve as a reference for sediment fingerprinting in large catchments, and our findings have implications for future water and soil conservation in the Yellow River basin.

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引用次数: 0

Simulation-based approach for reconstructing past relative sea-level changes using coral microatolls

IF 3.1 2区地球科学 Q2 GEOGRAPHY, PHYSICAL

Geomorphology

Pub Date : 2025-01-16 DOI: 10.1016/j.geomorph.2025.109609

Junki Komori, Rohan Gautam, Nurul Syafiqah Tan, Aron J. Meltzner

Coral microatolls track relative sea level (RSL) as they grow and can inform reconstructions of past RSL change, beyond the duration of instrumental observations. However, direct observation of coral growth history requires slabbing cross sections, which is destructive and logistically challenging. To address this complication, recent studies have explored analysis of coral surface morphologies using non-invasive methods. However, these methods are limited; they cannot directly access key features inside the corals that are indicative of past RSL change events. To overcome this limitation, we devised a method to formulate the growth pattern of massive corals through iteration to simulate coral growth in response to RSL changes. Additionally, we developed an alternative model that analytically approximates the same coral growth, suitable for stochastic analyses. To test the effectiveness of these models, we utilized observations of coral microatolls from Sumatra that emerged during the 2004 M_W 9.1 earthquake. We first compared actual coral cross sections with coral geometries modeled using the respective RSL histories interpreted for those corals in previous studies. Next, we attempted to reconstruct past RSL history using only coral surface profiles with a stochastic inversion. The forward simulation presented an approximate reproduction of the actual corals, although there were discrepancies due to localized variations in growth rate. The inversion study approximately reproduced the previous interpretation of RSL history; however, the effect of nonuniform growth speed was not negligible. While these results highlight the necessity of a comprehensive understanding of coral growth for a more robust interpretation, the simulators developed in this study are powerful tools for improving this understanding.

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引用次数: 0