Geomorphology最新文献_第7页

Back-analysis of the 2000 Yigong dam breach flood morphodynamics: Challenges and promises

IF 3.1 2区地球科学 Q2 GEOGRAPHY, PHYSICAL

Geomorphology

Pub Date : 2025-01-02 DOI: 10.1016/j.geomorph.2024.109588

Yunlong Lei , Marwan A. Hassan , Giorgio Rosatti , Luigi Fraccarollo , Daniel Zugliani , Xudong Fu , Chunhong Hu

Landslide Dam-Break Outburst Floods (LDBOF) are among the most devastating natural hazards, significantly altering downstream river morphologies. The challenge of collecting field data, compounded by the inaccessibility of such events and the risk of equipment loss, hampers our understanding and capability to issue timely warnings. The 2000 Yigong event in China is one of the most significant recorded modern LDBOF occurrences, yet it suffered from sparse data collection. In our study, we have compiled a dataset that includes open-source elevation data, literature-based records, satellite-derived flood inundation extents, and direct field observations. We utilized a hydro-morphodynamic model to simulate the 2000 Yigong event. Comparisons of the simulated lake emptying, dam breaching, flood inundation, bank erosion, and channel infilling with field observations and similar studies indicate that our results are reasonable. Our analysis of the bed evolution during the event revealed it could be divided into two stages influenced by the flow dynamics and primarily by the sediment supply from the dam breach. In the initial stage, the breach development was transport-limited, resulting in intense erosion of dam material, which caused widespread aggradation in the downstream river channel over a distance of around 12 km. In the latter stage, the flow became sediment-supply-limited, redistributing the previously deposited sediments in the downstream reach. This process involved eroding sediment in the broader valley near the dam and depositing it downstream, creating an aggradation area. The aggradation ceased when the river reached a narrow valley, where the transported sediment load balanced with transport capacity, halting further aggradation downstream. The local valley characteristics significantly influenced flow hydraulics and subsequent bed evolution. Furthermore, our findings contribute to interpreting field observations, including forming new channels, deposition on bars, and the varying textures of bar surfaces from coarse near the dam to finer further downstream. We advocate for expanded data collection to advance the study of LDBOF events and enhance hazard mitigation efforts.

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引用次数: 0

Decoding Late Quaternary faulting through marine terraces and MIS 5.5 tilted tidal notches: Insights from central Mediterranean Sea (NW Sicily, Italy)

IF 3.1 2区地球科学 Q2 GEOGRAPHY, PHYSICAL

Geomorphology

Pub Date : 2024-12-31 DOI: 10.1016/j.geomorph.2024.109587

Mauro Agate , Fabrizio Antonioli , Francesco Caldareri , Stefano Devoto , Maurizio Gasparo Morticelli , Attilio Sulli , Nicolò Parrino , Stefano Furlani

This study investigates the recent tectonic evolution of coastal landscapes, focusing on integrating fossil tidal notches and fossil marine terraces as tools for coastal tectonic studies in the Capo Rama promontory (central Mediterranean, southern Italy, NW Sicily). These geomorphological features are crucial for understanding the tectonic forcings that shape coastal landscapes (e.g. active faulting or regional uplift), especially in the context of the high resolution topographic and morphometric data available today. This research addresses a significant gap in the current understanding of the combined use of these markers to study the evolution of the coastal landscape and its tectonic drivers. The aim is to elucidate the interplay between coastal geomorphology and tectonics in areas with elusive tectonic activity (i.e., regions deforming at a rate lesser than 1 mm/yr), hosting previously undetected seismogenic sources and, for that reason, assumed as having low seismic hazard. Employing a multidisciplinary approach, the study integrates surveys conducted along the emerged and submerged coastline with analytic/statistical morphometric analyses and fault modelling. This methodology offers a comprehensive view of the elevation and distribution of MIS 5.5 littoral deposits and coastal geomorphological markers such as marine terrace inner edges and tidal notches. Key findings reveal substantial elevation differences in these markers, varying between +34 and +1.9 m above sea level along a north-south transect, highlighting an active seaward tilting in the study area. Such tilting is related to the Quaternary deformation of a previously unknown buried fault crossing the study area. Achieved outcomes allowed exploring the integration of tidal notches and marine terraces' inner edges as geomorphological markers for coastal tectonic analyses. Moreover, this study lays foundations for future research, enabling a more detailed understanding of the hypothesized buried fault, and its contributions to the understanding of the active faulting processes in the southern Tyrrhenian region.

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引用次数: 0

Paleoenvironmental interpretation of sinkhole sediments on a flat low-lying carbonate platform, a case study from Chassahowitzka River, west-central Florida

IF 3.1 2区地球科学 Q2 GEOGRAPHY, PHYSICAL

Geomorphology

Pub Date : 2024-12-31 DOI: 10.1016/j.geomorph.2024.109589

Philip Edward van Beynen, Ping Wang

After rapid increases in ocean volumes during the early Holocene, sea levels rose more slowly from the mid- to late-Holocene. The flat shelf of the eastern Gulf of Mexico meant even small rises in sea level shifted the coastline inland many kilometers. The impact of this transgression on the karst environments of western Florida is not well known. Here we investigate how one Floridian location responded to changing climate from the mid- and late-Holocene. Chassahowitzha River, representing one of many west-central Florida rivers, is spring fed and discharges into the Gulf of Mexico. Sinkholes along this river have the potential to preserve complete and un-disturbed sedimentary records. Three sediment cores were collected from a sinkhole complex just north of the river. All three cores contain their sedimentary record down to the limestone bedrock. Ten radiocarbon dates were used to create the core chronologies. Interpretation of paleoenvironmental changes is based on sediment grain size analysis, microphotography, loss-on-ignition organic carbon contents and identification of microfossils in the sediments. Prior to 7 ka BP, sediments are dominated by quartz sand followed by an organic-rich layer ending at 6 ka BP. We interpret the organic sediments as the onset of a freshwater wetland/marsh environment along the river. Most of the marsh sediments are deposited between 7 and 6 ka BP when the coastline was 30 kms seaward. Next, there is a 3.8 kyr gap in deposition as demonstrated by the radiocarbon chronology. This hiatus could have been caused by changes in sea level, periods of aridity, draining of the sinkhole lakes or the development of the sinkhole complex. After this interval the sedimentary record is characterized by inorganic deposits which contain an abundance of microfossils. The topmost sediments of each core were interspersed with discrete shell layers which may be indicative of extreme storm events.

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引用次数: 0

Effects of islands on sediment transport in a narrow strait: Strengthening or choking?

IF 3.1 2区地球科学 Q2 GEOGRAPHY, PHYSICAL

Geomorphology

Pub Date : 2024-12-29 DOI: 10.1016/j.geomorph.2024.109585

Xingmin Liu , Yongzhi Wang , Lulu Qiao , Yi Zhong , Hongbing Miao

Straits are important pathways for material exchange in the ocean, and understanding the dynamics of these conduits is critical for quantifying regional and global sediment balances. Many straits contain complex island chains, yet little is understood about the role of these mid strait islands in controlling hydrodynamics and sediment dynamics. We examine the impact of island distribution on sediment transport in the Bohai Strait using in-situ observations and numerical modeling. Observations of water level, velocity, and suspended-sediment concentration around an archipelago in the Bohai Strait demonstrated that increases in water velocity and sediment flux were generated by Island topography. The model results showed that the distributions of current and sediment transport in the Bohai Strait were mainly controlled by the barotropic gradient force, and the presence of islands increased the sea level height difference across the axis of the strait. This change in sea level height enhanced the current velocity between islands, improved the efficiency of suspended sediment transport, and thus increased suspended sediment transport. Altering the width/average depth ratios of the channel and distributions of islands affected the total suspended sediment flux. Through many numerical experiments, we proposed a simple parametric equation, hoping to provide some reference for the simulation of sediment transport in complex topography.

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引用次数: 0

Navigating uncertainty: Stochastic simulation prediction of the Yellow River tail channel (fluvial reach) and its implications on 21st century floodplain management

IF 3.1 2区地球科学 Q2 GEOGRAPHY, PHYSICAL

Geomorphology

Pub Date : 2024-12-26 DOI: 10.1016/j.geomorph.2024.109584

Yanjie Sun , Xiaolong Song , Haijue Xu , Yuchuan Bai

Quantifying long-term morphological evolution of fluvial reach in river tail channels is crucial for floodplain management and ecological conservation in large river systems, yet remains challenging due to inherent complexities and uncertainties. This study introduces an integrated stochastic-data modeling framework to simulate the fluvial reach dynamics in the Yellow River tail channel, China. Stochastic differential equations (SDEs) incorporate white and correlated noise to capture stochastic responses of reach-averaged hydraulic geometry relationships governing channel changes. Gated recurrent unit (GRU) networks and gradient boosting machine algorithms extract signals from water-sediment data to forecast drivers like mean discharge and sediment load during the flood season. The models demonstrate strong performance, with the R² values for width, depth, and migration rate predictions reaching a maximum of 0.859, 0.445, and 0.540, respectively. The model experiments capture uncertainties and deliver probabilistic projections of future channel changes, with mean forecasts for this century indicating 50 % decrease in channel width, relatively stable depth (±5 % variation), and 80 % reduction in migration rate by 2100 relative to 2022 levels. While, integrated simulations with a channel centerline evolution model not only reveal significant and inescapable migration trends in the studied reach but also identify localized high-risk zones (e.g., the north-south migration of the river segments near the Qing 7 section could be up to 250 m in the future). Strategic interventions (dredging, fortifications, sediment replenishments) are recommended to balance navigability, habitability and ecological needs. The innovative methodology establishes foundations for advancing predictive process-based modeling of morphodynamic systems under climate shifts and anthropogenic stressors.

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引用次数: 0

Various wind activity proxies unmixed from grain-size distributions of surface eolian sands at the desert scale in the Tengger Desert, Northwest China

IF 3.1 2区地球科学 Q2 GEOGRAPHY, PHYSICAL

Geomorphology

Pub Date : 2024-12-26 DOI: 10.1016/j.geomorph.2024.109586

Shipei Dong , Zhuolun Li , Qiujie Chen , Yingyibing Shen , Xuehua Che , Cheng Zhang , Yinzhou Huang

Reconstructing wind activity strength enhances our understanding of desert evolution and environmental changes. Unmixing the grain-size components from eolian sands can serve as a proxy for wind activity in deserts. However, the links between the grain-size components of eolian sands and the strength of wind activity throughout the desert have rarely been explored. In this study, 81 surface eolian sand samples were analyzed from flat sandy areas or interdunes across the Tengger Desert in northwestern China, each with a similar depositional environment. The three grain-size components were separated from the samples using a parametric end-member mixing algorithm (EMMA). Based on their grain-size distribution characteristics, the three end-members (EMs) represent transport processes affected by various wind forces, including the East Asian winter monsoon (EAWM, EM1), local wind (EM2), and sandstorms (EM3). Additionally, the content of EM1 and the 63–158 μm components both showed significant positive correlations with EAWM indices, whereas the content of EM3 exhibited a significant negative correlation with the strong wind frequency (SWF). Therefore, these three new proxies (EM1, 63–158 μm components, and EM3) hold significant relationships with the wind activity indices, aiding in the quantitative reconstruction of paleo-wind activity strength in the drylands. This study enhances our understanding of the relationship between sedimentary proxies and wind activity strength, contributing to our knowledge of dryland eolian deposits and paleoenvironmental changes.

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引用次数: 0

Fault geometry, strain partitioning and deformation history inferred by fluvial topography and marine terraces analyses

IF 3.1 2区地球科学 Q2 GEOGRAPHY, PHYSICAL

Geomorphology

Pub Date : 2024-12-24 DOI: 10.1016/j.geomorph.2024.109583

F. Pavano

Advancements in the quantitative investigation of fluvial topography in tectonically active regions account for the emerging numerical modelling of river profiles and their linear inversions. Applications of a geomorphic approach strive for the reconstruction of long-term tectonic deformation histories by decoding base-level fall signals transiently embedded in the geomorphic record. I present integrated results from river profile inversions and marine terraces analyses, here used to outline the deformation model associated to a debated crustal fault system at the southern termination of the Calabrian Forearc High (Central Mediterranean). The study aims at constraining spatial and temporal variations in geometry, strain partitioning, slip rate, and time-transgressive propagation of the tectonic deformation associated with a fault system. In particular, I systematically analyze river profiles draining the eastern flank of the Peloritani Mts. in northeastern Sicily (southern Italy), a NNE-SSW-trending mountain ridge thought as located at the footwall of an active, ESE-dipping normal fault. I perform the linear inversions of fluvial topography by applying recently available MATLAB scripts, and I carry out the analysis of terraced surfaces by both GIS tools and MATLAB-based software packages. The results I obtain suggest that the eastern flank of the Peloritani Mts. have been deformed according to at least three main stages of uplift accommodated along distinct, ∼10–15 km-long en-échelon arranged fault segments. The reconstructed evolution of tectonic deformation unveils time-transgressive, southward propagation since the last ∼600 kyr, inset in a general increase, through time, of the regional component of uplift. The results of this study contribute to address the issues of the deformation style and strain partitioning along complex and/or debated fault systems. These results also demonstrate the potential of the geomorphic approach in defining the spatial and temporal tectonic evolutionary model of a region.

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引用次数: 0

Cultural georesources: Two study cases to promote tourism in the northern landscapes of Tierra del Fuego, Argentina

IF 3.1 2区地球科学 Q2 GEOGRAPHY, PHYSICAL

Geomorphology

Pub Date : 2024-12-16 DOI: 10.1016/j.geomorph.2024.109578

Soledad Schwarz , Andrea Coronato , Sabrina Labrone , Jimena Oría , Alejandro Montes , Federico Ponce , Ramiro López , Mónica Salemme

A methodology to assess cultural georesources (CG) to promote tourism and leisure in a semiarid, steppe region of southern South America is presented. Two localities, Cabo Peñas at the coast, and Amalia shallow-lake inland, were analysed in terms of geodiversity, archaeological/historical record and recreational/tourist use. The methodological framework applied allows us to select, describe, hierarchize and validate CG among a list of several. The CG description includes the geological/geomorphological and cultural aspects as well as the available tourist infrastructure and equipment resulting from field work and surveys. The two CG herein presented are representative of different natural environments that were inhabited by native populations since the Middle Holocene times and nowadays have different level of accessibility and different degree of knowledge among the local people. A parametric assessment including the 3 analysed axes was contrasted to the perceptions of the key actors of the territory through a participative workshop. The hierarchization shows that Peñas cape is homogeneously ranked in the three axes while Amalia shallow-lake reveals that the geological/geomorphological and archaeological/historical axes are better valued than the recreational/tourist one. The validation step of the framework evidences the high interest the CG arouse among local people in order to visit and learn about them and a different level of identification towards them, that is, high for Peñas cape and low for Amalia shallow-lake, probably because of their distance to the city where these people live. The concept of CG offers the possibility to broaden the value of several geodiversity elements and gives relevance to the result of the human being's approach to the physical environment in the present times but also in the past. The methodology proposed to assess CG proved to be useful to reach an integral and deep analysis that takes into account scientific information and people's perceptions.

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引用次数: 0

Origin and evolution of slope-confined canyons and their relationship with gas hydrate accumulation in the northwestern Qiongdongnan Basin, South China Sea

IF 3.1 2区地球科学 Q2 GEOGRAPHY, PHYSICAL

Geomorphology

Pub Date : 2024-12-16 DOI: 10.1016/j.geomorph.2024.109579

Zigui Chen , Tao Jiang , Wenzhao Sun , Yue Chen , Cong Cheng , Ru Yin

Submarine canyons are important channels for sediment transportation in sloped areas and are key locations for the accumulation of gas hydrates and shallow gases. Understanding the evolution of submarine canyons and gas migration is crucial for natural gas exploration in the petroleum industry. In this study, we integrated bathymetric, seismic, logarithmic, and lithological data derived from slope-confined canyons in the Qiongdongnan Basin (QDNB) to examine their geomorphologies and filling patterns. This study has delved into the deposition processes, influencing factors, and evolutionary processes of these submarine canyons, as well as their relationship with gas hydrate accumulation. The results show five slope-confined submarine canyons in the study region, with water depths of 300–1700 m and NW-SE orientation. Canyon fills can be categorized into five types: turbidity-dominated muddy deposits, mass transport deposits, slumps, slides, and bottom current-dominated muddy deposits. These submarine canyons have developed from approximately 5.5 Ma and migrated toward the northeast. In addition, significant gas chimneys and bottom-simulating reflectors indicating gas hydrate accumulation were identified and were primarily located in the canyon ridge strata. Canyon evolution can be divided into three stages, with progression from turbidite channels to linear canyons, and eventually to dendritic canyons. The final evolutionary stage is closely linked to hydrate accumulation and decomposition. The canyon infillings controlled gas hydrate accumulation in the submarine canyon ridges. Gas hydrates located in the upper layer are prone to decomposition, promoting dendritic development of canyon walls. Gravity-flow activity through the evolution of slope-confined canyons is likely induced by factors such as high slope gradients, sea-level fluctuations, fault activity, hydrate decomposition, and earthquakes. The along-slope bottom currents reshaped the canyon landforms and facilitated their lateral migration.

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引用次数: 0

Does anthropogenic morphogenesis contribute to geomorphodiversity in urban environments?

IF 3.1 2区地球科学 Q2 GEOGRAPHY, PHYSICAL

Geomorphology

Pub Date : 2024-12-16 DOI: 10.1016/j.geomorph.2024.109582

Martina Burnelli , Alessia Pica , Maurizio Del Monte , Michele Delchiaro , Laura Melelli , Francesca Reame , Francesca Vergari , Massimiliano Alvioli

Urban geomorphology studies the landscape in cities, and changes induced by human activities to the natural landscape. Cities have different geological-geomorphological substrates, and humans as “geomorphic agents” have been operating within them in different times since the Paleolithic, threatening the Earth-surface heterogeneity and ecological sustainability, especially in urban areas. Urban geomorphology helps understanding natural and historical landscape evolution, changes to natural morphologies, and the effects of the development of cities on natural geomorphological processes. Quantitative geomorphodiversity describes the variety of landforms and morphological processes characterizing the landscape. Geomorphodiversity maps can be prepared using heterogeneous spatial data, at different geographical scales. Here, we adopt the land surface diversity index of Italy, which approximates field-based geomorphological maps. One relevant example of the latter, in Italy, is the geomorphological survey carried out in Rome, which integrates field surveys, historical maps, aerial photographs, archaeological and geomorphological literature. In this work, we compare the land surface diversity index, obtained with a simple and objective approach, with comprehensive geomorphological maps of locations describing the rural-urban gradient within the Rome urban area. We aim at understanding the representativeness of the geomorphodiversity index at the local scale, and its advantages and limitations, in urban areas. We describe a simple approach to compare the geomorphodiversity index and the geomorphological dataset. The method pins down to a common ground the five diversity classes, in the raster index, and the number of landforms mapped in the field, in the geomorphological map. Most notably, the latter distinguishes natural and anthropogenic landforms, allowing us a different assessment for these substantially different geomorphological elements. Results highlight that both natural and anthropogenic processes contribute to geomorphodiversity in urban environment, and in areas having different urbanization level. They are relevant to understand the anthropogenic morphogenesis impact on geomorphodiversity in urban environment.

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引用次数: 0