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Journal of Mountain Science 2017年第5期14卷 926-935页

作者： CHEN Liu-qin GUO Fu-sheng State Key Laboratory Breeding Base of Nuclear Resources and Environment East China University of TechnologyNanchang 330013 China School of Earth Sciences East China University of Technology Nanehang 330013 China

The Jianglangshan Geopark in the western Zhejiang Province of Southeast China is well-known for its spectacular red-colored sandstone landforms. Little is known about the depositional processes of the conglomerate-dominated fangyan Formation, the lithologic base of the Danxia landforms in this geopark. Based on detailed field investigation of lithology, sedimentary structures, bed thickness and geometry, five facies are recognized: facies A(matrixsupported cobble conglomerate), facies B(pebble conglomerate), facies C(pebbly sandstone), facies D(fine-grained sandstone) and facies E(mudstone). The results show that streamflow-dominated fans were the main depositional processes responsible for the accumulation of the fangyan Formation along the mountain fronts. These fan conglomerates form the base for the evolution of the Danxia landscapes owing to the uplift and erosion of the study area. In contrast, the fine-grained sedimentary successions produced by fluvial floodplains in the distal part of the fans were thinner and more easily weathered. Such sedimentary facies distribution patterns were thought to be similar during Late Cretaceous across Southeast China. The Danxia landforms are largely the geographical expressions of the conglomerate-dominated redbeds in the proximal-middle fans.

关键词： Danxia landform Late Cretaceousredbeds alluvial fan Jianglangshan Geopark Landscape evolution

Machine learning-based identification for the main influencing factors of alluvial fan development in the Lhasa River Basin,Qinghai-Tibet Plateau

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Journal of Geographical Sciences 2022年第8期32卷 1557-1580页

作者： CHEN Tongde WEI Wei JIAO Juying ZHANG Ziqi LI Jianjun State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau Institute of Soil and Water ConservationNorthwest A&F UniversityYangling 712100ShaanxiChina School of Automation Northwestern Polytechnical UniversityXi'an 710072China Institute of Soil and Water Conservation Chinese Academy of Sciences and Ministry of Water ResourcesYangling 712100ShaanxiChina

alluvial fans are an important land resource in the Qinghai-Tibet Plateau with the expansion of human activities. However, the factors of alluvial fan development are poorly understood. According to our previous investigation and research, approximately 826 alluvial fans exist in the Lhasa River Basin(LRB). The main purpose of this work is to identify the main influencing factors by using machine learning. A development index(Di) of alluvial fan was created by combining its area, perimeter, height and gradient. The 72% of data, including Di, 11 types of environmental parameters of the matching catchment of alluvial fan and 10 commonly used machine learning algorithms were used to train and build *** 18% of data were used to validate models. The remaining 10% of data were used to test the model accuracy. The feature importance of the model was used to illustrate the significance of the 11 types of environmental parameters to Di. The primary modelling results showed that the accuracy of the ensemble models, including Gradient Boost Decision Tree,Random Forest and XGBoost, are not less than 0.5(R^(2)). The accuracy of the Gradient Boost Decision Tree and XGBoost improved after grid research, and their R^(2) values are 0.782 and 0.870, respectively. The XGBoost was selected as the final model due to its optimal accuracy and generalisation ability at the sites closest to the LRB. Morphology parameters are the main factors in alluvial fan development, with a cumulative value of relative feature importance of 74.60% in XGBoost. The final model will have better accuracy and generalisation ability after adding training samples in other regions.

关键词： alluvial fan machine learning feature importance XGBoost Lhasa River Basin

Flood risk on arid alluvial fans:a case study in the Joghatay Mountains,Northeast Iran

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Journal of Mountain Science 2023年第5期20卷 1183-1200页

作者： Kaveh GHAHRAMAN Balázs NAGY Department of Physical Geography Eotvos Loránd UniversityPázmány Péter stny.1/CH-1117 BudapestHungary

Among the common hazards related to alluvial fans,flooding is one of the most ***,in populated alluvial fans,not only the natural processes are effective in floods,but the artificial structures and modifications can change the behavior of flooding and its potential *** study aims to indicate the flood-prone landforms in a set of populated alluvial fans in an arid region and investigate the role of anthropogenic activities in controlling/exacerbating flooding in alluvial *** achieve this goal,15 Ground Range Detected in High resolution(GRDH)SAR Sentinel-1 images,covering a total of 24 alluvial fans,were ***-processing and post-processing steps were applied to all images to identify flood-prone sections of the studied alluvial *** results showed that feeder channels,spreading sites,and wide interfluves are the most flood-prone landforms of alluvial *** terms of anthropogenic modifications to mitigate flooding,a rampart system is distributed in the study *** are levee like structures formed from the fan *** aim to mitigate flood hazard on residential areas,infrastructures,and agricultural lands of the study *** show that the rampart system can reduce the danger of floods,but it cannot be considered a long-term ***,a comprehensive flood protection system distributed throughout the whole alluvial fan system is *** also reveal that in regions where flood monitoring is challenging,SAR images can be used as a freely available data set to monitor and identify flooding hotspots.

关键词： alluvial fan Flood Anthropogenic activities Rampart Sentineli SAR

Geomorphometric Features of the alluvial fans around the Chaka-Qinghai Lake in the Northeastern Tibetan Plateau

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Journal of Earth Science 2014年第1期25卷 109-116页

作者： Huiping Zhang Yuanyuan Lü State Key Laboratory of Earthquake Dynamics Institute of GeologyChina Earthquake Administration Key Laboratory of Saline Lake Resources and Environment Institute of Mineral ResourcesChinese Academy of Geological Sciences

This article aims to study the geomorpometric features of alluvial fans since they act as a small-scale geomorphic unit response to tectonics and climate changes around the Chaka-Qinghai Lake area in the northeastern Tibetan Plateau. We quantitatively extracted geomorphic parameters, such as the surface area and slope of alluvial fans adjacent to the Qinghai Nan Shan and Ela Shan. alluvial fans in the Chaka Lake partition area, south of the Qinghai Nan Shan, are featured by a small area and short length, but the largest slope. Geomorphic parameters of the alluvial fans in Ela Shan area are in- termediate in size, and the alluvial fans in the Qinghai Lake partition area north of Qinghai Nan Shan have the gentlest slope. Together with the regional faulting activity analysis, we suggest that the alluvial fans with the high slopes in the south of Qinghai Nan Shan are mainly controlled by the reverse faulting along the Qinghai Nan Shan faults, and the strike-slip movement of the Eia Shan fault zone plays a weak role. In contrast, due to the lack of active faults, the alluvial fans near the Qinghai Lake area north of the Qinghai Nan Shan only respond to regional erosion, transportation, and deposition proc- esses, thereby forming relatively gentle geomorphic units.

关键词： northeastern Tibetan Plateau Chaka-Qinghai Lake alluvial fan geomorphometric fea- ture geomorphic process.

How do stream processes affect hazard exposure on alluvial fans? Insights from an experimental study

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Journal of Mountain Science 2020年第4期17卷 753-772页

作者： Bruno MAZZORANA Elisa GHIANDONI Lorenzo PICCO Universidad Austral de Chile Faculty of SciencesInstituto de Ciencias de la Tierra5090000 ValdiviaChile Universidad Austral de Chile RINA–Natural and Anthropogenic Risks Research Center5090000 ValdiviaChile Universidad Austral de Chile Laboratory of HydromorphologyFaculty of Forest Sciences and Natural Resources5090000 ValdiviaChile University of Padova Department of LandEnvironmentAgriculture and Forestry35020 LegnaroItaly

alluvial fans are among the most privileged settlement areas in many mountain regions. These landforms are particularly dynamic being episodically affected by distributary processes generated by extreme flood events. Addressing risk assessment entails determining hazard exposure and unravelling how it might be related to process loading and to process dynamics once the flow becomes unconfined on the surface of alluvial fans. By following a ‘similarity of process concept’, rather than by attempting to scale a real-world prototype, we performed a set of 72 experimental runs on an alluvial fan model. Thereby, we considered two model layouts, one without a guiding channel and featuring a convex shape and the other one with a guiding channel, a bridge, and inclined but planar overland flow areas as to mirror an anthropic environment. Process magnitude and intensity parameters were systematically varied, and the associated biphasic distributary processes video recorded. For each experiment, the exposure was detected by mapping the exposed area in a GIS, thereby discerning between areas exposed to biphasic flows and the associated depositional phenomena or to the liquid flow phase only. Our results reveal that total event volume, sediment availability and stream power in the feeding channel, as well as depositional effects, avulsion, and channelization on the alluvial fan concur to determine the overall exposure. Stream process loading alone, even when rigorously defined in terms of its characterizing parameters, is not sufficient to exhaustively determine exposure. Hence, further developing reliable biphasic simulation models for hazard assessment on settled alluvial fans is pivotal.

关键词： alluvial fan Hazard Exposure Flood risk Experimental model Process similarity

Distribution and land use characteristics of alluvial fans in the Lhasa River Basin,Tibet

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Journal of Geographical Sciences 2021年第10期31卷 1437-1452页

作者： CHEN Tongde JIAO Juying CHEN Yixian LIN Hong WANG Haolin BAI Leichao State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau Institute of Soil and Water ConservationNorthwest A&F UniversityYangling 712100ShaanxiChina Institute of Soil and Water Conservation CAS and Ministry of Water ResourcesYanglingShaanxi 712100China

In Lhasa River Basin(LRB),land suitable for settlement or living is experiencing a shortage of *** fans have the potential to alleviate this ***,basic information,such as the distribution and land use types of alluvial fans,is rarely *** this study,Google Earth,ArcGIS and visual interpretation were used to obtain the outlines,areas,quantities and distribution of alluvial ***,to show the utilisation potential of alluvial fans,we analysed the land use,their distance from the roads,places(town and village)and *** results showed 826 alluvial fans exist in LRB,with a total area of 1166.03 *** number of alluvial fans with areas between 0.1 and 1 km2 is 517,accounting for 62.59%of the total number of alluvial *** is the dominant land use type,accounting for 68.70%of the total area of alluvial *** cropland area accounted for 2.16%of alluvial fans and accounted for 18.98%of the total cropland area in *** 93.70%,53.63%and 61.86%of the total number of alluvial fans were located within 5 km from the tertiary road,village,and river,*** sum up,our survey results showed that alluvial fans are important land resources in LRB and may have huge utilisation potential.

关键词： alluvial fan Lhasa River Basin distribution land use Tibet

RIVERS' FEATURES ON alluvial fanS IN NORTHWEST CHINA

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International Journal of Sediment Research 1999年第2期14卷 339-344页

作者： ZHU Zhongli MO Duowen (Department of Geography, Peking University, China)

Braided river is considered as the main river pattern developed on alluvial fans. But this is not true in Northwest China. Analysis and correlations of the characteristics of more than 10 rivers show that straight river is the main river pattern and braided river only develops on middle segment of the river in this district. The main factor to shape this river pattern on alluvial fans is the standing incision due to changes in precipitation and sedimentary condition caused by climate change since Holocene. Because of the tectonic movement and boundary condition from gravel to loess-like sediment. some rivers have fan-head trenching and others have fan-toe trenching with the U-shaped cross section.

关键词： alluvial fan River patterns Precipitation and sedimentary condition. Climate changes Boundary condition

Soil evolution along an alluvial-loess transect in the Herat Plain,western Afghanistan

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Journal of Arid Land 2022年第11期14卷 1317-1330页

作者： Farsila MAHMOUDIAN Alireza KARIMI Omid BAYAT Department of Soil Science Faculty of AgricultureHerat UniversityHerat 3001-272806Afghanistan Department of Soil Science Faculty of AgricultureFerdowsi University of MashhadMashhad ***Iran

Afghanistan is located in the Eurasian loess belt,however,there is little information on the soils in the *** has covered the Herat Plain in western Herat City,*** the diversity of landform and parent material,there is no information on the soil and landform evolution in this *** objectives of this study were to identify the soils along a transect of different landforms in the Herat Plain and determine the role of geomorphic processes on the soil and landform *** pedons from an alluvial fan,the depression between alluvial fan and piedmont plain,saline and non-saline piedmont plains,and the flood plain of the Hariroud River,were ***,the physical-chemical properties,mineralogy,and micromorphology of the samples were *** showed that the soil parent material in the piedmont plain is loess,whereas,in the flood plain it is a combination of loess and river alluvial ***,lessivage,salinization,and gleization are the most important pedogenic *** calcification and lessivage appear to be the result of a wetter climate during the late Quaternary,whereas the present topography causes the gleization and *** coatings on carbonate nodules and iron nodules are abundant pedofeatures in the Btk(argillic-calcic)*** oxides nodules are common in the soils of the flood *** formation of palygorskite in both alluvial-and loess-derived soils implies the onset of aridity and the trend of increase in environmental aridity in the *** seems that after the formation of a well developed paleosol on the alluvial fan in a more humid climate in the past,the piedmont plain has been covered by loess deposits,and the calcification,gleization,and salinization cause the formation of weakly developed surficial *** study highlights the role of the late Quaternary climatic changes on the evolution of landforms and soils in western Afghanistan.

关键词： alluvial fan loess-derived soils paleosol gleization Hariroud River

GIS tools for preliminary debris-flow assessment at regional scale

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Journal of Mountain Science 2017年第12期14卷 2498-2510页

作者： cavalli marco crema stefano trevisani sebastiano marchi lorenzo consiglio nazionale delle ricerche istituto di ricerca per la protezione idrogeologicaCorso Stati Uniti 435127 PadovaItaly universitàdi padova dipartimento territorio e sistemi agro-forestaliVia dell’Universita 1635020 Legnaro(PD)Italy universitàiuav di venezia dipartimento di architettura costruzione conservazioneDorsoduro 220630123 VeneziaItaly

The assessment of the areas endangered by debris flows is a major issue in the context of mountain watershed management. Depending on the scale of analysis, different methods are required for the assessment of the areas exposed to debris *** 2-D numerical models are advised for detailed mapping of inundation areas on individual alluvial fans, preliminary recognition of hazard areas at the regional scale can be adequately performed by less data-demanding methods, which enable priority ranking of channels and alluvial fans at risk by debris flows. This contribution focuses on a simple and fast procedure that has been implemented for regionalscale identification of debris-flow prone channels and prioritization of the related alluvial fans. The methodology is based on the analysis of morphometric parameters derived from Digital Elevation Models(DEMs). Potential initiation sites of debris flows are identified as the DEM cells that exceed a threshold of slope-dependent contributing area. Channel reaches corresponding to debris flows propagation, deceleration and stopping conditions are derived from thresholds of local slope. An analysis of longitudinal profiles is used for the computation of the runout distance of debris flows. Information on erosion-resistant bedrock channels and sediment availability surveyed in the field are taken into account in the applications. A set of software tools was developed and made available(https://***/Hydrogeomorphology Tools) to facilitate the application of the procedure. This approach, which has been extensively validated by means of field checks, has been extensively applied in the eastern Italian Alps. This contribution discusses potential and limitations of the method in the frame of the management of small mountain watersheds.

关键词： Debris flow Geographic information system Digital elevation models Runout alluvial fan Watershed management Geomorphometry

Tectonic and climatic controls on late Quaternary bajada sedimentation along Narmada-Son Fault(NSF),Gujarat,Western India

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International Journal of Sediment Research 2013年第1期28卷 66-76页

作者： Parul N.JOSHI D.M.MAURYA L.S.CHAMYAL Department of Geology The M.S.University of BarodaVadodara-390002GujaratIndia Department of Geology Faculty of ScienceThe Maharaja Sayajirao University of BarodaVadoadra-390002GujaratIndia

An alluvial bajada has been recognized along a part of the active Narmada-Son Fault(NSF) and confined by the Karjan River on the eastern side and by the Madhumati River on western *** bajada sequence exposed along the incised cliffs of various north flowing parallel streams has been studied in their proximal,medial and distal part. The sediments are characterized on the basis of grain size,fabric,sedimentary structures,bed geometry and sorting, and lithologs prepared from the mapped cliff *** study of sedimentary characteristics,lithofacies analysis and facies associations indicate that sediments are mainly of three types-sediments that were deposited by debris flows and sediment gravity flows,and as extensive bar *** major aggredational sequences are *** sequence is composed of coarsening-upward sequence of proximal facies overlain by fining-upward sequence of distal *** upward sequence record periods of tectonic activity related to uplift along the NSF and fan progradation,whereas fining-upward sequence results from tectonic quiescence *** presence of rhizocretions,calcium carbonate nodules and calcite sheets within the basal debris flow and sediment gravity flow indicate semi-arid climate,whereas the formation of pedoginized paleosol indicate relatively wetter climate prevailing in the study *** activity along the NSF has played dominant role by controlling the geometry and volume of bajada *** is found to be responsible for compositional and temporal distribution of bajada *** dating suggests that the bajada sediments were deposited during the later part of late *** incision of the sediments is attributed to uplift due to inversion of the lower Narmada basin during the early Holocene.

关键词： Bajada alluvial fan Sedimentary facies Late Quaternary Tectonics Climate Narmada-Son Fault(NSF) Western India