Geomorphic effects of large debris flows on channel morphology at North Fork Mountain,eastern West Virginia,USA     

Daniel A. Cenderelli  J. Steven Kite 《地球表面变化过程与地形》1998,23(1):1-19

Extreme rainfall in June 1949 and November 1985 triggered numerous large debris flows on the steep slopes of North Fork Mountain, eastern West Virginia. Detailed mapping at four sites and field observations of several others indicate that the debris flows began in steep hillslope hollows, propagated downslope through the channel system, eroded channel sediment, produced complex distributions of deposits in lower gradient channels, and delivered sediment to floodwaters beyond the debris-flow termini. Based on the distribution of deposits and eroded surfaces, up to four zones were identified with each debris flow: an upper failure zone, a middle transport/erosion zone, a lower deposition zone, and a sediment-laden floodwater zone immediately downstream from the debris-flow terminus. Geomorphic effects of the debris flows in these zones are spatially variable. The initiation of debris flows in the failure zones and passage through the transport/erosion zones are characterized by degradation; 2300 to 17 000 m³ of sediment was eroded from these zones. The total volume of channel erosion in the transport/erosion zones was 1·3 to 1·5 times greater than the total volume of sediment that initially failed, indicating that the debris flows were effective erosion agents as they travelled through the transport/erosion zones. The overall response in the deposition zones was aggradation. However, up to 43 per cent of the sediment delivered to these zones was eroded by floodwaters from joining tributaries immediately after debris-flow deposition. This sediment was incorporated into floodwaters downstream from the debris-flow termini causing considerable erosion and deposition in these channels. © 1998 John Wiley & Sons, Ltd.  相似文献   

Basic characteristics and controlling factors of anastomsing fluvial systems     

WANG Sui ji  LI Jin song  YIN Shou peng 《中国地理科学(英文版)》2000,10(1):30-37

1　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｔｅｒｍ“ａｎａｓｔｏｍｏｓｉｎｇｒｉｖｅｒ”ｗａｓｆｉｒｓｔａｐｐｌｉｅｄｂｙＳＣＨＵＭＭ ( 1968) ,ｒｅｆｅｒｒｅｄｔｏｓｔａｂｌｅ ,ｌｏｗｂｅｄ ｌｏａｄ ,ｍｕｌｔｉｐｌｅｃｈａｎｎｅｌｓｙｓｔｅｍｗｉｔｈｌｏｗ ｇｒａｄｉｅｎｔ,ｈｉｇｈｓｉｎｕｏｓｉｔｙａｎｄｓｅｐａｒａｔｅｄｖｅｇｅｔａｔｅｄｉｓｌａｎｄｓ .Ｔｈｉｓｓｐｅｃｉｆｉｃｍｅａｎｉｎｇｏｎ“ａｎａｓｔｏｍｏｓｉｓ”ｗｈｉｃｈｗａｓｆｉｒｓｔｕｓｅｄｂｙＪａｃｋｓｏｎｉｎ 1834ｅｎｄｅｄｔｈｅｓｙ…  相似文献   

PREDICTING SHORELINE CHANGES AT TIDAL INLETS ON A DEVELOPED COAST     

Karl F. Nordstrom 《The Professional geographer》1987,39(4):457-465

Implementation of shore protection measures at tidal inlets in New Jersey has reduced the rate of shoreline change and altered mechanisms for sediment transfer. Shoreline mobility has been reduced to 19 percent of pre-development rates updrift of inlets where new breaches in the islands are prevented by bulkheads or accretion related to human activities. Rates of change downdrift of inlets have been influenced by protection structures and channel dredging. A conversion from cyclic to unidirectional shoreline change has occurred in some areas. Prediction of future changes must be based on probabilities of human action, calibrated with knowledge of physical processes.  相似文献   

Sensitivity of the Eastern Mediterranean geomorphic system towards environmental change during the Late Holocene: a chronological perspective     

Bert Dusar  Gert Verstraeten  Koen D'haen  Johan Bakker  Eva Kaptijn  Marc Waelkens 《第四纪科学杂志》2012,27(4):371-382

Alluvial and colluvial sediment deposition provide a vital record of environmental change during the Holocene. Firm chronological control on these archives is necessary to enable us to relate sediment dynamics to human activity and climate variability. In the Eastern Mediterranean, such relationships are hard to establish due to the lack of spatially well‐distributed sediment archives with good chronological control. This scarcity is problematic with respect to regional‐scale reconstructions of the temporal variation of sediment dynamics. Here, we present a radiocarbon database (n = 178) of geomorphological activity collected from multiple distinct sediment archives within the territory of Sagalassos in south‐western Turkey. The data were grouped according to their sedimentary facies for analysis using cumulative probability distributions (CPDs) and sedimentation rate (SR) modelling. Two small‐scale colluvial valleys, where chronological information was abundant, were investigated in more detail. Results show that sedimentation chronology differs between individual, nearby cores, as it depends strongly on the local geomorphic situation. A generalizing approach combining multiple core results yields more widely valid conclusions. High sedimentation rates coincided with the initial major anthropogenic disturbance of the landscape and decreased afterwards, probably due to hillslope soil depletion. CPD and SR analysis indicates that in general colluvial sedimentation rates did not change much from 2000 BC onwards. River floodplain sedimentation, in contrast, increased markedly during the first millennium BC and during recent times, and a significant time lag in enhanced sediment deposition between the upper and lower reaches of the river valleys was observed. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

九龙江北溪流域河流特征及其构造指示意义     

田立佳  张明华  张辰光 《华南地质与矿产》2012,28(1):79-83

本文利用DEM数据,运用基岩河道侵蚀模型提取九龙江北溪流域的河流下凹程度、陡峭指数和蜿蜒度等地貌指数研究北溪流域地质构造活动特点。通过对流域地貌参数的分析发现九龙江北溪流域陡峭指数存在自NW向SE递减的规律,陡峭指数和蜿蜒度有很好的对应关系.排除气候因素和基岩性质等影响因子,认为河道陡峭指数的分布特征揭示了九龙江北溪流域的地壳抬升速率自西北向东南递减的分布特征,此认识与前人采用精密水准资料计算地壳垂直运动速率结果相一致。  相似文献   

不同地貌条件下AW3D30 DEM数据空洞修复方法的对比分析     

周小宇  赵尚民 《测绘通报》2022,(11):84-89

DEM数据被广泛应用于多个领域,但生产过程中数据空洞的出现严重制约了其适用性。因此,对DEM数据空洞修复的研究至关重要。本文选择太原市4个不同地貌条件下的河谷、盆地、丘陵和山地试验区作为空洞区,利用ASTER GDEM数据和直接镶嵌法、反距离加权插值法及三角洲表面镶嵌法对AW3D30 DEM数据进行修复,对不同方法的修复效果进行对比分析。研究结果表明:在盆地区域,反距离加权插值法修复效果最好,三角洲表面镶嵌法次之,直接镶嵌法最弱;在起伏度稍大的河谷、丘陵和山地区域,三角洲表面镶嵌法的修复效果最好,空洞区域内部的纹理特征明显,空洞边缘区域过渡平滑,而反距离加权插值法最弱。  相似文献   

气候变化影响下藏东南帕隆藏布流域高山区泥石流的地貌效应     

余国安  鲁建莹  李志威  侯伟鹏 《地理学报》2022,77(3):619-634

高海拔或高纬度山区（尤其高山冰川及冻土急剧消退区）常孕育适宜泥石流发育的地形和物源条件。气候变化（如升温、强降雨事件增多等）影响下,高山区潜在孕灾环境更易于成灾,泥石流成为主要的灾害类型和物质输移方式,也是高山区地貌变化的重要驱动力。由于野外监测困难,数据资料匮乏,鲜有针对高山区泥石流过程地貌效应的分析报道。以中国藏东南高山区泥石流多发的帕隆藏布流域为研究区,以古乡沟、天摩沟和扎木弄沟为典型小流域,结合遥感影像、DEM数据、无人机航拍、高精度RTK测量和野外踏勘调查,分析泥石流沟道地貌发育特征（冲淤变化、平面摆动）及其对主河河流地貌的影响,并探讨大规模泥石流事件影响下河谷地貌的长期演变趋势。高山区泥石流过程强烈塑造沟道自身地貌,上游物源区深切展宽和溯源蚀退,沟口堆积扇冲淤变化受控于泥石流事件规模和水流强度。泥石流过程显著影响主河道河流地貌,造成主河道横向冲淤和摆动,并影响堰塞体上游河段平面形态发育。长时间尺度上,河谷地貌在平面上发育形成宽窄相间的藕节状而在纵剖面上形成台阶状形态。  相似文献   

六棱山北麓中段冲沟地貌发育的定量研究及其新构造意义   总被引：1，自引：1，他引：0  

闫冬冬  吕胜华  赵洪壮  李有利 《地理科学》2011,(2):244-250

利用地貌形态指标对六棱山北麓断层中段的5条冲沟进行定量化研究,流域的冲沟比降指标(SL)、面积--高度积分值(HI)和流域盆地形态因子(Bs)的异常值表明5条冲沟的发育对六棱山北麓断层活动性有明显的响应,流域发育处于壮年期.秋林沟口野外实测数据验证并揭示了六棱山北麓断裂晚第四纪以来的活跃性.  相似文献   

Appraisal of relative tectonic activity along the Kazerun Fault Zone,Zagros Mountains,Iran: insight from spatial analysis of geomorphic indices     

Ali Faghih  Ahmad Nourbakhsh 《Geological Journal》2015,50(6):783-798

This paper investigates the impact of active tectonics on the geomorphic processes and landscape evolution along the Kazerun Fault Zone (KFZ) in the Zagros Mountains of Iran using spatial analysis of geomorphic indices. We document how topography and morphology are influenced by active tectonic deformation. The Zagros fold–thrust belt is an area of active crustal shortening where northwest–southeast oriented fault‐related folds become younger from north to south and from southeast to northwest. This temporal and spatial evolution of the belt was tested using geomorphic indices of active tectonics that include mountain front sinuosity index (Smf), the valley width/height ratio (Vf), drainage basin asymmetry factor, hypsometric integral, drainage basin shape ratio and mean axial slope of the channel. Change in the geomorphic indices is the result of active fold growth and change in the uplift rate. Decreasing Smf and Vf values from north (Smf = 2.01; Vf = 0.5) to south (Smf = 1.12; Vf = 0.2) and from southeast (Smf = 1.84; Vf = 0.8) to northwest (Smf = 1.54; Vf = 0.1) points to a migration of the active crustal shortening towards W–SW. The combined geomorphic (field evidences) and morphometric data (quantitative analysis of geomorphic indices) provide evidence of relative variation in the tectonic activity along the Kazerun Fault Zone and related landforms. The utilization of geomorphic parameters with comparison to the field observations exhibits change in relative tectonic activities mostly corresponding to the change in mechanism of the prominent fault zones in the study area. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

Research on the spatial structure of karst massif     

Zhang Zhaogan  Zhang Jianxin  Yang Jianmin  Shen Ping 《中国地理科学(英文版)》1997,8(3):256-263

Eight spatial structure types are determined through morphology, hydrogeology, hydrology and impulse response in karst districts, with the well studied Houzhai subterranean stream in Puding, Guizhou Province as a sample research area. These types contain peak-forest basin, peak-forest laterite platform, resurrected peak-forest basin, old peak-forest-funnel depression, peak-forest-funnel, peak-forest-funnel depression, peak-cluster valley and peak-forest-doline. In the area, each of them has its respective surface and subterranean structural feature, and morphology, hydrogeology, hydrology and impulse response as well. The difference of responses of subsurface system in different spatial structure types are obtained by time series analysis, frequency spectrum research and decline curve calculation of material current. According to the analysis of the aquifer feature, the upper reaches of suburfall stream is dominated by pipeline flow, the lower reaches is characterized by braided fissure flow drainage system and mixed characteristic exists in the middle reaches. The result of the impulse test shows that the large ascending range of stage in the test on swash condition is in fissure system. However, in pipeline type, especially in the subterranean stream where there is waterfall or incomplete fill of underground water, the ascending range of stage is one quantity level less than the impulse range of stage at some fissure types, showing that change range of stage can indicate the spatial structure characteristics of certain area upper the station. The main direction of karst geomorphic evolution there is positive course except in the west area. It can be seen that karst geomorphological evolution direction can change when discharge datum plane influences some part of a relatively large drainage. In certain time unit, the upper reaches are controlled by old datum plane and the lower reaches by new datum plane. Two opposite geomorphological evolution directions can exist in one drainage.  相似文献