河水入渗过程中蒸发损失的实验模拟研究   总被引：2，自引：0，他引：2  

王润兰  康卫东  李俊亭  仇小强  杨涛 《地下水》2005,27(5):350-351,400

为了深化河流入渗机理的认识以及提高地下水资源评价的精度,本文就河水入渗过程中蒸发损失量的计算进行了室内模拟试验研究.试验结果表明,常年有水河流的河水入渗量的蒸发损失率小于10%,即有90%以上的河水入渗量补给地下水.  相似文献   

荥经-马边-盐津逆冲构造带断裂运动组合及地震分段特征   总被引：9，自引：5，他引：9       下载免费PDF全文

张世民  聂高众  刘旭东  任俊杰  苏刚 《地震地质》2005,27(2):221-233

逆冲构造带的分段性研究是评价该类发震构造地震危险性的基础工作。荥经-马边-盐津逆冲构造带是青藏高原东南边缘重要的NW向强震构造带,该构造带以逆冲错动为主要活动形式,其组合形式与逆冲强度存在南北差异。通过NE向横向断裂的构造地貌分析,发现横向断裂以右旋走滑活动为主,兼有倾滑活动。根据其与纵向断裂的交接关系,将横向断裂概括为横向分割断裂、横向撕裂断裂和横向转换断裂3种类型,讨论了3类横向断裂在逆冲构造带分段中所起的不同作用,进而将荥经-马边-盐津逆冲构造带分为独立的3段,并分析了各段的地震活动特征。研究表明,荥经-马边-盐津逆冲构造带以横向断裂为标志的3分段特点,既体现了段与段之间断裂活动强度、地震破裂强度与步调的差异,又体现了段内地震破裂步调的一致性,表明横向断裂在一定程度上控制了逆冲构造带的破裂分段,只是横向断裂的类型不同,其所起的作用也不同  相似文献   

Overbank deposition along the concave side of the Red River meanders,Manitoba, and its geomorphic significance     

Gregory R. Brooks 《地球表面变化过程与地形》2005,30(13):1617-1632

Slow earth sliding is pervasive along the concave side of Red River meanders that impinge on Lake Agassiz glaciolacustrine deposits. These failures form elongated, low‐angled (c. 6 to 10°) landslide zones along the valleysides. Silty overbank deposits that accumulated during the 1999 spring freshet extend continuously along the landslide zones over hundreds of metres and aggraded the lower slopes over a distance 50 to 80 m from the channel margin. The aggradation is not obviously related to meander curvature or location within a meander. Along seven slope profiles surveyed in 1999 near Letellier, Manitoba, the deposits locally are up to 21 cm thick and generally thin with increasing distance from, and height above, the river. Local deposit thickness relates to distance from the channel, duration of inundation of the landslide surface, mesotopography, and variations in vegetation cover. Immediately adjacent to the river, accumulated overbank deposits are up to 4 m thick. The 1999 overbank deposits also were present along the moderately sloped (c. 23 to 27°) concave banks eroding into the floodplain, but the deposits are thinner (locally up to c. 7 cm thick) and cover a narrower area (10 to 30 m wide) than the deposits within the landslide zones. Concave overbank deposition is part of a sediment reworking process that consists of overbank aggradation on the landslide zones, subsequent gradual downslope displacement from earth sliding, and eventually reworking by the river at the toe of the landslide. The presence of the deposits dampens the outward migration of the meanders and contributes to a low rate of contemporary lateral channel migration. Concave overbank sedimentation occurs along most Red River meanders between at least Emerson and St. Adolphe, Manitoba. © Her Majesty the Queen in right of Canada.  相似文献   

Ethiopia and the Eastern Nile Basin   总被引：1，自引：0，他引：1  

Yacob Arsano  Imeru Tamrat 《Aquatic Sciences - Research Across Boundaries》2005,67(1):15-27

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Latent Compositional Factors in The Llobregat River Basin (Spain) Hydrogeochemistry     

R. Tolosana-Delgado  N. Otero  V. Pawlowsky-Glahn  A. Soler 《Mathematical Geology》2005,37(7):681-702

The study of hydrogeochemical data sets frequently calls for statistical dimension reducing techniques. It is well known that hydrochemical parameters are compositions and, for this type of data, the direct application of classical statistical methods based on the correlation matrix yield spurious results. But new results on compositional data analysis have identified the sampling space, the simplex, with an Euclidean space, a fact that allows us to define a simplicial factor analysis strategy, thus overcoming the problem. For illustration, we use samples from the Llobregat River and its tributaries (NE Spain). Three unobservable or latent factorial components are extracted, which are identified with pristine waters, potash-mining influence and urban sewage influence. These three factorial components or compositional factors are plotted in a factorial ternary diagram, which reflects the relative influence of each one of these factors on each observation.  相似文献   

Magnitude and frequency in proglacial rivers: a geomorphological and sedimentological perspective     

Philip M.   《Earth》2005,70(3-4):203-251

Proglacial fluvial sedimentary systems receive water from a variety of sources and have variable discharges with a range of magnitudes and frequencies. Little attention has been paid to how these various magnitude and frequency regimes interact to produce a distinctive sedimentary record in modern and ancient proglacial environments. This paper reviews the concept of magnitude and frequency in relation to proglacial fluvial systems from a geomorphic and sedimentary perspective rather than a hydrological or statistical perspective. The nature of the meltwater inputs can be characterised as low-magnitude–high-frequency, primarily controlled by ablation inputs from the source glacier, or high-magnitude–low-frequency, primarily controlled by ‘exceptional’ inputs. The most important high-magnitude–low-frequency inputs are catastrophic outburst floods, often referred to by the term jökulhlaup (Icelandic for glacier-burst). Glacier surges are an additional form of cyclical variation impacting the proglacial environment, which briefly alter the volumes and patterns of meltwater input. The sedimentary consequences of low-magnitude–high-frequency discharges are related to frequent variations in stage, the greater directional variability that sediment will record, and the increased significance of channel confluence sedimentation. In contrast, the most significant characteristics of high-magnitude–low-frequency flooding include the presence of large flood bars and mid-channel ‘jökulhlaup’ bars, hyperconcentrated flows, large gravel dunes, and the formation of ice-block kettle hole structures and rip-up clasts. Glacier surges result in a redistribution of low-magnitude–high-frequency processes and products across the glacier margin, and small floods may occur at the surge termination. Criteria for distinguishing magnitude and frequency regimes in the proglacial environment are identified based on these major characteristics. Studies of Quaternary proglacial fluvial sediments are used to determine how the interaction of the various magnitude and frequency regimes might produce a distinctive sedimentary record. Consideration of sandur architecture and stratigraphy shows that the main controls on the sedimentary record of proglacial regions are the discharge magnitude and frequency regime, sediment supply, the pattern of glacier advance or retreat, and proglacial topography. A model of sandur development is suggested, which shows how discharge magnitude and frequency, in combination with sandur incision and aggradation (controlled by glacier advance and retreat) can control sandur stratigraphy.  相似文献   

Glacial meltwater impounding: Evidence from the late Quaternary glaciogenic sediments in the Sangla valley, district Kinnaur, Himachal Pradesh, India     

R. K. Ganjoo  M. N. Koul 《Journal of Earth System Science》2005,114(4):381-385

Sangla valley is situated at an altitude of ~ 3500 m above mean sea level and lies in the Kinnaur district of Himachal Pradesh. It is fed by river Baspa, a tributary of river Sutlej, that entrenches through the Quaternary glaciogenic deposits before emerging out of the valley and joining the river Sutlej at Karcham. The unstratified to stratified glaciogenic deposits consist of large boulders to fine silt and are classified into four major depositional facies on the basis of sedimentary texture and depositional environment. The facies — basal conglomerates, debris flow, water/sheet flow and laminites — represents the change in the environment of deposition from glaciofluvial to lacustrine and also the extent of the glacier to the valley floor during late Quaternary.  相似文献   

内陆河流域用水结构与产业结构双向优化仿真模型   总被引：2，自引：0，他引：2  

鲍超  方创琳  陈凡 《地理学报(英文版)》2006,16(1):87-98

1 Introduction The great development of western China greatly increases the demand for water. However, in arid inland river basins of Northwest China, water resources are very limited. Shortage of water has been one of the key restricting factors of eco-e…  相似文献   

Does scientific conjecture accurately describe restoration practice? Insight from an international river restoration survey     

Joseph M Wheaton  Stephen E Darby  David A Sear  Jim A Milne 《Area》2006,38(2):128-142

Few sources exist to draw generalizations about the incredibly diverse international river restoration community. Generalizations in the restoration literature tend to be grounded on individual experiences or logical conjecture. To fill this perceived gap, an international web-based survey was launched. Over 500 respondents from 37 different countries participated. The results, posted on the web, act as a database of perceptions and individual experiences, from which the restoration community can make their own interpretations. With three examples, we contrast scientific conjecture with the perceptions of the restoration community who participated in this survey.  相似文献   

Allogenic and autogenic influences upon riparian vegetation dynamics     

Robert A Francis 《Area》2006,38(4):453-464

Riparian vegetation dynamics are regarded as being driven by allogenic hydrogeomorphological factors, with autogenic (plant-induced) influences becoming more important as landform stability is achieved. Autogenic processes, however, may have a substantial influence on both plant dynamics and the river environment from the earliest stages of plant establishment. Various aspects of both allogenic and autogenic processes in riparian vegetation dynamics are discussed here; in particular how plants may promote bank stability and sedimentation, and river island development. Riparian restoration often fails to incorporate autogenic processes, thereby restricting the re-establishment of natural functioning, and further interdisciplinary work is needed to address this.  相似文献