陕北黄土高原沟道小流域形态特征分析

本文就黄土高原不同地貌类型区的小流域进行了形态量计分析。并以河网密度为地表切割程度指标,建立了河网密度与流域形态要素的复相关方程式。     

Impact of a pre-existing transverse drainage system on active rift stratigraphy: An example from the Corinth Rift,Greece

Models to explain alluvial system development in rift settings commonly depict fans that are sourced directly from catchments formed in newly uplifted footwalls, which leads to the development of steep-sided talus-cone fans in the actively subsiding basin depocentre. The impact of basin evolution on antecedent drainage networks orientated close to perpendicular to a rift axis, and flowing over the developing hangingwall dip slope, remains relatively poorly understood. The aim of this study is to better understand the responses to rift margin uplift and subsequent intrabasinal fault development in determining sedimentation patterns in alluvial deposits of a major antecedent drainage system. Field-acquired data from a coarse-grained alluvial syn-rift succession in the western Gulf of Corinth, Greece (sedimentological logging and mapping) has allowed analysis of the spatial distribution of facies associations, stratigraphic architectural elements and patterns of palaeoflow. During the earliest rifting phase, newly uplifted footwalls redirected a previously established fluvial system with predominantly southward drainage. Footwall uplift on the southern basin margin at an initially relatively slow rate led to the development of an overfilled basin, within which an alluvial fan prograded to the south-west, south and south-east over a hangingwall dip slope. Deposition of the alluvial system sourced from the north coincided with the establishment of small-scale alluvial fans sourced from the newly uplifted footwall in the south. Deposits of non-cohesive debris flows close to the proposed hangingwall fan apex pass gradationally downstream into predominantly bedload conglomerate deposits indicative of sedimentation via hyperconcentrated flows laden with sand- and silt-grade sediment. Subsequent normal faulting in the hangingwall resulted in the establishment of further barriers to stream drainage, blocking flow routes to the south. This culminated in the termination of sediment supply to the basin depocentre from the north, and the onset of underfilled basin conditions as signified by an associated lacustrine transgression. The evolution of the fluvial system described in this study records transitions between three possible end-member types of interaction between active rifting and antecedent drainage systems: (a) erosion through an uplifted footwall, (b) drainage diversion away from an uplifted footwall and (c) deposition over the hangingwall dip slope. The orientation of antecedent drainage pathways at a high angle to the trend of a developing rift axis, replete with intrabasinal faulting, exerts a primary control on the timing and location of development of overfilled and underfilled basin states in evolving depocentres.     

黄河中游流域地貌形态对流域产沙量的影响

在黄河中游地区 ,选择了 5 0多个面积约 5 0 0～ 2 5 0 0平方公里的水文测站流域 ,分别代表 6种不同自然地理类型 ,在流域沟壑密度、沟间地坡度小于 15°面积百分比等地貌形态指标量计的基础上 ,进行了流域产沙量与地貌形态指标相关分析。结果表明 ,对于不同类型流域 ,流域产沙量随流域地貌的变化遵循不同的响应规律 ,而且视流域其它下垫面环境条件的均一程度 ,其相关程度和响应速率各不相同。受地面物质、植被、地貌发育阶段等流域其它下垫面环境条件的制约 ,除沟壑密度外 ,流域产沙量与流域地貌形态的关系都没有人们以前所预期的好。     

黑河上游水系发育特征分析

对黑河上游山区部分的水系发育特征进行了分析。在1:250 000比例尺的地形图上,黑河河道可以划分为五级。根据Horton的地貌关系统计结果,黑河水系特征不都服从于Horton的河道定律。河道数量定律适用于本地区,但河道分岔比较高。河道长度定律不适用于本地区,在半对数纸上,平均河道长度的累计值与河道级序有较好的直线关系,而河道总长度与级序则呈双对数直线关系。河道频率及河网密度与河谷局地气候呈正相关,湿润气候条件下,河道频率与河网密度较大;反之,干旱气候条件下,河道频率与河网密度较小。但河流的产流则与区域降水量有关。河川径流的泥沙含量与河流切割程度呈正相关,祁连山北坡河流的泥沙主要来源于横向深切河谷。     

ROAD DRAINAGE AND EQUILIBRIUM IN SMALL STREAM BASINS*

Roads and road drainage accompany the development of the physical landscape for cultural purposes. The addition of a road network to a small stream basin creates a situation of geomorphic disequilibrium by adding to the length of surface drainage channels. Effects of road drainage on the geomorphic equilibrium of small stream basins are analyzed using Horton's Law of Stream Lengths. The effects of different types of road networks are analyzed using an hypothetical stream basin and eight hypothetical road networks, suggesting a method of predicting the location and extent of disequilibrium in a stream basin system as a result of road drainage.     

RELATIONSHIPS BETWEEN THE MORPHOMETRY OF ALPINE AND SUBALPINE BASINS AND REMOTELY SENSED ESTIMATES OF LAKE TURBIDITY,GLACIER NATIONAL PARK,MONTANA

Relationships between characteristics of alpine and subalpine drainage basin form and estimates of lake turbidity were examined. The study was designed to provide insight into sediment removal and delivery systems in an environment where direct process studies are difficult because of logistical constraints. Remote sensing techniques were developed to assess lake turbidity levels through the acquisition of spectral responses by the Landsat Thematic Mapper. Topographic maps were interpreted to derive measurements of morphometric characteristics of 25 study basins within Glacier National Park, Montana. The morphometric variables were chosen to describe basin characteristics related to sediment removal and transport processes. Correlation analysis, principal components analysis (PCA), hierarchical clustering, and analysis of variance (ANOVA) were used to assess characteristics of basin form and the relationship to levels of lake turbidity. A significant correlation between the first principal component, which accounted for the general morphometric character of basins, and estimated lake turbidity was discovered. The areal extent of glacial ice and total stream length within the basins were the most significant variables related to estimated levels of lake turbidity.     

The interaction between normal faulting and drainage in active extensional basins, with examples from the western United States and central Greece

Faulting exerts an important control upon drainage development in active extensional basins and thus helps determine the architecture of the sedimentary infill to a synrift basin. Examples of the interaction between faulting and drainage from the western United States and central Greece may be grouped into a relatively small number of classes based upon the structural position of a drainage catchment: footwall, hangingwall, fault offset and axial. Our examples illustrate the diversity of erosional effects that might arise because of variations in the spacing, orientation and segmentation of faults and their interactions. Where basement lithology is similar, footwall catchments are generally smaller, shorter and steeper than those of the hangingwall. Footwall-sourced alluvial fans and fan deltas are: generally smaller in area than those sourced from similar lithologies in the hangingwall. Wide fault offsets often give rise to large drainage catchments in the footwall. The development of axial drainage depends upon the breaching of transverse bedrock ridges by headward stream erosion or by lake overflow. Once breaching has occurred the direction of axial stream flow is controlled by the potential developed between basins of contrasting widths. Fault migration and propagation leads to the uplift, erosion and resedimentation of the sedimentary infill to formerly active basins, leading to the cutting of footwall unconformities. The outward sediment flux from structurally controlled catchments is modulated in an important way by lithology and runoff. The greatest contrasts in basement lithology arise when fault migration and propagation have occurred, such that the sedimentary fill to previously active basins is uplifted, incised and eroded by the establishment of large new drainage systems in the footwalls of younger faults. Drainage patterns in areas where faults interact can shed light on the relative timing of activity and therefore the occurrence of fault migration and propagation. Facies and palaeocurrent trends in ancient grabens may only be correctly interpreted when observations are made on a length scale of 10–20 km, comparable to that of the largest fault segments.     

黄河源区典型河网平面形态特征及影响因素

黄河源区不同地貌环境下的河网发育模式、平面形态等具有显著差异,存在羽状、矩形状、对称羽状和树状4种典型的河网类型。选取黄河源区83个典型子流域,计算了河网平面特征参数,探讨了河网参数与地形和气候因子的关系及河网类型的分布规律。结果表明,4类河网平面特征差异性通过流域宽长比、河网密度和流域内河流流向最大频数得到了较好的体现。流域坡度和降雨量对河网密度及流向的影响显著,且能较好解释河网密度及流向最大频数的变化;降雨对流域宽长比的影响显著。羽状主要分布在源区上游北部边缘地带,气候干旱,地表裸露,流域坡度均值为4.5°,流域高差均值为730 m。矩形状集中分布在若尔盖地区,气候相对湿润,且有大量的沼泽湿地,流域坡度和流域高差均值分别为2.3°和177 m。对称羽状处于高山峡谷地带,流域坡度和流域高差均值分别为16.9°和1167 m,降雨量变化范围大。树状分布在黄河源中游山区及中下游的冲积地貌,流域坡度和流域高差均值分别为15.4°和968 m,植被覆盖较好。结合4类河网的空间分布特征及河网参数与环境因子的多元回归分析结果分析,认为地形是决定河网平面形态分异的主要原因;当地形限制减小,气候条件和植被覆盖情况对河网的发展起了重要作用。     

艾比湖水盐变化原因及影响研究

从湖泊水文要素出发,基于湖泊和流域的关系,对半个世纪来艾比湖面积、矿化度等水文要素变化趋势进行了分析,并对变化原因进行了探讨,结果表明,相对封闭及较小尺度的流域面积等自身特性,决定了其水资源系统自我调节能力的脆弱性;而近年来流域上的人类活动,增大了降水径流滞留时间和蒸发作用,加大了对水资源的利用量,最终导致汇入湖泊的水量不断减少,矿化度在湖水量不断减少的情况下浓缩升高,最后就艾比湖水盐趋势变化及影响进行了讨论。     

岔巴沟流域次暴雨产沙统计模型

流域综合治理规划、防治土壤侵蚀、合理利用水沙资源 ,无不需要掌握流域产沙情况。流域产沙统计模型结构简单 ,计算方便 ,是现有产沙预报的强有力工具。本文以陕西省岔巴沟流域及其支流实测降雨水文资料为基础 ,系统地分析了流域产沙的降雨、径流、地貌因子在流域产沙中的作用 ,进而将影响产沙的因素概括为径流深、洪峰流量、流域面积、流域沟道密度 ,并作为产沙预报的指标 ,建立了岔巴沟流域次暴雨产沙的统计模型。经检验 ,该预报公式具有一定的精度。     

黑河流域水资源动态变化与绿洲发育及发展演变的关系

通过探讨流域及绿洲发育及其发展演变的水资源动态变化的特征,阐明它们之间的独特关系,并以此来揭示绿洲系统发育的河流流域地带性问题及特征。研究表明,本区水资源动态变化主要在径流形成、利用和消失三个区域内具有依次性体现的特征。其中占总流域面积10%左右的河川径流形成区,对全流域的水资源动态变化具有先决性作用,并在各个区域水动态变化体现上又受到系统对水的吞吐、留存、蒸散和转化能力大小的影响。因此,河流流域是地域分异现象中通过水流作用所体现出的水平地带性与垂直地带性的一种交汇,同时也是地带性与非地带性系统分异的主要区域。作为河流流域地带发育的绿洲系统,其发展演变规律和特征是相当独特的,如开放性、动态性、脆弱性以及资源有限性等。其中有限的水土资源及其动态变化是制约区域内各层次流域发展及绿洲系统发育的关键,并在不同区段上存在着显著差异性,且彼此间常体现出互为依存、互为消长的依次性制约关系。如水资源量的多寡、质的优劣和时空动态变化及分布、以及人为作用等决定着绿洲类型体现和规模分布、发育层次及阶段或发展演变过程及趋势、和社会经济价值体现等。     

基于栅格数字高程模型提取特征地貌技术研究

本文对近年来基于栅格数字高程模型提取特征地貌技术进行了详细的研究,认为该技术的关键在于两个方面：一是如何定义地貌形态结构,二是提取算法的设计。本文提出了基于地貌学角度来定义地貌形态结构的方法,利用有限个数的形态要素的空间组合和对比分析来获取特征地貌,并可以对各种特征地貌形态进行符合物理意义的改进。     

The Fractal Characteristics of Drainage Networks and Erosion Evolution Stages of Ten Kongduis in the Upper Reaches of the Yellow River,China

The fractal characteristics of drainage in the ten kongduis of the upper Yellow River were obtained using the box counting dimension, and the evolution stages of the watershed topography were defined by different ranges of the fractal dimensions of river networks (Dg). The results show that the fractal scaleless range of the Maobula River is 20–370 m based on a combination of artificial judgment, correlation coefficient test and fitting error. Other kongduis show good fractal characteristics in this fractal scaleless range as well. The box counting dimension can be used as a quantitative index of watershed topography fractal characteristics. The fractal dimension of stream networks is independent of the threshold contributing area used for extracting the drainage networks from the DEM. The values of Dg in the upper ten kongduis are in the range of 1.08?1.14. Both the runoff yield and the sediment yield are positively and linearly related with Dg. The positive relation between the sediment yield and Dg reflects the effect of landform features on sediment yield in the young and/or mature stages of landform evolution of the study area. By revising the critical value of Dg, the value of Dg of the basin in the young evolution stage is less than 1.06, while it is more than 1.06 for the basin in mature or old evolution stage. The upper ten kongduis are in the mature stage of landform evolution.     

River and basin morphometric indexes to detect tectonic activity: a case study of selected river basins in the South Indian Granulite Terrain (SIGT)

Abstract

The effects and influence of tectonic processes on the Anjarakandy, Thalassery, Mahe, and Kuttiyadi watersheds and rivers of the South Indian Granulite Terrain in Kerala were examined to determine their spatial heterogeneity. Drainage basin asymmetry (Af), transverse topographic symmetry factor (T), hypsometric integral and curve (HI), longitudinal profile, stream length gradient index (SL), and stream concavity index (SCI) suggest heterogeneity in tectonic influence. Clusters of geomorphic anomalies in similar lithology rule out lithologic control on drainage development. However, the orientations of the drainage networks and predominant fractures/lineaments compare closely and reveal strong tectonic influence. Though the watersheds are considered to be in an advanced stage of erosion by the low HI (<30) and high values of SCI, variations in the shape of the hypsometric curves and differences in the SCI values indicate the different influence of tectonic process from watersheds in the north to the south. Among the watersheds, the Mahe and Kuttiyadi are more sensitive to tectonic processes than the Anjarakandy and Thalassery and indicate spatial heterogeneity in the influence of tectonic activity, confirming the grouping of watersheds based on structural and drainage patterns.     

Tectono-sedimentary evolution of active extensional basins

We present conceptual models for the tectono-sedimentary evolution of rift basins. Basin architecture depends upon a complex interaction between the three-dimensional evolution of basin linkage through fault propagation, the evolution of drainage and drainage catchments and the effects of changes in climate and sea/lake level. In particular, the processes of fault propagation, growth, linkage and death are major tectonic controls on basin architecture. Current theoretical and experimental models of fault linkage and the direction of fault growth can be tested using observational evidence from the earliest stages of rift development. Basin linkage by burial or breaching of crossover basement ridges is the dominant process whereby hydrologically closed rifts evolve into open ones. Nontectonic effects arising from climate, sea or lake level change are responsible for major changes in basin-scale sedimentation patterns. Major gaps in our understanding of rift basins remain because of current inadequacies in sediment, fault and landscape dating.     

泥石流流域集水区面积限值与一级水系数目关系

文章利用ArcInfo的水文分析功能,从不同区域的三条典型泥石流沟的数字高程模型中提取出不同限值下的水系,然后研究了不同集水区面积下限导致的流域水系细节层次的变化,发现一级水系的数目和集水区面积下限成近似于反比的关系,而反比关系的比例系数只与流域面积有关。这种关系反映了泥石流流域的水系在空间尺度变换下的某种自相似性,也说明了泥石流流域在相当宽的空间尺度范围内一级子流域的物质活动能力是一定的。     

侯马盆地冲积扇及其流域地貌发育规律

根据从DEM数据中提取的侯马盆地冲积扇及其流域的多项地貌指标,分析了各地貌指标的空间分布规律,并通过地貌指标的空间分布曲线与山前地形高程曲线形态的对比以及地貌指标相关性分析来揭示冲积扇及其流域地貌的发育规律。结果表明,在侯马盆地相对隆起部位的冲积扇及其流域的地貌指标与在盆地凹陷部位的冲积扇及其流域的地貌指标有较大差异;流域地貌指标的空间分布受到盆地边界断层构造活动性的影响;冲积扇的发育主要受到流域规模、山前构造活动以及盆地基准面等多种因素共同的影响;流域内岩性的差异不是造成研究区域内冲积扇地貌差异的主要因素。     

内流河流域水资源利用对径流年际年内变化影响的分析——以塔里木河流域为例

以塔里木河流域为例 ,探讨了干旱区内流河流域近 40年来 ,由于人口增长、灌溉面积扩大、河流水资源引用程度日益增加等原因所引起的河流径流多年变化及年内变化等水文效应及其变化的原因。     

内流河流域水资源利用对径流年际年内变化影响的分析——以塔里木河流域为例

以塔里木河流域为例,探讨了干旱区内流河流域近40年来,由于人口增长、灌溉面积扩大、河流水资源引用程度日益增加等原因所引起的河流径流多年变化及年内变化等水文效应及其变化的原因。     

Interplay between lithospheric flexure and river transport in foreland basins

ABSTRACT Foreland basins form by lithospheric flexure under orogenic loading and are filled by surface transport of sediment. This work readdresses the interplay between these processes by integrating in a 3D numerical model: the mechanisms of thrust stacking, elastic flexural subsidence and sediment transport along the drainage network. The experiments show that both crustal tectonic deformation and vertical movements related to lithospheric flexure control and organise the basin-scale drainage pattern, competing with the nonlinear, unpredictable intrinsic nature of river network evolution. Drainage pattern characteristics are predicted that match those observed in many foreland basins, such as the axial drainage, the distal location of the main river within the basin, and the formation of large, long-lasting lacustrine systems. In areas where the river network is not well developed before the formation of the basin, these lithospheric flexural effects on drainage patterns may be enhanced by the role of the forebulge uplift as drainage divide. Inversely, fluvial transport modifies the flexural vertical movements differently than simpler transport models (e.g. diffusion): Rivers can drive erosion products far from a filled basin, amplifying the erosional rebound of both orogen and basin. The evolution of the sediment budget between orogen and basin is strongly dependent on this coupling between flexure and fluvial transport: Maximum sediment accumulations on the foreland are predicted for a narrow range of lithospheric elastic thickness between 15 and 40 km, coinciding with the T _e values most commonly reported for foreland basins.