共查询到20条相似文献，搜索用时 15 毫秒
1.
基于IDL的地形三维可视化实现 总被引：3，自引：0，他引：3
作为一种第四代的编程语言,IDL具有对海量数据进行获取、分析、可视化以及对多种图像进行处理和交互式操作的功能。在分析IDL的基础上,应用组件编程技术实现了对遥感图像和DEM数据进行地形三维合成及动态模拟的可视化系统设计,经对环境的三维再现和模拟,对生态环境的演变研究可以起到指导作用,而且它具有较好的系统维护和重复使用功能、易于扩展以及面向对象的特点。用该系统建立了吉林西部虚拟自然环境,对三维地形进行空间分析,及吉林西部生态环境数据库的空间和属性数据的查询。 相似文献
2.
The physical risk from snow avalanches poses a serious threat to mountain backcountry travelers. Avalanche risk is primarily managed by (1) assessing avalanche hazard through analysis of the local weather, snowpack, and recent avalanche activity and (2) selecting terrain that limits exposure to the identified hazard. Professional ski guides have a tremendous wealth of knowledge about using terrain to manage avalanche risk, but their expertise is tacit, which makes it difficult for them to explicitly articulate the underlying decision rules. To make this existing expertise more broadly accessible, this study examines whether it is possible to derive quantitative measures for avalanche terrain severity and condition-dependent terrain guidance directly from observed terrain selection of professional guides. We equipped lead guides at Mike Wiegele Helicopter Skiing with GPS tracking units during the 2014/2015 and 2015/2016 winters creating a dataset of 10,592 high-resolution tracked ski runs. We used four characteristics—incline, vegetation, down-slope curvature (convexities/concavities), and cross-slope curvature (gullies/ridges)—to describe the skied terrain and employed a mixed-effects ordered logistic regression model to examine the relationship between the character of most severe avalanche terrain skied on a day and the associated field-validated avalanche hazard ratings. Patterns in the regression parameter estimates reflected the existing understanding of how terrain is selected to manage avalanche risk well: the guides skied steeper, less dense vegetation, and more convoluted slopes during times of lower avalanche hazard. Avalanche terrain severity scores derived from the parameter estimates compared well to terrain previously zoned according to the Avalanche Terrain Exposure Scale. Using a GIS implementation of the regression analysis, we created avalanche condition-dependent maps that provide insights into what type of terrain guides deemed acceptable for skiing under different avalanche hazard conditions. These promising results highlight the potential of tracking guides’ terrain selection decisions as they manage avalanche hazard for the development of evidence-based avalanche terrain ratings and decision aids for professional and recreational backcountry travelers. 相似文献
3.
Thick, commonly lateritic, regoliths are widespread in inter-tropical regions of the world and present particular challenges in exploration. These are best tackled through a sound understanding of the evolution of the landscapes in which they occur. The regoliths formed under humid, warm to tropical conditions and, although they may have been modified by later climatic changes, i.e., to more humid or more arid conditions, many chemical and mineralogical characteristics are retained. These include the geochemical expressions of concealed mineralization. Erosional and depositional processes control the preservation and occurrence of specific regolith units that may be used as sample media and, in turn, target size, element associations and contrast, thereby influencing sampling procedures, analysis and data interpretation. These parameters are best summarized in terms geochemical dispersion models based on the degree of preservation of the pre-existing lateritic regolith. Regolith–landform mapping permits an assessment of the terrain in terms of such models. In relict regolith–landform regimes, in which the lateritic regolith is largely preserved, broad multi-element anomalies in the upper ferruginous horizons (lateritic residuum) can be detected using sample intervals of 1 km or more. In contrast, in erosional regimes, where this material is absent, anomalies in upper saprolite, and the soil and lag derived from it, are more restricted in area and closer sampling intervals, (200×40 m or less) may be necessary. Lag and soil are, generally, ineffective in depositional areas, except where the sediments are very thin (e.g.,<2 m) or overburden provenance can be established. Stratigraphic drilling is necessary to establish whether the overburden overlies a buried lateritic horizon or an erosion surface cut in saprolite. Lateritic residuum remains an excellent sample medium if present, again with widespread haloes, but where it is absent, leaching and the restricted haloes in upper saprolite present formidable problems. Ferruginous saprolite or composites across the unconformity may be effective, but otherwise carefully targeted drilling and sampling through saprolite and saprock may be necessary. Partial extraction analyses have yet to demonstrate significant results except in very specific environments. In arid regions, pedogenic carbonate (calcrete, caliche) may be a valuable sample medium for Au exploration, principally in erosional regimes, and in depositional areas where the overburden is shallow. Sample intervals range from 1 km for regional surveys, through to 100×20 m in prospect evaluation. Saprolite is an essential sample medium in all landform environments, but the restricted halos and possibility of leaching requires that drilling and sampling should be at close intervals. 相似文献
4.
Dr. J. Karte 《GeoJournal》1983,7(4):329-340
As formed by frost-action and the presence of intensely frozen ground periglacial phenomena, especially microrelief features, are good examples for geomorphic phenomena as being clearly dependent upon specific climatic conditions. Whereas climate controls and delimits the formation and occurrence of periglacial phenomena at a zonal and regional scale, non-climatic vegetational, topographical and edaphic factors are significant within the climatically defined boundary conditions at a smaller scale. It can be shown that each type of periglacial phenomenon is dependent on specific climatic and edaphic conditions. Data on these conditions are compiled in several tables. On the other hand, because of this dependence on specific environmental conditions periglacial phenomena are at the same time diagnostic indicators for such conditions. As to climate they are indicators for specific climatically defined types of frozen ground and for thermal conditions in terms of mean values, such as mean air temperatures, freezing and thawing indexes. Spatial associations of genetically different types of periglacial phenomena indicate the extent and regional subdivision of the periglacial environment and its climatic limits. The definition of the climate-diagnostic value of present periglacial phenomena is an essential perequisite for the palaeoclimatic interpretation phenomena are sensitive to climatic variations of small amplitude and as such they are also indicators of recent short-term climatic changes. As to edaphic conditions they indicate frost-action potential of the groud and various soil properties which have practical implications. As edaphic indicators periglacial phenomena are of significance for terrain evaluation programmes in the Arctic for practical purposes. 相似文献
5.
以云南省东川区小江流域中游左岸大白泥河支流的泥石流沟谷为研究对象,利用无人机遥感技术采集该泥石流沟谷地表地貌数据,提出结合地面三维激光扫描建模数据进行同名地物控制点提取,实现无人机影像数据的绝对定向方法。通过Smart3D影像数据处理,构建研究区三维地形模型,得到数字正射影像（Digital Orthophoto Map,DOM）、数字表面模型（Digital Surface Model,DSM）和高密集匹配点云。利用PhotoScan软件中的不规则三角网渐进加密技术对点云数据进行处理,得到0.5 m分辨率的数字高程模型（Digital Elevation Model,DEM）。结合ArcGIS和Cloud Compare中的相关地形分析模块,实现对该段泥石流沟谷地区的地形特征分析。基于无人机遥感的泥石流沟谷地形建模及特征分析研究中采用的技术路线和方法,对于定性、定量探测高原复杂山区地质灾害及其监测、防治等具有重要实证案例参考价值与实践指导意义。 相似文献
6.
Modelling of ground water recharge-potential in the hard-rock Aravalli terrain,India: a GIS approach 总被引：2，自引：2，他引：0
Modelling of ground water recharge-potential in hard-rock areas principally aims at water-resource evaluation. Various techniques
are available to assess recharge-potential, and their capability in estimating recharge is also variable. However, the water
level fluctuation method is found capable in computing actual ground water recharge. Demarcation of ground water recharge-potential
zones in arid and semi-arid regions is of great importance for human survival and sustainable development. Remote sensing
and geographic information systems (GIS) techniques have been widely used by numerous researchers for qualitative assessment
of ground water potential of a basin or terrain. In the present study, a GIS-based water table fluctuation method has been
attempted for quantitative modelling of ground water recharge of the hard-rock Aravalli terrain. This GIS-based model is further
used to evaluate recharge-potential of the terrain by integrated assessment of infiltration capacity, normal rainfall, and
its cumulative frequency. 相似文献
7.
Vegetation contributes to weak soil stabilisation through reinforcement of the soil, dissipation of excess pore pressure and increasing the shear strength by induced matric suction. This paper describes the way vegetation influences soil matric suction, shrinkage and ground settlement in the vadose zone through transpiration. A mathematical model for the rate of root water uptake, including the root growth rate considering ground conditions, type of vegetation and climatic parameters, has been developed. A finite element approach is employed to solve the transient coupled flow-deformation equations. The finite element mesh is built using partially saturated soil elements capable of representing the salient aspects of unsaturated permeability and the soil water characteristic curve. The model formulation is based on the effective stress theory of unsaturated soils. Based on this proposed model, the distribution of the ground matric suction profile adjacent to the tree is numerically analysed. Current field measurements of soil matric suction and moisture content collected from Miram site located in Victoria State, Australia by the authors are compared with the numerical predictions. The results indicate that the proposed root water uptake model incorporated in the numerical analysis can be used for prediction of ground properties influenced by tree roots. 相似文献
8.
Paulo Cesar Fernandes-da-Silva Ricardo Vedovello Claudio Jose Ferreira John Canning Cripps Maria Jose Brollo Amelia Joao Fernandes 《Environmental Earth Sciences》2010,61(8):1657-1675
Geo-environmental terrain assessments and territorial zoning are useful tools for the formulation and implementation of environmental
management instruments (including policy-making, planning, and enforcement of statutory regulations). They usually involve
a set of procedures and techniques for delimitation, characterisation and classification of terrain units. However, terrain
assessments and zoning exercises are often costly and time-consuming, particularly when encompassing large areas, which in
many cases prevent local agencies in developing countries from properly benefiting from such assessments. In the present paper,
a low-cost technique based on the analysis of texture of satellite imagery was used for delimitation of terrain units. The
delimited units were further analysed in two test areas situated in Southeast Brazil to provide estimates of land instability
and the vulnerability of groundwater to pollution hazards. The implementation incorporated procedures for inferring the influences
and potential implications of tectonic fractures and other discontinuities on ground behaviour and local groundwater flow.
Terrain attributes such as degree of fracturing, bedrock lithology and weathered materials were explored as indicators of
ground properties. The paper also discusses constraints on- and limitations of- the approaches taken. 相似文献
9.
根据滑坡地形特征,将沟谷偏转型滑坡划分为坡脚偏转型、凹面偏转型和凸面偏转型三种类型,其主要地形参数为滑源区坡度、斜坡坡度、沟谷坡度和偏转角度。通过数值模拟,采用正交分析、极差分析和方差分析初步探讨主要地形参数对沟谷偏转型滑坡运动参数的影响。结果表明:沟谷偏转型滑坡的视摩擦系数、前缘速度恢复系数均主要受地形起伏的影响。斜坡坡度对视摩擦系数的影响最大,沟谷坡度次之,偏转角度最小;斜坡坡度、沟谷坡度对前缘速度恢复系数的影响大于偏转角度的影响。斜坡坡度是视摩擦系数的显著性因素,斜坡坡度、沟谷坡度是前缘速度恢复系数的显著性因素。视摩擦系数、前缘速度恢复系数与主控地形因子之间存在显著的非线性关系,可分别用二次函数、二次型函数进行描述。 相似文献
10.
地铁隧道施工引起地层位移规律的探讨 总被引：9，自引：0，他引：9
目前对城市隧道开挖所引起的地表以下地层的位移规律的认识还很不充分，长期以来只有定性地认识。英国学者Mair等人（1993年）根据在黏土中的有限实测资料，基于预测地表位移的Peck公式，考虑了沉降槽宽度随深度变化，从而提出了地表以下的位移计算公式。他们的研究成果被广泛引用，但是由于其仅适用于黏性土，且假定地表处沉降槽宽度参数为0.5，因此在应用上受到很大的限制。在Mair公式的基础上，着重讨论了沉降槽宽度参数随地层深度的变化趋势，并提出了修正计算公式，不仅可以考虑地表沉降槽宽度参数与0.5相差较大的情况，还适用于砂类土地层，因此比Mair公式具有更广泛的适用性。 相似文献
11.
N. Subba Rao 《Environmental Geology》2006,50(7):1067-1076
Demand for groundwater for drinking, agricultural and industrial purposes has increased due to uncertainty in the surface water supply. Agriculture is the main occupation of the rural people in Guntur district, Andhra Pradesh, India. Development of groundwater in the district is very less, indicating a lot of scope for further development of groundwater resources. However, assessment of groundwater conditions, particularly in a crystalline terrain, is a complex task because of variations in weathering and fracturing zones from place to place. Systematic studies for evaluation of groundwater potential zones have been carried out in a crystalline terrain of the district. Information on soils, geological formations and groundwater conditions is collected during the hydrogeological survey. Topographical and drainage conditions are derived from the Survey of India topographical maps. Geomorphological units and associated landform features inferred and delineated from the Indian remote sensing satellite imagery (IRS ID LISS III FCC) are moderately buried pediplain (BPM), shallow buried pediplain (BPS), valley fills (VF), structural hill (SH), residual hills (RH), lineaments and land use/land cover. A groundwater potential index (GPI) is computed for relative evaluation of groundwater potential zones in the study area by integrating all the related factors of occurrence and movement of groundwater resources. Accordingly, the landforms, BPM, BPS, VF, SH and RH, of the area are categorized as very good groundwater potential zone, good to moderate groundwater potential zone, moderate to poor groundwater potential zone, poor to very poor groundwater potential zone and very poor groundwater potential zone, respectively, for development and utilization of both groundwater and surface water resources for eliminating water scarcity. This study could help to improve the agrarian economy for better living conditions of the rural people. Taking the total weight-score of the GPI into account, a generalized classification of groundwater potential zones is evaluated for a quick assessment of the occurrence of groundwater resources on regional scale. 相似文献
12.
13.
为保护黄河流域矿区生态环境,以府谷县庙哈孤矿区安山煤矿125203工作面为背景,采用数值模拟实验、相似材料模拟实验和理论分析相结合的手段,基于工作面过双沟地形开采时地表裂缝发育位置、发育形态等参数,总结出开采诱发地表裂缝发育规律。通过理论分析,建立了浅埋煤层过双沟地形开采地表裂缝发育相对位置函数T及其判别条件,讨论了双沟地形沟谷参数与地表裂缝发育相对位置之间的关系。研究表明,工作面过支沟G1时,共发育地表裂缝4条,最大裂缝宽度23 cm,最大错台11 cm,裂缝发育超前于工作面推进;过主沟G2时共发育地表裂缝7条,最大裂缝宽度79 cm,最大错台45 cm,裂缝发育滞后于工作面推进。裂缝发育相对位置受地质条件、沟深、坡度和沟谷跨度等因素共同影响。地表裂缝发育相对位置函数与裂缝超前(滞后)距离、裂缝宽度和错台以及单沟裂缝总条数密切相关。双沟相互影响程度与工作面推进方向有关。研究结果可为浅埋煤层沟谷下开采地表裂缝发育研究提供一定的理论依据。 相似文献
14.
Estimation of spectral reflectance of snow from IRS-1D LISS-III sensor over the Himalayan terrain 总被引：1，自引：0，他引：1
The sensor onboard the satellite views the earth as a plain surface and consequently the satelliteobtained spectral radiances
cannot represent true values over a mountainous terrain. The relative magnitudes of terrain slope and its aspect with respect
to the sun's position will determine the amount of direct solar radiation incident on an undulating surface. Estimation of
spectral reflectance from satellite data forms an important component in many of the snow and glacier studies. The spectral
reflectance of snow is influenced by its various parameters. The changes in snowpack characteristics as a result of various
metamorphic processes, with age, can cause variations in its spectral reflectances. Since, the terrain geometry also modifies
the amount of reflected radiation from a rugged surface, one has to correct the estimated spectral reflectances for terrain
topography so as to use them in deriving the snowpack characteristics accurately. Also, the amounts of melt runoff originating
from glaciers having different slopes and orientations will not be the same. Considering these aspects, a model has been developed
to estimate the terrain corrected spectral reflectances over the Himalayan terrain using the Linear Imaging Self Scanner-III
data of the Indian Remote Sensing Satellite. The model computes spectral reflectances from satellitebased radiance measurements
and includes the effect of the terrain topography on the incident solar radiation. The terrain slope and its aspect are generated
from the digital elevation model of the region. The analysis carried out over the Beas Basin, Himachal Pradesh, India, indicated
a variation of 22% in the amount of incident solar radiation for an increase of 10‡ in terrain slope. Further, the terrain
with south-east aspect received maximum amount of solar radiation. The large differences observed between the uncorrected
and terrain corrected reflectances in the shortwave infrared band (B5), which is not saturated over the snow covered region,
suggest that the terrain slope and its aspect cannot be neglected in estimating the accurate spectral reflectances over the
Himalayan terrain. 相似文献
15.
Soil erodibility is one of the most important factors used in spatial soil erosion risk assessment. Soil information derived from soil map is used to generate soil erodibility factor map. Soil maps are not available at appropriate scale. In general, soil maps at small scale are used in deriving soil erodibility map that largely generalized spatial variability and it largely ignores the spatial variability since soil map units are discrete polygons. The present study was attempted to generate soil erodibilty map using terrain indices derived from DTM and surface soil sample data. Soil variability in the hilly landscape is largely controlled by topography represented by DTM. The CartoDEM (30 m) was used to derive terrain indices such as terrain wetness index (TWI), stream power index (SPI), sediment transport index (STI) and slope parameters. A total of 95 surface soil samples were collected to compute soil erodibility factor (K) values. The K values ranged from 0.23 to 0.81 t ha?1R?1 in the watershed. Correlation analysis among K-factor and terrain parameters showed highest correlation of soil erodibilty with TWI (r 2= 0.561) followed by slope (r 2= 0.33). A multiple linear regression model was developed to derive soil erodibilty using terrain parameters. A set of 20 soil sample points were used to assess the accuracy of the model. The coefficient of determination (r 2) and RMSE were computed to be 0.76 and 0.07 t ha?1R?1 respectively. The proposed methodology is quite useful in generating soil erodibilty factor map using digital elevation model (DEM) for any hilly terrain areas. The equation/model need to be established for the particular hilly terrain under the study. The developed model was used to generate spatial soil erodibility factor (K) map of the watershed in the lower Himalayan range. 相似文献
16.
Assessment of landslide susceptibility on the natural terrain of Lantau Island, Hong Kong 总被引：33，自引：1，他引：33
Steep terrain and the high frequency of tropical rainstorms make landslide occurrence on natural terrain a common phenomenon
in Hong Kong. For example, more than 800 slope failures were triggered by a rainstorm in November 1993 on Lantau Island, Hong
Kong. Maps of recent landslides interpreted from aerial photographs, in combination with a geographical information system,
were used to evaluate the frequency and distribution of landslides, with particular reference to such physical parameters
as lithology, slope gradient, slope aspect, elevation, vegetation cover, and proximity to drainage line, all of which are
considered to be influential in the occurrence of landslides. A stepwise logistic regression model was obtained between landslide
susceptibility and the above mentioned physical parameters. The study area has been classified into five classes of relative
landslide susceptibility, namely, very low, low, moderate, high, and very high, based on this methodology.
Received: 17 December 1999 · Accepted: 21 March 2000 相似文献
17.
COMSOL是一个多物理场仿真软件,笔者尝试将其应用于大地电磁法的数值模拟,研究起伏地形对大地电磁响应的影响及解决方案。本文由麦克斯韦方程组出发,施加第一类边界条件,将地形起伏数字化为参数化曲面,导入COMSOL进行计算。在对COMSOL的精度进行了验证的基础上,分析不同频点所需内存以及自由度,然后选择合适的频点进行研究。将三维起伏地形的模拟结果与无地形起伏时的结果进行对比,总结出山谷、山峰地形对三维大地电磁响应的影响,发现在XY模式下,地形对视电阻率的影响大于相位,在视电阻率等值线图中能够清晰地看出起伏地形的轮廓,而在YX模式下,地形对相位的影响大于对视电阻率的影响。最后,利用“比值法”进行地形校正,校正前由于起伏地形影响,在异常体附近会出现部分视电阻率数值跳跃现象,通过校正有效抑制了起伏地形对异常体附近视电阻率的影响,校正后的视电阻率曲线整体上移,并且异常体周围的视电阻率值也趋于背景场值,获得了较好的效果。 相似文献
18.
Ruzinoor Che Mat Abdul Rashid Mohamed Shariff Biswajeet Pradhan Ahmad Rodzi Mahmud Mohd Shafry Mohd Rahim 《Arabian Journal of Geosciences》2013,6(12):4881-4889
The objective of this paper is to discuss the effectiveness of visualizing online 3D terrain draped with different satellite imageries. The topographic data of the study area were obtained from the contour maps of Universiti Putra Malaysia, Selangor, Malaysia. The high resolution satellite imageries used in this project involving QUICKBIRD (0.6 m resolution), IKONOS (1 m resolution), and SPOT5 (5 m resolution). R2V software was used for editing the contour data, whereas Arc GIS was used for overlaying the imageries over the 3D terrain data. Then the data were exported into Virtual Reality Markup Language to compare the effectiveness of different satellite imageries based on the data file size, imageries size, number of images tile, loading time during office hours (from 8 a.m. to 5 p.m.) and out of office hours (after 5 p.m.), frame rate per second, and visualization quality. The results revealed that IKONOS satellite imageries are better for an effective online 3D terrain visualization utilizing GIS data even though it has lower resolution compared to QUICKBIRD. 相似文献
19.
目前区域（盆地）地下水流系统模拟研究中,常用的定水头与通量两种上边界条件刻画方法与实际条件存在差距。通过对比两种方法的差异和各自适用条件,采用解析法讨论地下水位的形成控制机制,提出了改进后的变通量上边界数值模型,并以鄂尔多斯盆地北部白垩系地下水流系统为例分析了盆地地下水流系统的形成与影响因素。研究表明,鄂尔多斯盆地北部白垩系水流系统地下水位受地形、补给条件和渗透系数三者共同控制,同时特有的气候、地形和岩性组合通过控制地下水位影响地下水流系统的发育演化。采用变通量上边界法探讨上边界条件改变对盆地水流系统的影响,对深刻认识区域地下水流系统形成演化机制,揭示地下水系统与上边界气候变化、植被生态变化之间的相互作用关系具有一定优势。 相似文献
20.
Ice, moraine, and landslide dams in mountainous terrain 总被引：4，自引：0，他引：4
We review recent work on ice, moraine, and landslide dams in mountainous terrain, thus complementing several comprehensive summaries on glacier dams in intracontinental and Arctic areas of low relief. We discuss the roles of tectonic and climatic forcing on ice-, moraine-, and landslide-dam formation and sudden drainage, and focus on similarities and differences between their geomorphic impacts on confined valleys drained by steep bedrock and gravel-bed rivers.Despite numerous reported failures of natural dams in mountain belts throughout the world, their relevance to long-term dynamics of mountain rivers remains poorly quantified. All types of dams exert local base-level controls, thus trapping incoming sediment and inhibiting fluvial bedrock incision. Pervasive geomorphic and sedimentary evidence of outburst events is preserved even in areas of high erosion rates, suggesting that sudden dam failures are characterized by processes of catastrophic valley-floor aggradation, active-channel widening, and downstream dispersion of sediment, during which little bedrock erosion seems to be achieved.We find that, in the absence of direct evidence of former dams, a number of similarities among the geomorphic and sedimentologic characteristics of catastrophic outburst flows may give rise to ambiguous inferences on the dam-forming process. This is especially the case for tectonically active mountain belts where there is ample and comparable potential for the formation and failure of ice, moraine, landslide, and polygenetic dams concomitant with climatic oscillations or earthquake disturbance. Hence, the palaeoclimatic implications of erroneously inferring the cause of dam formation may be significant.We recommend that future research on natural dams in mountainous terrain addresses (a) climate- and earthquake-controlled systematics in the pattern of formation and failure; (b) quantification of response of mountain rivers to catastrophic outburst events and their concomitant process sequences; (c) elaboration of a comprehensive classification of natural dams in mountainous terrain with special attention to polygenetic dams; (d) physical-based modelling of dam formation, failure, and routing of water and sediment outbursts; and (e) quantitative controls on the contribution of natural dams to sediment budgets in mountainous terrain. 相似文献