遥感技术在石棉县地质灾害调查中的应用     

张景华  张建龙  欧阳渊 《地质灾害与环境保护》2011,22(1):92-97

采用SPOT5和Quickbird遥感影像,结合地面调查,分析石棉县地质灾害类型、规模和分布.结果表明,石棉县地质灾害以中小型滑坡、崩塌和泥石流为主,其分布与降雨、海拔,岩性、断裂构造和地形密切相关.  相似文献   

柴达木盆地干柴沟-咸水泉地区中-深层成岩演化及其对储集体性能的影响          下载免费PDF全文

欧成华  董兆雄  魏学斌 《古地理学报》2011,13(1):85-95

通过剖面观察、岩心描述、分析化验等手段,系统研究了柴达木盆地干柴沟-咸水泉地区中-深层储集体岩石学特征、主要成岩作用类型及特征、储集空间类型及特征、成岩阶段及成岩演化序列,以及成岩作用对储集体性能的影响程度和规律.结果表明:研究区中-深层储集体主要由成分及结构成熟度均为低-中等的各类砂岩和部分泥灰岩组成;以压实作用、胶...  相似文献   

A note on the derivation of wave action balance equation in frequency space     

Tai-Wen HSU  Jian-Ming LIAU  Shin-Jye LIANG  Shan-Hwei OU  Yi-Ting LI 《中国海洋工程》2011,25(1):133-138

In this paper the wave action balance equation in terms of frequency-direction spectrum is derived.A theoretical formulation is presented to generate an invariant frequency space to replace the varying wavenumber space through a Jacobian transformation in the wave action balance equation.The physical properties of the Jacobian incorporating the effects of water depths are discussed.The results provide a theoretical basis of wave action balance equations and ensure that the wave balance equations used in the SWAN or other numerical models are correct.It should be noted that the Jacobian is omitted in the wave action balance equations which are identical to a conventional action balance equation.  相似文献   

Nature Conservation versus Scenic Quality：A GIS Approach towards Optimized Tourist Tracks in a Protected Area of Northwest Yunnan,China     

YANG Ming-yu  VAN COILLIE Frieke  HENS Luc  DE WULF Robert  OU Xiao-kun  ZHANG Zhi-ming 《山地科学学报》2014,11(1):142-155

Development of appropriate tourism infrastructure is important for protected areas that allow public access for tourism use.This is meant to avoid or minimize unfavourable impacts on natural resources through guiding tourists for proper use.In this paper,a GIS-based method,the least-cost path（LCP） modelling,is explored for planning tourist tracks in a World Heritage site in Northwest Yunnan（China）,where tourism is increasing rapidly while appropriate infrastructure is almost absent.The modelling process contains three steps：1） selection of evaluation criteria（physical,biological and landscape scenic） that are relevant to track decision; 2） translation of evluation criteria into spatially explicit cost surfaces with GIS,and 3） use of Dijkstra＇s algorithm to determine the least-cost tracks.Four tracks that link main entrances and scenic spots of the study area are proposed after optimizing all evaluation criteria.These tracks feature lowenvironmental impacts and high landscape qualities,which represent a reasonable solution to balance tourist use and nature conservation in the study area.In addtion,the study proves that the LCP modelling can not only offer a structured framwork for track planning but also allow for different stakeholders to participate in the planning process.It therefore enhances the effectivenss of tourism planning and managemnt in protected areas.  相似文献   

Determination of the anisotropy of an upper streambed layer in east-central Nebraska, USA   总被引：1，自引：0，他引：1  

Chengpeng Lu  Xunhong Chen  Gengxin Ou  Cheng Cheng  Longcang Shu  Donghui Cheng  Emmanuel Kwame Appiah-Adjei 《Hydrogeology Journal》2012,20(1):93-101

Information on the anisotropy of streambed hydraulic conductivity (K) is a necessity for analyses of water exchange and solute transport in the hyporheic zone. An approach is proposed for the determination of K, developed from existing in-situ permeameter test methods. The approach is based on determination of vertical and horizontal hydraulic conductivity of streambed sediments on-site and eliminates the effects of vertical flow in the hyporheic zone and stream-stage fluctuation, which normally influence in situ permeameter tests. The approach was applied to seven study sites on four tributaries of the Platte River in east-central Nebraska, USA. On-site permeameter tests conducted on about 172 streambed cores for the determination of vertical hydraulic conductivity (K _v) and horizontal hydraulic conductivity (K _h) at the study sites indicate that the study sites have relatively small anisotropic ratios, ranging from 0.74 to 2.40. The ratios of K _h to K _v from individual locations within a study site show greater variation than the anisotropic ratios from the mean or median K at each of the study sites.  相似文献   

利用GPS计算的TEC变化率监测太阳耀斑   总被引：1，自引：1，他引：0  

张健  欧吉坤 《大地测量与地球动力学》2002,22(4):77-80

给出了利用双频GPS载波相位观测值计算各个卫星沿观测方向的电子总量 (TEC)变化率的方法 ,用该方法计算了 2 0 0 0年 7月 12日和 7月 14日两次级别分别为X1.9级和X5 .7级太阳耀斑前后一周各个卫星的TEC变化率。分析表明 ,在太阳耀斑爆发当天 ,如果卫星交叉点是在中纬度地区运动 ,沿观测方向TEC变化率除耀斑爆发的一段时间外 ,其它时间变化相对平稳 ,并且在耀斑爆发一天后 ,TEC变化率趋于正常 ;如果卫星交叉点纬度低于 30° ,那么在耀斑爆发前一天 ,各个卫星沿观测方向的TEC变化率发生“异常” ,即变化率增加很快 ,而且交叉点运行的纬度越低 ,TEC变化率的增量越大。比较了分析太阳耀斑的两种数据处理方法 :求解沿天顶方向上电子总量 (VTEC)和求解TEC变化率的方法 ,指出求解TEC变化率的方法不必考虑仪器偏差的影响 ,能更好地监测较小级别的太阳耀斑。  相似文献   

Simplified approach to estimate the maximum wall deflection for deep excavations with cross walls in clay under the undrained condition     

Pio-Go Hsieh  Chang-Yu Ou 《Acta Geotechnica》2016,11(1):177-189

Previous studies have shown that use of cross walls in deep excavations can reduce the wall deflection to a very small amount. However, design of cross walls is costly because the deflection behavior of the diaphragm wall with cross walls is in nature three dimensional. The objective of this study was to establish a simplified approach used as a first approximation to design cross walls such that the lateral wall deflection can satisfy a design criterion. A series of parametric studies using a three-dimensional numerical method was performed to obtain the influence factors on wall deflections, including excavation geometry, wall system stiffness, axial stiffness of strut, axial stiffness of the cross wall, normalized undrained shear strength of clay and the cross wall depth. Then, a simplified formula for predicting the wall deflection for excavations without and with cross walls was established using multivariate regression analysis, respectively. The formulas were validated through 36 excavation cases without cross walls and 12 cases with cross walls. The simplified formulas can be used to develop a spreadsheet that estimates the cross wall sizes and intervals based on the entered excavation geometry, material properties of retaining-strut system, in situ undrained shear strength and tolerable wall deflection. The estimated cross wall sizes and intervals should be verified by an appropriate full numerical analysis.  相似文献   

A minimal model of the Atlantic Multidecadal Variability: its genesis and predictability     

Hsien-Wang Ou 《Climate Dynamics》2012,38(3-4):775-794

Through a box model of the subpolar North Atlantic, we examine the genesis and predictability of the Atlantic Multidecadal Variability (AMV), posited as a linear perturbation sustained by the stochastic atmosphere. Postulating a density-dependent thermohaline circulation (THC), the latter would strongly differentiate the thermal and saline damping, and facilitate a negative feedback between the two fields. This negative feedback preferentially suppresses the low-frequency thermal variance to render a broad multidecadal peak bounded by the thermal and saline damping time. We offer this “differential variance suppression” as an alternative paradigm of the AMV in place of the “damped oscillation”—the latter generally not allowed by the deterministic dynamics and in any event bears no relation to the thermal peak. With the validated dynamics, we then assess the AMV predictability based on the relative entropy—a difference of the forecast and climatological probability distributions, which decays through both error growth and dynamical damping. Since the stochastic forcing is mainly in the surface heat flux, the thermal noise grows rapidly and together with its climatological variance limited by the THC-aided thermal damping, they strongly curtail the thermal predictability. The latter may be prolonged if the initial thermal and saline anomalies are of the same sign, but even rare events of less than 1% chance of occurrence yield a predictable time that is well short of a decade; we contend therefore that the AMV is in effect unpredictable.  相似文献   

Social-ecological and regional adaptation of agrobiodiversity management across a global set of research regions     

L.E. Jackson  M.M. Pulleman  L. Brussaard  K.S. Bawa  G.G. Brown  I.M. Cardoso  P.C. de Ruiter  L. García-Barrios  A.D. Hollander  P. Lavelle  E. Ouédraogo  U. Pascual  S. Setty  S.M. Smukler  T. Tscharntke  M. Van Noordwijk 《Global Environmental Change》2012,22(3):623-639

To examine management options for biodiversity in agricultural landscapes, eight research regions were classified into social-ecological domains, using a dataset of indicators of livelihood resources, i.e., capital assets. Potential interventions for biodiversity-based agriculture were then compared among landscapes and domains. The approach combined literature review with expert judgment by researchers working in each landscape. Each landscape was described for land use, rural livelihoods and attitudes of social actors toward biodiversity and intensification of agriculture. Principal components analysis of 40 indicators of natural, human, social, financial and physical capital for the eight landscapes showed a loss of biodiversity associated with high-input agricultural intensification. High levels of natural capital (e.g. indicators of wildland biodiversity conservation and agrobiodiversity for human needs) were positively associated with indicators of human capital, including knowledge of the flora and fauna and knowledge sharing among farmers. Three social-ecological domains were identified across the eight landscapes (Tropical Agriculture-Forest Matrix, Tropical Degrading Agroecosystem, and Temperate High-Input Commodity Agriculture) using hierarchical clustering of the indicator values. Each domain shared a set of interventions for biodiversity-based agriculture and ecological intensification that could also increase food security in the impoverished landscapes. Implementation of interventions differed greatly among the landscapes, e.g. financial capital for new farming practices in the Intensive Agriculture domain vs. developing market value chains in the other domains. This exploratory study suggests that indicators of knowledge systems should receive greater emphasis in the monitoring of biodiversity and ecosystem services, and that inventories of assets at the landscape level can inform adaptive management of agrobiodiversity-based interventions.  相似文献   

基于ArcGIS的DEM水系盒维数的计算   总被引：2，自引：0，他引：2  

欧阳晓  赵牡丹  秦慧杰 《地下水》2010,32(6):184-185

水系分形维数的计算与分析,有助于深入理解其与地貌发育、流域径流和侵蚀产沙等过程之间的关系。本文从分形维数的计算原理出发,结合目前最流行的GIS软件,提出了新的水系盒维数计算方法,并以安塞纸坊沟流域为例,说明该方法能较好地反映流域地貌特征。  相似文献