植被淹没程度对坡面流水动力学特性影响          下载免费PDF全文

杨帆  张宽地  杨明义  杨婕 《水科学进展》2016,27(6):832-840

为深入揭示植被覆盖条件下坡面水流结构的内在规律,采用水槽模拟试验,系统研究了植被处于淹没及非淹没工况下淹没度对坡面流水动力学特性的影响。研究结果表明:坡度一定条件下,平均流速和雷诺数与淹没度均成正相关关系;柔性植被覆盖下,水流流型由缓流区过渡到急流区,综合阻力系数随淹没度的增加而减小,刚性植被覆盖条件下水流流型均处于缓流区;综合阻力系数呈单驼峰形式变化;峰值处淹没度为0.9,淹没度对相对摩阻流速的影响与其对阻力系数呈相反变化趋势,基于淹没度的阻力计算经验公式决定系数均达到0.97以上;由于淹没度对各水动力学参数的影响受制于坡度,在坡面水土保持中应根据山区坡度和水深选择适当的植被高度。  相似文献   

南极普通球粒陨石风化等级的重新厘定     

尚颖丽  李世杰  王世杰  李雄耀  李阳 《岩石学报》2016,32(1):71-76

在南极格罗夫山普通球粒陨石的风化等级划分中出现了和Wlotzka(1993)标准矛盾的现象。部分普通球粒陨石的金属和陨硫铁氧化不足20%,然而硅酸盐却发生了蚀变。如果考虑金属的氧化量,这种风化程度应为W1,如果考虑硅酸盐的蚀变,这种风化程度应为W5。对于存在如此大的差异本文给出了折衷的解决办法——对金属和硅酸盐同时进行风化等级划分。金属的风化等级划分为W_m0-W_m4五个,硅酸盐风化等级划分为W_s0-W_s3四个。依据新方案,GRV 021588、021636、021772和021957等4块无法用Wlotzka(1993)标准来确定风化等级的陨石的风化等级均为W_m1-W_s1。而陨石GRV 023312的风化等级为W_m3-W_s0,其相当于Wlotzka(1993)标准中的W3。  相似文献   

Landslide Hazard and Risk Assessment on the Northern Slope of Mt. Changbai, China   总被引：1，自引：0，他引：1  

LIU Zhenghu  ZHANG Yanbin  Yoshiharu ISHIKAWA  Hiroyuki NAKAMURA 《《地质学报》英文版》2008,82(1):214-224

Landslide hazard and risk assessment on the northern slope of Mt. Changbai, a well-known tourist attraction near the North Korean-Chinese border, are assessed. This study is divided into two parts, namely, landslide hazard zonation and risk assessment. The 1992 Anbalagan and Singh method of landslide hazard zonation （LHZ） was modified and used in this area. In this way, an Associative Analysis Method was used in representative areas to get a measure for controlling factors （slope gradient, relative relief, vegetation, geology, discontinuity development, weak layer thickness and ground water）. For the membership degree of factor to slope failure, the middle range of limited values was used to calculate LHZ. Based on an estimation of the potential damage from slope failure, a reasonable risk assessment map was obtained using the relationship of potential damage and probable hazard to aid future planning and prediction and to avert loss of life.  相似文献   

基于关联度分析法的土地整理生态环评研究   总被引：1，自引：0，他引：1  

朱彦刚  胡石元  张奇 《测绘信息与工程》2008,33(1):30-32

介绍了关联度分析法的基本原理,建立了一套生态环境影响评价指标体系,并采用关联度分析法实现了对项目区的生态环境影响评价.  相似文献   

Omnibus Weights of Evidence Method Implemented in GeoDAS GIS for Information Extraction and Integration     

张生元  成秋明  陈志军 《中国地质大学学报(英文版)》2008,19(4):404-409

Weights of evidence (WofE) is an artificial intelligent method for integration of information from diverse sources for predictive purpose in supporting decision making. This method has been commonly used to predict point events by integrating point training layer and binary or ternary evidential layers (multiclass evidence less commonly used). Omnibus weights of evidence integrates fuzzy training layer and diverse evidential layers. This method provides new features in comparison with the ordinary WofE method. This new method has been implemented in a geographic information system-geophysical data analysis system and the method includes the following contents: (1) dual fuzzy weights of evidence (DFWofE), in which training layer and evidential layers can be treated as fuzzy sets. DFWofE can be used to predict not only point events but also area or line events. In this model a fuzzy training layer can be defined based on point, line, and areas using fuzzy membership function; and (2) degree-of-exploration model for WofE is implemented through building a degree of exploration map. This method can be used to assess possible spatial correlations between the degree of exploration and potential evidential layers. Importantly, it would also make it possible to estimate undiscovered resources, if the degree of exploration map is combined with other models that predict where such resources are most likely to occur. These methods and relevant systems were validated using a case study of mineral potential prediction in Gejiu (个旧) mineral district, Yunnan (云南), China.  相似文献   

后压浆旋挖钻孔灌注桩单桩竖向承载力分析   总被引：1，自引：0，他引：1  

梁金国 《岩土工程技术》2008,22(3):139-144

通过后压浆旋挖钻孔灌注桩现场测试结果,分析了后压浆旋挖钻孔灌注桩的承载力、桩身荷载传递规律、桩的极限侧阻力分布规律。桩在竖向荷载作用下,桩的极限侧阻力发挥度,随桩的入土深度而衰减。提出了侧摩阻发挥度分布表达式及后压浆旋挖钻孔灌注桩单桩承载力计算方法,计算结果与试验结果较为符合。为后压浆旋挖钻孔灌注桩的设计提供了理论依据。  相似文献   

砂土密实度的成因分析及其评价方法的探讨     

孔祥国 《岩土工程技术》2008,22(6):289-291,311

砂土的密实程度是影响其工程性质的重要因素,评价砂土密实度的方法很多,但所得结果可能有差异．通常认为这是试验方法不同引起的试验误差。实际上砂土的成因及埋藏条件、地下水也是影响砂土密实度的重要因素。承压水的承压力会改变土中有效自重应力的分布,致使砂土密实度出现反常现象。工程中应注重砂土密实度的成因分析,运用理论知识．分辨各种评价方法的适用条件及其优缺点。  相似文献   

昆明市泥石流风险性评价研究   总被引：1，自引：1，他引：0  

张绪教  刘光旭  吴文祥 《地质灾害与环境保护》2008,19(2):79-85

采用比较成熟的泥石流危险性评价模型,结合ESRI（Environment System Research Institute）公司开发的新一代GIS软件——ARCGIS9．2,对昆明市泥石流进行危险度评价,得出了昆明市各县区的危险度。易损性评价是泥石流灾害风险性评价的一部分,根据国内有关易损性的理论成果,我们建立了昆明市泥石流易损性评价模型,对昆明市以各县区为单位进行了易损性评价,得出了昆明市各县区的易损度。利用联合国给出的自然灾害风险性评价模型：R—H×V,易损度和危险度相乘,得出了昆明市的风险度。使用ARCGIS9．2的自然分级和制图输出功能,对昆明市泥石流风险性进行了分区和制图,给出了昆明市泥石流风险性评价图。结合实际情况综合评判之后发现昆明市各县区呈现出泥石流灾害易损度和危险度不均衡的现象,因此,泥石流灾害发生时,外部社会救援工作就显得特别重要。  相似文献   

松辽盆地西斜坡水动力场与油气的聚集成藏   总被引：2，自引：0，他引：2  

康德江  庞雄奇  吕延防  付广 《地球学报》2008,29(2):205-212

本文以松辽盆地西斜坡大量水化学分析数据和钻井、地球化学等资料为基础,利用对水动力场的计算,通过平面和纵向上的研究认为,西斜坡高台子油层和萨尔图油层地层水化学性质和分布特征较为相似,表明两者间应该存在允许地下流体（包括油气）相互连通的窗口,从而导致高台子油层的规模弱于萨尔图油层;研究区内地层水以压实流和渗人流两种为主,由四周向中心交汇,在水动力方面,泥岩层以向上下排出为主,砂岩层则是顺层向上倾方面流动;寻找有利勘探区应以压实流和渗人流的交汇区为主,在其中以高矿化度的浓缩亚区为主要目标,即高台子油层应富裕构造带以南至泰康隆起带中部,萨尔图油层应以齐齐哈尔至平洋地区为下一步的重点考虑对象。  相似文献   

The Impact of Spatial Heterogeneity on Ecosystem Service Value in a Case Study in Liuyang River Basin,China     

WANG Mingkuan  MO Hongwei 《资源与生态学报(英文版)》2018,9(2):209-217

In previous studies the value of ecosystem services was evaluated microscopically by ecological indicators such as soil properties, biomass, carbon storage, oxygen release, water quality, and others. In this paper, the spatial heterogeneity of ecosystem services in Liuyang River basin was studied from the perspective of Geographic Information System (GIS) based spatial relationships by using a combination of geographic data and spatial analysis technologies. The Liuyang River basin was divided into grids with a resolution of 1km×1km. The weights of factors that affect the value of ecosystem services (such as topography, geological disasters, roads, scenic spots, vegetation coverage, and plant net primary productivity) were evaluated using the entropy method and analytic hierarchy process (AHP) in order to investigate the influence of natural and social factors on the value of ecosystem services in a quantitative manner. The results demonstrate that the value of ecosystem services is mainly affected by vegetation coverage, plant net primary productivity, and road network density. The value of ecosystem services grows with the increase in either vegetation coverage, plant net primary productivity, or road network density. Different types of land play different roles in ecosystem services. Cultivated land, grassland, and water each have significant supply and regulating functions while forest has significant regulating and supporting functions. The value of ecosystem services of cultivated land and water that are closely related to human activity is significantly influenced by spatial heterogeneity. In contrast, the effect of spatial heterogeneity on the value of ecosystem services of forest land and grassland that are located in mountains and hills, far away from the human accumulation zone, is insignificant.  相似文献