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1.
中国数字地貌分层分类体系的结构和内容研究(英文)   总被引:9,自引:2,他引:7  
This paper presents the structure and contents of a standardized layered classification system of digital geomorphology for China.This digital classification method combines landforms characteristics of morphology with genesis.A total of 15 categories of exogenic and endogenic forces are divided into two broad categories:morpho-genetic and morpho-structural landforms.Polygon patches are used to manage the morpho-genetic types,and solitary points,lines and polygons are used to manage the morpho-structural types.The classification method of digital morpho-genetic types can be divided into seven layers,i.e.basic morphology and altitude,genesis,sub-genesis,morphology,micro-morphology,slope and aspect,material and lithology.The method proposes combinations of matrix forms based on layered indicators.The attributes of every landform types are obtained from all or some of the seven layers.For the 15 forces categories,some classification indicators and calculation methods are presented for the basic morphology,the morphologic and sub-morphologic landforms of the morpho-genetic types.The solitary polygon,linear and point types of morpho-structural landforms are presented respectively.The layered classification method can meet the demands of scale-span geomorphologic mapping for the national primary scales from 1:500,000 to 1:1,000,000.The layers serve as classification indicators,and therefore can be added and reduced according to mapping demands,providing flexible expandability.  相似文献   

2.
Downstream hydrologic and geomorphic effects of large dams on American rivers   总被引:12,自引:4,他引:12  
William L. Graf   《Geomorphology》2006,79(3-4):336
The hydrology and geomorphology of large rivers in America reflect the pervasive influence of an extensive water control infrastructure including more than 75,000 dams. One hundred thirty-seven of the very large dams, each storing 1.2 km3 (106 acre feet) of water or more, alter the flows of every large river in the country. The hydrologic effects of these very large dams emerge from an analysis of the stream gage records of 72 river reaches organized into 36 pairs. One member of each pair is an unregulated reach above a dam, whereas the other is a regulated reach downstream from the same structure. Comparison of the regulated and unregulated reaches shows that very large dams, on average, reduce annual peak discharges 67% (in some individual cases up to 90%), decrease the ratio of annual maximum/mean flow 60%, decrease the range of daily discharges 64%, increase the number of reversals in discharge by 34%, and reduce the daily rates of ramping as much as 60%. Dams alter the timing of high and low flows and change the timing of the yearly maximum and minimum flows, in some cases by as much as half a year. Regional variation in rivers, dams, and responses are substantial: rivers in the Great Plains and Ozark/Ouachita regions have annual maximum/mean flow ratios that are 7 times greater than ratios for rivers in the Pacific Northwest. At the same time, the ratio of storage capacity/mean annual water yield for dams is greatest for Interior Western, Ozark/Ouachita and Great Plains rivers and least for Pacific Northwest streams. Thus, in many cases those rivers with the highest annual variability have the greatest potential impact from dams because structures can exert substantial control over downstream hydrology. The hydrologic changes by dams have fostered dramatic geomorphic differences between regulated and unregulated reaches. When compared to similar unregulated reaches, regulated reaches have 32% larger low flow channels, 50% smaller high flow channels, 79% less active flood plain area, and 3.6 times more inactive flood plain area. Dams also affect the area of active areas, the functional surfaces that are functionally connected to the present regime of the river. Regulated reaches have active areas that are 72 smaller than the active areas of similar unregulated reaches. The geomorphic complexity (number of separate functional surfaces per unit of channel length) is 37% less in regulated reaches. Reductions in the size of hydrologically active functional surfaces are greatest in rivers in the Great Plains and least in Eastern streams. The largest differences in geomorphic complexity are in interior western rivers. The shrunken, simplified geomorphology of regulated large rivers has had direct effects on riparian ecology, producing spatially smaller, less diverse riparian ecosystems compared to the larger, more complex ecosystems along unregulated reaches of rivers.  相似文献   

3.
袁爽  许强  赵宽耀  王绚  王崔林 《地理研究》2020,39(8):1920-1933
黄土地貌是按独特的演化模式形成当今复杂多样且有序分异的地貌形态组合。基于数学形态法将合水县地区黄土地貌分类并计算得出塬梁峁地貌单元的分类指标,再通过黄土地貌单元的形态特征及分类指标,对黄土塬梁峁地貌演化模式作出定量化和可视化表达,并预测塬即将消失的区域。研究发现:① 似圆度是界定黄土地貌单元演化进程的重要指标,黄土地貌单元在演化过程中,其形状规律程度逐渐增加;可用周长面积比和平均坡度界定塬梁的分界,可用边界临接指数界定梁峁的分界。② 塬向梁演化实质就是残塬向树杈梁演化。残塬是人类赖以生存的地貌单元,是固沟保塬工程的重点实施对象。  相似文献   

4.
荒漠化分类分级理论的初步探讨   总被引:17,自引:1,他引:16  
孙武  李保生 《地理研究》1999,18(3):225-230
简要回顾了二十多年来联合国荒漠化代表性分类分级理论的发展,评价了1977年、1984年、1992年和1997年提出的最有代表性分类分级理论,归纳出目前三种分类分级理论的评价思想:以指标体系为基础的绝对退化评价,生产力与经营水平相结合的相对退化评价和以生态系统中植被土壤地形差异退化为依据的多样性评价。在对比分析的基础上,针对各体系存在的问题,指出通过荒漠化退化生态基准的恢复和确定可提高分类分级理论的科学性与权威性,并提出确定时间尺度和空间类型的初步建议。  相似文献   

5.
本文对我国“雪龙号”船第22次南极考察(2005/2006)时采集的一尾章鱼的形态特征进行描述与鉴定。鉴定认为,系无须亚目、蛸科(章鱼科)、爱尔斗蛸亚科Pareledone属的Parele-done turqueti种。皮肤柔软光滑,无疣突。漏斗器官VV型。中腕型,腕式为Ⅱ=Ⅲ.Ⅰ=Ⅳ。腕吸盘单列,无扩大的吸盘。腕间膜较深,腕间膜式为c=d.e.b.a。雄性右侧第三腕茎化,茎化部分(端器)具独特的舌叶和交接基结构,舌叶勺状,凹槽无横脊,交接基短。具前后唾液腺、嗉囊和墨囊。齿舌发达,由7列异形小齿组成。半鳃内外侧各具鳃小片7个。  相似文献   

6.
刘锡清  刘洪滨 《地理研究》2008,27(1):119-127
岛屿对于发展海洋经济,确定海洋权属,以及国家安全等方面都具有重要地位。因此,岛屿的成因分类研究具有重要理论意义和应用价值。传统上将岛屿分为大陆岛、海洋岛(火山岛与珊瑚岛)和冲积岛。这种分类已经不能适应现代地球学科的新进展。本文根据板块构造理论和大洋地貌体系,提出新的岛屿分类意见,即分为内力和外力两个成因系列,包括近岸大陆岛、隆起大陆岛、大陆火山岛、岛弧陆块岛、岛弧火山岛、俯冲增生岛、无震海岭火山岛、微型陆块岛、海山火山岛、中脊火山岛、构造断层岛、河口沙岛、障壁岛、侵蚀沙岛、珊瑚岛15个类型。  相似文献   

7.
戈壁分类体系与编目研究   总被引:5,自引:0,他引:5  
建立统一的戈壁分类和编目体系,是进一步深入研究戈壁的理论基础,也是合理开发利用戈壁资源的前提。到目前为止,只有少量文献或著作提到戈壁或戈壁类型,关于戈壁编目的研究更鲜有报道。为了促进戈壁研究的规范化,本文在参照现有戈壁分类基础上,结合戈壁科学考察成果,根据戈壁的形成原因、地表物质组成与植被类型,分三级建立了戈壁分类体系,并对每一级每一类的戈壁特征进行了较为详细的阐述。在戈壁分类基础上,提出戈壁编目设想,以期为进一步深入开展戈壁研究奠定基础。  相似文献   

8.
西藏冻融侵蚀的分级和评价   总被引:4,自引:0,他引:4  
Freeze-thaw erosion is the third largest soil erosion type after water erosion and wind erosion. Restricted by many factors, few researches on freeze-thaw erosion have so far been done at home and abroad, especially those on the assessment method of freeze-thaw erosion. Based on the comprehensive analysis of impact factors of free-thaw erosion, this paper chooses six indexes, including the annual temperature range, annual precipitation, slope, aspect, vegetation and soil, to build the model for relative classification of freeze-thaw erosion using weighted and additive methods, and realizes the relative classification of the freeze-thaw erosion in Tibet with the support of GIS software. Then a synthetic assessment of freeze-thaw erosion in Tibet has been carried out according to the relative classification result. The result shows that the distribution of freeze-thaw eroded area is very extensive in Tibet, accounting for 55.3% of the total local land area; the spatial differentiation of freeze-thaw erosion with different intensities is obvious; and the difference in distribution among different regions is also obvious.  相似文献   

9.
Freeze-thaw erosion is the third largest soil erosion type after water erosion and wind erosion. Restricted by many factors, few researches on freeze-thaw erosion have so far been done at home and abroad, especially those on the assessment method of freeze-thaw erosion. Based on the comprehensive analysis of impact factors of free-thaw erosion, this paper chooses six indexes, including the annual temperature range, annual precipitation, slope, aspect, vegetation and soil, to build the model for relative classification of freeze-thaw erosion using weighted and additive methods, and realizes the relative classification of the freeze-thaw erosion in Tibet with the support of GIS software. Then a synthetic assessment of freeze-thaw erosion in Tibet has been carried out according to the relative classification result. The result shows that the distribution of freeze-thaw eroded area is very extensive in Tibet, accounting for 55.3% of the total local land area; the spatial differentiation of freeze-thaw erosion with different intensities is obvious; and the difference in distribution among different regions is also obvious.  相似文献   

10.
Landform classification is commonly done using topographic altitude only.However,practice indicates that locations at a same altitude may have distinctly different landforms,depending on characteristics of soils underneath those locations.The objectives of this study were to:1) develop a landform classification approach that is based on both altitude and soil characteristic;and 2) use this approach to determine landforms within a watershed located in northern Ordos Plateau of China.Using data collected at 134 out of 200 sampling sites,this study determined that D10(the diameter of soil particles 10% finer by weight) and long-term average soil moisture acquired in 2010,which can be estimated at reasonable accuracy from remote sensing imagery,can be used to represent soil characteristics of the study watershed.Also,the sampling data revealed that this watershed consists of nine classes of landforms,namely mobile dune(MD),mobile semi-mobile dune(SMD),rolling fixed semi-fixed dune(RFD),flat sandy land(FD),grassy sandy land(GS),bedrock(BR),flat sandy bedrock(FSB),valley agricultural land(VA),and swamp and salt lake(SW).A set of logistic regression equations were derived using data collected at the 134 sampling sites and verified using data at the remaining 66 sites.The verification indicated that these equations have moderate classification accuracy(Kappa coefficients > 43%).The results revealed that the dominant classes in the study watershed are FD(36.3%),BR(27.0%),and MD(23.5%),while the other six types of landforms(i.e.,SMD,RFD,GS,FSB,VA,and SW) in combination account for 13.2%.Further,the landforms determined in this study were compared with the classes pre-sented by a geologically-based classification map.The comparison indicated that the geo-logically-based classification could not identify multiple landforms within a class that are de-pendent upon soil characteristics.  相似文献   

11.
余炯  孙毛明  曹颍  林炳尧  严齐斌 《地理研究》2009,28(4):1115-1127
河流等级划分是认识河流规律的一项基础性工作,对河流的治理和保护管理具有现实意义。现有的河流等级划分难以反映河流的时空特性,有的人为影响较大,有的不具备河流地貌特征,有的仅具备物理特征,有的仅方便行政管理。本研究基于河流连续体概念,综合了河流的物理、生物特征,引用北美新近提出的"基于生态功能的河流等级划分",阐明了对浙江省河流进行基于生态功能的等级划分意义。从流域尺度上构建了浙江省河流的等级层次结构,分析了浙江省河流各等级层次的物理特征和生态特征的共性和差异,明确了河流各等级层次的生态保护目标和相关对策。以钱塘江流域为例,对其进行了详细的等级划分,探讨了基于生态功能的河流等级划分在确定浙江省河流生态需水的作用及应用前景,并明确了在人类活动影响下,浙江省水行政管理机构在河流等级层次的相关管理范围和内容。  相似文献   

12.
祁连山及周边区域地形复杂,降水分布极不均匀,如何科学地分区分型,对把握研究区域降水分布特征具有极为重要的意义。利用该区域31个国家基本站1961—2020年5—9月降水量资料,采用主成分分析方法(PCA)对该区域降水量进行分析,再通过聚类分析(CAST)对该结果进行显著性检验,最后将分区分型结果应用于人工增雨作业效果评估。结果表明:(1) 祁连山及周边可分成7个区域(Z1~Z7),累积方差贡献率超过78%。(2) 这7个区域分别以乐都、海晏、野牛沟、武威、高台、临泽、刚察为中心点,划分结果与降水量、地理地形、海拔高度显著关联。(3) 依托区域历史回归统计方法对人工增雨作业效果进行评价,发现1992—2020年石羊河流域5—9月绝对增雨量、相对增雨率分别为8.91 mm、6.51%,其中7月最高(6.30 mm、21.86%),8月次之(5.44 mm、16.11%)。基于地面降水量的作业效果评价往往受对比区选择的影响,聚类检验方法不仅有助于复杂地形下降水量的分区研究,还为科学选择对比区提供了客观依据。  相似文献   

13.
胡瑞山  董锁成  胡浩 《地理科学进展》2012,31(12):1600-1607
精确评价医疗设施可达性的空间分异样状况是合理配置医疗资源的前提。本文在回顾国内外关于医疗空间可达性研究的基础上, 采用两步移动搜索法, 以江苏省贫困县--东海县为案例, 以行政村和医院为分析单元, 基于迪卡斯特拉算法计算出各村到医院(卫生院)的最短通行时间, 进而分析各村医疗空间可达性分异情况。采用不用服务时间阈值范围进行空间敏感性分析, 综合研判缺医地区分布特点。与传统的医卫人员和人口比值的方法相比, 两步移动搜索法能有效显示县域范围内医疗可达性的空间分异情况。采用较大的时间阈值, 医疗空间可达性分异较为平滑, 采用较小服务阈值则空间分异显著, 缺医范围也较大。东海县医疗空间可达性整体呈单核结构, 并沿主要交通线延伸, 缺医地区多分布于边缘乡镇。提高边缘乡镇的行政村的甲级卫生院等级和乡村道路等级将会改善边缘乡镇的就医可达性。  相似文献   

14.
黄土丘陵沟壑区流域系统侵蚀与产沙关系   总被引:13,自引:1,他引:13  
陈浩 《地理学报》2000,55(3):354-363
从长期来看流域系统的侵蚀与产沙基本可以达到平衡,泥沙输移比约等于1。但次降雨或分年度泥沙输移比有相当大的变幅,在短期内会经常存在泥沙的滞留和滞留的泥沙被重新锓蚀搬运,而出现泥沙输移比小于1和大于1的情况。这主要与降雨的空间分布和洪峰增减幅度及径流深度增减幅度密切相关。流域系统次降雨泥沙输移比及各级沟道含沙水流的挟沙能力变化可用单位面积上洪峰增减幅度变化时暴雨洪水的剪切力的转化机制来描述。  相似文献   

15.
全球多机场区域空间格局与类型划分   总被引:1,自引:1,他引:0  
曹小曙  廖望 《地理科学进展》2018,37(11):1473-1484
基于2016年的全球官方航空指南(Official Aviation Guide, 简称OAG)计划航班数据,本文重点分析了全球多机场区域的空间格局和主要类型。研究发现:除美国和欧洲的英、法、德、意等国外,中国、日本、泰国和巴西等国的多机场区域数量占有绝对优势。南欧、澳大利亚和新西兰、西亚等地的多机场区域内的机场等级呈现两端极化,缺少中间层级的辅助机场。以车程时间作为衡量,英、美两国多机场区域内机场布局更为紧凑,特别是英国其他主要机场或辅助机场到达核心机场的时间相对中国减少了约0.5~1 h。根据各多机场区域赫芬达尔—赫希曼指数(HHI指数)和可售座位数对比结果,多机场区域可分为9个类型,对照多机场区域不同的演化阶段,目前共有22个多机场区域发展较成熟。未来在保证多机场区域整体发展的前提下,中国应注重其他重要机场向中间层级的辅助机场的转化进程,提高区域内地面交通水平,以减少机场间的到达时间,引导区域内机场维持高水平竞争。  相似文献   

16.
国家自然科学基金项目资助的地貌学研究现状与效应   总被引:2,自引:2,他引:0  
程维明  刘樯漪  申元村 《地理学报》2016,71(7):1255-1261
通过对2010-2015年国家自然科学基金资助下地貌学研究项目的总体状况、项目类型、依托单位、研究区域、人才队伍、研究热点、成果产出、获奖及社会效应等方面的分析,归纳概括地貌学的研究现状与态势等。结果表明:近5年来,地貌学获得的资助项目呈上升趋势,相关研究不断深入,各类研究团队显著壮大;研究系统已由高等院校为主逐渐发展成高等院校与科研机构并行的格局;不同地域地貌学研究的发展程度、研究对象及热点问题均表现出一定的区域不均衡性;构造、河流水文、黄土、冰川、风沙等是目前中国地貌学研究的主体方向。从资助项目的研究成果和产生效应来看,地貌学研究得到恢复和较快速发展,发表论文的数量和质量稳步提升,资助项目成果获奖层次高、社会效益显著。  相似文献   

17.
全月球撞击坑识别、分类及空间分布   总被引:2,自引:1,他引:2  
撞击坑是月球表面分布广泛的地貌单元,是研究月球的最直接窗口。本文以嫦娥一号卫星获取的遥感影像和DEM,以及国际天文学联合会(IAU)公布的撞击坑名录为基础数据源,以全月球表面撞击坑为研究对象,采用遥感图像处理与专家知识融合的目视解译法确定撞击坑的边界,识别出全月球表面直径大于500 m的撞击坑共计106030个,采用累积频率和与IAU公布撞击坑对比两种方法对目视解译的撞击坑进行精度评价,其识别的总体误差率为10.97%;按照形态特征指标,将全月球撞击坑分为六大类,对比分析了不同类的撞击坑影像及形貌差异性;对全月球撞击坑分类进行统计分析,得出了不同类型撞击坑在月球表面的数量与密度特征及空间分布情况。  相似文献   

18.
张红旗  李达净 《地理研究》2021,40(3):597-612
厘清西北干旱区不稳定耕地的资源清单对于维持区域生态平衡至关重要.当前,全国对不稳定耕地的定义和分类比较笼统,难以突出西北干旱区不稳定耕地的特征.本文阐明了西北干旱区不稳定耕地的概念,并根据不稳定因素构建了分类体系.同时以昌吉州为例,分析不稳定耕地的数量、质量与空间分布.结果表明:①昌吉州不稳定耕地面积为14.56万hm...  相似文献   

19.
The publication of the European Landscape Convention (2000) had a stimulating effect on the development of both new systems of landscape classification and new methods of their evaluation and mapping. As an example, a new classification of physiognomic landscape types was developed in Poland in 2014. The objectives of the paper are to (1) popularize, on the international scale, the classification of physiognomic landscape types in a new, improved version, (2) present the original method of physiognomic landscape types mapping with the use of the system of basic landscape units, and (3) present the results of testing of the method in the area of the Kazimierz Landscape Park, Poland. In the area of the Kazimierz Landscape Park, 491 basic landscape units were delimited, within which, on the basis of the leading traits of land relief and cover forms, the physiognomic landscape types were identified. Maps of this type can be important tools in implementing the recommendations of the European Landscape Convention. The total number of physiognomic landscape types identified within a specific area can be one of the key indicators of landscape diversity.  相似文献   

20.
选用2000—2019年11月—次年3月塔城地区7个国家气象观测站逐日降水、温度、常规地面和高空观测资料、美国国家环境预报中心(NCEP)再分析资料,确定近20 a塔城地区暖区暴雪天气过程并进行分析。结果表明:(1) 塔城地区暖区暴雪发生于塔额盆地的塔城站、裕民站和额敏站,塔城站出现频次最多;时间分布上,11月和12月出现暖区暴雪的频次最高,且主要集中在11月中旬—12月上旬,1月次之,2月最少。(2) 塔城地区暖区暴雪分为3类:低槽前部型、横槽底部型和西北急流型,地面低压为西方和西北路径。低槽前部型是最典型的暖区暴雪形势,主要出现在11月—12月上旬,发生在西西伯利亚低槽前部锋区与南支中纬度短波槽汇合区,地面低压为西北路径;横槽底部型主要出现在11月—次年1月,发生在极锋锋区底部偏西气流和中纬度暖湿西南气流汇合的强锋区中,地面低压为西方路径;西北急流型主要出现在11—12月,发生在极锋锋区西北气流中,地面低压为西北路径。(3) 500~300 hPa强西北或偏西急流、700 hPa偏西低空急流、850 hPa暖式切变的叠置区与暖区暴雪落区一致,低槽前部型和西北急流型为锋前暖区产生暴雪,横槽底部型为低压右前部暖锋锋生产生暴雪。(4) 低槽前部型和横槽底部型的水汽均为偏西路径,来自地中海、阿拉伯海的水汽经里海、咸海增强后向暴雪区输送;西北急流型有偏西和西北2条水汽输送路径,来自高纬度巴伦支海的水汽与来自中低纬度里海、咸海、地中海、阿拉伯海的水汽在巴尔喀什湖附近汇合后向暴雪区输送,较强的水汽输送伴随低层明显的水汽辐合,强辐合中心位于850~700 hPa之间。  相似文献   

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