等高线拓扑关系的构建以及应用   总被引：9，自引：1，他引：9  

王涛  毋河海 《武汉大学学报(信息科学版)》2004,29(5):438-442

提出了等高线拓扑关系的描述框架 ,其规范化描述形式具有更强的适用性 ,使用三角网作为工具设计了建立拓扑关系的算法。以提出的拓扑关系描述为基础 ,具体实现了等高线高程自动赋值 ,处理过程可以同时考虑开曲线 (包括断线 )和闭曲线 ,提高了可靠性和自动化程度 ,并进一步将断线连接为完整目标 ,减少了人机交互的编辑工作  相似文献   

Fractionation mechanism of stable isotope in evaporating water body     

ZHANG Xinping  TIAN Lide  LIU Jingmiao 《地理学报》2005,15(3):375-384

Under Rayleigh equilibrium condition, stable isotopic ratio in residual water increases with the decrease of the residual water proportion f exponentially, and the fractionation rate of stable isotopes is inversely proportional to temperature. However, under kinetic evaporation condition, the fractionation of stable isotopes is not only related to the phase temperature but also influenced by the atmospheric humidity and the mass exchange between liquid and vapor phases. The ratio δ in residual water will not change with f after undergoing evaporation of a long time for great relative humidity. The rate that the evaporating water body reaches isotopic steady state is mainly dependent on the relative humidity in atmosphere. The analysis shows that the actual mean linear variety rates, about -30.0, of the δ18O in residual water versus the residual water proportion at Nagqu and Amdo stations are consistent with the simulated process under temperature of 20 oC and relative humidity of 50%. The distillation line simulated under Rayleigh equilibrium condition is analogous to the global meteoric water line (MWL) as the temperature is about 20 oC. Under non-equilibrium condition, the slope and constant values of distillation line are directly proportional to temperature and relative humidity. According to the basic data, the simulated distillation line is very consistent with the actual distillation line of Qinghai Lake.  相似文献   

青藏高原腹地植物碳同位素组成对环境条件的响应   总被引：7，自引：0，他引：7  

王谋  李勇  黄润秋  李亚林  张玉修 《山地学报》2005,23(3):274-279

现代植物碳同位素组成是特定环境影响的结果,通过对植物碳同位素组成的研究可以揭示植物生长期环境信息。针对青藏高原腹地高寒草甸~高寒草原过渡区植被碳同位素组成进行研究;该区高山嵩草样δ13C值在-25.63‰~-27.95‰间,平均值-26.63‰;高寒草原区混合样δ13C值于-26.29‰~-27.73‰间,平均值-27.04‰。高山嵩草样δ13C值总体呈现由南东往北西方向正偏趋势,研究区北部高寒草原区混合植物样也呈现出由南向北富重碳同位素趋势。这些变化规律被认为是主要受降水环境影响的结果,而区域内降水条件的展布规律则是受高原夏季风运移方式的控制。对植物δ13C值与地理位置的回归分析表明,该区植被碳同位素组成与地理位置相关,高山嵩草样(r=0.44603,n=29,p<0.05)和混合样(r=0.8112,n=5,p<0.1)均表现出对区域降水环境条件的良好响应。据此,以该区植物δ13C值为背景,进行合理推算,拟定了研究区内干旱区和湿润区界限的位置。  相似文献   

Intensification of Southern Hemisphere westerly winds 2000–1000 years ago: evidence from the subantarctic Campbell and Auckland Islands (52–50°S)          下载免费PDF全文

Chris S. M. Turney  Matt McGlone  Jonathan Palmer  Christopher Fogwill  Alan Hogg  Zoë A. Thomas  Mathew Lipson  Janet M. Wilmshurst  Pavla Fenwick  Richard T. Jones  Ben Hines  Graeme F. Clark 《第四纪科学杂志》2016,31(1):12-19

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Characterizing spatial and temporal variation in 18O and 2H content of New Zealand river water for better understanding of hydrologic processes     

Jing Yang  Bruce D. Dudley  Kelsey Montgomery  Will Hodgetts 《水文研究》2020,34(26):5474-5488

Time series of hydrogen and oxygen stable isotope ratios (δ²H and δ¹⁸O) in rivers can be used to quantify groundwater contributions to streamflow, and timescales of catchment storage. However, these isotope hydrology techniques rely on distinct spatial or temporal patterns of δ²H and δ¹⁸O within the hydrologic cycle. In New Zealand, lack of understanding of spatial and temporal patterns of δ²H and δ¹⁸O of river water hinders development of regional and national-scale hydrological models. We measured δ²H and δ¹⁸O monthly, together with river flow rates at 58 locations across New Zealand over a two-year period. Results show: (a) general patterns of decreasing δ²H and δ¹⁸O with increasing latitude were altered by New Zealand's major mountain ranges; δ²H and δ¹⁸O were distinctly lower in rivers fed from higher elevation catchments, and in eastern rain-shadow areas of both islands; (b) river water δ²H and δ¹⁸O values were partly controlled by local catchment characteristics (catchment slope, PET, catchment elevation, and upstream lake area) that influence evaporation processes; (c) regional differences in evaporation caused the slope of the river water line (i.e., the relationship between δ²H and δ¹⁸O in river water) for the (warmer) North Island to be lower than that of the (cooler, mountain-dominated) South Island; (d) δ²H seasonal offsets (i.e., the difference between seasonal peak and mean values) for individual sites ranged from 0.50‰ to 5.07‰. Peak values of δ¹⁸O and δ²H were in late summer, but values peaked 1 month later at the South Island sites, likely due to greater snow-melt contributions to streamflow. Strong spatial differences in river water δ²H and δ¹⁸O caused by orographic rainfall effects and evaporation may inform studies of water mixing across landscapes. Generally distinct seasonal isotope cycles, despite the large catchment sizes of rivers studied, are encouraging for transit time analysis applications.  相似文献   

基于ArcGIS Server的服务器对象扩展方法研究     

徐亮 《测绘与空间地理信息》2016,(1):67-69

针对ArcGIS Server现有功能无法满足一些特殊业务逻辑的问题,本文对Arc GIS Server服务器扩展方法进行了研究。阐述了ArcGIS Server面向服务的底层架构,在此架构下对三种主要GIS服务器扩展方法进行对比分析,得出服务器对象扩展是最可行的方法。最后对该方法的模型结构和实现流程进行研究,并通过具体的项目实例进行说明。  相似文献   

基于温度植被干旱指数的电网输电线路走廊干旱分析     

孙洋杰  唐华林 《测绘与空间地理信息》2016,(10):94-97

以湖北省输电线路走廊地区作为研究区,利用2013年1~9月MODIS卫星影像数据,处理得到月尺度的归一化植被指数(Normalized Differential Vegetation Index,NDVI)与地表温度(Land Surface Temperature,LST)数据,构建NDVI-Ts特征空间,计算得到温度植被干旱指数(Temperature Vegetation Dryness Index,TVDI),用TVDI监测结果分析湖北省输电线路走廊区域2013年干旱时空分布情况。结果表明,湖北省输电线路走廊地区TVDI和土壤含水量之间存在显著的负相关,相关系数达到0.525(p0.05),由MODIS卫星影像计算得到TVDI影像可以有效表明湖北省输电线路走廊地区的土壤含水情况。  相似文献   

高分一号遥感影像地质灾害信息提取方法研究   总被引：1，自引：0，他引：1  

李启源  王明常  王凤艳  谭洋  卢立吉 《测绘与空间地理信息》2016,(2):17-20

山区地质灾害发生频繁,受灾范围大,危害严重。提取地质灾害信息、估算受灾情况,对救灾工作极为重要。传统的遥感人工解译方法速度慢、效率低;计算机自动解译速度快但解译精度受影像质量影响大,大范围地区很难建立起普适性的解译模型。本文利用洮南市西部高分一号遥感数据,结合DEM生成三维影像,建立解译标志,解译基础地质信息,分析地质灾害成因;根据研究区泥石流地质灾害的主要影像特征,提取影像的分类属性,基于面向对象的分类方法,建立信息提取模型,快速提取出地质灾害敏感区域;再进行人机交互,精确提取出地质灾害的类型和范围,通过野外验证,该方法十分可靠,为大范围地质灾害信息快速提取和灾后救援提供科学依据。  相似文献   

浅析工程测量竞赛中的测图方法     

冯传勇  杨柳 《测绘与空间地理信息》2016,(8):192-194

目前,国家测绘地理信息局已经举办了4届工程测量竞赛,外业测图是工程测量操作部分最常见的比赛形式。针对具体的比赛规则,先后实践了多种测图方法。本文将对几种典型的测图方法进行系统的总结和比对,并提出一套高效、可行的外业测图完整解决方法,目前,该方法已成功应用于长江委第八届工程测量竞赛、湖北省第四届工程测量竞赛、全国第四届工程测量竞赛中,并取得了理想的效果。  相似文献   

基于线要素动态化简的匹配算法比较与评价     

陈竞男  钱海忠  王骁  何海威  胡慧明 《测绘科学技术学报》2016,(1)

矢量线要素数据来源多样,细节层次不一,限制了已有匹配算法正确率的提高,同时也给算法评价带来困难。化简可以减少线要素细节层次,提取其主要形态,据此提出一种基于线要素动态化简的匹配算法评价新方法。对不同匹配算法采用相同数据,在相同化简算法支撑下进行匹配,从而实现对不同匹配算法的评价。首先,阐述动态化简方法提取线要素主要形态的过程;其次,利用动态化简分别辅助4种已有匹配算法,获取每个匹配算法的最优匹配正确率;最后,将4种匹配算法的原始匹配结果与加入动态化简后的匹配结果进行对比,分析化简对匹配结果的影响,并把该影响运用到匹配算法的比较和评价中来。其中,1通过匹配正确率变化、误匹配等分析了匹配算法的数据适用性;2通过化简比例系数K变化时新增匹配数量的统计,评价了匹配算法对线要素局部细节的敏感程度并提出该指标的量化方法;3结合匹配算法采用的匹配相似度指标对其作出评价。  相似文献