基于最大似然法和SVM法的太湖流域HJ-1B影像分类     

孙琳  宋爱红  高文秀 《测绘信息与工程》2012,37(3):30-33

以太湖流域作为研究对象,基于环境减灾卫星HJ-1B影像数据,比较利用最大似然法和支持向量机法进行土地利用/覆盖分类的效果。结果显示,SVM法在总体分类精度和Kappa系数上较传统最大似然法有所提高。SVM分类方法对于有限样本的分类表现出优越的性能,改善了传统分类方法的局限性,具有很大的应用潜力。  相似文献   

基于BP神经网络的遥感影像分类研究     

卢柳叶  张青峰  李光录 《测绘科学》2012,37(6):140-143

BP神经网络具有收敛速度快和自学习、自适应功能强的特点,能最大限度地利用样本集的先验知识,自动提取合理的模型。本文采用Landsat TM遥感图像作为数据源,以山西省定襄县为研究区,通过主成分分析方法来压缩输入数据,并结合NDVI和纹理特征来建立BP神经网络的土地利用分类模型,将分类结果与基于光谱单元信息的神经网络分类和基于纹理特征的神经网络分类结果进行定性和定量比较分析。结果表明:该方法总精度达到了80.50%,分别比基于光谱单元信息的神经网络分类和基于纹理特征的神经网络分类提高了18.89%和6.23%,能够有效地解决地物光谱混淆、分类精度不高等问题。  相似文献   

A geospatial approach to assessing land change in the built-up landscape of Wa Municipality of Ghana     

《Geografisk tidskrift / udgivet af Bestyrelsen for Det Kongelige danske geografiske selskab》2012,112(2):121-135

ABSTRACT

Urban landscapes are changing in response to changes in socio-economic conditions. Land change scientists seek to understand these land dynamics in the coupled human-environment system of urban landscapes. This study assessed land change in the built-up area of Wa Municipality between 1986 and 2016 using Landsat images. We used the Support Vector Machine algorithm for classifying the images. We recorded image classification accuracies of 97%, 95%, 92% and 96% for the 1986, 1996, 2006 and 2016 classified images, respectively. Our study finds that over the 1986–2016 period, agricultural land and bare land transitioned to build-up land by 9.23% and 3.79%, respectively, as compared to 2.79% for vegetation and 0.05% for water. Our in-municipal level analysis thus shows that urban landscapes could expand more sustainably by targeting other dominant land categories instead of the vegetation cover. The findings in this paper could serve as a spatial model for planning and reducing the unintended socio-ecological impacts of expansion in the built-up area.  相似文献   

Cities and Urban Land Use in Advanced Placement Human Geography     

《The Journal of geography》2012,111(3-4):153-168

Abstract

This article examines key topics and concepts in the cities and urban land use section of the Advanced Placement human geography course. Among the topics discussed are definitions of urbanism, the origin and evolution of cities, functional character of contemporary cities, the built environment and social space, and responses to urban growth.  相似文献   

A Mirror Cracked: Ten Keys to the Landscape of the Calumet Region     

《The Journal of geography》2012,111(3):104-110

Abstract

Southeast Chicago's Calumet region is many things to many people. Home to wetlands and wildlife, mills and millgate communities, landfills and brownfields, it seems to defy easy characterization. This paper argues that it is the jarring juxtaposition of each of these features that best reflects the area. Ten interpretive “keys” -or significant landscape-shaping elements form an interpretive frame.  相似文献   

Economic Development Threatens Groundwater in Puerto Rico: Results of a Field Study     

《The Journal of geography》2012,111(6):558-569

Abstract

This report addresses the question of groundwater quality in a context of economic development and heterogeneous land use. Seven wells, each actively producing for the public water supply, and together providing 37 percent of the total aquifer production of four municipios, were tested in three topographic basins. Major land use categories, including agriculture, urbanization, and industry, were identified throughout the basins. Well samples were drawn three times during a six-month period and analyzed for a set of 15 water quality parameters including biological indicators. The most common pollutants detected were heavy metals, nitrate, arsenic, and semivolatile organic compounds. Wells surrounded by agricultural and commercial activities were contaminated by nitrate, mercury, lead, and phthalates. Wells in mixed residential and industrial settings had concentrations of semivolatile organic compounds and lead. The presence of noxious chemicals in the public water supply, even in relatively small amounts, threatens the viability of the groundwater reservoir. Both operational and policy aspects of water quality should be discussed in the context of urban and economic development.  相似文献   

Samar i R ros-traktene     

《Norsk geografisk tidsskrift. Norwegian journal of geography》2012,66(2):87-88

The article explores whether marine biodiversity mappings can contribute to the mapping of the material basis of Sami culture. Four different mapping practices are analysed in the article, all related to the seascape in the Lyngen fjord (Lyngenfjorden) in northern Norway. Initiatives undertaken by the Norwegian Directorate of Fisheries and the Institute of Marine Research (IMR) to map cod spawning grounds, and by the Sami Rights Commission (SRC) to map customary use of a fjord are compared with local fishing practices. Although the seascape was initially mapped to find spawning grounds (the IMR and the Directorate) and to record social practices (the Directorate and the SRC), the outcomes also express social relations between the mappers and the mapped materials. Whereas the mappings that included fishermen's relations with fishing grounds are compatible with each other, the marine scientists' mapping documented biodiversity independent of local relations with it. The author argues that the marine environment should be seen as expressing social relations between groups of people and certain materialities instead of as separated in natural and social layers. Thus, even though marine biodiversity mapping practices reveal biodiversity in Sami settlement areas, they inform little about the material basis of Sami culture.  相似文献   

World heritage and landscape change – heritage buildings and their changed visibility in the coastal landscape of Vega,Norway     

《Norsk geografisk tidsskrift. Norwegian journal of geography》2012,66(3):121-134

Part of the Vega archipelago in north-western Norway is a cultural landscape listed as a UNESCO World Heritage site. Its buffer zone comprises most of the main island of Vega, where agriculture is an important land use. The authors describe interdisciplinary research carried out in the buffer zone. The research revealed the significant role of agriculture for the maintenance of the traditional open coastal landscape. The finding was further underlined by the fact that many visitors to the site never reach the outer archipelago, which is the core of the listed site. Based on interpretations of aerial photographs, land cover maps were produced for three cross-sections in time (1965, 1986, and 2009). A further reclassification of the land cover was performed to capture the change in openness due to change in land cover. Viewshed maps of each building found on the aerial photographs were overlain with the openness classes to capture the visual consequences of the buildings due to changes in land cover. A marked decrease in open land surrounding the buildings was found in the study area, which comprised Holand and Floa-Kjul in Vega Municipality, which in turn comprises the islands of the Vega archipelago. The regrowth of the land seemed to be happening regardless of building category.  相似文献   

基于土地利用变化的近18 a新疆沙地动态及其驱动力分析   总被引：2，自引：0，他引：2  

张良侠  吴世新  穆桂金  黄凤 《中国沙漠》2012,32(1):17-23

 基于新疆1990—2008年的土地利用变化数据库利用土地利用转移矩阵和土地利用变化状态与趋势指数模型分析新疆沙地的动态,依据沙地的转化方向及转化源探讨新疆沙地变化的驱动力。研究区沙地在1990—2000年呈增加趋势,增加速率为84.40 km2·a-1,草地转换为沙地的面积最大;2000—2008年呈减少趋势, 2000—2005年和2005—2008年减少速率分别为86.98 km2·a-1和118.26 km2·a-1,且主要转换为耕地。沙地面积的增加和减少受气候干湿变化和人类活动控制。同20世纪50—90年代相比,1990—2000年新疆沙地扩张速率降低了近一半,局部荒漠地区生态环境有所改善,原因为大规模的土地开垦与气候的暖湿变化。2000—2008年新疆沙地面积不断减少,原因为土地开垦模式发生着变化、生态建设的较快发展以及气候处于相对暖湿的状态。但一些地区沙化问题仍然存在,新疆干旱脆弱的生态环境本质没有根本改变,依然存在着土地沙漠化的潜在危机。  相似文献   

氢氧稳定同位素技术在生态系统水分耗散中的应用研究进展   总被引：2，自引：0，他引：2  

张玉翠  孙宏勇  沈彦俊  齐永青 《地理科学》2012,(3):289-293

氢氧稳定同位素作为水的"DNA",对于研究水分的传输和转化具有重要的意义,而水分耗散是水循环的重要组成部分。简单介绍氢氧稳定同位素在水分耗散研究中应用的主要原理和比较新的一些技术方法,主要对其在森林、草原生态系统和农田生态系统中蒸散发分离,植物水分来源区分、叶片水同位素富集和水分利用效率等方面做较为详细的归纳总结和探讨,最后指出国内此类研究仍然存在的问题和可能的发展方向,以期对未来氢氧稳定同位素技术在水分循环和水分耗散方面的应用研究有借鉴作用。  相似文献