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1.
The Koshi River Basin is in the middle of the Himalayas, a tributary of the Ganges River and a very important cross-border watershed. Across the basin there are large changes in altitude, habitat complexity, ecosystem integrity, land cover diversity and regional difference and this area is sensitive to global climate change. Based on Landsat TM images, vegetation mapping, field investigations and 3S technology, we compiled high-precision land cover data for the Koshi River Basin and analyzed current land cover characteristics. We found that from source to downstream, land cover in the Koshi River Basin in 2010 was composed of water body (glacier), bare land, sparse vegetation, grassland, wetland, shrubland, forest, cropland, water body (river or lake) and built-up areas. Among them, grassland, forest, bare land and cropland are the main types, accounting for 25.83%, 21.19%, 19.31% and 15.09% of the basin’s area respectively. The composition and structure of the Koshi River Basin land cover types are different between southern and northern slopes. The north slope is dominated by grassland, bare land and glacier; forest, bare land and glacier are mainly found on northern slopes. Northern slopes contain nearly seven times more grassland than southern slopes; while 97.13% of forest is located on southern slopes. Grassland area on northern slope is 6.67 times than on southern slope. The vertical distribution of major land cover types has obvious zonal characteristics. Land cover types from low to high altitudes are cropland, forest, Shrubland and mixed cropland, grassland, sparse vegetation, bare land and water bodies. These results provide a scientific basis for the study of land use and cover change in a critical region and will inform ecosystem protection, sustainability and management in this and other alpine transboundary basins. 相似文献
2.
基于Landsat 8 OLI数据与面向对象分类的昆嵛山地区土地覆盖信息提取 总被引：1，自引：0，他引：1
利用2015年Landsat 8 OLI遥感影像和DEM作为分类数据源,结合野外调查数据,采用面向对象的分类方法对昆嵛山地区土地覆盖信息进行提取,并对分类结果进行精度评价与比较分析。研究表明：面向对象分类方法提取的各地类连续且边界清晰,分类效果与实际情况基本吻合。昆嵛山地区占主导地位的土地覆盖类型是针叶林,面积为1 546.81 km2。研究区土地覆盖分类的总体精度和Kappa系数分别为91.5%和0.88,其中针叶林、草地、水体和建设用地的生产者精度均达到87%以上。相对于监督分类方法,本研究提出的土地覆盖信息提取方法的总体分类精度和Kappa系数分别提高14.7%和0.17。基于面向对象的中分辨率遥感影像,能够获取较高精度的土地覆盖信息,为大范围土地覆盖分类研究提供方法参考。 相似文献
3.
Chandra Kant Pawe 《Geografisk tidskrift / udgivet af Bestyrelsen for Det Kongelige danske geografiske selskab》2018,118(1):88-100
Unplanned urban growth, particularly in developing countries has led to changes in land use/land cover (LULC). Numerous Indian cities face problems of unplanned LULC change due to nominal or non-existent planning efforts compounded by rapid urban population growth. The Guwahati Metropolitan Area (GMA) is one such urban centre. The present study assesses the trajectories of LULC change using Landsat imageries acquired in 1976, 1989, 2002 and 2015. Natural and semi natural vegetated area and artificial and natural water bodies decreased while built-up areas, cultivated and managed areas, and natural and semi natural non-vegetated areas increased. The built-up area increased from 23.9 in 1976 to 115.1 km2 in 2015 becoming the dominant land cover class accounting for 41.8% of the total geographical area. During this period, natural and semi natural vegetated land were reduced by 88.9 km2 at an annual rate of 2.2 km2. Over the years there was an increasing trend of built-up land and cultivated and managed areas in the peripheral areas of the city while natural and semi natural vegetated land diminished. Consequently, as in many other developing countries, there is an urgent need for the governmental authorities and other stakeholders to implement effective urban planning policies. 相似文献
4.
利用2000-2010年16 d合成的MODIS/[NDVI]数据,结合植被异常指数、趋势线分析和Hurst指数等分析方法,对新疆伊犁河谷植被覆盖的时空变化特征进行了分析。结果表明：（1） 伊犁河谷内植被覆盖随海拔增高而先增加后减小,最高植被覆盖区位于2 000～2 500 m的高程带;2000-2010年伊犁河谷各高程带内植被覆盖整体下降趋势明显,但海拔低于1 000 m的高程带除外。（2）受干湿环境影响,伊犁河谷全区平均被植异常指数最高值出现在降水最多的2002年,最低值出现在降水最少的2008年,但不同区域植被异常指数的变化存在较大差异。（3）伊犁河谷内植被覆盖增加和减小的区域分别占总面积的4.09%和19.34%,增加区域主要位于伊犁河两岸的平原区,减小区域主要位于乌孙山两端以及伊犁河谷周围海拔2 000 m左右的低山区域;变标度极差分析结果表明,伊犁河谷内植被覆盖年际变化呈现很强的持续性,未来一定时间内将保持现有变化趋势不变。 相似文献
5.
Nazarin Ezzaty Mohd Najib Kasturi Devi Kanniah 《Singapore journal of tropical geography》2019,40(2):272-290
This study aims to map forest cover in Peninsular Malaysia using satellite images as deforestation is of concern in the recent decades, and is an important environmental issue for the future too. The Carnegie Landsat Analysis System‐Lite (CLASlite) program was used in this study to detect forest cover in Peninsular Malaysia using Landsat satellite data. The results of the study show that CLASlite algorithm misclassified some oil palm, rubber and urban areas as forest vegetation. A reliable forest cover map was produced by first combining Landsat and ALOS PALSAR images to identify oil palm, rubber and urban areas, and then subsequently removing them. The HH and HV polarization data of ALOS PALSAR (threshold method) could detect oil palm plantations with 85.26 per cent of overall accuracy. For urban area detection, Enhance Build up Index (EBBI) using spectral bands from Landsat provided higher overall accuracy of 94 per cent. These methods produced a forest cover reading of 5 914 421 ha with an overall classification accuracy of 94.5 per cent. The forest cover (including rubber areas) detected in this study is 0.38 per cent higher than the percentage of 2010 forest cover detected by the Forestry Department of Peninsular Malaysia. The technique described in this paper presents an alternative and viable approach for updating forest cover maps in Malaysia. 相似文献
6.
湿地景观格局的动态变化与区域土地利用/覆盖格局的变化有着十分紧密的联系。以纳帕海、碧塔海和属都湖三块高原湿地所在的云南省香格里拉县建塘镇为例,在遥感和GIS技术的支持下,对该区域1974、1987和2000三期Landsat TM(ETM)影像进行了解译,分析了26 a间的土地利用/覆盖变化规律,并结合景观格局动态分析的方法,借助FRAGSTATS软件定量分析了该区景观格局特征及其动态变化。结果表明:该区土地利用/覆盖状况变化显著,主要土地利用/覆盖类型有林地以822 hm2/a的速度在大面积减少,并主要转为灌木林地,使得后者在26 a间扩大高达17倍,变化幅度最大。建设用地和耕地的面积分别扩大了6倍和2倍,而草地和雪地面积持续减少。相应地,该区景观格局定量分析显示,有林地的斑块密度增大而平均斑块面积减小迅速,呈破碎化趋势,灌木林地的斑块密度、平均斑块面积均增加,草地则与之相反均减小,耕地的斑块密度降低而平均斑块面积增加,在不断融合成大斑块,其余各景观单元斑块密度增大平均斑块面积减小,同时各斑块几何形状在1987年变化最剧烈,景观格局趋于复杂。 相似文献
7.
巴西土地利用/覆盖变化时空格局及驱动因素 总被引：6，自引：1，他引：5
土地利用/覆盖变化(LUCC)是全球变化研究的热点问题之一。本文采用人机交互方法基于2005 年基准年的Landsat TM/ETM遥感影像修正欧空局GlobalCover 2005 年土地利用数据,进而采用逆时相目视解译法从1980年基准年的Landsat MSS/TM遥感影像数据提取1980-2005 年土地利用/覆盖变化信息,分析其变化的时空格局及驱动因素。结果表明:1980-2005年的25年间,巴西土地利用/覆盖变化面积达79.43万km2,占土地总面积的9.33%。其中,单纯耕地像元面积增加了20.18 万km2;耕地/自然植被镶嵌混合像元区面积增加了10.70 万km2;林地面积减少了53.12 万km2;灌丛与草地净增加21.10 万km2;水体面积增加0.46 万km2;城乡建设用地面积增加7573.87 km2。由此导致热带和亚热带湿润阔叶林生态地理区、热带和亚热带干旱阔叶林生态地理区、热带及亚热带草原生态地理区、草原和沼泽湿地生态地理区、沙漠和旱生植物生态地理区以及红树林生态地理区内分别呈现不同的土地利用/覆盖变化特征。近25 年间,地形地貌、气候、植被等自然地理条件深刻影响着土地利用的宏观格局,而土地利用政策调控、经济及对外贸易发展、人口增加及空间迁移、道路修建等是导致巴西土地利用变化的主要原因。 相似文献
8.
Land use and land cover change in Greater Dhaka, Bangladesh: Using remote sensing to promote sustainable urbanization 总被引：12，自引：0，他引：12
This study evaluates land use/cover changes and urban expansion in Greater Dhaka, Bangladesh, between 1975 and 2003 using satellite images and socio-economic data. Spatial and temporal dynamics of land use/cover changes were quantified using three Landsat images, a supervised classification algorithm and the post-classification change detection technique in GIS. Accuracy of the Landsat-derived land use/cover maps ranged from 85 to 90%. The analysis revealed that substantial growth of built-up areas in Greater Dhaka over the study period resulted significant decrease in the area of water bodies, cultivated land, vegetation and wetlands. Urban land expansion has been largely driven by elevation, population growth and economic development. Rapid urban expansion through infilling of low-lying areas and clearing of vegetation resulted in a wide range of environmental impacts, including habitat quality. As reliable and current data are lacking for Bangladesh, the land use maps produced in this study will contribute to both the development of sustainable urban land use planning decisions and also for forecasting possible future changes in growth patterns. 相似文献
9.
大渡河上游地区土地利用/土地覆被变化与驱动力分析 总被引：62，自引：6，他引：56
本文以1967年、1987年、2000年三期遥感资料和1∶25万数字高程模型（DEM）及多种历史文献资料为基础,分析了大渡河上游地区18665 km2范围内的土地利用/土地覆被变化与驱动力。结果显示：1967～2000年,研究地区以林地为主导的覆被格局转变为以草地为主。其中,有林地面积的大幅度减少发挥着关键作用。33年间,有林地面积减少了319774 hm2,所占比例从30.92%下降为13.78%。通过对景观格局变化特征的分析,尤其是有林地斑块在破碎化过程中规则性的增强,同时结合历史资料分析,论证了政策因素在该地区土地利用/土地覆被变化中所发挥的主导作用。文中应用Logistic逐步回归方法,通过空间分析,在15个生物物理和社会经济因素中筛选出对不同地类具有重要影响的关键因素,并确定了它们之间的定量关系和影响大小。 相似文献
10.
于2016年7~12月和2017年4月的旱、雨季期间，以金沙江干热河谷苴那小流域内的银合欢（Leucaena Benth）林地、车桑子（Dodonaea angustifolia）灌丛地和扭黄茅（Heteropogon cantortus）草地为研究对象，通过网格法和土钻法采集并测定了（0~100 cm）土层的土壤含水量，应用经典统计法和地统计学方法分析该区域不同林草植被下坡面土壤水分的动态变化特征。结果表明：（1）研究区土壤含水量总体较低，雨季显著大于旱季，旱、雨季均表现为灌丛地>草地>林地，呈中度至强度变异（0.07~0.28之间）。（2）不同林草植被下旱、雨季土壤水分具有相似的空间自相关性，自相关系数均由正向负转变，但由正向负转变的滞后距离有所不同，且雨季大于旱季，呈中等或强等空间自相关性。（3）不同林草植被下的土壤水分空间结构不同，林地、灌丛地和草地旱雨季最佳拟合模型均为球状模型；相同林草植被下各土层旱、雨季土壤水分的空间分布特征相似，但旱季的分布格局差异更显著，不同林草植被下深层土壤水分分布比表层土壤水分的分布更为复杂，土壤水分呈明显的斑块或条带状分布，含水量高值区和低值区位置不固定。总之不同林草植被类型会改变局部地段土壤水分空间分布，降雨会加强这种差异的趋势，但土壤水分仍具一定空间连续性。 相似文献
11.
Hanbin Kwak Joachim Saborowski Si-Young Lee Myoung-Soo Won Kyo-Sang Koo 《International journal of geographical information science》2013,27(9):1589-1602
Most forest fires in Korea are spatially concentrated in certain areas and are highly related to human activities. These site-specific characteristics of forest fires are analyzed by spatial regression analysis using the R-module generalized linear mixed model (GLMM), which can consider spatial autocorrelation. We examined the quantitative effect of topology, human accessibility, and forest cover without and with spatial autocorrelation. Under the assumption that slope, elevation, aspect, population density, distance from road, and forest cover are related to forest fire occurrence, the explanatory variables of each of these factors were prepared using a Geographic Information System-based process. First, we tried to test the influence of fixed effects on the occurrence of forest fires using a generalized linear model (GLM) with Poisson distribution. In addition, the overdispersion of the response data was also detected, and variogram analysis was performed using the standardized residuals of GLM. Second, GLMM was applied to consider the obvious residual autocorrelation structure. The fitted models were validated and compared using the multiple correlation and root mean square error (RMSE). Results showed that slope, elevation, aspect index, population density, and distance from road were significant factors capable of explaining the forest fire occurrence. Positive spatial autocorrelation was estimated up to a distance of 32 km. The kriging predictions based on GLMM were smoother than those of the GLM. Finally, a forest fire occurrence map was prepared using the results from both models. The fire risk decreases with increasing distance to areas with high population densities, and increasing elevation showed a suppressing effect on fire occurrence. Both variables are in accordance with the significance tests. 相似文献
12.
Soil erosion is a major threat to sustainable agriculture. Evaluating regional erosion risk is increasingly needed by national and in-ternational environmental agencies. This study elaborates a model (using spatial principal component analysis [SPCA]) method for the evaluation of soil erosion risk in a representative area of dry-hot valley (Yuanmou County) at a scale of 1:100,000 using a spatial database and GIS. The model contains seven factors: elevation, slope, annual precipitation, land use, vegetation, soil, and population density. The evaluation results show that five grades of soil erosion risk: very low, low, medium, high, and very high. These are divided in the study area, and a soil erosion risk evaluation map is created. The model may be applicable to other areas of China because it utilizes spatial data that are generally available. 相似文献
13.
南水北调中线水源区土地利用/土地覆被的空间格局 总被引：25，自引：1，他引：24
土地利用/土地覆被 (简称LULC) 变化对流域水资源动态具有深刻的影响。这对于我国大规模跨流域的南水北调工程规划尤为重要。本文制定了该工程中线水源区约95 000 km2 面积的LULC分类系统,利用2000年前后的TM影像完成LULC分布现状图,并结合DEM分析了其土地利用/土地覆被的空间格局特征。结果表明：① 研究区域森林覆盖率为50.97%,灌丛25.58%;农田约占15%,其中旱地与水田的比例约10:3;石砾裸地等强烈退化类型合占5.66%;水域约占1%。② 区内秦岭南坡、汉-丹平原丘陵、巴山北坡三部分的LULC结构存在显著差异,强度土地利用类型和退化土地类型主要分布在汉-丹平原丘陵地区;秦岭南坡耕地的水分条件较巴山北坡好,但局部土地退化现象也更严重。③ 地形对LULC具有明显影响。海拔高度控制着自然植被的垂直分异和各种土地利用类型及利用强度的分布;各土地覆被类型的分布显示了坡度对土地开发强度的限制作用;坡向对局部LULC格局的影响并不显著,但在区域尺度上可能对秦岭南坡与巴山北坡的LULC结构差异具有贡献。南水北调中线工程水源区当前的LULC结构和空间格局显示,总体上植被状况良好,高强度的土地利用类型主要集中于海拔1000m以下的平缓地区,而退化土地类型也主要存在于这一区域,是流域水质保护和环境治理的关键区域。 相似文献
14.
Assessing and monitoring forest health using a forest fragmentation approach in Sariska Tiger Reserve,India 总被引：1，自引：0，他引：1
Purva Jain Raihan Ahmed 《Norsk geografisk tidsskrift. Norwegian journal of geography》2016,70(5):306-315
The relationship between trajectories of forest cover change and fragmentation due to physical and anthropogenic activities in Sariska Tiger Reserve is addressed in the article. The authors conducted a field visit to the reserve to collect groundtruth data and perform a village survey. Thereafter, their main method consisted of using Landsat TM images for three days, one in each of the years 1989, 1994, and 2014, to assess spatial-temporal variation in forest cover. A fragmentation model was used to examine the extent and pattern of forest degradation. The results showed an overall increase in forest cover in Sariska Tiger Reserve from 53% in 1989 to 55% in 2014. However, the fragmentation statistics revealed a deterioration in forest health. There was an increase in the fragmentation categories perforated, edge, and patch in their respective areas, while the core areas decreased at the expense of other fragmentation classes. The existence of villages, roads, and pilgrimage sites had increased the pace of degradation and fragmentation of forest in the reserve. The authors conclude that the fragmentation model was effective for analysing forest degradation and identifying the priority areas for strategic planning of nature conservation. 相似文献
15.
西南地区山地不同土地退化类型特征及调控途径 总被引：4，自引：7，他引：4
土地退化不仅是目前全还需性的重大环境问题之一，而且也是重大的社会和经济问题之一，西南地区的土地退化是以水力侵蚀为主要动力形成的，文中简述了西南地区的土地退化状况，选择了4个（楚雄市、遂宁市，毕节地区及元谋县）山地不同土地退化类型进行分析，讨论了土 退化过程，提出了土地退化调控途径。 相似文献
16.
A new approach, based on the application of multi-spectral remote sensing data of Landsat imagery, is introduced to determine large-scale spatiotemporal variations of forest cover changes quantitatively and with a high degree of precision. The test area covers about 837,330.5 ha of a mountainous region in Central Italy. The approach employs several multi-temporal Landsat acquisitions to account for forest cover changes larger than 0.5 ha for the period from March 2002 to July 2011. In contrast to automated approaches that strongly curtail mapping time, the approach introduced here allowed us to map only the real forest cover change, based on a robust validation and rectification of the detected forest change. Derived high spatial resolution data of forest change estimates indicate that about 5.7% (47,670.5 ha) of the observed forest area was subject to human-induced change between 2002 and 2011. Moreover, the detected forest cover changes, most of which are identifiable as timber harvesting, are considerably larger than those reported in the official statistics and often fall within the perimeter of restricted areas (i.e., national parks and natural reserves). 相似文献
17.
中国南方不同土地利用/覆被类型对气温升温的影响 总被引：2，自引：0，他引：2
基于我国南方六省国家气象台站历史气象资料、1:10万土地利用/覆被数据和NCEP再分析气温资料,通过比较气温变化在不同观测环境气象站之间的差异,分析中国南方三种主要土地利用/覆被类型对气温趋势的影响。结果显示:土地利用/覆被类型对气温趋势具有稳定的影响,建设用地的年均温、年均最高和最低气温的升温幅度均最高,耕地次之,林地最小。进一步利用再分析资料剔除区域大尺度气候背景影响后,建设用地的年均温升温趋势仍最大(0.105℃/10a),其次是耕地(0.056℃/10a),林地的升温趋势最小(-0.025℃/10a),且为负。这表明对于研究区气温的升温趋势,林地具有抑制作用,建设用地具有增强作用,且增强作用较耕地强。林地的各季节平均气温的变化幅度同样低于非林地。 相似文献
18.
Land change was assessed in the Albertine rift region (ARR) using its central section of north-western Rwanda as case study. This region is one of Africa's most ecologically sensitive environments under severe pressure from human activities. The study maps and quantifies the spatial extent of land use-land cover (LULC) changes between 1987 and 2016 from Landsat images. Transitions between five major land classes were identified in order to understand the trajectory of observed changes. In terms of gains, the forest class, the urban built-up and bare land class increased by 9% and 4% respectively over the study period. The gains of forest were mainly derived from the afforestation of some agricultural lands in the southern part, whereas the gains of built-up and bare lands were mostly from cultivated land which was a net losing class. Forest increase is in line with government's policy to increase the national forest cover to 30% by 2020. Forest losses occurred mostly outside protected areas due to land conversion for settlement and agricultural purposes. Much needed information about changes in LULC over the last three decades is provided. This study demonstrates in a timely manner how to analyse and monitor LULC change and the drivers in an environment where field based research is a challenge due to the mountainous terrain. The ecological richness of the region, which coincides with heightened human population pressure, necessitates the monitoring of land change as input for improving land use planning with focus on conserving biodiversity. 相似文献
19.
Tom Akkermans Anton Van Rompaey Nicole Van Lipzig Pieter Moonen Bruno Verbist 《自然地理学》2013,34(6):417-440
State-of-the-art impact-modeling studies in environmental and climatological sciences require detailed future deforestation scenarios that allow forest to be replaced by a mosaic of multiple successional land-cover types, rather than the simple conversion of forest to a single land-cover type, such as bare soil or cropland. Therefore, not only the amount and location of forest removal has to be known (as is typically provided by scenarios), but also knowledge about the successional land-cover types and their relative areal proportions is needed. The main objective of this study was to identify these successional land-cover types and quantify their areal proportions in regions deforested during the past 37 years around the city of Kisangani, D.R. Congo. The fallow vegetation continuum was categorized in different stages, adapted from existing classifications. Ground-truth points describing the present-day vegetation were obtained during a field campaign and used for supervised and validated land-cover classification of these categories, using the Landsat image of 2012. Areal proportions of successional land-cover types were then derived from the resulting land-cover map. The second objective of this study was to relate these areal proportions to time since deforestation, which is expected to influence fallow landscapes. Landsat images of 1975, 1990, and 2001 were analyzed. Present-day mature tree fallow is less abundant on areas deforested during 1975–1990. The relative areal proportions were used to refine a deforestation scenario and apply it to existing data-sets of LAI and canopy height (CH). Assuming a simple conversion of forest to cropland, the deforestation scenario projected a reduction of grid-cell-averaged CH from 25.5 to 7.5 m (within deforested cells), whereas the refined scenarios that we propose show more subtle changes, with a reduced CH of 13 m. This illustrates the importance of taking successional land cover correctly into account in environmental and climatological modeling studies. 相似文献
20.
This study aims to understand GIS based ecotourism potential of Munessa Shashemene Concession Forest and its surrounding area in Ethiopia. Landsat images from 2009/2010 and 2013 were used to drive baseline data including land cover, land use, stream and road. Elevation based agro-ecology and slope map were derived from SRTM DEM. Rapid wild animals survey, identifying the location of known historical, cultural and unique features were carried out in the filed with the help of key-informants. A suitability model was designed in GIS environment to assess the suitability of an area for tourism considering suitability factors such as land cover types, wild animal zone, unique features, topography and distance to a road. The result showed areas which are highly suitable, moderately suitable, marginally suitable, or unsuitable for tourism. The old giant, Podocarpus (Podocarpus falcatus) trees that serve as habitat of the endangered and endemic mountain nyala (Tragelaphus buxtoni), were identified as very high suitable areas for tourists. The highly suitable areas include forest area along the lake which is seasonally visited by mountain nyala and areas of plantation forest that are found adjacent to natural forest. These areas follow remnants of the natural forest and found along boundary between the mid-highland and the highland agro-ecologies. The agricultural land use types consisting of maize/haricot-bean and wheat/barley were evaluated as marginally suitable, nevertheless these could be considered as potential for agri-tourism. The study revealed that the concession area is found to be a suitable area with its huge potential for ecotourism development. 相似文献