39 resultados para LANDSAT


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Four models are employed in the landscape change detection of the newly created wetland. The models include ones for patch connectivity. ecological diversity, human impact intensity and mean center of land cover. The landscape data of the newly created wetland in Yellow River Delta in 1984, 1991, and 1996 are produced from the unsupervised classification and the supervised classification on the basis of integrating Landsat TM images of the newly created wetland in the four seasons of the each year. The result from operating the models into the data shows that the newly created wetland landscape in Yellow River Delta had a great chance. The driving focus of the change are mainly from natural evolution of the newly created wetland and rapid population growth, especially non-peasant population growth in Yellow River Delta because a considerable amount of oil and gas fields have been found in the Yellow River Delta. For preventing the newly created wetland from more destruction and conserving benign Succession of the ecosystems in the newly created wetland, six measures are suggested on the basis of research results. (C) 2003 Elsevier Science B.V. All rights reserved.

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It is more and more acknowledged that land-use/cover dynamic change has become a key subject urgently to be dealt with in the study of global environmental change. Supported by the Landsat TM digital images, spatial patterns and temporal variation of land-use change during 1995 -2000 are studied in the paper. According to the land-use dynamic degree model, supported by the 1km GRID data of land-use change and the comprehensive characters of physical, economic and social features, a dynamic regionalization of land-use change is designed to disclose the spatial pattern of land-use change processes. Generally speaking, in the traditional agricultural zones, e.g., Huang-Huai-Hai Plains, Yangtze River Delta and Sichuan Basin, the built-up and residential areas occupy a great proportion of arable land, and in the interlock area of farming and pasturing of northern China and the oases agricultural zones, the reclamation I of arable land is conspicuously driven by changes of production conditions, economic benefits and climatic conditions. The implementation of "returning arable land into woodland or grassland" policies has won initial success in some areas, but it is too early to say that the trend of deforestation has been effectively reversed across China. In this paper, the division of dynamic regionalization of land-use change is designed, for the sake of revealing the temporal and spatial features of land-use change and laying the foundation for the study of regional scale land-use changes. Moreover, an integrated study, including studies of spatial pattern and temporal process of land-use change, is carried out in this paper, which is an interesting try on the comparative studies of spatial pattern on change process and the change process of spatial pattern of land-use change.

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The interactions among industrial development, land use/cover change (LUCC), and environmental effects in Changshu in the eastern coastal China were analyzed using high-resolution Landsat TM data in 1990, 1995, 2000, and 2006, socio-economic data and water environmental quality monitoring data from research institutes and governmental departments. Three phases of industrial development in Changshu were examined (i.e., the three periods of 1990 to 1995, 1995 to 2000, and 2000 to 2006). Besides industrial development and rapid urbanization, land use/cover in Changshu had changed drastically from 1990 to 2006. This change was characterized by major replacements of farmland by urban and rural settlements, artificial ponds, forested and constructed land. Industrialization, urbanization, agricultural structure adjustment, and rural housing construction were the major socio-economic driving forces of LUCC in Changshu. In addition, the annual value of ecosystem services in Changshu decreased slightly during 1990-2000, but increased significantly during 2000-2006. Nevertheless, the local environmental quality in Changshu, especially in rural areas, has not yet been improved significantly. Thus, this paper suggests an increased attention to fully realize the role of land supply in adjustment of environment-friendly industrial structure and urban-rural spatial restructuring, and translating the land management and environmental protection policies into an optimized industrial distribution and land-use pattern.

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黑白仰鼻猴(Rhinopithecus bieti)目前分布在金沙江和澜沧江之间横断山脉的一个狭小的区域范围内(26o14’N-29o20’N,99o15’E-99o37’E),海拔2 600 m(南部) - 4 200 m(北部)之间;目前大约有15 群,数量估计约1700 个体。是我国特有的灵长类之一,为国家Ⅰ级保护动物,在IUCN(世界自然保护联盟)2007 受威胁物种红皮书中被列为濒危物种并处于小种群、高度片断化状态(ENC 2a)。西藏是黑白仰鼻猴分布的北端,约有300 个体。基于前人的野外调查和报道确认,暗针叶林和针阔叶混交林是其适宜栖息地,人们在低海拔和高海拔砍伐或者火烧暗针叶林和针阔叶混交林的产物-农田和夏季牧场正在逐渐侵蚀着其适宜栖息地。尽管当地藏族村民信奉佛教,禁止猎杀任何野生动物,但是近些年来,黑白仰鼻猴栖息地不断丧失,这与牧场和农田扩张、当地人们薪柴采集等活动有关。黑白仰鼻猴西藏种群主要在原始暗针叶林和和针阔叶混交林里活动。为了评估该物种的栖息地现状和变化情况,我们通过野外调查工作,应用GIS 和RS 技术,分别解译了1986 年、1992 年、1997 年、2001 年和2006 年的Landsat TM/ETM+ 冬季卫星影像,并对解译结果进行了计算和分析,得到了以下西藏种群栖息地的主要结果: 1)现有暗针叶林(包括原始针叶林和针阔混交林)面积是30 500 hm2 ,夏季牧场面积是13 100 hm2 ,农田面积是6 400 hm2 ;2)在过去20 年间(1986-2006 年),暗针叶林面积减少了14.6%(5 200 hm2 ),夏季牧场面积增加了47.2%(4 200 hm2 ),农田面积增加了14.3%(800 hm2 );3)在过去20 年间,暗针叶林的斑块数量增加了68.4%,平均斑块面积下降了49.3%(从1986 年的15.1 hm2 下降到2006 年的7.6 hm2 ),最大的斑块指数下降了54.9%;景观丰富度并没有变化,但Shannon 多样性指数和Shannon 均匀度指数分别增加了2.7%。这都表明栖息地丧失和破碎化程度越来越严重。在上述结果的基础上,我们进一步对栖息地变化的主要原因进行了初步分析和探讨。通过暗针叶林面积、夏季牧场面积和农田面积和当地各乡村的家庭户数、人口数量、平均家庭人口数和牲畜存栏数等统计数据的Spearman秩相关分析表明,暗针叶林面积变化分别与当地的人口数量、家庭户数和平均家庭人口数呈显著负相关,与牲畜存栏数呈负相关;而夏季牧场面积和农田面积都分别与人口数量、家庭户数和平均家庭人口数呈显著正相关,与牲畜存栏数呈正相关。这意味着在目前当地传统生产方式基本未发生改变的情况下,因人口数量增加所带来的生产等活动强度的增加是黑白仰鼻猴栖息地丧失与破碎化加剧的主要原因(R2 = 0.972);当地人类经济活动的增加,如牧场和农田扩张,牲畜存栏数增加以及薪材采集和木质建筑等导致了栖息地丧失、退化和破碎化。但另一方面,当地一妻多夫的婚配制度(仅在西藏部分地区仍有保留)对黑白仰鼻猴的栖息地保护有积极的作用,因为大家庭(家庭人口数)的人均资源消耗,如薪柴需求、房屋数量、牧场和农田等,都比小家庭低。在过去20 年中(1983-2003 年),当地家庭户数的增加比人口数量增加要慢,这对黑白仰鼻猴的栖息地保护起到了一定的积极作用。因此,西藏种群作为单独的遗传亚种群,其保护工作任重而道远。

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Hydrological statistical data, remote sensing images, and bathymetric charts were used to study the recent evolution of the Huanghe (Yellow) River delta under human-induced interventions. It was clear that water and sediment discharge from the Huanghe River had dropped rapidly since 1970, particularly after 1986. The water and sediment discharges for the period of 1986-2000 were found to have been reduced to only 29.2% and 31.2% of those in the period of 1950-69. This was caused by human factors in the upper and middle reaches of the Huanghe River, including water diversion, damming and reservoir construction, and water and soil conservation. Based on the results from visual interpretation of processed Landsat (MSS or TMJETM+) images dated from 1976 to 2001 and two digital elevation models generated from bathymetric charts surveyed in 1976 and 1992, we found that human-induced reduction of water and sediment discharge led to coastline retrogradation, with the maximum mean recession rate of -0.51 km yr-1 over the period of 1976-98, and seabed erosion beyond the -20 m isobath between 1976 and 1992. Other impacts of human activities on the recent evolution of the Huanghe River delta, including tidal flats shrinking, artificial coastline increasing, land surface sinking and so on, were also analyzed. We found that: (i) the whole delta, including subaerial and subaqueous, has turned from a highly constructive period to a destructive phase; (ii) channelization and dredging were two of the main causes of delta destruction; (iii) land loss in the Huanghe River delta caused by submersion will be increased in the near future; (iv) the Huanghe River delta was becoming more fragile and susceptible to natural hazards.

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本文以具有典型特征的苏北淤泥质潮滩海岸作为研究区,利用1975-2003年间14景覆盖该地区的Landsat和SPOT卫星影像作为主要数据源,结合地面调查和验证工作,在遥感影像处理和地理信息系统分析技术的支持下,对区内潮滩、岸线、水边线和盐沼植被等进行遥感解译,分析苏北辐射沙脊群和沿岸地貌的空间分布特征和动态演变趋势。研究结果表明:苏北辐射沙脊群海域的潮汐水位过程的不同步现象普遍存在,限制了常规遥感数据在苏北潮滩地貌研究中的适用范围和解译精度;在人工判别的辅助下,多光谱遥感的非监督分类方法可以有效解译淤泥质潮滩的水边线;利用修改型土壤调整植被指数(MSAVI)可以较好地提取潮滩上的盐沼植被信息;苏北沿岸潮滩的快速淤长促进了盐沼植被带向海侧快速扩展,近年来持续的潮滩围垦工程则不断从陆侧侵占盐沼植被带,使盐沼植被带宽度减小乃至消失;在大规模人类活动和自然条件的共同影响下,苏北辐射沙脊群海岸的岸线发育趋于平直化,无序的潮滩围垦项目使得可垦滩地资源被过度消耗;1975~2002年间,研究区北部和南部沿岸的高潮滩整体上处于淤长状态,中部沿岸潮滩和离岸沙洲高潮滩则被大面积侵蚀;1999年以来,研究区内低潮滩部位开始形成有序排列的滩面地物,并表现出逐年大面积蔓延的趋势,可能是滩涂紫菜养殖区扩展的结果。

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本文收集了三峡截流前后长江口海区1988-2007年间十二景landsat TM遥感影像并进行了表层悬浮泥沙含量的反演,定性的描述了长江口海区洪、枯季的表层悬沙扩散外界和高浑浊水域范围的变化趋势,分析了河流泥沙输移入海形态的变化特征及表层悬沙浓度的变化特征。 通过对2002-2004年在长江口滨外区表层悬浮体取样数据的实验室处理,揭示了三峡截流后表层悬沙的分布特征;通过多船同步定点观测捕捉到了长江口河口锋带的位置并分析了河口锋带的动力特征,结果表明:长江口河口锋位于(122o10′E,30o50′N)至(122o20′E,31o00′N)一线附近,在河口锋带位置有着较为强烈的河海相互作用,流速不符合典型的对数流速曲线,河水与海水的相互消长局限于海面以下5m的表层范围,在河口锋面区悬浮泥沙为泥沙流伏在海水之上输运。长江口悬沙体浓度由于三峡蓄水作用表现为下降趋势,悬浮体扩散范围相比截流前向口门后退,长江口滨外区羽状锋带随之向口门后退。 利用二维潮流数值模型较成功地模拟出了每个季度长江河口外的流场情况及河口锋带的发育情况,模拟表明:春、夏、秋三季河口锋带较易出现,且小潮期间发育最好。冬季长江河口海洋动力较强,易于发生海水入侵,尤其是北支;夏季是长江三角洲的主要建设期,锋带作用的存在使得泥沙大部分在锋带的内外区域沉积;春秋两季是平衡期;冬季主要是冲刷的时期。

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The VEGETATION (VGT) sensor in SPOT 4 has four spectral bands that are equivalent to Landsat Thematic Mapper (TM) bands (blue, red, near-infrared and mid-infrared spectral bands) and provides daily images of the global land surface at a 1-km spatial resolution. We propose a new index for identifying and mapping of snow ice cover, namely the Normalized Difference Snow/Ice Index (NDSII), which uses reflectance values of red and mid-infrared spectral bands of Landsat TM and VGT. For Landsat TM data, NDSII is calculated as NDSIITM =(TM3 -TM5)/(TM3 +TM5); for VGT data, NDSII is calculated as NDSIIVGT =(B2- MIR)/(B2 + MIR). As a case study we used a Landsat TM image that covers the eastern part of the Qilian mountain range in the Qinghai-Xizang (Tibetan) plateau of China. NDSIITM gave similar estimates of the area and spatial distribution of snow/ice cover to the Normalized Difference Snow Index (NDSI=(TM2-TM5)/(TM2+TM5)) which has been proposed by Hall et al. The results indicated that the VGT sensor might have the potential for operational monitoring and mapping of snow/ice cover from regional to global scales, when using NDSIIVGT.

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以3S技术为手段,研究了藏羚在青海最主要分布区曲麻莱、治多和可可西里境内藏羚生境状况及其坡度、道路、和居民点对藏羚生境的影响。通过野外考察基本掌握了藏羚的生境的基本特征,取得了考察路线附近区域内藏羚分布的GPS数据及其具有对应的数量、地形地貌、生境类型、人类活动状况等属性数据的藏羚分布点图层。对研究地区LANDSAT TM / ETM+ 5(红)、4(绿)、3(蓝)波段组合影像进行非监督分类,共分出水体和裸岩、沼泽地、沙地、砾石地、低草地、中草地和高草地7种生境类型,将藏羚生境适宜等级划分为不适宜、较差、适宜和非常适宜,其中适宜等级和非常适宜等级的生境类型为藏羚适宜的生境。 首先,将藏羚分布点图层分别和遥感影像假彩色合成图像、坡度图层、道路图层、居民点图层进行叠加分析、距离查询等分析了遥感影像非监督分类的判图依据,设立了坡度、道路、居民点对藏羚生境影响强度的评价原则。然后,通过对研究地区遥感影像进行非监督分类分析研究了藏羚不同适宜程度的生境面积。通过坡度分析和地图查询分析研究了坡度对藏羚生境的影响。通过缓冲区分析研究了道路和居民点对藏羚生境的影响。最后将坡度、道路和居民点三个因素结合起来通过地图综合查询分析研究了这三个因素对藏羚生境的综合影响,并给出了研究地区藏羚不同适宜等级的生境面积。 主要的研究结果和结论如下: 1、从不同类型生境在研究地区中所占比例的趋势上看,治多地区和曲麻莱地区的植被要明显优于可可西里地区,这与整个研究地区从西北到东南地势逐渐降低、水热条件逐渐变好的趋势相一致,至少可以说,从食物条件来看,治多地区和曲麻莱地区比可可西里地区更适于藏羚的栖息。 在曲麻莱地区藏羚的潜在生境面积共26861 km2,占该地区总面积的69%;在治多地区藏羚的潜在生境面积共21617 km2,占该地区总面积的68%;在可可西里地区藏羚的潜在生境面积共26398 km2,占该地区总面积的54%。 2、根据藏羚分布点图层与坡度分析图层的地图查询分析,把藏羚的生境按坡度分为2类,坡度小于等于30度时为适宜生境,坡度大于30度时为不适宜生境。将研究地区坡度栅格图像(grid文件)和非监督分类结果栅格图像(grid文件)进行地图查询分析,结果表明,在整个研究地区坡度大于30度的生境面积所占的比例不到总面积的3%,坡度影响下研究地区藏羚适宜栖息的生境面积变化不大。考虑到坡度的影响,曲麻莱、治多和可可西里适合藏羚栖息的面积分别为26663 km2(68%)、21187 km2(66%)和26350 km2(54%)。 3、根据最近原则连接藏羚分布点图层与道路图层空间数据,通过Distance综合查询分析,把道路对藏羚的影响程度划分为4个等级:距离道路0-1000m,强烈影响;距离道路1000-2000m,中度影响;距离道路2000-3000m,轻度影响;距离道3000m以外,无影响。然后在ArcView GIS 3.2a软件环境的支持下对研究地区的道路图层分别做距离道路为1000m、2000m和3000m的缓冲区分析研究,则曲麻莱、治多和可可西里地区藏羚生境受道路累计影响的面积及其分别占各研究地区总面积的比例分别为20215 km2(51.80%)、19480 km2(61%)和4437 km2(9 %)。考虑道路对藏羚生境的影响,在治多和曲麻莱地区,由于道路的影响将使得藏羚生境大面积丧失,生境高度破碎化。 4、根据最近原则连接藏羚分布点图层与居民点图层空间数据,通过Distance综合查询分析,把居民点对藏羚的影响程度划分为4个等级:距离居民点0-3000m,强烈影响;距离居民点3000-6000m,中度影响;距离居民点6000-9000m,轻度影响;距离居民点9000m以外,无影响。然后在ArcView GIS 3.2a软件环境的支持下对研究地区的居民点图层分别做距离居民点距离为3000m、6000m和9000m的缓冲区分析。曲麻莱、治多和可可西里地区藏羚生境受居民点影响的面积及其分别占总面积的比例分别为11282 km2(29%)、15258 km2(48%)和3846 km2(8%)。从居民点对藏羚生境的影响看,由于居民点的影响使得治多和曲麻莱地区,尤其是治多地区,藏羚生境大面积丧失,生境高度破碎化。 5、人类活动(主要是道路和居民点)对藏羚生境适宜生境面积的影响是研究中主要的内容,鉴于道路和居民点对藏羚生境影响的评价原则分类方法一致,我们把道路和居民点对藏羚的影响程度合并为4个等级(距离道路0-1000m内或距离居民点0-3000m内,强烈影响;距离道路1000-2000m内或距离居民点3000-6000m内,中度影响;距离道路2000-3000m内或距离居民点6000-9000m内,轻度影响;距离道路3000m以外或距离居民点9000m以外,无影响,对道路和居民点相应距离的缓冲区分析图层进行合并等操作,测定曲麻莱、治多和可可西里地区藏羚生境受人类活动影响的面积及其占总面积的比例分别为21595 km2(55%)、22271 km2(70%)和4775 km2(10%)。 在治多和曲麻莱地区,由于人类活动的影响使得藏羚生境大面积丧失,生境高度破碎化,尤其是治多地区,影响面积达将近70%。在可可西里地区,10%的影响面积虽然不是太大,但是近几年来由于各种形式的旅游日趋升温,尤其是青藏铁路建设开通,将增加道路对藏羚生境的影响程度。人类活动影响在研究地区分布极不平均,在曲麻莱的中东部、治多的东部以及可可西里的109国道附近人类活动影响的强度较大,在这些地区藏羚的生存条件恶劣,甚至部分地区已经不适合藏羚栖息了。 6、最后,基于研究地区的坡度grid图层、非监督分类grid图层以及不同程度人类活动影响的grid图层,对不同坡度、道路和居民影响的生境面积进行综合查询分析。把人类活动对藏羚生境的影响强度重新划分为如下3个等级,A、短距离影响,距离道路1000m或距离居民点3000m范围内的影响,也就是人类活动的强烈影响;B、中距离影响,距离道路2000m或距离居民点6000m范围内的影响,也就是人类活动的强烈影响和中度影响之和;C、长距离影响,距离道路3000m或距离居民点9000m范围内的影响,也就是人类活动的强烈影响、中度影响和轻度影响的总和。曲麻莱、治多和可可西里研究地区中坡度小于等于30度并且人类活动长距离范围影响下藏羚适合栖息的生境面积及占相应研究地区总面积的比例为12597 km2(32%)、6117km2(19%)和23564km2(48%)。 在研究地区,治多地区人类活动对藏羚生境适宜性的影响最为严重,其次为曲麻莱地区,而可可西里地区的人类活动影响较小。尤其是治多地区和曲麻莱地区,当人类活动的影响最大距离时,治多地区藏羚适宜生境面积竟然不到总面积的1/5,曲麻莱地区不到1/3。这两地区人类活动主要集中在东部,导致治多东部地区和曲麻莱中东部地区几乎没有藏羚分布。于是,由于人类活动的影响,使得拥有良好生境条件的治多和曲麻莱地区适合藏羚栖息的生境却较少,而生境条件相对较差的可可西里地区反而拥有相对较多的适合藏羚栖息的生境。