Remote sensing and GIS for wetland inventory, mapping and change analysis

A multiple purpose wetland inventory is being developed and promoted through partnerships and specific analyses at different scales in response to past uncertainties and gaps in inventory coverage. A partnership approach is being promoted through the Ramsar Convention on Wetlands to enable a global inventory database to be compiled from individual projects and analyses using remote sensing and GIS. Individual projects that are currently part of this global effort are described. They include an analysis of the Ramsar sites' database to map the distribution of Ramsar sites across global ecoregions and to identify regions and wetland types that are under-represented in the database. Given the extent of wetland degradation globally, largely due to agricultural activities, specific attention is directed towards the usefulness of Earth Observation in providing information that can be used to more effectively manage wetlands. As an example, a further project using satellite data and GIS to quantify the condition of wetlands along the western coastline of Sri Lanka is described and trends in land use due to changes in agriculture, sedimentation and settlement patterns are outlined. At a regional scale, a project to map and assess, using remote sensing, individual wetlands used for agriculture in eight countries in southern Africa is also described. Land cover and the extent of inundation at each site is being determined from a multi-temporal data set of images as a base for further assessment of land use change. Integrated fully within these analyses is the development of local capacity to plan and undertake such analyses and in particular to relate the outcomes to wetland management and to compile data on the distribution, extent and condition of wetlands globally.     

节事活动对苏州“东方水城”形象推广效应的分析——以“金鸡百花奖”落户苏州为例

通过市场抽样调查方法,以"金鸡百花奖"评奖基地永久落户苏州为例,分析了游客对苏州"东方水城"旅游新形象推广的效应感知,并在此基础上对节事活动效应的可持续发展进行了分析.研究结果表明,"金鸡百花奖"评奖基地永久落户苏州,推动苏州的经济增长、吸引更多旅游者来苏州和丰富苏州市民的文化生活是推动苏州最主要的方面.同时,通过整合与水有关的节事活动,有助于游客认知和宣传苏州的水城形象,延长游客停留时间.     

A Calibrated,High‐Resolution GOES Satellite Solar Insolation Product for a Climatology of Florida Evapotranspiration1

Paech, Simon J., John R. Mecikalski, David M. Sumner, Chandra S. Pathak, Quinlong Wu, Shafiqul Islam, and Taiye Sangoyomi, 2009. A Calibrated, High‐Resolution GOES Satellite Solar Insolation Product for a Climatology of Florida Evapotranspiration. Journal of the American Water Resources Association (JAWRA) 45(6):1328‐1342. Abstract: Estimates of incoming solar radiation (insolation) from Geostationary Operational Environmental Satellite observations have been produced for the state of Florida over a 10‐year period (1995‐2004). These insolation estimates were developed into well‐calibrated half‐hourly and daily integrated solar insolation fields over the state at 2 km resolution, in addition to a 2‐week running minimum surface albedo product. Model results of the daily integrated insolation were compared with ground‐based pyranometers, and as a result, the entire dataset was calibrated. This calibration was accomplished through a three‐step process: (1) comparison with ground‐based pyranometer measurements on clear (noncloudy) reference days, (2) correcting for a bias related to cloudiness, and (3) deriving a monthly bias correction factor. Precalibration results indicated good model performance, with a station‐averaged model error of 2.2 MJ m^?2/day (13%). Calibration reduced errors to 1.7 MJ m^?2/day (10%), and also removed temporal‐related, seasonal‐related, and satellite sensor‐related biases. The calibrated insolation dataset will subsequently be used by state of Florida Water Management Districts to produce statewide, 2‐km resolution maps of estimated daily reference and potential evapotranspiration for water management‐related activities.     

基于遥感技术的鄱阳湖-长江水体清浊倒置现象的分析

长期以来,在鄱阳湖和长江的交汇处,江水混浊而湖水清澈,然而,近年来江水清澈而湖水混浊。这种鄱阳湖 长江清浊倒置现象引起了广泛的关注,但鲜有研究人员系统分析这种现象的成因。借助中分辨率成像光谱仪（MODIS）和Landsat影像分析这种清浊倒置现象的起始时间和成因。基于MODIS影像反演的鄱阳湖和长江水体透明度显示在2004年以前鄱阳湖北部的水体透明度明显高于长江,而在2005和2006年长江水体透明度高于鄱阳湖北部,出现清浊倒置现象;同期鄱阳湖北部和长江水体透明度对比分析发现这种水体清浊倒置现象受长江水体透明度增加和鄱阳湖水体透明度下降的双重影响,但鄱阳湖北部水体透明度的变化在其中扮演主要角色;由Landsa影像识别的采（运）砂船数量及其与鄱阳湖北部水体透明度关系的分析表明,自2001年开始的鄱阳湖北部的采砂活动引起此区域水体透明度的显著下降.     

图像挖掘技术在林火影像中的应用

提出了林火遥感图像挖掘的概念,描述了图像挖掘技术在林火遥感图像上的具体应用及实现,针对林火部门每天产生并存储的有价值的林火遥感图像,结合林火上所特有的领域知识,提出了一种通过对林火遥感图像进行图像挖掘,可以将林火遥感图像分成有火或无火两类图像的方法。该方法的实现对帮助林火工作人员及早发现火情,做出火灾预测并采取相应措施具有重大的意义。     

Understanding large-scale deforestation in southern Jinotega, Nicaragua from 1978 to 1999 through the examination of changes in land use and land cover

Nicaragua, home to the largest remaining extent of rainforest in Central America (total surface area) and to a significant indigenous population, has lost approximately half of its forest cover since 1950. This major and rapid loss of forest cover has been explained as the consequence of an eastward moving agricultural frontier that cuts through the region of Jinotega. If the current deforestation rate continues, the country could lose its remaining forest cover over the course of the next two decades; therefore, it is essential that the dynamics and relationships of land-use and land-cover change (LUCC) in this region are understood. To examine LUCC in Nicaragua over time, Landsat imagery from the southern portion of the region of Jinotega, taken in 1978, 1987, and 1999 was utilized. A remote-sensing method, supervised classification, which allows for the grouping of spectrally similar values for each year, followed by an image change detection analysis (postclassification comparison) was conducted. Groundtruthing (field validation) was conducted in 2006 to validate the data, which yielded increasing overall accuracy rates of 71.68% for 1978, 82.35% for 1987, and 84.38% for 1999. The classification and change detection results showed that if the agricultural cultivation overtook this region, it happened before 1978. Therefore, the possibility that either deforestation did not actually occur along an agricultural frontier or that it was located further east exists; this would be an interesting subject for future studies. There was, however, clear evidence of increased forest cover from 1987 to 1999 near the urban center, correlating with the enforced reforestation law in the city of Jinotega.     

利用混合水体指数模型(CIWI)提取滨海湿地水体的信息

根据对滨海湿地区域光谱特性分析和背景信息的反射特点,对主要的水体信息提取方法进行比较分析,将混合水体指数模型（CIWI）应用于TM遥感影像,针对滨海湿地区域水体信息进行提取实验,并与近年得到广泛应用和承认的水体指数模型：归一化差异水体指数（NDWI）、改进的归一化差异水体指数（MNDWI）等进行比较。实验证明CIWI的区分度最高,水体与植被、水体与城镇、植被与城镇之间的区分度分别为505%、292%与267%;水体、植被、城镇像元之间的差异比NDWI和MNDWI增大,减少了混淆信息的影响,对江苏盐城滨海湿地研究区的水体信息提取精度达到949%,实现了滨海湿地区域水体信息的准确快速提取。     

城市复杂地表TM温度反演及其与MODIS产品的比较

在利用决策树模型将城市复杂地表分为植被、建筑物、水体、裸土等4类进行地表比辐射率估算和利用MODIS近红外数据反演大气水分含量的基础上,采用Jimenez-Munoz单通道算法进行了城市复杂地表TM温度的反演,并将反演结果与EOS MODIS地表温度产品进行了比较分析.结果表明:(1)基于地表信息分类提取后的地表比辐射率和MODIS反演的大气水汽含量得到的地表温度接近于实际状况;(2)反演结果与EOS MODIS地表温度产品对比发现Landsat TIM的陆表温度均值和标准差高于EOS MODIS的陆表温度产品.     

嫩江下游土地沙化的时空变化——基于MODIS数据的遥感分析

以2000,2004和2008年的MODIS数据为主要数据源,以嫩江流域下游为研究对象,在Arc-GIS9.0和ERDAS IMAGE9.0等软件支持下,建立沙化模型,并对沙化进行了信息提取与分析;借助ArcGIS强大的空间分析功能,完成了土地沙漠化的定量分析及其时空变化规律,在此基础上进一步探讨了土地沙化的过程、机理和成因.结果表明:研究区域沙漠化土地以轻度和中度沙漠化土地为主;重度和极重度沙漠化土地的年增长率较大,水域的年减少率最大;重度、极重度沙漠化土地主要向较低等级的沙漠化土地和水域转变,呈现一定的逆转移.     

滑坡灾害遥感解译不确定性研究

滑坡灾害遥感解译是遥感技术在滑坡灾害应用中的关键技术.研究表明,滑坡易发性和危险性区划图的误差主要来源于滑坡编目,其中大部分的误差则是源于滑坡编目时航卫片的解译,尤其是小比例尺航卫片的解译.从滑坡灾害解译、解译标志、解译过程等论述了滑坡灾害遥感解译,探讨了影响滑坡灾害遥感解译的不确定性因素,为减少滑坡编目和区划的误差提供参考.