Spatial modelling of road network development,population pressure and biophysical properties of upland crop and forest conversions in Lop Buri province,Thailand, 1989–2006

Over the past few decades, land use and land cover change has become a global concern. In the Lop Buri province of Thailand, rapid land cover change, specifically conversion of forests to agriculture, has occurred. The purpose of the study is to identify the predictors of land cover change in Lop Buri province for land that has been converted to upland crops or has undergone deforestation between 1989 and 2006. Four logistic regression models were constructed using spatially explicit biophysical and geo‐social data, to account for changes to upland crops and forest loss from1989–98 and 1998–2006. Across the four models, slope, distance to forest edge, distance to towns, distance to roads, population size, and population density in various stand‐alone and interactive forms were found to be the most consistent predictors of land cover change.     

ESTARFM模型在西藏色林错湖面积时空变化中的应用分析(1976-2014年)

湖泊（特别是内陆湖）作为全球气候变化的敏感区域,是气候变化与环境变异的指示器,其面积变化在一定程度上可反映区域的气候变化。因此,精确监测湖泊面积的时空变化,对分析区域生态环境变化具有重要的意义。本文基于ESTARFM时空数据融合模型,利用MODIS数据模拟了2000年后无法得到的Landsat数据;利用NDWI和MNDWI 2种水体指数并辅以DEM数据分析了1976-2014年西藏色林错湖湖面面积的时空变化;综合湖区周围6个气象站点的气象数据(1970-2014年),探究了湖面面积变化的原因及其对气候变化的响应。结果表明：(1)利用ESTARFM时空融合模型得到的Landsat-Like数据与真实的Landsat数据在水体信息提取方面具有较高的相关性,R²可达0.93,时空数据融合的结果可用于湖泊水体的信息提取;(2)近40年来（1976-2014年）,色林错湖处于持续扩张状态,面积呈较显著的增长趋势,增加了近711.652 km²,增幅为42.36%,年平均增长速率约为18.728 km²a^-1,增长最快时可达55.954 km²a^-1;湖面面积变化先后经历了平稳变化-迅速变化-平稳变化3个阶段;北部湖区在40年间变化最为明显,向北扩展了约22.812 km;2003-2005年,南部湖区已与雅根错湖连为一体,随后二者共同扩张;(3)气温的持续升高造成的冰雪融水补给增加可能是导致湖泊面积扩张的主要因素,风速的降低为次要因素,湖面的面积变化与降水量、日照时数的变化相关性不明显。     

基于Landsat8与GEOEYE-1数据融合的天山北坡县域蒸散量计算——以呼图壁县为例

基于Landsat 8与GEOEYE-1遥感数据,使用多尺度遥感方法,以新疆呼图壁县为例,利用SEBS模型计算天山北坡县域蒸散量,服务小流域和县域为管理单元的最严格水资源管理。针对军塘湖河流域耕地、呼图壁河流域耕地和北部荒漠-绿洲过渡带,应用2 m分辨率GEOEYE-1影像计算得NDVI和基于NDVI-T_R法模拟的地表温度。将获得的地表温度和NDVI作为SEBS模型的重要参数计算地表蒸散量,采用自制小型蒸渗仪观测数据对估算结果进行评估。结果表明:在使用中分辨率影像Landsat 8估算地表蒸散量过程中加入GEOEYE-1反演的个别参数,大部分估算结果更加接近自制微型蒸渗仪测定值,估算绝对误差最大值出现在裸地,为28.5%,远低于使用Landsat 8影像的54.8%,说明高分影像的参与有助于提高模型估算效率。     

煤矸石堆场信息遥感提取方法对比

煤矸石作为工业特殊固体废物之一,产生于煤炭的采掘与洗煤的过程中,影响着周围的生态环境,因此,通过遥感影像获得煤矸石堆场的位置、面积信息,对于后续的调查也有很好的指导作用。本文选择2011年9月的LandSat5 TM影像,通过将研究区的光谱信息与地形、温度等辅助信息相结合的方式,分别使用非监督分类、监督分类、谱间关系法、分层分类法4种方法对研究区煤矸石堆场进行提取。通过对比,分层分类法提取煤矸石堆场信息的识别精度可达到78%。另外,该方法对于继续在高分辨率遥感影像上进行煤矸石堆场位置、面积的提取也有指导作用。     

Retrieval of suspended sediment concentrations in large turbid rivers using Landsat ETM+: an example from the Yangtze River,China

Suspended sediment concentration (SSC) is a critical parameter in the study of river sediment transport and water quality variation, but traditional measurement methods are costly and time‐consuming. This paper is focused on presenting a methodology that may be useful in estimating SSC which is of key importance in process geomorphology and hydrology. In previous studies, remote sensing has been applied to estimate the SSC of sea waters as well as low turbid inland waters like lakes, reservoirs and short river reaches visible within a single Landsat satellite image coverage. Rivers, especially highly turbid large rivers, have largely been ignored. The dataset used in this paper includes measured SSC and multi‐temporal Landsat ETM+ images covering most part of the Yangtze River. Using an effective easy‐to‐use atmospheric correction method that does not require in situ atmospheric conditions, retrieved water reflectance of Band 4 was found to be a good SSC indicator within the large SSC range 22–2610 mg l^–1. The newly developed regression relation between SSC and water reflectance of Band 4 appears to be able to provide a relatively accurate SSC estimate directly from Landsat ETM+ images for the Yangtze River from the upper, the middle to the lower reaches. With the relation it is possible to estimate or map out SSC dynamics of large rivers which lack SSC data due to constraints of conventional measurements. Copyright © 2009 John Wiley & Sons, Ltd.     

Up-scaling of SEBAL derived evapotranspiration maps from Landsat (30 m) to MODIS (250 m) scale

Remotely sensed imagery of the Earth’s surface via satellite sensors provides information to estimate the spatial distribution of evapotranspiration (ET). The spatial resolution of ET predictions depends on the sensor type and varies from the 30–60 m Landsat scale to the 250–1000 m MODIS scale. Therefore, for an accurate characterization of the regional distribution of ET, scaling transfer between images of different resolutions is important. Scaling transfer includes both up-scaling (aggregation) and down-scaling (disaggregation). In this paper, we address the up-scaling problem.The Surface Energy Balance Algorithm for Land (SEBAL) was used to derive ET maps from Landsat 7 Enhanced Thematic Mapper Plus (ETM+) and Moderate Resolution Imaging Spectroradiometer (MODIS) images. Landsat 7 bands have spatial resolutions of 30–60 m, while MODIS bands have resolutions of 250, 500 and 1000 m. Evaluations were conducted for both “output” and “input” up-scaling procedures, with aggregation accomplished by both simple averaging and nearest neighboring resampling techniques. Output up-scaling consisted of first applying SEBAL and then aggregating the output variable (daily ET). Input up-scaling consisted of aggregating 30 m Landsat pixels of the input variable (radiance) to obtain pixels at 60, 120, 250, 500 and 1000 m before SEBAL was applied. The objectives of this study were first to test the consistency of SEBAL algorithm for Landsat and MODIS satellite images and second to investigate the effect of the four different up-scaling processes on the spatial distribution of ET.We conclude that good agreement exists between SEBAL estimated ET maps directly derived from Landsat 7 and MODIS images. Among the four up-scaling methods the output simple averaging method produced aggregated data and aggregated differences with the most statistically and spatially predictable behavior. The input nearest neighbor method was the least predictable but was still acceptable. Overall, the daily ET maps over the Middle Rio Grande Basin aggregated from Landsat images were in good agreement with ET maps directly derived from MODIS images.     

CPF变化对Landsat TM/ETM+辐射校正结果的影响

随着时间的推移,卫星传感器的老化会使得原有的辐射定标参数文件(CPF)失效。最典型的当属Landsat-5卫星,该卫星自1984年发射以来,已经进行了多次CPF修正;而Landsat-7卫星的CPF也经过了数次修改,以保证辐射校正结果的准确性。以Landsat TM/ETM+遥感影像为例,分别以2003、2009年的CPF对它们进行辐射校正,并对结果进行对比。结果表明,除ETM+的绿光波段外,TM、ETM+影像基于2009年CPF计算的各波段均值都要小于2003年。而这一变化也使得由此计算的指数产生差异：归一化植被指数(NDVI)间的差异可达0.48%,建筑用地指数(IBI)间的差异可达5.94%。     

基于Landsat 8的辽宁弓长岭区遥感蚀变信息提取

在详细解读辽宁弓长岭区Landsat 8影像数据的基础上,结合矿物光谱理论和弓长岭地区（地表植被覆盖严重）的基础地质资料,采用主成分分析法与比值法相结合的方式对该区2017-05和2017-08两个时段的Landsat 8多光谱遥感数据的蚀变异常信息进行了提取。结果表明：利用主成分分析法与比值法相互结合所形成的波段组合比单独运用主成分分析所提取的蚀变异常信息更加明显;此次研究中2017-05数据所提取出的羟基蚀变信息及2017-08数据所提取的铁染蚀变信息主要分布于弓长岭一矿区、二矿区、三矿区和独木-八盘岭矿区地表出露矿体的外围。这也说明将主成分分析法与比值法相结合对于植被覆盖严重区域的蚀变信息提取仍具有较好的效果。     

喀喇昆仑山克勒青河谷近年来发现有跃动冰川

根据冰川编目、Landsat MSS/TM/ETM 影像和相关的历史考察制图,利用GIS进行了不同时期的冰川分布图的制作,对比分析了不同时期冰川范围.重点监测了喀喇昆仑山北坡克勒青河的5Y654D48、5Y654D97的不同时段内的冰川运动状况.结果发现:5Y654D48冰川和5Y654D97冰川分别在1990-2000年与1977-1990年间运动速度达272 m·a-1,213.1 m·a-1,比其它时段运动速度大7～20倍,具备跃动冰川的运动特征.分析认为,5Y654D48冰川在1990-2000年、5Y654D97在1977-1990年间曾分别发生过冰川跃动.