基于植被指数和土地表面温度的干旱监测模型   总被引：79，自引：4，他引：79  

王鹏新  WAN Zheng-ming  龚健雅  李小文  王锦地 《地球科学进展》2003,18(4):527-533

干旱是一种周期性发生的自然现象,其发生过程中有关参数如地表覆盖度、温度和土壤表层含水量等可以通过遥感的途径进行定量反演,而这些参数客观地反映了地表的综合特征。综述了运用遥感反演产品---土地表面温度和归一化植被指数在干旱监测中的应用前景和进展,分析了距平植被指数、条件植被指数、条件温度指数和归一化温度指数等干旱监测方法的优缺点,在前人研究的基础上,提出了条件植被温度指数的干旱监测模型,探讨了其应用前景。  相似文献   

一个基于模拟退火法的陆面数据同化算法   总被引：15，自引：3，他引：15  

李新  小池俊雄  程国栋 《地球科学进展》2003,18(4):632-636

陆面数据同化系统是近年来兴起的新领域。我们发展了一个实验型的陆面数据同化方案,它使用一种启发式优化算法——模拟退火法极小化目标泛函。与变分法和Kalman滤波方法比较,这一算法具有独立于目标泛函的优点,可处理模型和观测算子的非线性和不连续性。使用GAME—Tibet实验中的土壤水分观测值进行单点数值实验,成功地将土壤水分观测同化到陆面过程模型SiB2中。结果表明,与不进行同化相比,土壤水分的估计值有较大改善。  相似文献   

多步骤分类法在上海市闵行区土地利用/覆盖信息提取中的应用     

聂芹  李连运 《国土资源遥感》2006,17(1):79-82

遥感图像分类是进行土地利用/覆盖变化研究的基础。采用多步骤分类法对上海市闵行区4期遥感图像进行分类，总分类精度达到了85%。  相似文献   

农牧交错带土地沙化遥感监测   总被引：17，自引：1，他引：17  

邝生爱  田淑芳  程博 《国土资源遥感》2002,13(2):10-14

以内蒙古多伦县为研究对象,作时隔5a的两次遥感调查,对内蒙古东南部农牧业交错带的土地沙化进行监测。建立了土地沙化分类体系,把土地沙化与土地利用紧密联系,依据植被指数概念,采用了一组比值组合,有效地将土地沙化类别分层分离。通过第一次遥感调查,了解到多伦县由于过度耕种和过度放牧,致使土地沙化十分严重。经第二次调查对比分析,退耕还林、退牧还草的治沙效果显著,土地沙化发展趋势得到遏制,遥感监测为地方政府的防沙治沙起了重要作用。  相似文献   

Comparative analysis of land use/cover change trajectories and their driving forces in two small watersheds in the western Loess Plateau of China     

《International Journal of Applied Earth Observation and Geoinformation》2013

To prevent soil loss and achieve better ecological environments, soil conservation measures have been taken during the past decades in the western Loess Plateau of China. In this paper, a case study was taken in Luoyu valley and Lver valley, two sub-watersheds of Xihe watershed and comparison was carried out between them. The main object of this study is to monitor land use/cover changes in the two similar small watersheds utilizing SPOT5 imageries by object-oriented human–computer interactive classification method, further develop the method of spatio-temporal analysis of land use/cover change by using pattern metrics of change trajectories and relative land use suitability index (R) in smaller watersheds, and make comparisons between the two similar small watersheds, taking water and soil conservation measures into consideration. Results show that combining GIS and RS, this method can be perfectly applied to make comparisons between different small watersheds with similar geographical backgrounds. And land use/cover spatiotemporal dynamic change characteristics can be preferably expressed by pattern metrics of change trajectories and R values based on topographical data. Different emphases have been laid according to their own geological backgrounds in the two watersheds and human activities have different effects on the landscapes of the two watersheds. The main change pattern is from slope farmland to terrace (322, the largest in Luoyu valley) or to economic fruit forest (344, the largest in Lver valley). R value of every slope grade in both of the two watersheds drops with the rising of slope degree on the whole and it shows that there is still much to do for people in the two watersheds in consideration that all the R values are still lower than 0.7.  相似文献   

Mapping natural and urban environments using airborne multi-sensor ADS40–MIVIS–LiDAR synergies     

《International Journal of Applied Earth Observation and Geoinformation》2013

The recent and forthcoming availability of high spatial resolution imagery from satellite and airborne sensors offers the possibility to generate an increasing number of remote sensing products and opens new promising opportunities for multi-sensor classification. Data fusion strategies, applied to modern airborne Earth observation systems, including hyperspectral MIVIS, color-infrared ADS40, and LiDAR sensors, are explored in this paper for fine-scale mapping of heterogeneous urban/rural landscapes. An over 1000-element array of supervised classification results is generated by varying the underlying classification algorithm (Maximum Likelihood/Spectral Angle Mapper/Spectral Information Divergence), the remote sensing data stack (different multi-sensor data combination), and the set of hyperspectral channels used for classification (feature selection). The analysis focuses on the identification of the best performing data fusion configuration and investigates sensor-derived marginal improvements. Numerical experiments, performed on a 20-km stretch of the Marecchia River (Italy), allow for a quantification of the synergies of multi-sensor airborne data. The use of Maximum Likelihood and of the feature space including ADS40, LiDAR derived normalized digital surface, texture layers, and 24 MIVIS bands represents the scheme that maximizes the classification accuracy on the test set. The best classification provides high accuracy (92.57% overall accuracy) and demonstrates the potential of the proposed approach to define the optimized data fusion and to capture the high spatial variability of natural and human-dominated environments. Significant inter-class differences in the identification schemes are also found by indicating possible sub-optimal solutions for landscape-driven mapping, such as mixed forest, floodplain, urban, and agricultural zones.  相似文献   

A data mining approach for evaluation of optimal time-series of MODIS data for land cover mapping at a regional level     

《ISPRS Journal of Photogrammetry and Remote Sensing》2013

Optical Earth Observation data with moderate spatial resolutions, typically MODIS (Moderate Resolution Imaging Spectroradiometer), are of particular value to environmental applications due to their high temporal and spectral resolutions. Time-series of MODIS data capture dynamic phenomena of vegetation and its environment, and are considered as one of the most effective data sources for land cover mapping at a regional and national level. However, the time-series, multiple bands and their derivations such as NDVI constitute a large volume of data that poses a significant challenge for automated mapping of land cover while optimally utilizing the information it contains. In this study, time-series of 10-day cloud-free MODIS composites and its derivatives – NDVI and vegetation phenology information, are fully assessed to determine the optimal data sets for deriving land cover. Three groups of variable combinations of MODIS spectral information and its derived metrics are thoroughly explored to identify the optimal combinations for land cover identification using a data mining tool.The results, based on the assessment using time-series of MODIS data, show that in general using a longer time period of the time-series data and more spectral bands could lead to more accurate land cover identification than that of a shorter period of the time-series and fewer bands. However, we reveal that, with some optimal variable combinations of few bands and a shorter period of time-series data, the highest possible accuracy of land cover classification can be achieved.  相似文献   

重庆市国土房管信息化工作回顾与展望     

颜英 《国土资源信息化》2013,(4):7-9

本文回顾了重庆市国土资源和房地产信息中心成立十年以来的国土房管信息化主要工作,并对未来工作做了展望。  相似文献   

Remotely sensing the spatial and temporal land cover changes in Eastern Mau forest reserve and Lake Nakuru drainage basin,Kenya     

《Applied geography (Sevenoaks, England)》2013

This study aimed at characterizing land cover dynamics for four decades in Eastern Mau forest and Lake Nakuru basin, Kenya. The specific objectives were to: (i) identify and map the major land cover types in 1973, 1985, 2000 and 2011; (ii) detect and determine the magnitude, rates and nature of the land cover changes that had occurred between these dates, and; (iii) establish the spatial and temporal distribution of these changes. Land cover types were discriminated through partitioning, hybrid classification and spatial reclassification of multi-temporal Landsat imagery. The land cover products were then validated and overlaid in post-classification comparison to detect the changes between 1973 and 2011. The accuracies of the land cover maps for 1973, 1985, 2000 and 2011 were 88%, 95%, 80% and 89% respectively. Six land cover classes, namely forests-shrublands, grasslands, croplands, built-up lands, bare lands and water bodies, were mapped. Forests-shrublands dominated in 1973, 1985 and 2000 covering about 1067 km², 893 km² and 797 km² respectively, but were surpassed by croplands (953 km²) in 2011. Bare lands occupied the least area that varied between 2 km² and 7 km² during this period. Overall, forests-shrublands and grasslands decreased by 428 km² and 258 km² at the annual average rates of 1% each, whereas croplands and built-up lands expanded by 660 km² and 24 km² at the annual rates of 6% and 16% respectively. The key hotspots of these changes were distributed in all directions of the study area, but at different times. Therefore, policies that integrate restoration and conservation of natural ecosystems with enhancement of agricultural productivity are strongly recommended. This will ensure environmental sustainability and socio-economic well-being in the area. Future research needs to assess the impacts of the land cover changes on ecosystem services and to project the future patterns of land cover changes.  相似文献   

A quantitative assessment of vegetable farming on vacant lots in an urban fringe area in Metro Manila: Can it sustain long-term local vegetable demand?     

《Applied geography (Sevenoaks, England)》2013

The aim of this study was to quantitatively assess vegetable production and consumption in an urban fringe area in Metro Manila, the Philippines. We conducted field investigations into vegetable production at a farm within a subdivision, monitored customers for 1 week at the farm's vegetable stand, interviewed customers of the stand, and conducted household monitoring and interviews to identify purchasing behavior. We also conducted an object-based WorldView-2 image analysis of a larger area to identify current and potential future vegetable farming plots and a spatial analysis using GIS to visualize the vegetable production/consumption ratio. We found that about one-third of current vegetable demand could be supplied by greater promotion of vegetable farming in vacant lots and by setting up more vegetable stands at spatial intervals less than 1-km. Subdivision regulations also influenced vegetable farming because of the level of social acceptance of caretakers of vacant lots. The current planning and institutional framework does not consider social contexts in land use and planning. We suggested that a new framework is necessary; it should consider balancing the formation of social capital and formalize planning and institutional procedures to support sustainable local vegetable production.  相似文献