Assessment of shallow landslides from Hurricane Mitch in central America using a physically based model   总被引：5，自引：2，他引：3  

Zonghu Liao  Yang Hong  Dalia Kirschbaum  Chun Liu 《Environmental Earth Sciences》2012,66(6):1697-1705

Shallow landslides induced by heavy rainfall events represent one of the most disastrous hazards in mountainous regions because of their high frequency and rapid mobility. Recent advancements in the availability and accessibility of remote sensing data, including topography, land cover and precipitation products, allow landslide hazard assessment to be considered at larger spatial scales. A theoretical framework for a landslide forecasting system was prototyped in this study using several remotely sensed and surface parameters. The applied physical model SLope-Infiltration-Distributed Equilibrium (SLIDE) takes into account some simplified hypotheses on water infiltration and defines a direct relation between factor of safety and the rainfall depth on an infinite slope. This prototype model is applied to a case study in Honduras during Hurricane Mitch in 1998. Two study areas were selected where a high density of shallow landslides occurred, covering approximately 1,200 km². The results were quantitatively evaluated using landslide inventory data compiled by the United States Geological Survey (USGS) following Hurricane Mitch’s landfall. The agreement between the SLIDE modeling results and landslide observations demonstrates good predictive skill and suggests that this framework could serve as a potential tool for the future early landslide warning systems. Results show that within the two study areas, the values of rates of successful estimation of slope failure locations reached as high as 78 and 75%, while the error indices were 35 and 49%. Despite positive model performance, the SLIDE model is limited by several assumptions including using general parameter calibration rather than in situ tests and neglecting geologic information. Advantages and limitations of this physically based model are discussed with respect to future applications of landslide assessment and prediction over large scales.  相似文献   

Monitoring global land surface drought based on a hybrid evapotranspiration model     

Yunjun Yao  Shunlin Liang  Qiming Qin  Kaicun Wang  Shaohua Zhao 《International Journal of Applied Earth Observation and Geoinformation》2011

The latent heat of evapotranspiration (ET) plays an important role in the assessment of drought severity as one sensitive indicator of land drought status. A simple and accurate method of estimating global ET for the monitoring of global land surface droughts from remote sensing data is essential. The objective of this research is to develop a hybrid ET model by introducing empirical coefficients based on a simple linear two-source land ET model, and to then use this model to calculate the Evaporative Drought Index (EDI) based on the actual estimated ET and the potential ET in order to characterize global surface drought conditions. This is done using the Global Energy and Water Cycle Experiment (GEWEX) Surface Radiation Budget (SRB) products, AVHRR-NDVI products from the Global Inventory Modeling and Mapping Studies (GIMMS) group, and National Centers for Environmental Prediction Reanalysis-2 (NCEP-2) datasets. We randomly divided 22 flux towers into two groups and performed a series of cross-validations using ground measurements collected from the corresponding flux towers. The validation results from the second group of flux towers using the data from the first group for calibration show that the daily bias varies from −6.72 W/m² to 12.95 W/m² and the average monthly bias is −1.73 W/m². Similarly, the validation results of the first group of flux towers using data from second group for calibration show that the daily bias varies from −12.91 W/m² to 10.26 W/m² and the average monthly bias is −3.59 W/m². To evaluate the reliability of the hybrid ET model on a global scale, we compared the estimated ET from the GEWEX, AVHRR-GIMMS-NDVI, and NECP-2 datasets with the latent heat flux from the Global Soil Wetness Project-2 (GSWP-2) datasets. We found both of them to be in good agreement, which further supports the validity of our model's global ET estimation. Significantly, the patterns of monthly EDI anomalies have a good spatial and temporal correlation with the Palmer Drought Severity Index (PDSI) anomalies from January 1984 to December 2002, which indicates that the method can be used to accurately monitor long-term global land surface drought.  相似文献   

基于背景迭代搜索的高分辨遥感图像汽车检测     

吴小波  杨辽  沈金祥  王杰 《国土资源遥感》2011,(4):46-51

提出了一种基于高分辨率卫星遥感图像检测汽车的新方法——背景迭代搜索(Background Iterative Search,BIS)算法。该算法首先利用背景与目标的局部差异,用距离作为判别准则逐步迭代搜索并去除背景,根据汽车的物质特性初步检测汽车;然后采用动态双峰阈值分割方法,利用全局信息把道路和非道路分开,并根据形状特征粗略提取道路;最后利用道路信息约束初步检测的汽车,得到最终的汽车检测结果。通过使用IKONOS和QuickBird卫星遥感数据进行实验,验证了BIS算法的有效性。  相似文献   

基于非下采样Contourlet变换的极化SAR图像融合与去噪     

孙晓霞  张继贤  燕琴 《测绘科学》2011,36(3):70-72

针对非下采样Contourlet变换(NSCT)在处理噪声影像中具有的优势,以及同极化SAR图像(HH、VV)之间的相关性与互补性,本文实验了一种基于非下采样Contourlet变换的极化图像融合方法。该方法首先对每个极化图像进行多尺度、多方向分解,然后对不同分解子带系数分别采用有利于斑点噪声去除和信息增强的融合规则进行融合,最终通过NSCT反变换得到融合图像。通过信息熵、相关系数以及等效视数等指标的评价,验证了该方法可以有效地实现信息增强,同时该方法也在一定程度上降低了斑点噪声的负面影响。  相似文献   

Application of Spatial Database in Quantitative Analysis of Litho-Paleogeography—A Case Study of a Middle Ordovician Sequence Interval in the Ordos Basin     

Bin Li  Feiyan Liao  Hao Meng  Yanchun Zhong 《地球空间信息科学学报》2011,14(1):27-38

In the study of sequence stratigraphy and litho-paleogeography,quantitative analysis,precise calculation and detailed comparison of tremendous geological data,such as field profiles,logging records and seismic curves from different areas,are the basic requirements.In order to obtain a more reliable and precise result,this paper presents a novel method that combines spatial database analysis with the single-factor mapping technology to establish sequence stratigraphical succession and to map the Ordo-vician litho-paleogeography of the Ordos Basin,one of the largest oil-gas bearing basins in North China Platform.By using this method,all of the related basic geological data can be quantitatively analyzed and effectively managed.Various attributes of the ba-sic stratigraphic units and their characters,such as sequence thickness,penecontemporaneous dolostone content,shallow water parget content,and terrigenous material content,can be fully utilized statistically in facies analysis and in mapping.Based on this analysis,this paper has be exerted single-factor isopachous mapping quantitatively for each of the Ordovician sequences in the ba-sin,and finally synthesized multiple factors to reconstruct the litho-paleogeography for each of the sequence intervals.The study shows that the proposed method is quite effective and has a much higher resolution in recognizing litho-paleogeographic subunits compared with traditional ways.For example,in one of the Middle Ordovician sequence intervals(SQ19 in the Lower Majiagou Formation) of the Ordos Basin,the authors have successfully developed a mathematical formula to divide the distribution of various facies units substantially,such as old lands,submarine uplifts,supratidal zones,intertidal zones and subtidal zones.  相似文献   

利用目标点最小生成树的路面裂缝检测   总被引：1，自引：0，他引：1  

邹勤  李清泉  毛庆洲  陈龙 《武汉大学学报(信息科学版)》2011,(1):71-75

分析路面裂缝的成像特点,提出了一种基于目标点最小生成树的路面裂缝检测方法。最小生成树具有描述空间线性聚集特征的优点,有利于实现对裂缝的全局分析和提取。实验结果表明,对不连续裂缝的处理,本文方法优于传统方法。  相似文献   

Response of hydrological cycle to recent climate changes in the Tibetan Plateau   总被引：14，自引：0，他引：14  

Kun Yang  Baisheng Ye  Degang Zhou  Bingyi Wu  Thomas Foken  Jun Qin  Zhaoye Zhou 《Climatic change》2011,109(3-4):517-534

The Tibetan Plateau (TP) surfaces have been experiencing an overall rapid warming and wetting while wind speed and solar radiation have been declining in the last three decades. This study investigated how climate changes influenced the hydrological cycle on the TP during 1984??2006. To facilitate the analysis, a land surface model was used to simulate surface water budget at all CMA (China Meteorological Administration) stations on the TP. The simulated results were first validated against observed ground temperature and observation-derived heat flux on the western TP and observed discharge trends on the eastern TP. The response of evaporation and runoff to the climate changes was then analyzed. Major finding are as follows. (1) Surface water balance has been changed in recent decades. Observed precipitation shows insignificant increasing trends in central TP and decreasing trends along the TP periphery while evaporation shows overall increasing trends, leading to decreased discharge at major TP water resource areas (semi-humid and humid zones in the eastern and southern TP). (2) At the annual scale, evaporation is water-limited in dry areas and energy-limited (radiation and air temperature) in wet areas; these constraints can be interpreted by the Budyko-curve. Evaporation in autumns and winters was strongly controlled by soil water storage in summers, weakening the dependence of evaporation on precipitation at seasonal scales. (3) There is a complementary effect between the simulated actual evaporation and potential evaporation, but this complementary relationship may deviate from Bouchet??s hypothesis when vapor pressure deficit (or air temperature) is too low, which suppresses the power of vapor transfer.  相似文献   

Eigen analysis of tree-ring records: Part 1, a limited representativeness of regional curve     

Bao Yang  Dmitry M. Sonechkin  Nina M. Datsenko  Nadezda N. Ivashchenko  Jingjing Liu  Chun Qin 《Theoretical and Applied Climatology》2011,106(3-4):489-497

Based on a set of very long-living (2,000?years) Qilian junipers (Sabina przewalskii Kom.) from the north-eastern part of the Tibetan Plateau (the region of Dulan), we carefully consider the regional curve standardization (RCS) technique. For this goal, we correlate deviations of individual tree-ring width records from their regional mean age-dependent curve (RC). It turns out that these correlations keep their positivity for almost all shifts between ages compared (up to 500?years and even more) evidencing each Dulan juniper to be a unique ??thermometer??. Just the unification of these ??thermometers?? in the form RC creates a spurious positive trend in the Dulan chronology. We modify the RCS technique to closer attach RC to these ??thermometers?? in order to construct a new chronology in which the trend is absent.  相似文献   

利用MSU序列研究高空大气温度变化的进展   总被引：2，自引：0，他引：2  

廖蜜  张鹏  吴雪宝  邱红 《气象》2011,37(9):1151-1157

美国NOAA卫星上搭载的微波大气探测仪MSU以及后续继承改进仪器AMSU,自1978年投入运行以来,已经积累了超过30年的全球大气温度的观测资料。近年来,国外学者通过仪器定标误差订正、卫星轨道衰减订正、观测时间差异导致的温度日变化订正、仪器间的相互定标处理等技术,发现并剔除了一些影响较大的非气候因素,提高了该序列资料的质量,并用于全球气候变化研究,特别是对流层和平流层近30年的温度变化研究,研究结果是对常规地面和探空资料分析结果的重要补充。本文对目前国际上3种常用的MSU序列资料集的定标误差、偏差订正和不同卫星上仪器观测序列的一致化处理方法进行了综合介绍,并比较分析了3种资料用于30年高空大气温度变化趋势分析的异同。  相似文献   

In situ high-pressure study of FeP: Implications for planetary cores     

Tingting Gu  Xiang Wu  Shan Qin  Leonid Dubrovinsky 《Physics of the Earth and Planetary Interiors》2011,184(3-4):154-159

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