Earthquake-induced landslide hazard and vegetation recovery assessment using remotely sensed data and a neural network-based classifier: a case study in central Taiwan   总被引：4，自引：1，他引：3  

Wen-Tzu Lin  Wen-Chieh Chou  Chao-Yuan Lin 《Natural Hazards》2008,47(3):331-347

A catastrophic earthquake with a Richter magnitude of 7.3 occurred in the Chi-Chi area of Nantou County on 21 September 1999. Large-scale landslides were generated in the Chiufenershan area of Nantou County in central Taiwan. This study used a neural network-based classifier and the proposed NDVI-based quantitative index coupled with multitemporal SPOT images and digital elevation models (DEMs) for the assessment of long-term landscape changes and vegetation recovery conditions at the sites of these landslides. The analyzed results indicate that high accuracy of landslide mapping can be extracted using a neural network-based classifier, and the areas affected by these landslides have gradually been restored from 211.52 ha on 27 September 1999 to 113.71 ha on 11 March 2006, a reduction of 46.24%, after six and a half years of assessment. In accordance with topographic analysis at the sites of the landslides, the collapsed and deposited areas of the landslide were 100.54 and 110.98 ha, with corresponding debris volumes of 31,983,800 and 39,339,500 m³. Under natural vegetation succession, average vegetation recovery rate at the sites of the landslides reached 36.68% on 11 March 2006. The vegetation recovery conditions at the collapsed area (29.17%) are shown to be worse than at the deposited area (57.13%) due to topsoil removal and the steep slope, which can be verified based on the field survey. From 1999 to 2006, even though the landslide areas frequently suffered from the interference of typhoon strikes, the vegetation succession process at the sites of the landslides was still ongoing, which indicates that nature, itself, has the capability for strong vegetation recovery for the denudation sites. The analyzed results provide very useful information for decision-making and policy-planning in the landslide area.  相似文献   

青藏高原冻土区域的相干特性分析     

谢酬  李震  李新武 《冰川冻土》2008,30(5)

由季节性的冻胀和融沉导致的地表变形是在多年冻土区域进行工程施工的最主要危害, 青藏铁路建设和维护中的一个主要问题就是如何监测冻土的形变. 利用北麓河地区的ASAR数据, 联系冻土的相关变化规律, 对于冻土区域的相干特性进行了分析. 通过对不同自然地物的相干性进行对比分析, 发现冻土区域地物的相干性不仅与地物特性相关, 同时也与冻土的冻结和融化密切相关. 不同时间段干涉对的相干性的差别反映了冻土在不同季节的变化规律. 青藏铁路和公路在不同空间基线和时间基线上的相干性表现, 为该区域的稳定散射体的选择提供了一种可能, 对于进行北麓河区域的冻土形变的时间序列分析具有重要的指导意义.  相似文献   

Abundances and isotopic compositions of rhenium and osmium in pyrite samples from the Huaibei coalfield,Anhui, China     

Guijian Liu  Chen-Lin Chou  Zicheng Peng  Gang Yang 《International Journal of Earth Sciences》2008,97(3):617-621

Two pyrite samples from the Shihezi Formation (Lower Permian), Huaibei coalfield, Anhui, China, have been analyzed for abundances and isotopic compositions of rhenium and osmium using negative thermal ion mass spectrometry. The Re–Os ages of the pyrites are 64.4 and 226 Ma, which are younger than the formation age of the coal seam. The pyrite samples may consist of pyrite formed at various stages during the history of coal formation. The γ_Os values of the two pyrite samples are + 17 and + 18, respectively. Such high γ_Os values are reported for the first time for recycles crustal materials from a sedimentary basin.  相似文献   

Potential negative effects of groundwater dynamics on dry season convection in the Amazon River basin     

Yen-Heng Lin  Min-Hui Lo  Chia Chou 《Climate Dynamics》2016,46(3-4):1001-1013

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关于气候变化对社会经济系统影响的机理和途径的探讨   总被引：2，自引：1，他引：1  

丑洁明  董文杰  延晓冬 《大气科学》2016,40(1):191-200

本文基于考虑气候变化影响应与经济系统的特征时空尺度相匹配的观点,讨论了气候变化对经济系统影响的途径.认为:气候变化是年代际尺度的气温变化,直接影响的是冰冻圈、海平面、水资源、陆面状况、生态系统、微生物、人体健康等七个领域;觉察不到日变化、季节变化、年际变化而呈现出年代际变化的事物才是受全球变暖影响的事物;由于时间尺度不匹配,经济系统几乎不会受气候变化的直接影响;就间接影响而言,全球变暖导致的极端气候事件加剧和人类为应对与适应气候变化的积极响应,对经济系统的影响要显著得多.  相似文献   

Landslide at Su-Hua Highway 115.9k triggered by Typhoon Megi in Taiwan   总被引：2，自引：2，他引：0  

Chia-Ming Lo  Ching-Fang Lee  Hsien-Ter Chou  Ming-Lang Lin 《Landslides》2014,11(2):293-304

This study focused on the landslide case at Su-Hua Highway 115.9k, Taiwan. A preliminary investigation was conducted on geomorphologic features change and landslide mechanisms using digital elevation models, geographical maps, and remote sensing images at different times in conjunction with geological surveys and analysis results. Using the results of geological surveys and physical model experiments, we constructed a discrete element method to simulate the process of landslide movement. The results revealed deformation in the metamorphic rock slopes upstream of 115.9k. The slopes around the erosion gully upstream presented visible slope toes cutting and tension cracks at the crest as well as unstable rock masses. According to the results of numerical simulation for typhoon Megi event, intense rains could induce slippage in the rock debris/masses in the source area, initially at a speed of 5–20 m/s. Subsequently, steeper terrain could cause the rock debris/masses to accelerate to form a high-speed (>30 m/s) debris slide quickly moving downstream to form an alluvial fan downstream by the sea.  相似文献   

长江中游高位砾石层的磁性特征与物源分析     

张玉芬  李长安  周稠  康春国  熊德强  江华军 《吉林大学学报(地球科学版)》2014,(5):1669-1677

在长江中游分布着一些高位的砾石层,尤其是在宜昌与武汉的阳逻附近。为了探讨这些砾石层的磁性特征及物质来源,对它们进行了磁性特征研究,结果表明:1不同砾石层剖面磁性物质的含量明显不同,其中云池砾石层磁性物质的含量最高,善溪窑、红花套、白洋渡砾石层次之,阳逻砾石层含量最低。2SIRM/χ和F300值显示,长江中游砾石层磁性矿物类型主要是磁铁矿等亚铁磁性矿物,其中阳逻砾石层不完全反铁磁性矿物含量比例比其他砾石层高。3χARM/χ、χARM/SIRM、χfd值表明,白洋渡、红花套及善溪窑砾石层的磁性矿物中以较粗的磁性颗粒为主,而云池和李家院的磁性矿物颗粒都较细,武汉阳逻砾石层的磁性颗粒以单畴、超顺磁颗粒为主。4宜昌附近的善溪窑、云池、白洋渡、红花套砾石层的磁性特征与长江现代沉积物的特征接近,指示其物质主要来自于长江沉积物;而阳逻砾石层的磁性特征却与江汉平原周边河流的现代沉积物磁性特征有些类似,结合野外砾石层岩性特征,认为阳逻砾石层是长江、汉江与江汉平原周边河流共同作用的产物。  相似文献   

Optimized object-based image classification: development of landslide knowledge decision support system     

Shiuan Wan  Tsu Chiang Lei  Tein Yin Chou 《Arabian Journal of Geosciences》2014,7(5):2059-2070

Landslide spatial decision support systems (LS-DSS) are computer-based systems that combine the geographic storage, search, and retrieval capabilities of geographic information systems with the decision models and optimizing algorithms used to support decision-making for landslide problems. This study proposes an optimization process of region object-oriented classification (ROC) to analyze the landslide image information. The surface information from the Wan Da reservoir area is collected and studied. We collected different spectrum with several texture information to analyze the surrounding area of the Wan Da reservoir. ROC is used to classify the landslide area. Entropy-based classification is used as a classifier in ROC to determine the landslide/nonlandslide area. The parameters of S (similarity) and A (area) are used and then the best combinations are found. An optimize algorithm is developed to access the above variables to perform the best classification outcomes. The relations of occurrence vs. non-occurrence of landslide which are linked to the attributes of land surface are studied. An improved translation model (Expert Knowledge Translation Platform) is also presented to increase the accuracy. This could be of help to manage/monitor the landslide area near the reservoir.  相似文献   

Application of wavelet‐based multi‐model Kalman filters to real‐time flood forecasting     

Chien‐Ming Chou  Ru‐Yih Wang 《水文研究》2004,18(5):987-1008

This paper presents the application of a multimodel method using a wavelet‐based Kalman filter (WKF) bank to simultaneously estimate decomposed state variables and unknown parameters for real‐time flood forecasting. Applying the Haar wavelet transform alters the state vector and input vector of the state space. In this way, an overall detail plus approximation describes each new state vector and input vector, which allows the WKF to simultaneously estimate and decompose state variables. The wavelet‐based multimodel Kalman filter (WMKF) is a multimodel Kalman filter (MKF), in which the Kalman filter has been substituted for a WKF. The WMKF then obtains M estimated state vectors. Next, the M state‐estimates, each of which is weighted by its possibility that is also determined on‐line, are combined to form an optimal estimate. Validations conducted for the Wu‐Tu watershed, a small watershed in Taiwan, have demonstrated that the method is effective because of the decomposition of wavelet transform, the adaptation of the time‐varying Kalman filter and the characteristics of the multimodel method. Validation results also reveal that the resulting method enhances the accuracy of the runoff prediction of the rainfall–runoff process in the Wu‐Tu watershed. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

Simplified formulae system for resonant inverse Compton scattering of a fast electron in an intense magnetic field     

J. H. You  W. P. Chen  S. N. Zhang  L. Chen  D. B. Liu  C. K. Chou 《Monthly notices of the Royal Astronomical Society》2003,340(2):687-693

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