基于InSAR技术的秦岭南部略阳县潜在滑坡灾害识别研究

秦岭山区因构造活动、人类活动、气候变化等多重因素作用而面临较高的地质灾害风险,由于地形高差大、坡度陡,植被覆盖率高,滑坡灾害识别调查难度高,急需发展先进的地质灾害监测识别技术体系,提升高植被覆盖山区地质灾害隐患详细调查识别能力.不同的InSAR技术和SAR数据有各自的优势,单一InSAR技术难以在高植被覆盖山区进行区域...     

基于D—InSAR的煤矿区开采沉陷遥感监测技术分析

该文在综合分析国内外开采沉陷监测技术现状、合成孔径雷达干涉测量(InSAR)和差分干涉测量(D—InSAR)技术发展及其在地表沉陷监测中应用成果的基础上，分析了D—InSAR技术在煤矿开采沉陷变形监测中的特点与技术优势。指出：应用D—InSAR进行煤矿区开采沉陷监测的具体目标是矿区地表沉降演变过程分析、采区地表沉陷动态监测与分析和矿区DEM数据更新；亟须研究解决的关键技术问题有：源数据获取与选择、数据处理方法、地面配合措施、精度与可靠性评价、多源信息集成分析等。D—InSAR为煤矿区地表时空演变过程研究和开采沉陷实时动态监测提供了新的技术方法；作为“数字矿山”的重要内容，D—InSAR可以有效地指导矿区生产、整体规划与长远发展，并为矿区可持续发展服务。     

震后大渡河流域丹巴—乐山段地质灾害隐患

泸定地震导致大渡河沿线及周边区域分布有大量次生地质灾害和地质灾害隐患点，极大制约了流域内社会经济发展，对该区域进行大范围隐患普查和早期识别，有助于防灾减灾工作的展开。本文基于时序InSAR技术对大渡河流域丹巴—乐山段超过1000 km范围进行了大面积滑坡隐患点普查，并结合PS与SBAS技术有效降低西南地区复杂的时间去相干问题。研究结果表明：(1)8处重点关注区域存在明显的滑坡和崩塌隐患点，主要集中在石棉和泸定地区，其中部分隐患点对流域有较大安全威胁。(2)泸定地震导致黄草坪、郑家坪与新华村典型隐患区产生加速沉降趋势，地面人员应重点观测。本研究可为后续分析泸定地震后灾害分布情况及流域内大坝及边坡变形机理分析和灾害预警提供可靠信息及数据支撑。     

多时相InSAR技术及其在滑坡监测中的关键问题分析

多时相InSAR(Multi-Temporal InSAR,MT-InSAR)技术可以提取毫米级、大范围的地表形变结果,因此在滑坡监测领域引起国内外的研究热潮。但是,由于滑坡所处地理环境的特殊性,如地形崎岖起伏,植被覆盖率高,大气环境复杂多变等,使得InSAR观测值中的固源误差相比城市地区更加难以消除。该文首先针对MT-InSAR在滑坡监测中的关键技术(即相干点目标选取、形变参数估计和大气误差改正),阐述了目前国际上的主流方法,并对比和分析了它们在滑坡监测中的优劣势和适用条件;进而总结了目前MT-InSAR在滑坡监测中面临的主要挑战,包括由山区地形导致的几何畸变、植被覆盖引发的失相关和无法监测真实三维形变等;最后指出MT-InSAR在滑坡监测领域的未来发展方向,包括面向滑坡监测的MT-InSAR技术、星载和地基MT-InSAR联合监测以及建立MT-InSAR形变监测与滑坡触发因子之间的时空响应模式。     

DEM地形分析在山区地质灾害研究中的应用——以云南省漾濞县为例

云南省漾濞县具有典型的山地特点,每年其境内发生的地质灾害都给人民生命和财产造成了极大的损失。在漾濞县的地质灾害调查中,通过"3S"技术的应用,建立了漾濞县的数字高程模型,进行了基于ArcGIS的地形分析,提取出了坡度和坡向等重要的地形因子。通过研究发现:坡度是漾濞县地质灾害频发的最主要控制因素,漾濞江及其支流上游的滑坡和崩塌为泥石流的发生提供了物源基础;同时阳坡是地质灾害发生的主要坡向,滑坡和崩塌等灾害发生频繁。最后,制作了漾濞县坡度、坡向分析图,指出了漾濞县较易发生地质灾害的地区,为其他山地地区地质灾害研究提供了一种借鉴模式。     

合成孔径雷达干涉测量（InSAR）技术在地表沉降监测中的应用

近年来,合成孔径雷达干涉测量（InSAR）技术应用于地表沉降监测研究领域的方法与实例在国内外工程实践和科研活动中经常出现。近几十年来由于地下水的长期超量开采,华北平原已成为世界上超采地下水最严重、地下水降落漏斗面积最大、地面沉降面积最大、沉降类型最复杂的地区,地表沉降监测周期长、成本高、数据量大,通过In SAR技术的应用可有效提高地表沉降观测的精确性,为预防和减少经济损失发挥积极重要作用。     

洪江市地质灾害经济损失评估

洪江市位于湖南省的西部,地形以山地为主,属于地质灾害多发区。由于自然和人类工程一经济活动的影响,以滑坡、崩塌为主的地质灾害时有发生。这些地质灾害严重危害了人民的生命财产,造成了重大的损失。通过调查与评估,到2008年底为止,全市发生各类大小的地质灾害共77处,其中滑坡66处、崩塌8处、地面塌陷1处、地面沉陷1处、泥石流1处,导致死亡5人,毁房234间,毁田26.4hm^2（396亩）,直接经济损失达到642.5万元,间接经济损失更是达到了8744.0万元。     

基于多旋翼无人机倾斜摄影测量的沙丘三维形态研究

无人机倾斜摄影技术是近年来发展起来的新型测量方法,具有高效率、高精度、非接触、大范围等优点。本研究采用多旋翼无人机,结合精确测定的地面控制点,实现了对新月形沙丘群三维形态的精确测量。结果表明：无人机倾斜摄影测量的均方根误差小于18 mm,可以满足大比例尺地形测量的要求。利用该技术获取的多种测量参数表明,新月形沙丘二维与三维形态之间存在良好的相关性,基于这些关系,可以实现二维遥感影像量测结果向沙丘高度、沙丘体积等三维参数的转换。沙丘剖面形态可以采用非线性函数精确描述,为沙丘形态精确建模提供了参考。无人机倾斜摄影技术获取的沙丘三维形态参数,对于深入认识沙丘形态动力过程具有重要参考价值。     

基于D-InSAR的煤矿区开采沉陷遥感监测技术分析

该文在综合分析国内外开采沉陷监测技术现状、合成孔径雷达干涉测量(InSAR)和差分干涉测量(D-In SAR)技术发展及其在地表沉陷监测中应用成果的基础上,分析了D-InSAR技术在煤矿开采沉陷变形监测中的特点与技术优势。指出:应用D-InSAR进行煤矿区开采沉陷监测的具体目标是矿区地表沉降演变过程分析、采区地表沉陷动态监测与分析和矿区DEM数据更新;亟须研究解决的关键技术问题有:源数据获取与选择、数据处理方法、地面配合措施、精度与可靠性评价、多源信息集成分析等。D-InSAR为煤矿区地表时空演变过程研究和开采沉陷实时动态监测提供了新的技术方法;作为"数字矿山"的重要内容,D-InSAR可以有效地指导矿区生产、整体规划与长远发展,并为矿区可持续发展服务。     

顾及时空特性的InSAR对流层延迟建模与改正

正星载合成孔径雷达干涉测量(InSAR)作为一项新型的空间大地测量与现代遥感技术,不仅已经广泛应用于监测地球陆地表面的各类地表形变,而且已成功应用于监测高空间分辨率的大气水汽,为小尺度气象现象的研究与预测提供了新的方法和途径。InSAR观测值中的对流层延迟,一方面是当前InSAR技术进行地表形变监测的主要误差源之一,另一方面也是InSAR水汽估计中需要用到的关键信号源。因此,合理、可靠地对InSAR大气对流层延迟进行建模和估计,不仅是提高     

Fault slip in the 1997 Manyi, Tibet earthquake from linear elastic modelling of InSAR displacements

The M _w 7.6 1997 Manyi earthquake occurred in an area of central northern Tibet where sparse vegetation coverage and a lack of human habitation provide excellent conditions for Interferometric Synthetic Aperture Radar (InSAR) studies. We use coseismic pairs of radar images acquired by the ESA ERS-2 satellite to construct interferograms of the surface displacement field due to the earthquake. The location and extent of the coseismic fault rupture are mapped using a combination of optical satellite imagery, high-resolution digital topography, interferometric correlation and azimuth offset measurements; in so doing, we are able to relate prominent geomorphic features in the fault zone to bends in the fault.
Using elastic dislocation models consistent with this mapped fault trace, we then test a range of fault geometries and slip conditions to find the combination which best explains the InSAR displacements. Our favoured model contains a reversal in fault dip, approximately halfway along its length, occurring at the location of a restraining bend. Slip on this model fault is heterogeneous, with two areas of peak slip of 7 m or greater, and components of dip-slip displacement which vary significantly along-strike. The success of this model in fitting the data implies that an observed asymmetry in the coseismic interferograms can be explained in terms of the local fault geometry, rather than by using non-linear elastic rheologies as suggested by earlier authors.     

Web data mining for automatic inventory of geohazards at national scale

In this study, we present a fully automated procedure to analyze online news using data mining techniques. It is then used to compile and continually update a geohazard database. The procedure is based on new technologies that publish news on the internet, i.e., the news is analyzed, georeferenced and attributed to a category of geohazards (the current categories are landslides, floods and earthquakes). A continuous flow of georeferenced events is established to populate and update the geodatabase automatically and in near-real time. We tested the procedure for 2 years at a national scale, creating a geodatabase containing more than 20,000 news items concerning geohazards that occurred in Italy. This procedure enables continuous feedback from events in the real world, such that information about geohazards can be fully exploited rapidly (compared to traditional techniques based on remote sensing, field surveys and historical inventories).     

On the application of SAR interferometry to geomorphological studies: estimation of landform attributes and mass movements

This paper presents two examples of application of Synthetic Aperture Radar (SAR) interferometry (InSAR) to typical geomorphological problems. The principles of InSAR are introduced, taking care to clarify the limits and the potential of this technique for geomorphological studies. The application of InSAR to the quantification of landform attributes such as the slope and to the estimation of landform variations is investigated. Two case studies are presented. A first case study focuses on the problem of measuring landform attributes by interferometric SAR data. The interferometric result is compared with the corresponding one obtained by a Digital Elevation Model (DEM). In the second case study, the use of InSAR for the estimation of landform variations caused by a landslide is detailed.     

基于WebGIS的汶川地震次生地质灾害信息管理系统

汶川地震次生地质灾害数量多、分布广且类型复杂,严重威胁灾区人民的生命财产安全。为了分析次生地质灾害发育分布规律,并用于减灾防灾,急需一种有效的方法来对现场调查获取的大量地质灾害数据进行管理。以信息建模理论为指导,运用统一建模语言UML,并结合GIS空间数据模型分析,以建立面向对象的空间数据模型,及实现海量地灾信息综合管理为目的,研发了汶川地震次生地质灾害信息综合管理系统(WIMS)。利用GIS的强大空间图形管理能力、数据库技术以及网络开发等技术,以发布图形服务与数据服务的方式实现地质灾害数据共享,解决了空间数据编辑及提升地图访问速度的关键技术问题。该系统不仅能够为灾害管理部门制定防治方案提供一定的参考依据,并且能够为广大群众提供一个认识地质灾害的公共平台,提高全民防灾意识。     

ŒDIPUS: a new tool to study the dynamics of planetary interiors

We present a new numerical method to describe the internal dynamics of planetary mantles through the coupling of a dynamic model with the prediction of geoid and surface topography. Our tool is based on the simulation of thermal convection with variable viscosity in a spherical shell with a finite-volume formulation. The grid mesh is based on the 'cubed sphere' technique that divides the shell into six identical blocks. An investigation of various numerical advection schemes is proposed: we opted for a high-resolution, flux-limiter method. Benchmarks of thermal convection are then presented on steady-state tetrahedral and cubic solutions and time-dependent cases with a good agreement with the few recent programs developed to solve this problem.
A dimensionless framework is proposed for the calculation of geoid and topography introducing two dimensionless numbers: such a formulation provides a good basis for the systematic study of the geoid and surface dynamic topography associated to the convection calculations. The evaluation of geoid and surface dynamic topography from the gridded data is performed in the spectral domain. The flow solver is then tested extensively against a precise spectral program, producing response functions for geoid as well as bottom and surface topographies. For a grid mesh of a reasonable size (6 × 64 × 64 × 64) a very good agreement (to within ∼1 per cent) is found up to spherical harmonic degree 15.     

Microtopographic analysis of plant distribution in polar desert

We suggest methods for the analysis of the spatial distribution of plant species in a research area divided into a quadrat lattice. In particular, information about the topography and the spaces without plants is used for the analysis. At sites with a homogeneous substratum, we classify the topography by whether a target grid is concave or convex with respect to a standard surface of altitude. At other sites, we classify the topography according to whether the grid is located at the edge of rock and/or at a water pool. Information about the topography and the plant existence is used for constructing 2 × 2 contingency tables. In order to determine the strength of dependence between the topography and plant existence, the Akaike information criterion (AIC) is used. The methods are applied to data of the microtopography and distribution of mosses in continental Antarctica.     

基于光学立体和InSAR的Grove山地区DEM建立和分析

本文分别利用光学立体和In SAR技术生成了东南极Grove山地区15 m分辨率的ASTER DEM和20 m分辨率的In SAR DEM。在利用ASTER立体像对生成DEM的过程中引入ICESat测高数据作为高程控制以减少错误匹配,提高DEM垂直精度;而在利用ERS tandem数据生成DEM后,选取ICESat测高数据对In SAR DEM进行倾斜面纠正,以消除基线不精确估计等带来的影响。通过与未作控制的ICESat测高数据进行比较,评价了两种DEM的精度并对误差进行了分析。同时,比较了两种DEM的差异,并分析了造成这些差异的原因,探讨了两种技术生成南极冰盖DEM的优势和不足。最后结合两DEM的优势,融合生成了Grove山地区高精度的DEM。     

基于改进的频谱位移雷达干涉去平算法研究

雷达干涉处理过程中,平地相位去除在整个干涉处理过程中是不可忽视的一步.平地相位一方面使干涉条纹密集化,另一方面加大了后续相位解缠以及相位到DEM转化的难度,基于频谱位移的去平算法是目前比较常用的方法,常规的频谱位移算法忽视了图像本身特点,通过圆周位移之后,仍然有大量的残余相位,导致去平结果不够准确.文中采用改进的常规频移去平算法,根据干涉纹图距离向与方位向平地相位分布情况,采用分块插值频移算法;并用短基线的SRTM数据以及长基线的JERS-1数据进行了实验.通过与常规频移方法比较,结果表明,该改进算法能有效去除干涉纹图中的平地相位.     

Reconstructing pre-erosion topography using spatial interpolation techniques:A validation-based approach

Understanding the topographic context preceding the development of erosive landforms is of major relevance in geomorphic research, as topography is an important factor on both water and mass movement-related erosion, and knowledge of the original surface is a condition for quantifying the volume of eroded material. Although any reconstruction implies assuming that the resulting surface reflects the original topography, past works have been dominated by linear interpolation methods, incapable of generating curved surfaces in areas with no data or values outside the range of variation of inputs. In spite of these limitations, impossibility of validation has led to the assumption of surface representativity never being challenged. In this paper, a validation-based method is applied in order to define the optimal interpolation technique for reconstructing pre-erosion topography in a given study area. In spite of the absence of the original surface, different techniques can be nonetheless evaluated by quantifying their capacity to reproduce known topography in unincised locations within the same geomorphic contexts of existing erosive landforms. A linear method (Triangulated Irregular Network, TIN) and 23 parameterizations of three distinct Spline interpolation techniques were compared using 50 test areas in a context of research on large gully dynamics in the South of Portugal. Results show that almost all Spline methods produced smaller errors than the TIN, and that the latter produced a mean absolute error 61.4% higher than the best Spline method, clearly establishing both the better adjustment of Splines to the geomorphic context considered and the limitations of linear approaches. The proposed method can easily be applied to different interpolation techniques and topographic contexts, enabling better calculations of eroded volumes and denudation rates as well as the investigation of controls by antecedent topographic form over erosive processes.