On the application of SAR interferometry to geomorphological studies: estimation of landform attributes and mass movements   总被引：9，自引：0，他引：9  

Filippo Catani  Paolo Farina  Sandro Moretti  Giovanni Nico  Tazio Strozzi 《Geomorphology》2005,66(1-4):119

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.  相似文献   

Evidence for Proterozoic Collision from Airborne Magnetic and Gravity Studies in Southern Granulite Terrain, India and Signatures of Recent Tectonic Activity in the Palghat Gap     

D.C. Mishra  V. Vijaya Kumar 《Gondwana Research》2005,8(1):43-54

The composite airborne total intensity map of the Southern Granulite Terrain (SGT) at an average elevation of 7000' (≈ 2100 m) shows bands of bipolar regional magnetic anomalies parallel to the structural trends suggesting the distribution of mafic/ultramafic rocks that are controlled by regional structures/shear zones and thrusts in this region. The spectrum and the apparent susceptibility map computed from the observed airborne magnetic anomalies provide bands of high susceptibility zones in the upper crust associated with known shear zones/thrusts such as Transition Zone, Moyar-Bhavani and Palghat-Cauvery Shear Zones (MBSZ and PCSZ). The quantitative modelling of magnetic anomalies across Transition Zone, MBSZ and PCSZ suggest the presence of mafic rocks of susceptibility (1.5-4.0 × 10⁻³ CGS units) in upper crust from 8-10 km extending up to about 21-22 km, which may represent the level of Curie point geotherm as indicated by high upper mantle heat flow in this section.Two sets of paired gravity anomalies in SGT and their modelling with seismic constraints suggest gravity highs and lows to be caused by high density mafic rocks along Transition Zone and Cauvery Shear Zone (CSZ) in the upper crust at depth of 6-8 km and crustal thickening of 45-46 km south of them, respectively. High susceptibility and high density rocks (2.8 g/cm³) along these shear zones supported by high velocity, high conductivity and tectonic settings suggest lower crustal mafic/ultramafic granulite rocks thrusted along them. These signatures with lower crustal rocks of metamorphic ages of 2.6-2.5 Ga north of PCSZ and Neoproterozoic period (0.6-0.5 Ga) south of it suggest that the SGT represents mosaic of accreted crust due to compression and thrusting. These observations along with N-verging thrusts and dipping reflectors from Dharwar Craton to SGT suggest two stages of N-S directed compression: (i) between Dharwar Craton and northern block of SGT during 2.6-2.5 Ga with Transition Zone and Moyar Shear towards the west as thrust, and (ii) between northern and southern blocks of SGT with CSZ as collision zone and PCSZ as thrust during Neoproterozoic period (0.6-0.5 Ga). The latter event may even represent just a compressive phase without any collision related to Pan-African event. The proposed sutures in both these cases separate gravity highs and lows of paired gravity anomalies towards north and south, respectively. The magnetic anomalies and causative sources related to Moyar Shear, MBSZ and PCSZ join with those due to Transition Zone, Mettur and Gangavalli Shears in their eastern parts, respectively to form an arcuate-shaped diffused collision zone during 2.6-2.5 Ga.Most of the Proterozoic collision zones are highlands/plateaus but the CSZ also known as the Palghat Gap represents a low lying strip of 80-100 km width, which however, appears to be related to recent tectonic activities as indicated by high upper mantle heat flow and thin crust in this section. It is supported by low density, low velocity and high conductive layer under CSZ and seismic activity in this region as observed in case of passive rift valleys. They may be caused by asthenospheric upwarping along pre-existing faults/thrusts (MBSZ and PCSZ) due to plate tectonic forces after the collision of Indian and Eurasian plates since Miocene time.  相似文献   

A comparison of drainage networks derived from digital elevation models at two scales   总被引：2，自引：0，他引：2  

Xinhao Wang  Zhi-Yong Yin 《Journal of Hydrology》1998,210(1-4):221-241

Automated generation of drainage networks has become increasingly popular with powerful analytical functions in geographic information systems (GIS) and with the increased availability of digital elevation models (DEMs). This paper compares drainage networks derived from DEMs at two scales, 1:250 000 (250K) and 1:24 000 (24K), using various drainage parameters common in hydrology and geomorphology. The comparison of parameters derived from the 250K DEMs with those from the 24K DEMs in 20 basins ranging from 150 to 1000 km² in West Virginia shows that the goodness-of-fit between parameter estimates based on the DEMs varies. Results clearly show that superior estimations are produced from the 24K DEMs. Better estimates can be obtained from the 250K DEMs for stream length and frequency parameters than for gradient parameters. However, the estimation of the mean gradient parameters based on the 250K DEMs seems to improve with increasing terrain complexity. Finally, basin size does not strongly affect the accuracy of parameter estimates based on the 250K DEMs.  相似文献   

Landslide zoning in a part of the Garhwal Himalayas   总被引：21，自引：1，他引：20  

A. K. Pachauri  P. V. Gupta  R. Chander 《Environmental Geology》1998,36(3-4):325-334

 The Himalayas are undergoing constant rupturing in the thrust belt zone in the Garhwal Himalayas, due to which earthquake and mass movement activity is triggered. These processes of mass movement and landslides have been constantly modifying the landscape. Landslides are one of the indicators of the geomorphological modifications taking place in this active and fragile terrain. This work is aimed at providing another example of landslide susceptibility mapping based on geological and geomorphological attributes. The data collected from aerial photographs, topographic sheets and the image suggests that there is a correlation between the distribution of landslides and some of the geological and geomorphological factors, for example, the distance from an active fault, relative relief and slope. Parameters like factor of safety, altitude, relief, slope and the distance from the fault lineament have been included in the study. A rating system has been applied to the factors for arriving at a quantitative estimate of landslide susceptibility for each physiographic unit. Since terrain classification forms the foundation of this work, the entire study can be grouped into two sequential activities: (1) the terrain classification and (2) landslide susceptibility mapping. The result is the landslide susceptibility zoning map presented. The landslides have not been classified with respect to time and may represent the final result of the on-going geological, geomorphological and seismic activity since the Holocene period or late Pleistocene time when the glaciers retreated. The area chosen for the study lies between Badri gad and Barni gad in Yamuna valley region of the Garhwal Himalaya where a very large scale investment is in the pipe line for Hydroelectric power generation. Received: 12 August 1993 · Accepted: 13 January 1998  相似文献   

数字摄影测量系统生成的DEM数据精度的确定     

秦丽萍 《测绘学院学报》1997,(4)

论述一个由数字化画幅式像片（或数字影像）用数字摄影测量系统生成的DEM数据精度的确定方法。该方法的特点是只使用数字摄影测量系统的观测,避免了其它测量系统（如解析测图仪）的影响。通过在数字视频测图仪（DVP）上所作的大量实验证明本文中设计的方法是普遍实用的。实验结果表明,影响DEM数据的精度的主要因素是像元大小。  相似文献   

利用共线方程对空间实验室影象进行数字几何纠正     

舒宁 《武汉大学学报(信息科学版)》1988,(3)

本文论述了利用共线方程对空间实验室影象实施数字几何纠正的理论依据、数据准备、外方位元素解求过程中参量的确定及锚点纠正法的可行性和纠正精度,提出了纠正过程中几个必须注意的环节,以提高精度,缩短机时。同时还介绍了自编软件包的组成。  相似文献   

Rock magnetism and palaeomagnetism of the Oddanchatram anorthosite, Tamil Nadu, South India   总被引：1，自引：0，他引：1  

K. V. V. Satyanarayana  Baldev R. Arora  A. S. Janardhan 《Geophysical Journal International》2003,155(3):1081-1092

  相似文献   

GZCORS在广州市某测区地形测量中的应用     

蔡金繁  司顺奇 《现代测绘》2008,31(2):22-23

本文介绍了广州市连续运行参与站系统(GZCORS)和广州市似大地水准面精化成果确立的广州市城市三维定位系统在地形图测量中的应用,并通过实例分析其精度。  相似文献   

Automated classifications of topography from DEMs by an unsupervised nested-means algorithm and a three-part geometric signature   总被引：7，自引：3，他引：7  

Junko Iwahashi  Richard J. Pike 《Geomorphology》2007,86(3-4):409-440

An iterative procedure that implements the classification of continuous topography as a problem in digital image-processing automatically divides an area into categories of surface form; three taxonomic criteria–slope gradient, local convexity, and surface texture–are calculated from a square-grid digital elevation model (DEM). The sequence of programmed operations combines twofold-partitioned maps of the three variables converted to greyscale images, using the mean of each variable as the dividing threshold. To subdivide increasingly subtle topography, grid cells sloping at less than mean gradient of the input DEM are classified by designating mean values of successively lower-sloping subsets of the study area (nested means) as taxonomic thresholds, thereby increasing the number of output categories from the minimum 8 to 12 or 16. Program output is exemplified by 16 topographic types for the world at 1-km spatial resolution (SRTM30 data), the Japanese Islands at 270 m, and part of Hokkaido at 55 m. Because the procedure is unsupervised and reflects frequency distributions of the input variables rather than pre-set criteria, the resulting classes are undefined and must be calibrated empirically by subsequent analysis. Maps of the example classifications reflect physiographic regions, geological structure, and landform as well as slope materials and processes; fine-textured terrain categories tend to correlate with erosional topography or older surfaces, coarse-textured classes with areas of little dissection. In Japan the resulting classes approximate landform types mapped from airphoto analysis, while in the Americas they create map patterns resembling Hammond's terrain types or surface-form classes; SRTM30 output for the United States compares favorably with Fenneman's physical divisions. Experiments are suggested for further developing the method; the Arc/Info AML and the map of terrain classes for the world are available as online downloads.  相似文献   

Improving a digital elevation model by reducing source data errors and optimising interpolation algorithm parameters: An example in the Loess Plateau,China   总被引：1，自引：0，他引：1  

《International Journal of Applied Earth Observation and Geoinformation》2007,9(3):235-246

A hydrologically correct digital elevation model (DEM) forms a basis for realistic environmental modelling, especially in complex terrain. We have performed a study in the Coarse Sandy Hilly Catchments (CSHC) of the Loess Plateau, China, which demonstrates pragmatic, yet effective methods for improving the quality of the DEM by: (1) identifying and correcting source topographic data errors and (2) optimising ANUDEM algorithm parameters. Improvement in the DEM based on fixing over 1100 errors in the input topographic data, and optimising key ANUDEM parameters was assessed using higher accuracy independent validation of 32 contributing areas and 1474 spot heights, and by semi-quantitative analysis of DEM derivatives produced from ANUDEM and Triangular Irregular Network (TIN) algorithms. Improvement in the ANUDEM DEM over the original TIN DEM was shown where the percentage of the total absolute difference in contributing areas reduced from 10.43 to 3.51%, and the bias between the spot heights and DEM elevations reduced from 45 to 32 m. Large improvement in DEM quality was gained by using ANUDEM instead of TIN, with smaller improvement gained by fixing source data errors, and optimising ANUDEM parameters.  相似文献