Liquefaction Identification Using IRS-1D Temporal Indices Data     

S. S. Sengar  A. Kumar  S. K. Ghosh  H. R. Wason 《Journal of the Indian Society of Remote Sensing》2013,41(2):355-363

One of the major after effect of Bhuj Earthquake which occurred on January 26, 2001 was wide spread appearance of liquefaction of soil in the Rann of Kachchh and the coastal areas of Kandla port covering an area of more than tens of thousands of kilometers. Remote sensing data products allow us to explore the land surface parameters at different spatial scales. In this work, an attempt has been made to identify the liquefied soil area using conventional indices from IRS-1D temporal images. The same has been investigated and compared with Class Based Sensor Independent (CBSI) spectral indices, while applying fuzzy based noise classification as soft computing approach using supervised classification. Seven spectral indices have been investigated to identify liquefied soil areas using temporal multi-spectral images. The result shows that the temporal variations can be accounted by using appropriate remote sensing based spectral indices. It is found that CBSI based TNDVI using temporal data yields the best results for identification of liquefied soil areas, while CBSI based SR gives best results for water body identification.  相似文献   

Geospatial Technologies for National Geomorphology and Lineament Mapping Project – A Case Study of Goa State     

Tapas R. Martha  Deepshikha Ghosh  K. Vinod Kumar  A. Lesslie  M. V. Ravi Kumar 《Journal of the Indian Society of Remote Sensing》2013,41(4):905-920

A three level classification system, based on the genesis of landforms, was used to map the geomorphology of the Goa state. The first level corresponds to the process that was responsible for landform generation, the second level or the intermediate level was assigned based on the morphography, and the third level corresponds to the individual landforms units identified based on the morphostructure. The mapping was carried out using IRS-P6 LISS-III (23.5 m) satellite image as the primary data source. Ancillary data such as geological map, topographic map, digital elevation model (DEM), field data collected by global positioning system (GPS) and web portals for image visualisation, were also used for the mapping purpose. A new software designed for mapping landforms based on the genesis, was used in this study to create a seamless geomorphology and lineament database of the Goa state in a GIS environment. A total of 58 landforms within six types of genetic classes were mapped in this area. Similarly, structural and geomorphic lineaments were also delineated using the satellite data. The database created has multi-purpose usability such as environmental studies, mining activity assessment, coastal zone management and wasteland development, since the classification system used is focused on processes, not theme specific.  相似文献   

Factors affecting the vulnerability of female slum youth to HIV/AIDS in Delhi and Hyderabad, India     

Vandana Wadhwa  Jayati Ghosh  Ezekiel Kalipeni 《GeoJournal》2012,77(4):475-488

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Deformation Modulus of Fly Ash Modified with Lime and Gypsum     

Ambarish Ghosh  Chillara Subbarao 《Geotechnical and Geological Engineering》2012,30(2):299-311

Deformation modulus of fly ash is one of the most important mechanical properties generally used in different design problems and also as an input parameter to sophisticated numerical techniques employed to assess the response of different structures resting on fly ash fill or embankment made of fly ash. Deformation modulus is usually expressed in terms of compressive strength. This paper presents the deformation modulus of fly ash modified with lime alone or in combination with gypsum at different strain levels. The values of deformation modulus obtained from both unconfined compression test and unconsolidated undrained triaxial test results are presented herein. The specimens for unconfined compression test and for undrained triaxial tests were cured up to 90 and 28 days, respectively. The effects of addition of lime (4–10%) and gypsum (0.5 and 1.0%) on the deformation modulus of class F fly ash are highlighted. With addition of lime and gypsum, the class F fly ash achieved the deformation modulus in the range of 190 MPa in UCS test and up to 300 MPa in triaxial test specimens tested under all round pressure of 0.4 MPa. Based on the present test results empirical relationships are developed to estimate deformation modulus of modified fly ash from unconfined compressive strength and relationships between initial tangent modulus and secant modulus at different strain levels are also developed.  相似文献   

Seismic interference of two nearby horizontal strip anchors in layered soil   总被引：1，自引：0，他引：1  

Priyanka Ghosh  Rajusha Kumari 《Natural Hazards》2012,63(2):789-804

In the present analysis, an attempt is made to explore the seismic response of two nearby horizontal strip anchors embedded in non-homogenous c-? soil deposit at different depths. The analysis is performed by using two-dimensional finite-element software PLAXIS 2D. Each anchor carries equal static safe-working load without violating the ultimate uplift capacity under static condition. The soil is assumed to obey the Mohr?CCoulomb failure criterion. The behavior of single isolated anchor subjected to an earthquake loading is determined first to study the interference effect between two anchors. The horizontal acceleration response obtained from the Loma Prieta Gilroy Earthquake (1989) is considered as the input excitation in the analysis. A parametric study is performed by varying the clear spacing (S) between the anchors at different embedment ratios (??). The magnitude of vertical displacement, shear stress, and shear strain developed at different locations of the failure domain is determined for different clear spacings between the anchors.  相似文献   

A generalized geo-hazard warning system     

J. K. Ghosh  D. Bhattacharya  N. K. Samadhiya  P. Boccardo 《Natural Hazards》2012,64(2):1273-1289

An automated geo-hazard warning system is the need of the hour. It is integration of automation in hazard evaluation and warning communication. The primary objective of this paper is to explain a geo-hazard warning system based on Internet-resident concept and available cellular mobile infrastructure that makes use of geo-spatial data. The functionality of the system is modular in architecture having input, understanding, expert, output and warning modules. Thus, the system provides flexibility in integration between different types of hazard evaluation and communication systems leading to a generalized hazard warning system. The developed system has been validated for landslide hazard in Indian conditions. It has been realized through utilization of landslide causative factors, rainfall forecast from NASA??s TRMM (Tropical Rainfall Measuring Mission) and knowledge base of landslide hazard intensity map and invokes the warning as warranted. The system evaluated hazard commensurate with expert evaluation within 5?C6?% variability, and the warning message permeability has been found to be virtually instantaneous, with a maximum time lag recorded as 50?s, minimum of 10?s. So it could be concluded that a novel and stand-alone system for dynamic hazard warning has been developed and implemented. Such a handy system could be very useful in a densely populated country where people are unaware of the impending hazard.  相似文献   

Petrography and major element geochemistry of the Permo-Triassic sandstones, central India: Implications for provenance in an intracratonic pull-apart basin     

Sampa GhoshSoumen Sarkar  Parthasarathi Ghosh 《Journal of Asian Earth Sciences》2012,43(1):207-240

Detrital mode, composition of feldspars and heavy minerals, and major element chemistry of sandstones from the Permo-Triassic succession in the intracratonic Satpura Gondwana basin, central India have been used to investigate provenance. The Talchir Formation, the lowermost unit of the succession, comprises glacio-marine and glacio-fluvial deposits. The rest of the succession (base to top) comprising the Barakar, Motur, Bijori, Pachmarhi and Denwa formations, largely represent variety of fluvial depositional systems with minor fluvio-deltaic and fluvio-lacustrine sedimentation under a variety of climatic conditions including cold, warm, arid, sub-humid and semi-arid. QFL compositions of the sandstones indicate a predominantly continental block provenance and stable cratonic to fault-bounded basement uplift tectonic setting. Compositional maturity of sandstones gradually increases upwards from the Early Permian Talchir to the Middle Triassic Denwa but is punctuated by a sharp peak of increased maturity in the Barakar sandstones. This temporal change in maturity was primarily controlled by temporal variation in fault-induced basement uplift in the craton and was also influenced by climatic factors. Plots of different quartz types suggest plutonic source rocks for the Talchir sandstones and medium-to high-rank metamorphic plus plutonic source rocks for the younger sandstones. Composition of alkali feldspars in the Permo-Triassic sandstones and in different Precambrian rocks suggests sediment derivation from felsic igneous and metasedimentary rocks. Compositions of plagioclase in the Talchir and Bijori sandstones are comparable with those of granite, acid volcanic and metasedimentary rocks of the Precambrian basement suggesting the latter as possible source. Rare presence of high-K plagioclase in the Talchir sandstones, however, indicates minor contribution from volcanic source rock. Exclusively plagioclase-bearing metasedimentary rock, tonalite gneiss and mafic rocks are the probable sources of plagioclase in the Upper Denwa sandstones. Quartz-rich nature of the sandstones, predominance of K-feldspar over plagioclase and albite rich character of plagioclase in the sandstones is consistent with deposition in an intracratonic, pull-apart basin like the Satpura Gondwana basin. Composition of garnet and its comparison with that from the Precambrian basement rocks suggests mica-schist and amphibolite as possible sources. Predominance of dravite variety of tourmaline in the Permian sandstones suggests sediment supply from metasedimentary rocks. Presence of both dravite and schorl variety of tourmaline in subequal amount in the Triassic sandstones indicates sediment derivation from granitic and metasedimentary rocks. However, schorl-bearing rocks are absent in the basement complex of the study area. A-CN-K plot suggests granites, acid volcanic rock and meta-sediments of the basement as possible sources of the Talchir sandstones and metasedimentary rocks for the Barakar to Pachmarhi sandstones. The Denwa sandstones were possibly derived from K-feldspar-free, plagioclase-bearing metasediments, mafic rocks and tonalite gneiss. Chemical Index of Alteration (CIA) values suggest low intensity source rock weathering for the Talchir sandstones and higher intensity source rock weathering for the others. Various bivariate plots of major oxides composition of the sandstones suggest passive to active continental margin setting and even arc tectonic setting for a few samples.  相似文献   

Spatio-Temporal Coherence Based Technique for Near-Real Time Sea-Ice Identification from Scatterometer Data     

Sandip R. Oza  R. K. K. Singh  N. K. Vyas  B. S. Gohil  Abhijit Sarkar 《Journal of the Indian Society of Remote Sensing》2011,39(2):147-152

The identification of sea-ice has frequently been cited as one of the most important tasks for deriving the sea-ice parameters and to avoid erroneous retrieval of wind vector over sea-ice infested oceans using space-borne scatterometer data. Discrimination between sea-ice and ocean is ambiguous under the high wind and/or thin/scattered ice conditions. The pre-launch technique developed for Oceansat-2, utilizes the dual-polarized QuikSCAT scatterometer data by using the spatio-temporal coherence properties of sea ice in addition to backscatter coefficient and the Active Polarization Ratio. Results were compared with the operational sea-ice products from National Snow and Ice Data Center. The threshold API value of −0.025 was found optimum for sea-ice and ocean discrimination. The overall sea-ice identification accuracy achieved was of the order of 95 per cent, ranging from 92.5% (during December in Southern Hemisphere) to 98% (during March in Northern Hemisphere). The applicability of the algorithm for both the Arctic as well as Antarctic makes it suitable for its operational use with the Oceansat-2 scatterometer data.  相似文献   

Petrogenesis of zincian spinel from mamandur base metal sulphide prospect,Tamil Nadu     

Biswajit Ghosh  Sandip Some  Animesh Thakur 《Journal of the Geological Society of India》2011,78(4):365-369

Zincian spinels (gahnites) from the Mamandur Zn-Pb-Cu prospect of the Southern Granulite Terrain have been studied. Gahnites in the quartzofeldspathic gneiss occur either as (a) porphyroblastic grains closely in association with cordierite and sphalerite or as (b) inclusions in poikiloblastic quartz grains, restricted within quartz veinlets. Compositionally these gahnites belong to two different clusters corresponding to two modes of occurrences. The origin of the porphyroblastic gahnites is linked with the process of desulphidation of sphalerite whereas those occurring as inclusions within poikiloblastic quartz are direct crystallisation products from silica rich hydrothermal solution. A new compositional field for this latter group of gahnites is proposed here.  相似文献   

Seismic Passive Earth Pressure on Walls with Bilinear Backface Using Pseudo-Dynamic Approach     

Sreevalsa Kolathayar  Priyanka Ghosh 《Geotechnical and Geological Engineering》2011,29(3):307-317

By using pseudo-dynamic approach, a method has been proposed in this paper to compute the seismic passive earth pressure behind a rigid cantilever retaining wall with bilinear backface. The wall has sudden change in inclination along its depth and a planar failure surface has been considered behind the retaining wall. The effects of a wide range of parameters like soil friction angle, wall inclination, wall friction angle, amplification of vibration, variation of shear modulus and horizontal and vertical seismic accelerations on the passive earth pressure have been explored in the present study. For the sake of illustration, the computations have been exclusively carried out for constant wall friction through out the depth. Unlike the Mononobe-Okabe method, which incorporates pseudo-static analysis, the present analysis predicts a nonlinear variation of passive earth pressure along the wall.  相似文献