Spatial modelling for biological richness analysis in Nokrek biosphere reserve — north-eastern India     

G. Talukdar  N. Lele  M. C. Porwal 《Journal of the Indian Society of Remote Sensing》2005,33(3):435-440

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Change detection in Sal forest in Dehradun Forest Division using remote sensing and geographical information system     

Permeshwar S. Chauhan  Mahesh C. Porwal  Lalit Sharma  Jay Devs.negi 《Journal of the Indian Society of Remote Sensing》2003,31(3):211-218

The review of study site have revealed the change in vegetation cover of Sal Dense to Sal Medium and Sal Open in 6 forest Mosaics owing to biotic and abiotic conditions prevailing in the specific areas. Analysis carried out using thematic map derived from aerial photograph of 1976 and satellite data of IRS 1C LISS III False Colour Composite (FCC) of March 1999 revealed the cause for change in forest density classes. Deforestation, encroachment and agriculture have been identified as the underlying causes, which have affected some specific locations to a marked extent. There has been a progressive and remarkable change among vegetation classes from 1976 to 1999. It is evident from forest type and density map that Sal density has significantly reduced from Sal Dense 65.61 % in 1976 to Sal Dense 11.12% in the year 1999 followed by Sal Open 11.18 % and Sal Medium 18.24 %. The overall change has been estimated to be 42.11% of the total forested area.  相似文献   

Petrogenesis of Mesoproterozoic lamproite dykes from the Garledinne (Banganapalle) cluster,south-western Cuddapah Basin,southern India     

N. V. Chalapathi Rao  Atiullah  Alok Kumar  Samarendra Sahoo  Purnendu Nanda  Ngazimpi Chahong  B. Lehmann  K. V. S. Rao 《Mineralogy and Petrology》2016,110(2-3):247-268

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Hydrogeochemical characterization and quality assessment of groundwater in parts of Southern Gangetic Plain     

Satya N. Sethy  Tajdarul H. Syed  Alok Kumar  Debanjan Sinha 《Environmental Earth Sciences》2016,75(3):232

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Classification and Potential Utilization of Eocene Coals of Meghalaya,North East India     

Alok K. Singh 《Journal of the Geological Society of India》2018,91(2):181-187

In the present study, petrographic and geochemical investigation of Meghalayan coal deposits have been carried out to classify these coals in terms of rank, type and grade, using Indian and International classification schemes. Based on petrographic and geochemical characteristics, an attempt has also been made to identify the potential utilization of Meghalayan coals for various industrial applications. According to the study, these coals have been classified as sub-bituminous C to high volatile bituminous in rank, vitric in type and clean to ashy in grade. Considering their hydrocarbon potential, these coals are suitable for liquefaction and gasification.  相似文献   

A Preliminary Evaluation on the Prospects of Hydrocarbon Potential in the Carbonaceous Shales of Spiti and Chikkim Formations,Tethys Himalaya,India     

Bindhyachal Pandey  Deo Brat Pathak  Neeraj Mathur  Anand K. Jaitly  Alok K. Singh  Prakash K. Singh 《Journal of the Geological Society of India》2018,92(4):427-434

In the present investigation, an attempt has been made to explore the possibility of hydrocarbon prospects in the carbonaceous shale deposits of Spiti and Chikkim formations exposed in the Spiti valley of the Tethys Himalaya. Twenty samples, collected from successive levels of these litho-units, have been subjected to maceral analysis, Rock-Eval Pyrolysis and six samples to Fourier Transform Infra-red Spectroscopy (FTIR) and nuclear magnetic resonance (NMR) analyses. The study reveals the presence of mainly kerogen-III type of organic matter but some of the shale samples have shown a good amount of total organic carbon (TOC) to the tune of 3.19% which is sufficient to produce hydrocarbon. The results indicate the presence of methane occurring as free and fixed hydrocarbon in the shale samples. Few levels are especially rich in hydrocarbon. They have shown encouraging results with potential for generating liquid as well as lighter hydrocarbon. The data is also supported by the FTIR and NMR studies.  相似文献   

Foreword     

Alok K. Gupta 《Journal of Earth System Science》1990,99(1):1-4

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Characterisation of ecological parameters in tropical forest community—A remote sensing approach     

P S Roy  Sarnam Singh  M C Porwal 《Journal of the Indian Society of Remote Sensing》1993,21(3):127-149

Satellite Remote Sensing data has been used for vegetation mapping, initial stratification, distribution of sample plots and for calculating the area under different vegetation types. Primary and secondary analyses of vegetation has been done using phytosociological ground data collected from sample piots to assess the ecological importance of different species. Interrelationships among different communities have been evaluated through various available indices. The spatial distribution and vegetation analysis indicate that commercial extraction of natural forests of Andaman has set in retrogression. The evergreen forests subjected to shorter rotation of commercial exploitation are being invaded with seral deciduous species. The study highlights the status of forests (spatial and community) and stresses the need to conserve germplasm present in the natural evergreen forests.  相似文献   

Knowledge-Driven and Data-Driven Fuzzy Models for Predictive Mineral Potential Mapping   总被引：5，自引：0，他引：5  

Porwal  Alok  Carranza  E. J. M.  Hale  M. 《Natural Resources Research》2003,12(1):1-25

In this paper, we describe new fuzzy models for predictive mineral potential mapping: (1) a knowledge-driven fuzzy model that uses a logistic membership function for deriving fuzzy membership values of input evidential maps and (2) a data-driven model, which uses a piecewise linear function based on quantified spatial associations between a set of evidential evidence features and a set of known mineral deposits for deriving fuzzy membership values of input evidential maps. We also describe a graphical defuzzification procedure for the interpretation of output fuzzy favorability maps. The models are demonstrated for mapping base metal deposit potential in an area in the south-central part of the Aravalli metallogenic province in the state of Rajasthan, western India. The data-driven and knowledge-driven models described in this paper predict potentially mineralized zones, which occupy less than 10% of the study area and contain at least 83% of the model and validation base metal deposits. A cross-validation of the favorability map derived from using one of the models with the favorability map derived from using the other model indicates a remarkable similarity in their results. Both models therefore are useful for predicting favorable zones to guide further exploration work.  相似文献   

Estimation of maximum magnitude (M max ): Impending large earthquakes in northeast region,India     

Alok K. Mohapatra  William K. Mohanty  Akhilesh K. Verma 《Journal of the Geological Society of India》2014,83(6):635-640

In the present study, the cumulative seismic energy released by earthquakes (M _w ≥ 5) for a period of 1897 to 2009 is analyzed for northeast (NE) India. For this purpose, a homogenized earthquake catalogue in moment magnitude (M _w ) has been prepared. Based on the geology, tectonics and seismicity, the study region is divided into three source zones namely, 1: Arakan-Yoma Zone (AYZ), 2: Himalayan Zone (HZ) and 3: Shillong Plateau Zone (SPZ). The maximum magnitude (M _max ) for each source zone is estimated using Tsuboi’s energy blocked model. As per the energy blocked model, the supply of energy for potential earthquakes in an area is remarkably uniform with respect to time and the difference between the supply energy and cumulative energy released for a span of time, is a good indicator of energy blocked and can be utilized for the estimation of maximum magnitude (M _max ) earthquakes. The proposed process provides a more consistent model of gradual accumulation of strain and non-uniform release through large earthquakes can be applied in the assessment of seismic hazard. Energy blocked for source zone 1, zone 2 and zone 3 regions is 1.35×10¹⁷ Joules, 4.25×10¹⁷ Joules and 7.25×10¹⁷ Joules respectively and will act as a supply for potential earthquakes in due course of time. The estimated M _max for each source zone AYZ, HZ, and SPZ are 8.2, 8.6, and 8.7 respectively. M _max obtained from this model is well comparable with the results of previous workers from NE region.  相似文献