Arindam Guha

Integrated approach of using ASTER-derived emissivity and pixel temperature for delineating different granitoids – a case study in parts of Dharwar Craton, India

Abstract We have delineated different granitoids based on variation in emissivity and relative surface temperature recorded in thermal bands of Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) sensor of EO-1 satellite. In this regard, we have used emissivity normalization algorithm to derive broadband emissivity from thermal bands of ASTER sensor to delineate different lithounits of the granitoid family. We have compared emissivity and radiance image composites in terms of delineation of different granitoids. We have also used false colour composite (FCC) image derived using two emissivity bands and temperature (derived using emissivity normalisation method) bands to delineate different granitoids. We could differentiate different granitoids in the three-dimensional (3D) data space of ASTER-derived emissivity bands (second and third bands) and temperature bands. Based on the analysis of 3D scatter plot, we also proposed a ternary diagram of emissivity and temperature, which can be used to delineate different granitoids.

Satellite based mapping and morphogenetic analysis of the landforms in the tertiary fold belts of parts of Tripura, India

In the present study, satellite-based mapping and morphogenetic analysis of eastern part of Tripura has been attempted. Landforms are delineated based on conjugate analysis of satellite-imaged and satellite-derived digital elevation data. Further, landforms were classified based on hierarchical three-tier classification system where genesis is used as a criteria to classify the landforms in the first level followed by nature of their dissection and the geometric forms of the landform in second and third level, respectively. During the analysis, it has been observed that most of the landforms are structural in origin and their orientations are guided by the geological lineaments although the variations in the dissection pattern of the landforms are related to the changes in the underlying lithology. The implementation of quantitative analysis using hypsometric integral and ruggedness index of geomorphic parameters indicates that the landforms are immature but have been evolving towards maturity.

Comparative analysis on utilisation of linear spectral unmixing and band ratio methods for processing ASTER data to delineate bauxite over a part of Chotonagpur plateau, Jharkhand, India

We have attempted comparative analysis of the utility of linear spectral unmixing (LSU) method and band ratios for delineating bauxite from laterite within the lateritic bauxite provinces of Chotonagpur Plateau, Jharkhand of India. This was attempted based on processing of visible–near infrared (VNIR) and shortwave infrared (SWIR) spectral bands of Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) sensor. In LSU method, spectral features of main constituent minerals of lateritic bauxite are used to decompose the pixel spectra to estimate the relative abundance of bauxite and laterite in each pixel to spatially delineate bauxite within laterite. We have also compared the bauxite map derived using LSU method with bauxite maps of two band ratios in terms of spatial disposition of bauxite. We also have attempted to relate the abundance values of pixels of LSU-based bauxite map with band ratio values of bauxite pixels of two selected bauxite indices.

Structural Control on Occurrence and Dynamics of Coalmine Fires in Jharia Coalfield: A Remote Sensing Based Analysis

In the present study, attempt has been made to understand the structural controls on preservation and dynamics of coal fires by establishing spatial relations of these fires with the faults, in the Jharia coal field. This is carried out, using recent distribution of the coal fires mapped from Landsat 8 TIRS data and historical coal fire distribution data derived from earlier studies (2003, 2006 and 2012). The major mapped fires are restricted to five different locales in the coalfield, namely Kujama, Kusunda, Katras-Mudidih, Shatabdi and Nadhkarkee-Jayramdih. Spatial analysis of different coal fire locales with respect to the geological map indicates that the fires may be associated with faults. Areal extension of fires coincide with the trend of faults (NW-SE around Kusunda and E-W around Katras). Further, the temporal preservation of the fires are also controlled by these faults. Fires associated with faults sustain for longer time than the fires that are not in proximity to the faults. This indicates that, these faults may have acted as conduits in supplying oxygen for preserving the coal fires over a period of time. Further, these faults permit the propagation and spread of the fire, through the arealy exposed fractures developed along their trends.

Potential of polarimetric Radarsat-2 data in geological mapping – a case study in parts of Dharwar craton, India

Polarimetry is a technique for quantitatively estimating the change in polarization in a backscattered electromagnetic signal (in this case a radar signal) with reference to the polarization of the incident signal for estimating the geophysical properties (roughness and dielectric constant) of surface elements. In this study, quadrapole Radarsat-2 data have been utilized for mapping geological elements in Archaean terrain based on their geophysical parameters preserved in the four polarization channels of Radarsat-2 data. The study illustrates how single-look complex polarimetric data can be processed to extract information on lithology, geological structure, and land covers (i.e. soil type, etc.) preferentially developed over each rock type. The study revealed that C-band polarization power images can be used indirectly to delineate lithounits provided each unit has characteristic surface roughness and moisture resulting from the surface cover or exposure pattern developed over each lithounit. Moreover, polarimetric data (inclusive of phase and amplitude) provide complementary information when we compare this information with the information derived from simple polarization composites, derived from the backscattered image of each polarization channel. It is also observed that structural imprints are enhanced in co-polarized (HH, VV) data, whereas the cross-polarized channel (HV, VH) provides information on land cover.

Comparative Analysis of Potentials of ASTER Thermal Infrared Band Derived Emissivity Composite, Radiance Composite and Emissivity–Temperature Composite in Geological Mapping of Proterozoic Rocks in Parts of Banswara, Rajasthan

In this study, we have compared the potential utility of relative emissivity bands derived from Level 1B (at sensor georectified radiance) and Level 2 (multiband emissivity product provided by ASTER service provider) data products of Advanced Space-borne Thermal Emission and Reflection Radiometer (ASTER) sensor for delineating different geological units of volcano-sedimentary provinces in parts Banswara, Rajasthan. Reference channel method was used for deriving emissivity from Level 1B data whereas temperature emissivity separation algorithm was used to derive Level 2 emissivity data products. In the false colour composite image of emissivity bands of two different data products, quartzite was enhanced but other rocks were not discernible. On the other hand, other rocks of the study area were detectable (basalt, gneiss, dolomitic marble) in Level 1B radiance data. In radiance image, variations in surface temperature and emissivity were recorded and this was helpful for delineating different rocks. Surface temperature is sensitive to land cover, moisture and it helped in detecting rocks like dolomite which was covered with moisture rich soil and vegetation. Similarly, emissivity–temperature composite was also proved useful in delineating basalt, quartzite (chloritic), dolomite/dolomitic marble and associated gneiss/migmatites as it brought out the contrast of composition and the differences in the thermophysical parameters resulted temperature variation. An image composite prepared using emissivity band 13, ratio band derived using emissivity band 12 and band 11 and radiant temperature band also could delineate all the major rock types. Further, scatter plots of emissivity bands and temperature used for clustering of different rock units could delineate these rocks from each other. Therefore, conjugate composite images of emissivity and radiant temperature was suitable in delineating all the rocks than the emissivity composite images of different types.

Potential Utility of Spectral Angle Mapper and Spectral Information Divergence Methods for mapping lower Vindhyan Rocks and Their Accuracy Assessment with Respect to Conventional Lithological Map in Jharkhand, India

In this study, we have evaluated the potential use of spectral mapping algorithms in deriving spectrolithological maps of metasedimentary rocks of Vindhyan group of rocks. In this regard, we have processed visible near infrared (VNIR) and shortwave infrared (SWIR) bands of Advanced Speceborne Thermal Emission and Reflection Radiometer (ASTER) data using similarity based spectral mapping algorithms such as spectral angle mapper (SAM) and spectral information divergence (SID). Laboratory spectra were collected by Fieldspec 3© spectroradiometer for main rock types of study area and the spectra were resampled to ASTER bandwidth to compare laboratory spectra with image spectra of respective rocks. Overall matching of image spectra of rocks with their ASTER resampled laboratory counterparts justified the spectral integrity of these rocks on the image. Therefore, image spectra of rocks were used as end member for deriving spectral maps using SAM and SID method. These maps were compared with the conventional field based lithological map (consequently updated using ASTER false colour image composite and band ratio images). SAM spectral map had over all accuracy of 67.41% and the SID map had overall accuracy of 69.67%. Present study has brought out the fact that spectral mapping algorithms would be useful in deriving moderate accuracy lithological maps even if the sedimentary rocks are of close mineralogy and these rocks have very close reflectance spectra within the spectral bandwidth of ASTER sensor. Spectral maps corroborate well with the discrete geochemical data.

Integrated Use of LANDSAT 8, ALOS-PALSAR, SRTM DEM and Ground GPR Data in Delineating Different Segments of Alluvial Fan System in Mahananda and Tista Rivers, West Bengal, India

AbstractIn this study, visible near infrared, shortwave infrared spectral bands of Landsat 8 satellite sensor, two polarisation channel of L band ALOS-PALASAR sensor, SRTM-DEM derived digital elevation data were processed to delineate different geomorphic components of alluvial fans of Tista-Mahanada fan complex. We found image composite of independent components, principal components of Landsat 8 bands were effective in delineating proximal and distal fan segments. Fused images of Landsat 8 and ALOS data were used for enhancing incised distributaries and paleochannels. Field data on depositional sequence of fans, were used to substantiate the image based delineation. Topographic breaks along selected longitudinal profiles (identified with the changes in land use and drainage pattern) of digital elevation data were conjugately analysed using Landsat false colour composites. GPR survey along selected transect highlights the vertical dislocation in the recently deposited sequences of alluvial fan regime indicative of post depositional disturbances.

Broadband reflectance, emittance spectroscopy and Self potential geophysical survey for targeting gold sulphide lode deposit in Bhukia, Rajasthan, India

Abstract In this study, we have analyzed the comparative potential of reflectance and emittance bands of advanced spaceborne thermal emission and reflection radiometer (ASTER) sensor for detecting surface exposures of Proterozoic rocks and gossan capping of gold mineralization. In this regard, few new image analysis products are derived. These are matched filtering factor-modified ratio (MFR) image and the inverse of a difference image of the ratio and matched filtering map (IDRM). These image products are used with the conventional ratio images, relative band depth images and index-based principal component (PC) images of reflectance and emittance bands of ASTER for delineating metasediments of the study area. We have found that reflectance band products are superior for mapping metasediments and gossan capping than the emissivity products, which are only suitable to enhance quartzite. Self-potential (SP) geophysical survey is carried out around the identified gossan site as SP is sensitive to sulphide mineralization. Results of the SP survey indicated presence of sulphide enrichment underneath the gossan.

Multi-sensor Space-Borne Earth Observation Data for Characterizing Fluvial-Geomorphic Provinces: A Case Study from Kosi River, India

The dynamism of geomorphic provinces in fluvial systems present considerable ambiguities in mapping by remote sensing. This necessitates use of multiple satellite data to characterize such depositional provinces. We use, an integrated dataset to characterize the geomorphic provinces (e.g. active flood plain, older food plain, fan etc.) of the Kosi River (Bihar), India. This is done using contrast in spectral signatures derived from multispectral bands (of IRS-P6 LISS III), radiant temperature (from ETM+) and radar-roughness (from radar brightness image RISAT-1). ASTER DEM has been used in deriving topographic profiles. The optical imagery, enables regional characterization through direct tonal changes (e.g. active flood plain is brighter than older flood plain). The radiant temperatures show variations across provinces. Geomorphic transitions are represented by topographic breaks. Radar backscatter imagery, show differences in radar-return from different sub-provinces. Observations made using specific sensor characterize each provinces and is supplementary/complimentary to the parameter(s) from other sensors.