Shovan Lal Chattoraj

Simulation Outputs of Major Debris Flows in Garhwal Himalaya: A Geotechnical Modeling Approach for Hazard Mitigation

Landslides, one of the major geological hazards, contribute to natural disasters in mountainous region around the globe owing to a wide variety of causative as well as triggering factors like heavy rainstorms, cloudbursts, glacial lake outburst (GLOF), earthquakes, geo-engineering setting, unplanned human activities, etc. In different parts of the Himalaya, landslide has evolved as a frequent problem which severely affects life, property, and livelihood of this mountainous area thriving mainly on pilgrimage, tourism, and agriculture (Anbalagan et al. 2015; Anbalagan 1992; Champati Ray and Chattoraj 2014; Gupta et al. 1993; Kumar et al. 2012; Onagh et al. 2012; Sarkar et al. 1995, 2006; Sundriyal et al. 2007). With the background of higher elevation, rough hilly landscape, scanty cultivated land, strong monsoonal effect, and less industrial growth restricting economic progress, repeated landslide events keep human life and property at stake (Champati Ray et al. 2013a, b, 2015; Ketholia et al. 2015; Paul and Bisht 1993). Landslides in the Himalayan region are on an average smaller in dimension and have shallow depth, but these are more recurring in nature and thereby do not get noticed by authorities but cause higher cumulative losses over a period of time. Landslides, in the Himalaya, are observed particularly in highly fractured and sheared rock mass close to faults and also in weathered hard rocks. The climatic factors play an important role in weathering and disintegration of rock mass that are finally brought down by gravity (Kumar et al. 2007, 2012). Most of these landslides wreak havocked not only on life and property but manifest changes in landform due to large-scale mass wasting, landslide-dammed lake formation, and breaching leading to large-scale landform modification (Champati Ray 2013; Champati Ray et al. 2015).

Demarcation of mineral rich zones in areas adjoining to a copper prospect in Rajasthan, India using ASTER, DEM (ALOS) and spaceborne gravity data

The objective of this work is to identify the potential zones for detailed mineral exploration studies in areas adjoining to a copper prospect using Remotely Sensed data sets. In this study visualization of ASTER data has been enhanced to highlight the mineral-rich areas using various remote sensing techniques such as colour composites and band ratios. VNIR region of ASTER is significant to detect iron oxides while, clay minerals, carbonates and chlorites have characteristic absorption in the SWIR wavelength region. Therefore, an attempt has been made to target the mineral abundant regions through ASTER data processing. Height based information was extracted using high-resolution ALOSDEM to analyse the topographical controls in the region considering the fact that mineral deposits often found associated with geological structures and geomorphological units. Gravity data was used to generate gravity anomaly map which gives clues about subsurface density differences. In this context, base metal ores may show anomalous (high) gravity values in comparison to the non-mineralised areas. Outputs from all the data sets were analysed and correlated with the geological map and available literature. Final validation of results has been done through proper ground checks and laboratory analysis of rock samples collected from the litho-units present in the study area. Based on this study some new areas have been successfully demarcated which may be potential for base metal exploration.

Identification and mapping of minerals by using imaging spectroscopy in southeastern region of Rajasthan

Remote Sensing possess of new technological trend that empowered with advanced hyperspectral sensors which combine imaging and spectroscopy in a single system. Interpretation of remotely sensed imagery involve basics of spectroscopy for identifying and mapping minerals, as different minerals have unique reflectance and absorption pattern across different wavelengths, which act as their identifying signatures. In this paper Hyperion data have been used for mapping of minerals in Aravalli fold belt of the South-Eastern Rajasthan. Rock samples collected from the study area were used to generate spectra using Spectroradiometer in the laboratory conditions. The spectra generated were validated with USGS spectral library. The imageries have undergone standard image processing techniques, such as atmospheric correction through Fast line of sight atmospheric absorption for hypercubes (FLAASH) model, Minimum Noise Fraction (MNF), Pixel Purity Index (PPI), and N-d visualization for endmember selection. Further, Spectral Angle Mapper technique (SAM) was used for mapping minerals that belong to carbonate, clay and silicate groups.