The Coastal Springs of Southern Kerala,SW India – Hydrology and Water Quality Assessment

Spring water is a reliable source of potable water in many parts of the world. Uplifted coasts of the Southern Kerala host many high yielding cold water springs which emerge from the sand - clay interface of the Neogene outcrops. Lack of adequate studies on the hydrological and water quality aspects of these springs is challenging the wise use and management of these springs. Therefore, an attempt has been made to map the locations and study the water quality of the free-falling type of springs emerging from the Neogene outcrops exposed on the cliffed coasts of Southern Kerala, especially falling within the jurisdiction of Kollam and Thiruvananthapuram districts. A total of 31 springs from four distinct geomorphic settings has been located in our survey conducted in 2008–2009 period. But, our recent survey carried out in March 2017 revealed that about 10 % of the springs were dried out due to various reasons. The total spring water discharge during 2017 was about 450 liters/minute against the total discharge of 800 liters/minute in 2007–08 period. In general, the hydrochemistry of spring waters is dominated by alkali and strong acids, i.e. alkali-chloride type. Most of the hydrochemical parameters exhibit a great degree of seasonal and spatial variations and are well within the permissible limits (with the exception of pH) for all four groups of springs. The low mineral contents may be attributed to minimal weathering from silicate-rich rocks and insignificant leaching from soil due to infiltration from anthropogenic activities. The spring water quality in all the four groups of the study area is bacteriologically contaminated and therefore proper disinfection is required before human consumption. Most of the spring water samples are classified to be “excellent to good” for irrigation and is not expected to cause any salinity hazard.     

Last-five-decade heavy metal pollution records from the Rewalsar Lake,Himachal Pradesh,India

The lakes of the Himalaya are degrading due to increase in toxic heavy metal loading. This study reports the last 50-year heavy metal pollution loading in the Rewalsar Lake, Himachal Pradesh, India. Sediment cores were recovered to study the pollution loading in the lake sediments. The ¹³⁷Cs and ²¹⁰Pb isotope-based sedimentation rate suggest rapid sedimentation in the lake during the last ~50 years. The concentrations of Mn, Cu, Zn, Cd, Pb, Co, Ni, Cr metals in the lake sediments owe its contributions both to the natural and anthropogenic sources. Prior to ca 1990 AD, metal loading was dominated by the lithogenic input, whereas post ca 1990 AD the metal loading was controlled by the anthropogenic factors. The Pb concentration in the lake gradually increased during 1990–2004 and then decreased significantly till present. The higher concentration of Pb seems to be derived from the fossil fuel burning, while the Cr concentration in the lake indicates the use of fertilizer in the catchment area. The lowest concentrations of elements around ca 1990 AD seem to have occurred due to channelization of the lake feeding system.     

Geochemical implications of minerals and environmentally sensitive elements of Giral lignite,Barmer Basin,Rajasthan (India)

The Barmer Basin of Rajasthan is significant for its Paleogene lignite sequences. The lignite seam occurs in Akli Formation of Barmer Basin at the depth of 06–241 m. A total of 57 lignite samples were collected from the working faces of lignite mine and were subjected to proximate analysis (moisture, ash yield, volatile matter, and fixed carbon), ultimate analysis (carbon, hydrogen, nitrogen, oxygen and sulfur), elemental analysis (Fe, Ca, Mg, Cd, Mn, K, Na, Cu, Co, Ni, Cr, Zn, and Pb) and rock-eval pyrolysis for mineral carbon (MINC). Some elements like Cu, Cd, Co, Ni, Zn, Pb, Na, and K occur in high concentration, while Mg and Ca have their concentrations lower than World Clarke average. In addition, various minerals and functional groups present in the lignite samples were analyzed through X-ray diffraction and Fourier transform infrared (FTIR) spectroscopy. The mineral (weight and atomic) percentage has also been analyzed through scanning electron microscopy–energy dispersive spectroscopy (SEM–EDS).     

Soft X-ray Focusing Telescope Aboard AstroSat: Design,Characteristics and Performance

The Soft X-ray focusing Telescope (SXT), India’s first X-ray telescope based on the principle of grazing incidence, was launched aboard the AstroSat and made operational on October 26, 2015. X-rays in the energy band of 0.3–8.0 keV are focussed on to a cooled charge coupled device thus providing medium resolution X-ray spectroscopy of cosmic X-ray sources of various types. It is the most sensitive X-ray instrument aboard the AstroSat. In its first year of operation, SXT has been used to observe objects ranging from active stars, compact binaries, supernova remnants, active galactic nuclei and clusters of galaxies in order to study its performance and quantify its characteriztics. Here, we present an overview of its design, mechanical hardware, electronics, data modes, observational constraints, pipeline processing and its in-orbit performance based on preliminary results from its characterization during the performance verification phase.     

The Torino,H6, meteorite shower

Abstract— A meteorite shower fell at Torino, Italy on 18 May 1988. Petrographic studies indicate that the stone is an H6 chondrite having features of moderate to severe shock. Chemical analyses of the meteorite are reported. Cosmic ray produced ³He, ²¹Ne and ¹²⁶Xe yield an exposure age of about 48 Ma. The cosmic ray track densities in three fragments range between 1.8 to 5 × 10⁵/cm² suggesting about 99% mass ablation in the atmosphere. Twelve radioisotopes with half lives ranging between 5.6 days to 7.3 × 10⁵ years have been measured with high precision (2 to 10%). Marginal signals were observed for several short-lived nuclides and upper limits were obtained for the activity levels of eight radionuclides (²⁴Na, ⁴⁸Cr, ⁵⁷Ni, ⁴⁷Sc, ⁴⁷Ca, ⁵⁹Fe, ⁴²Ar and ⁴⁴Ti) some of which have not been hitherto detected in fresh falls. The data are generally consistent with the nuclide production by galactic cosmic rays when modulation due to the solar cycle is taken into consideration. The preatmospheric radius of the chondrite is estimated to be 20 cm, consistent with track densities and activity levels of ⁶⁰Co, ²⁶Al and other radionuclides.     

Spatio-temporal trends of rainfall across Indian river basins

Theoretical and Applied Climatology - Daily gridded high-resolution rainfall data of India Meteorological Department at 0.25° spatial resolution (1901–2015) was analyzed to detect the...     

Characteristics of landslide in Koshi River Basin,Central Himalaya

Koshi River basin, which lies in the Central Himalayas with an area of 71,500 km2, is an important trans-boundary river basin shared by China, Nepal and India. Yet, landslide-prone areas are all located in China and Nepal, imposing alarming risks of widespread damages to property and loss of human life in both countries. Against this backdrop, this research, by utilizing remote sensing images and topographic maps, has identified a total number of 6877 landslides for the past 23 years and further examined their distribution, characteristics and causes. Analysis shows that the two-step topography in the Himalayan region has a considerable effect on the distribution of landslides in this area. Dense distribution of landslides falls into two regions: the Lesser Himalaya(mostly small and medium size landslides in east-west direction) and the TransitionBelt(mostly large and medium size landslides along the river in north-south direction). Landslides decrease against the elevation while the southern slopes of the Himalayas have more landslides than its northern side. Change analysis was carried out by comparing landslide distribution data of 1992, 2010 and 2015 in the Koshi River basin. The rainfallinduced landslides, usually small and shallow and occurring more frequently in regions with an elevation lower than 1000 m, are common in the south and south-east slopes due to heavy precipitation in the region, and are more prone to the slope gradient of 20°~30°. Most of them are distributed in Proterozoic stratum(Pt3ε, Pt3 and Pt2-3) and Quaternary stratum. While for earthquake-induced landslides, they are more prone to higher elevations(2000~3000 m) and steeper slopes(40°~50°).     

Pullout capacity of multi-plate horizontal anchors in sand: an experimental study

Acta Geotechnica - A horizontal anchor is a structural member designed to resist the vertical pullout forces and ensure the stability of structures like the tower foundations, masts and bridges....     

Rain induced shallow landslide hazard assessment for ungauged catchments

A physically based distributed slope stability model derived from the integration of hydrologic analysis and slope stability analysis is presented for GIS based modeling on a catchment scale. The catchment is represented by a mesh of squares with vertical columns. The hydrologic model calculates subsurface flow and resulting pore-water pressure during rainfall in each cell for every time step. The slope stability module then calculates the stability of each cell for the changing water pressure scenario. There are very few input data requirements, which makes the model applicable to ungauged catchments, also where the record of the past landslides and associated rainfall are not available. The model was tested in Garjuwa catchment, Nepal where all landslide scars were documented. The model reproduces the observed distribution of landslide locations in a consistent way. Several model runs were conducted, increasing the intensity of rainfall to see corresponding increase in instability. The results show that there is a critical rainfall intensity for the catchment, beyond which increase in rainfall intensity does not increase instability significantly.