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91.
A hydrogeomorphic approach is used in analyzing hydrologic conditions in the Mehsana and Banaskantha districts of Gujarat state. Using Landsat images, it was possible to delineate geological units, hydrogeomorphic features and vegetation density levels on a regional scale. A relationship between hydrogeomorphic features and vegetation density levels along with ground based hydrologic data was established in Mehsana district and the same was extended to the adjoining Banaskantha district. The ground water potential areas identified were from alluvium and piedmont zone. On the basis of different vegetation density levels, these areas were further subdivided into three different potential zones as regards the availability of groundwater viz. good, fair and poor. The applicability of the remotely sensed data has been found quite useful in quick identification of regional hydrogeomorphic setting of the area. 相似文献
92.
The paper presents a computational algorithm designed for efficient modelling of apparent resistivity over complex geological
structures, using finite element method. The algorithm can be used to study variations of apparent resistivities using any
electrode configuration at any point on the earth’s surface, not necessarily regular. A Schlumberger apparent resistivity
sounding curve over a buried anticline, is presented here as an example and compared with the corresponding analytical curve,
to demonstrate the correctness of the FEM algorithm.
The various potential derivatives required for the computation of apparent resistivities evaluated through different electrode
configurations have been obtained by calculating the ‘influence coefficients’ using reciprocal theorems, an approach successfully
applied in structural engineering. In essence, a set of self balancing nodal currents, obtained from the appropriate derivative(s)
of the shape functions of the elements contributing to the point of observation, is applied as the load vector.
The resulting quantities corresponding to the potential distribution in traditional finite element method, then, turn out
to be the potential derivatives at the point of observation for different positions of the current electrodes. These are known
as influence coefficients.
The continuum nature of the domain beyond the region of interest has been modelled by using ‘infinite elements’ across which
the potential is assumed to decay exponentially. 相似文献
93.
Dipankar Chakraborti Mohammad Mahmudur Rahman Bhaskar Das Amit Chatterjee Dipankar Das Biswajit Nayak Arup Pal Uttam Kumar Chowdhury Sad Ahmed Bhajan Kumar Biswas Mrinal Kumar Sengupta Md. Amir Hossain Gautam Samanta M. M. Roy Rathindra Nath Dutta Khitish Chandra Saha Subhas Chandra Mukherjee Shyamapada Pati Probir Bijoy Kar Adreesh Mukherjee Manoj Kumar 《Hydrogeology Journal》2017,25(4):1165-1181
During a 28-year field survey in India (1988–2016), groundwater arsenic contamination and its health effects were registered in the states of West Bengal, Jharkhand, Bihar and Uttar Pradesh in the Ganga River flood plain, and the states of Assam and Manipur in the flood plain of Brahamaputra and Imphal rivers. Groundwater of Rajnandgaon village in Chhattisgarh state, which is not in a flood plain, is also arsenic contaminated. More than 170,000 tubewell water samples from the affected states were analyzed and half of the samples had arsenic >10 μg/L (maximum concentration 3,700 μg/L). Chronic exposure to arsenic through drinking water causes various health problems, like dermal, neurological, reproductive and pregnancy effects, cardiovascular effects, diabetes mellitus, diseases of the respiratory and gastrointestinal systems, and cancers, typically involving the skin, lungs, liver, bladder, etc. About 4.5% of the 8,000 children from arsenic-affected villages of affected states were registered with mild to moderate arsenical skin lesions. In the preliminary survey, more than 10,000 patients were registered with different types of arsenic-related signs and symptoms, out of more than 100,000 people screened from affected states. Elevated levels of arsenic were also found in biological samples (urine, hair, nails) of the people living in affected states. The study reveals that the population who had severe arsenical skin lesions may suffer from multiple Bowens/cancers in the long term. Some unusual symptoms, such as burning sensation, skin itching and watering of eyes in the presence of sun light, were also noticed in arsenicosis patients. 相似文献
94.
In this article, we investigate the possibilities of energy extraction from an over-spinning Kerr spacetime using collisional Penrose process. This phenomenon can produce a high-energy ejecta of particles under certain favourable conditions. Unlike black holes, in this case, the particles endowed with higher energy can escape to infinity. We use this model to explore various possibilities of jet formation in an over-spinning geometry. Primarily we concentrate on the energy extraction associated with collisions taking place on the off-equatorial planes and find the signature of jets from them. We also apply this formalism to a toy model which could be useful in practical astrophysical scenarios. This is motivated from the atomic model where we have considered the decay of a circular orbit because of energy extraction via Penrose mechanism. 相似文献
95.
Murlidhar Bhatawdekar Ramesh Kumar Deepak Jahed Armaghani Danial Mohamad Edy Tonnizam Roy Bishwajit Pham Binh Thai 《Natural Resources Research》2020,29(6):4103-4120
Natural Resources Research - Blasting is an economical technique for rock breaking in hard rock excavation. One of its complex undesired environmental effects is flyrock, which may result in human... 相似文献
96.
The aim of this study is to understand the various sources and factors controlling the abundance and distribution of the metals through the analyses of selected metals (iron, manganese, chromium, copper, zinc and cobalt), sand, silt, clay, organic carbon and magnetic susceptibility of the surface sediments of Zuari estuary in three different seasons. Total suspended matter (TSM) concentration and salinity of near surface and bottom waters were also measured. The study undertaken for three seasons, based on 18 selected stations all along the estuary, indicated that the concentration of most of the metals were comparatively higher during pre-monsoon than in monsoon and post-monsoon seasons. Further, along the length of the estuary, high concentrations were observed at lower middle and lower estuary and also at few stations at the upstream end. Salinity, distribution of TSM, size of the sediment, organic matter, geomorphological setup, fresh water input from land and release of industrial waste within the estuary played a role in distribution and concentration of metals. Magnetic measurements indicated the dominance of haematite like minerals and helped in understanding the source and depositional processes. 相似文献
97.
Ocean Dynamics - During the summer monsoon, the southern Bay of Bengal (BoB) hosts a cyclonic circulation known as Sri Lanka Dome (SLD) and the swift Summer Monsoon Current (SMC), which advects... 相似文献
98.
Investigations related to scientific deep drilling to study reservoir-triggered earthquakes at Koyna,India 总被引:1,自引:0,他引:1
Harsh Gupta N. Purnachandra Rao Sukanta Roy Kusumita Arora V. M. Tiwari Prasanta K. Patro H. V. S. Satyanarayana D. Shashidhar K. Mallika Vyasulu V. Akkiraju Deepjyoti Goswami Digant Vyas G. Ravi K. N. S. S. S. Srinivas M. Srihari S. Mishra C. P. Dubey D. Ch. V. Raju Ujjal Borah K. Chinna Reddy Narendra Babu Sunil Rohilla Upasana Dhar Mrinal Sen Y. J. Bhaskar Rao B. K. Bansal Shailesh Nayak 《International Journal of Earth Sciences》2015,104(6):1511-1522
99.
The eastern offshore of India covers a vast stretch of sedimentary tract fed by major rivers like Ganges, Brahmaputra and
Mahanadi in the north, Krishna and Godavari in the center, and Cauvery and Palar in the south, which led to variations in
shelf-slope characteristics, degree of slope and hence slope instability. The structure as well as seismic attribute maps
prepared from multibeam bathymetry and high-resolution 3D seismic data set has been analyzed to identify various geohazards
in the deep water offshore regions of the east coast of India. These can be categorized as slope instability, slope canyons,
shallow gas, mass transport complexes, sediment waves, gas hydrates, gas chimney, mud volcanoes and shallow faults. The slope
instability is primarily related to rapid sedimentation by the active river systems while the other geohazards are often developed
in association with shallow gas flows and leakages. The bottom simulating reflectors (BSRs) identified in the seismic sections
indicate the presence of gas hydrates. Rapid sedimentation, BSR formation, dissolution and expulsion of water as well as gas
and their subsequent vertical migration are responsible for the formation of shallow gas-related hazards. The results from
the above analysis are of immense help in minimizing the risk of shallow hazards during exploration, drilling and subsurface
installation activities along the eastern Indian offshore. 相似文献
100.
Dipankar Chakraborti Mohammad Mahmudur Rahman Bhaskar Das Bishwajit Nayak Arup Pal Mrinal Kumar Sengupta Md. Amir Hossain Sad Ahamed Manabendranath Sahu Kshitish Chandra Saha Subhash Chandra Mukherjee Shyamapada Pati Rathindra Nath Dutta Quazi Quamruzzaman 《Environmental Earth Sciences》2013,70(5):1993-2008
The authors’ survey of the Ganga–Meghna–Brahmaputra (GMB) plain (area 569,749 km2; population >500 million) over the past 20 years and analysis of more than 220,000 hand tube-well water samples revealed groundwater arsenic contamination in the floodplains of the Ganga–Brahmaputra river (Uttar Pradesh, Bihar, Jharkhand, West Bengal, and Assam) in India and the Padma–Meghna–Brahmaputra river in Bangladesh. On average, 50 % of the water samples contain arsenic above the World Health Organization guideline value of 10 μg/L in India and Bangladesh. More than 100 million people in the GMB plain are potentially at risk. The authors’ medical team screened around 155,000 people from the affected villages and registered 16,000 patients with different types of arsenical skin lesions. Arsenic neuropathy and adverse pregnancy outcomes have been recorded. Infants and children drinking arsenic-contaminated water are believed to be at high risk. About 45,000 biological samples analyzed from arsenic-affected villages of the GMB plain revealed an elevated level of arsenic present in patients as well as non-patients, indicating that many are sub-clinically affected. In West Bengal and Bangladesh, there are huge surface water in rivers, wetlands, and flooded river basins. In the arsenic-affected GMB plain, the crisis is not over water scarcity but about managing the available water resources. 相似文献