Some aspects of cast blasting techniques for dam construction     

G. R. Adhikari  R. N. Gupta 《Geotechnical and Geological Engineering》1989,7(4):301-313

Summary A proposal is under consideration to construct a dam on an experimental basis by a cast (or directional) blasting technique, DBT. The dam site is located at Bharari Khad, a tributary of the Sutlaz river in Himachal Pradesh. Site investigations have been completed and a large scale blast has been designed for construction of the experimental dam.The paper describes the basic design concept of DBT and application of throw and caving methods for construction of dams. The preliminary tests required to design the blasting pattern are detailed. The technique has a great potential because it reduces construction cost and time particularly in inaccessible mountain regions.  相似文献   

Response of Concrete and Masonry Dams to Ground Vibration due to Blasting     

G. R. Adhikari  A. I. Theresraj  R. N. Gupta 《Fragblast: International Journal for Blasting and Fragmentation》2004,8(1):41-49

The safety and stability of concrete and masonry dams is a great concern when blasting has to be conducted close to these dams in order to construct small hydro-electric projects. There is a danger of ground vibration amplification to those residential-type buildings that are built close to these dams.

Responses of three concrete and masonry dams were measured directly by conducting a number of blasts and by monitoring vibration in the ground as well as on the dams. The amplitudes and frequencies of the motions were analysed and vibration attenuation relations were derived. These relations were used to compare the vibration levels on the dams with those in the ground.

Because of close-in construction blasts that produced high frequency ground vibrations, there was no amplification of the ground vibrations by these dams. The measured amplitudes of ground vibration were comparable to those of the dams.  相似文献   

Analysis of the Statistical Behaviour of Daily Maximum and Monthly Rainfall Data at New Delhi During Monsoon Period     

C. V. Singh  R. S. Adhikari  H. P. Garg 《大气科学进展》2002,19(3):425-432

1．IRt回*CtZOllIndian Summer Monsoon Varlablllty Is a muchdscussed and researched field,yet thereIs a considerable scope IOr further work and It Is understanding．The south—west monsoonwhich contributes more than 75%of the annual ra!nfa!lin a major port!on of Ind!a,Is thespring of!he nallonaleconomy．The ralnmH has Qo sustain山e Increasing needs ofagrlculturelrrlgatlon,the Increasing population and the rapid Industrlallsatlon．It Is lowever noted thatthe monsoon rainfall over differe…  相似文献   

Monsoonal impact on circulation pathways in the Indian Ocean     

Priyantha Jinadasa Sinhalage Uday  Pathirana Gayan  Ranasinghe Pradeep Nalak  Centurioni Lu  Hormann Verena 《海洋学报(英文版)》2020,39(3):103-112

Monsoon driven water mass exchange between the Bay of Bengal(Bo B) and Arabian Sea(AS) is the common experience. However, it is not yet firmly confirmed that the exchange pathway is either passing through southern tip of Sri Lanka or Palk Strait. Local circulation patterns impact the pathways followed by the East Indian Coastal Currents(EICC) that drive exchange, thereby modulating mixing and water mass transformation in the Bay of Bengal around Sri Lanka. In this study, observations from surface drifters were incorporated with the satellite derived data to understand the monsoonal impact on circulation patterns in the Indian Ocean. This was the first multi-national scientific effort which was conducted in the Bo B and AS during 2013 to 2015 to understand the monsoonal impact on circulation patterns in the complex region. The results indicated that seasonally reversing monsoonal currents of southern Sri Lanka, traced by the wintertime freshwater export pathways of the EICC. The deflection of monsoon currents running along the east coast of Sri Lanka by forming cyclonic and anti-cyclonic eddies, which influence the mixing and stirring associated with these flows. Results further indicate the low salinity cold water flows from the Bo B to AS along the western boundary of the Bo B during northeast monsoon. In the same way, reverses the phenomena during southwest monsoon, transporting high salinity warm water from AS to the Bo B. This maintain the bay status which occurred due to freshwater influx from large rivers and high saline water from AS. However, no evidences were observed for the exchange through Palk Strait during the study.Also, there are some mis-matches in in-situ and remotely sensed measurements which imply the necessity of systematic observation system for the complex region as an alternative approach.  相似文献   

Modulation of ionospheric conductivities during high-power wave propagation     

S. S. De  B. K. Sarkar  B. Ghosh  A. C. Sen  S. Bandyopadhyay  S. K. Adhikari 《Earth, Moon, and Planets》1991,53(1):1-10

Enhancement of conductivity tensor modification within the ionospheric plasma by electron density modulation through the temperature dependence of the recombination rates of different ionspecies caused due to electron temperature modulation during high-power wave propagation is studied. Variation of Hall and Pedersen conductivities of the ionosphere has been investigated in the height range between 85 km to 250 km. The generation of waves at the modulation frequency and its harmonics in the ELF, VLF bands in the process is discussed.  相似文献   

Climate and Rural Income   总被引：3，自引：0，他引：3  

Robert Mendelsohn  Alan Basist  Pradeep Kurukulasuriya  Ariel Dinar 《Climatic change》2007,81(1):101-118

This paper tests whether climate has an impact on per capita rural income. The study finds that total (agricultural and nonagricultural) income in rural counties and municipios in the US and Brazil are affected by climate. The study demonstrates that this income effect is due to changes in the net value of agriculture. Regions with better climates for agriculture support higher rural incomes and regions with poor climates have more rural poverty. The results also suggest that global warming will likely increase rural poverty.  相似文献   

Combined effects of water pH and alkalinity on the accumulation of lead, cadmium and chromium to Labeo rohita (Hamilton)     

S. Adhikari Ph.D.  L. Ghosh Ph.D.  S. Ayyappan Ph.D. 《International Journal of Environmental Science and Technology》2006,3(3):289-296

Influence of pH (5.5, 7.0 and 8.5) and alkalinity (40 to 200 mg/L as CaCO₃) on the accumulation of Pb (NO₃)₂ CdCl₂, H₂O and K₂Cr₂O₇ to Labeo rohita (Hamilton) was investigated in the laboratory. Highest accumulation of Pb and Cr in whole fish occurred at pH 5.5 and at alkalinity level of 40 to 46 mg/L as CaCO₃ compared to 7.0 and 8.5. In case of Cd maximum accumulation occurred at pH 7.0 and at alkalinity of 100 mg/L as CaCO₃ than that of pH 5.5 and 8.5 and alkalinity 42 and 156 mg/L as CaCO₃. Maximum accumulation of lead and chromium occurred at total alkalinity level of 40 and 46 mg/L as CaCO₃, respectively while maximum accumulation of cadmium occurred at an alkalinity level of 200 mg/L as CaCO₃. A significant (p<0.05) linear relationship was demonstrated between increasing pH/ alkalinity and decreasing accumulation in Pb and Cr treatment at all exposure period while for Cd there was no significant linear relationship established.  相似文献   

Major ion chemistry of two cratonic rivers in the tropics: Weathering rates and their controlling factors     

Anupam Samanta  Gyana Ranjan Tripathy  Aswin T. Pradeep  Anirban Mandal 《水文研究》2021,35(2):e14035

Continental weathering plays a dominant role in regulating the global carbon cycle, soil chemistry and nutrient supply to oceans. The CO₂-mediated silicate weathering acts as a major CO₂ sink, whereas sulphuric acid-mediated carbonate dissolution releases CO₂ to the atmosphere–ocean system. In this study, dissolved major ions and silica concentrations of two tropical (Damodar and Subarnarekha) river systems from India have been measured to constrain the type and rate of chemical weathering for these basins. The total dissolved solids (TDS) of these rivers, a measure of total solute supply from all possible sources, are about 2–3 times higher than that of the global average for rivers. Mass balance calculations involving inverse modelling estimate that 63 ± 11% of total cations are derived from rock weathering, of which 27 ± 7% of cations are supplied through silicate weathering. The sulphide-S concentrations are estimated by comparing the water chemistry of these two rivers with that of a nearby river (Brahmani) with similar lithology but no signatures of sulphide oxidation. The outflows of Damodar and Subarnarekha rivers receive 17% and 55% of SO₄ through sulphide oxidation, respectively. The sulphide oxidation fluxes from the ore mining areas, such as upper Damodar (0.52 × 10⁹ mol/yr) and lower Subarnarekha (0.66 × 10⁹ mol/yr) basins, are disproportionally (~9 times) higher compared to their fractional areal coverage to the global drainage area. The corresponding CO₂ release rate (2.84 × 10⁴ mol/km²/yr) for the Damodar basin is lower by five times than its CO₂ uptake rate (1.38 × 10⁵ mol/km²/yr). The outcomes of this study underscore the dominance of sulphide oxidation in controlling the dissolved chemical (cationic and sulphur) fluxes.  相似文献   

Modelling of stream run-off and sediment output for erosion hazard assessment in Lesser Himalaya: need for sustainable land use plan using remote sensing and GIS: a case study     

Pradeep K. Rawat  P. C. Tiwari  C. C. Pant  A. K. Sharama  P. D. Pant 《Natural Hazards》2011,59(3):1277-1297

Assessment and inventory on soil erosion hazard are essential for the formulation of successful hazard mitigation plans and sustainable development. The objective of this study was to assess and map soil erosion hazard in Lesser Himalaya with a case study. The Dabka watershed constitutes a part of the Kosi Basin in the Lesser Himalaya, India, in district Nainital has been selected for the case illustration. The average rate of erosion hazard is 0.68 mm/year or 224 tons/km²/year. Anthropogenic and geo-environmental factors have together significantly accelerated the rate of erosion. This reconnaissance study estimates the erosion rate over the period of 3 years (2006–2008) as 1.21 mm/year (398 tons/km²/year) in the barren land having geological background of diamictite, siltstone and shale rocks, 0.92 mm/year (302 tons/km²/year) in the agricultural land with lithology of diamictite, slates, siltstone, limestone rocks, while in the forest land, it varies between 0.20 mm/year (66 tons/km²/year) under dense forest land having the geology of quartzwacke and quartrenite rocks and 0.40 mm/year (132 tons/km²/year) under open forest/shrubs land having geological setup of shale, dolomite and gypsum rocks. Compared to the intensity of erosion in the least disturbed dense forest, the erosion rate is about 5–6 times higher in the most disturbed agricultural land and barren land, respectively. The erosion hazard zones delineated following scalogram modelling approach. Integrated scalogram modelling approach resulted in severe classes of soil erosion hazard in the study area with numerical values of Erosion Hazard Index (EHI) ranging between 01 (very low hazard) and 5 (very high hazard).  相似文献   

Contributions of the International Atomic Energy Agency to the development and practice of isotope hydrology     

Pradeep K. Aggarwal  Klaus Froehlich  Roberto Gonfiantini 《Hydrogeology Journal》2011,19(1):5-8

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