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51.
Abstract Suspended sediment concentrations in the meltwater of Pindari Glacier were determined at regular intervals in four ablation seasons. The late ablation periods (September 1994 and October 1995) were characterized by a reduced level of sediment concentration, while the sampling periods of early ablation (May 1994 and July 1995) showed very high concentrations of suspended sediment in the meltwater. Grain size distribution shows the dominance of medium and coarse silt fractions of the mean size of the suspended sediments between 4.35 and 5.82 ø. Clay size constitutes about 7% of the total size population. The majority of the samples are poorly sorted, symmetrically to finely skewed and mesokurtic in nature. The grain shows texture of mechanical and chemical origin, in which mechanical texture is predominant on most of the grains. It was observed that the grains were mostly subangular to subrounded in shape with variable size ranges. Bulk sediment chemistry consists mostly (>70%) of the five elements, Si, Al, K, Fe and Mg. Iron (Fe) and Mn are dominant heavy metals and sediments show the elemental abundance in the order of Fe > Mn > Zn > Cu > Ni > Pb. The Chemical Index of Alteration (CIA) of suspended sediments (57) is relatively higher than in the case of average unweathered upper continental crust (~50) indicating a higher degree of weathering due to glacier grinding and crushing action. Quartz is the most dominant mineral, followed by mica, illite, feldspar and kaolinite. 相似文献
52.
Abstract: The Lower Cambrian Nagaur Sandstone (Marwar Supergroup) has yielded trace fossils Treptichnus, Cruziana, serially repeated Rusophycus, Diplichnites, Monomorphichnus, Bergaueria, arthropod swimming traces and leap frogging marks of Cruziana ichnofacies. This ichnofossils assemblage is dominantly preserved in fine to medium grained red sandstone beds of the Mohra Member (Nagaur Sandstone). The presence of graded rip-up clasts, current ripples, dune cross-stratification with mud drapes and tidal bundles indicates a subtidal paleoenvironment for the deposition of Nagaur Sandstone Formation, which is corroborated by the Cruziana ichnofacies trace fossil assemblage. 相似文献
53.
Spatial and temporal variability in maximum,minimum and mean air temperatures at Madhya Pradesh in central India 总被引:2,自引:0,他引:2
Darshana Duhan Ashish Pandey Krishan Pratap Singh Gahalaut Rajendra Prasad Pandey 《Comptes Rendus Geoscience》2013,345(1):3-21
In the present study, an investigation has been made to study the spatial and temporal variability in the maximum, the minimum and the mean air temperatures at Madhya Pradesh (MP), in central India on monthly, annual and seasonal time scale from 1901 to 2002. Further, impact of urbanization and cloud cover on air temperature has been studied. The annual mean, maximum and minimum temperatures are increased by 0.60, 0.60 and 0.62 °C over the past 102 years, respectively. Seasonally, the warming is more pronounced during winter than summer. The temperature decreased during the less urbanized period (from 1901 to 1951) and increased during the more urbanized period (1961 to 2001). It is also found that the minimum temperature increased at higher rate (0.42 °C) followed by the mean (0.36 °C) and the maximum (0.32 °C) temperature during the more urbanized period. Furthermore, cloud cover is significantly negatively related with air temperature in monsoon season and as a whole of the year. 相似文献
54.
55.
Krishna Kumar Singh Ravindra Pratap Patel Balraj Kumar Mohamad Altaf Prince Ahmad Ganai Abhay Kumar Singh Ram Pal Singh Lalmani 《Acta Geophysica》2009,57(2):536-547
The observation of hisslers during daytime at low latitude station Jammu, India, is reported. The hissler elements are quasi-periodic
falling tones observed during the period of hiss activity and appear in minutelong sequences with average spacing between
individual elements of the order of 0.15 s. Hissler elements exhibit almost no dispersion and no complex internal structure
in slope and intensity, and successive hissler elements do not overlap in time. It seems that the reported hisslers might
have propagated in prolongitudinal mode. 相似文献
56.
Mehul R. Pandya Raghavendra Pratap Singh Sushma Panigrahy Jai Singh Parihar 《Journal of the Indian Society of Remote Sensing》2012,40(2):215-223
Quantitative remote sensing involving accurate estimation of vegetation properties relies greatly on the measurements of the
near infrared (NIR) channel because of unique interaction property between light and leaf. It is generally assumed that the
NIR measurements are made in the absence of atmospheric absorption. However, relatively weak water vapour absorption features
still persist in the NIR channel, which has bearing on the quantitative estimates of the vegetation properties and long-term
data series. This paper reports the results of a study that was carried out to infer the possible influence of the atmospheric
water vapour (WV) on the NIR measurements (0.77–0.86 μm) of Indian Remote Sensing (IRS) satellite sensors through radiative
transfer simulations using MODTRAN model. The study also suggests and evaluates the alternate band-positions for the NIR channel
to improve the IRS NIR measurements. It was observed that the water absorption features present around 0.810 μm reduces the
WV transmission of IRS NIR channel from 1 to 0.91 when atmospheric WV content increased from 0 to 6 g/cm2 and thus hampered the NIR reflectance by 14% as compared to reference signal. A significant improvement of the order of 6.5
to 12% in the NIR reflectance and 4.2 to 7% in NDVI was observed, when IRS NIR channel was split into NIR1 (0.775–0.805 μm)
and NIR2 (0.845–0.875 μm) channels by avoiding the WV absorption features. The companion paper in this issue (Pandya et al.
2011) will support results of this simulation study through the EO1-Hyperion data analysis. 相似文献
57.
A route alignment planning has various stages. At different stages, multi-criteria decision analysis (MCDA) is required. This paper integrates geographical information system (GIS) and MCDA for designing the optimum route alignment. A GIS-based model using the multi-criteria decision analysis for finding the optimum route alignment to design major road from a source to a destination within two locations is proposed. Three different levels of analysis were performed in this study such as criteria map analysis, surface cost analysis, and least-cost path analysis. The optimum route has the least cost and satisfies other environmental, technical, social, and economic criteria. The proposed model is implemented to design optimum route alignment between two locations in the outer area of Allahabad City, India. Four route alignments are created, and one of the best routes is chosen. 相似文献
58.
Birendra P. SINGH 《地球学报》2009,30(Z1):79-80
Cambrian trace fossils and worm like impressions are described herein from the three stratigraphic units of Tal Group of rocks exposed along the track from Maldeota to Dhaulagiri in Gopi-Chand-Ka Mahal sec-tion, Mussoorie syncline. The upper 10 m thick sand-stone succession (Arenaceous Member) of Deo-Ka- Tibba Formation (lower Tal Group) contains high den-sity and low diversity Skolithos pipe rock. The Sko-lithos pipe rock in sandstone succession of Arenaceous Member (Deo-Ka-Tibba Formation) indicates shallow marine condition under sand shifting environment of deposition. Higher in the succession, in calcareous Member (Deo-Ka-Tibba Formation), Cruziana ichno-facies occurs in association with Monomorphichnus, Planolites and Paleophycus. 相似文献
59.
The paper presents the finite volume formulation and numerical solution of finite strain one‐dimensional consolidation equation. The equation used in this study utilises a nonlinear continuum representation of consolidation with varying compressibility and hydraulic conductivity and thus inherits the material and geometric nonlinearity. Time‐marching explicit scheme has been used to achieve transient solutions. The nonlinear terms have been evaluated with the known previous time step value of the independent variable, that is, void ratio. Three‐point quadratic interpolation function of Lagrangian family has been used to evaluate the face values at discrete control volumes. It has been shown that the numerical solution is stable and convergent for the general practical cases of consolidation. Performance of the numerical scheme has been evaluated by comparing the results with an analytical solution and with the piecewise piecewise‐linear finite difference numerical model. The approach seems to work well and offers excellent potential for simulating finite strain consolidation. Further, the parametric study has been performed on soft organic clays, and the influence of various parameters on the time ate consolidation characteristics of the soil is shown. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
60.