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231.
A. V. Shanwal S. K. Ghosh S. P. S. Karwasra A. K. Jain Vijender Singh 《Journal of the Indian Society of Remote Sensing》1989,17(1):7-11
A confirmatory study of soil physiographic units identified through aerial photo interpretation technique, in Yamuna alluvial plain, Haryana is presented here. The area under study is part of Yamuna alluvial plain in Sonepat district, Haryana. Shanwal and Malik (1980) studied and mapped this area (semi-detailed) on 1:25,000 scale through areial photo interpretation technique. The soil profile samples of major soil physiographic units of the area were fractionated into sand, silt and clay. Detail mineralagical studies were carried out through electron microscopic and X-ray diffractometer studies in order to know their nature and origin of the parent material. X-ray diffraction data shows that mineralogy of different fractions (Sand, silt and clay) of soils samples, of different physiographic units were similar except Lavee. In this area mica is the dominant day mineral in the soils followed by Kaolinite, chlorite, vermiculite and smectite in decreasing order of their abundances. The occurance of fibrous minerals in coarse clay and silt fraction of soil samples of Lavee physiographic unit is the interesting feature of this area. The presence of fibrous minerals indicates that this overlain material designated as natural Levee in this area is not the alluvium brought down by the river Yamuna but is aeolian material flown from adjoining deseret of Rajasthan and deposited as stabilized sand dune. The fibrous minerals have been reported earlier in the desert of Rajasthan. 相似文献
232.
S. K. Jain B. Storm J. C. Bathurst J. C. Refsgaard R. D. Singh 《Journal of Hydrology》1992,140(1-4):25-47
The results of SHE modelling of the 820 km2 Kolar catchment in Madhya Pradesh, Central India are presented. The data collection, the associated field investigations, the calibration and the modelling results are discussed along with the assessment of model parameters. Based on the experiences obtained in this study from modelling and field experiments, the necessity of fieldwork and the hydrological realism of the final model representation of the basin are discussed. 相似文献
233.
Assessing and monitoring forest health using a forest fragmentation approach in Sariska Tiger Reserve,India 总被引:1,自引:0,他引:1
Purva Jain Raihan Ahmed 《Norsk geografisk tidsskrift. Norwegian journal of geography》2016,70(5):306-315
The relationship between trajectories of forest cover change and fragmentation due to physical and anthropogenic activities in Sariska Tiger Reserve is addressed in the article. The authors conducted a field visit to the reserve to collect groundtruth data and perform a village survey. Thereafter, their main method consisted of using Landsat TM images for three days, one in each of the years 1989, 1994, and 2014, to assess spatial-temporal variation in forest cover. A fragmentation model was used to examine the extent and pattern of forest degradation. The results showed an overall increase in forest cover in Sariska Tiger Reserve from 53% in 1989 to 55% in 2014. However, the fragmentation statistics revealed a deterioration in forest health. There was an increase in the fragmentation categories perforated, edge, and patch in their respective areas, while the core areas decreased at the expense of other fragmentation classes. The existence of villages, roads, and pilgrimage sites had increased the pace of degradation and fragmentation of forest in the reserve. The authors conclude that the fragmentation model was effective for analysing forest degradation and identifying the priority areas for strategic planning of nature conservation. 相似文献
234.
The competency of any TBM in any geological condition is determined by a rock or rock mass breakage process. A 12.24 km long tunnel between Maroshi and Ruparel College was excavated by Brihanmumbai municipal corporation (BMC) to improve water supply system of greater Mumbai, India, using open-type hard rock tunnel boring machines (TBMs). In this paper an attempt has been made to establish the relationship between rock mass characteristics i.e. RMR and UCS of the Deccan trap rocks and TBMs performance characteristics for 5.83 km long Maroshi–Vakola tunnel section of the Maroshi–Ruparel college tunnel project. To analyze the effect of variable rock mass conditions on the TBM performance, the operating parameters i.e. thrust force, torque and RPM of the machine, were recorded and intact rock strength was determined. The effect of rock mass properties on machine penetration rate (PR) and the relation with other operational parameters were analyzed. The rock strength affects the rock behaviour under compression. When the rolling cutters indent the rock, the stress exerted must be higher than the rock strength i.e.; the rock strength is directly relevant to the performance of TBM. Studies show that the penetration rate decreases with increase in uniaxial compressive strength (UCS). The comparison of measured penetration rate with empirical model developed by Graham, in which, the penetration rate is computed using UCS and average thrust per cutter, showed good agreement with coefficient of determination (R2), i.e. 0.97. The study shows that the TBM performance was maximum in rock mass rating (RMR) range from 40 to 75, while slower penetration was recorded both in very poor and very good rock masses. 相似文献
235.
T. K. Manual Ateef Khan Y. Nazeer Ahammed R. S. Tanwar R. S. Parmar K. S. Zalpuri Prabhat K. Gupta S. L. Jain Risal Singh A. P. Mitra S. C. Garg A. Suryanarayana V. S. N. Murty M. Dileep Kumar Andrew J. Shepherd 《Journal of Earth System Science》2006,115(4):473-484
Characteristics of trace gases (O3, CO, CO2, CH4 and N2O) and aerosols (particle size of 2.5 micron) were studied over the Arabian Sea, equatorial Indian Ocean and southwest part
of the Bay of Bengal during the monsoon transition period (October–November, 2004). Flow of pollutants is expected from south
and southeast Asia during the monsoonal transition period due to the patterns of wind flow which are different from the monsoon
period. This is the first detailed report on aerosols and trace gases during the sampled period as the earlier Bay of Bengal
Experiment (BOBMEX), Arabian Sea Monsoon Experiment (ARMEX) and Indian Ocean Experiments (INDOEX) were during monsoon seasons.
The significant observations during the transition period include: (i) low ozone concentration of the order of 5 ppbv around
the equator, (ii) high concentrations of CO2, CH4 and N2O and (iii) variations in PM2.5 of 5–20μg/m3. 相似文献
236.
Impacts on Global Ozone and Climate from Use and Emission of 2,2-Dichloro-1,1,1-Trifluoroethane (HCFC-123) 总被引:4,自引:0,他引:4
Analyses of emissions, and consequent chlorine loading, show that projected use of 2,2-dichloro-1,1,1-trifluoroethane (HCFC-123) will result in a virtually indiscernible impact on stratospheric ozone. Parametric scenarios uphold this conclusion, even for extreme levels of emissions far exceeding those of current technologies and practices. Additional scenarios reaffirm the conclusion for continued use – beyond the scheduled phaseout date – as a refrigerant in closed systems. By contrast, use of this compound offers unique opportunities to reduce global warming. Moreover, time-dependent analyses show that the minimal contribution to stratospheric chlorine from HCFC-123 emissions will not peak until more than a decade after the residual peaks of chlorine and bromine, from prior chlorofluorocarbon and halon releases, subside. While no single index exists to compare the relative demerits of ozone depletion and climate change, three conclusions are clear. First, reversal of the buildup of bromine and chlorine (i.e., healing of the ozone layer) is underway and progressing on target, while sufficient practical remedies for global climate change are far more difficult. Second, the analyses show that phaseout of all chlorinated, and conceptually – but much less probably – all brominated, compounds of anthropogenic origin targets some compounds that provide environmental benefits. Most chlorinated and brominated compounds do warrant phaseout; the exceptions are those with very short atmospheric lifetimes, and consequent low ozone depletion potential (ODP), that also offer offsetting environmental benefits. And third, since new global environmental concerns may, and probably will, be identified in the future, a more scientific approach is needed to determine environmental acceptability or rejection. 相似文献
237.
A special feature of the Bay of Bengal circulation is its seasonal variation in response to the monsoonal winds. In the case
of the Bay of Bengal, observationally very little is known about the large scale circulation. Theoretically, the problem of
driving the circulation in the Bay of Bengal is more complex than that in other basins because of the presence of large quantities
of fresh water discharge from Ganga-Brahmaputra-Meghna river systems, and also because the atmospheric driving forces even
within a season are highly variable with frequent occurrences of tropical disturbances. Exploring the nature of the circulation
in the Bay of Bengal is a problem of great importance in itself as well as for the critical role this region plays in the
genesis of tropical disturbances which are the main source of large scale rainfall over the northern part of the Indian subcontinent.
The surface circulation of the Bay of Bengal may, therefore, help in understanding the variation of rainfall over time scales
ranging from the subseasonal to the interannual.
Keeping this in view, an attempt was made towards the development of an oceanic climatological circulation model for the Bay
of Bengal, which explains the seasonal variability of the currents. The model is fully non-linear and vertically integrated,
with realistic basin geometry. The treatment of coastal boundaries involves a procedure leading to a realistic curvilinear
representation of the western and eastern sides of the Bay of Bengal. This coastal representation has the advantage of taking
into account the finer resolution in the shallow regions of the northern Bay.
The model is forced by the monthly mean wind stress derived from 30 years (1950–79) of Comprehensive Oceanographic Atmospheric
Data Sets (COADS). Special emphasis is given to the southern open boundary condition for the model. For this purpose, sensitivity
experiments have been performed with six open boundary conditions and a comparative study of the results has been made. These
sensitivity tests for the open boundary condition will help the development of a suitable coupled ocean-atmosphere model for
this region. The model-generated main features are in general agreement with the known climatological circulation of the Bay
of Bengal. 相似文献
238.
Natural Hazards - Cyclone tracks over the Great Lakes of North America shift, both East–West as well as North–South. The reasons for the shifts are various small-scale as well as... 相似文献
239.
240.
Validation of a new meteorological forcing data in analysis of spatial and temporal variability of precipitation in India 总被引:3,自引:0,他引:3
Lu Li Chong-Yu Xu Zengxin Zhang Sharad K. Jain 《Stochastic Environmental Research and Risk Assessment (SERRA)》2014,28(2):239-252
During the past two decades, numerous datasets have been developed for global/regional hydrological assessment and modeling, but these datasets often show differences in their spatial and temporal distributions of precipitation, which is one of the most critical input variables in global/regional hydrological modeling. This paper is aimed to explore the precipitation characteristics of the Water and Global Change (WATCH) forcing data (WFD) and compare these with the corresponding characteristics derived from satellite-gauge data (TRMM 3B42 and GPCP 1DD) and rain gauge data. It compared the consistency and difference between the WFD and satellite-gauge data in India and examined whether the pattern of seasonal (winter, pre-monsoon, monsoon and post-monsoon) precipitation over six regions [e.g. North Mountainous India (NMI), Northwest India (NWI), North Central India (NCI), West Peninsular India (WPI), East Peninsular India (EPI) and South Peninsular India (SPI)] of India agrees well for the gridded data to be useful in precipitation variability analyses. The multi-time scale of precipitation in India was analysed by wavelet transformation method using gauged and WFD precipitation data. In general, precipitation from WFD is larger than that from satellite-gauge data in NMI and Western Ghats region whereas it is smaller in the dry region of NWI. Both WFD and satellite-gauge datasets underestimate precipitation compared to the measured data but the precipitation from WFD is better estimated than that from satellite-gauge data. It was found that the wavelet power spectrum of precipitation based on WFD is reasonably close to that of measured precipitation in NWI and NCI, while slightly different in NMI. It is felt that the WFD data can be used as a potential dataset for hydrological study in India. 相似文献