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1.
Surendra Singh K. D. Sharma Nepal Singh D. N. Bohra 《Journal of the Indian Society of Remote Sensing》1988,16(4):53-56
Temporal changes in ephemeral river courses and associated flood plains, which could not be detected by Landsat MSS due to its poor spatial resolution of 80m, have been identified and mapped within 10% accuracy by Landsat TM False colour composite because of its higher spectral and spatial resolution of 30 m. Over a period of 28 years (1958–86) the river courses widened upto 1.8 times through bank erosion due to the recurring flash floods. The flash floods have also caused morphological, soil fertility and landuse changes in the associated flood plains, which could also be monitored by the Landsat TM. 相似文献
2.
Bohra DM 《GeoJournal》1979,3(1):63-68
In this research paper attempts have been made to analyze the distribution of 68 urban settlements in 14 regions of the country.
The value of near-neighbour statistic (R) shows nearly random pattern of urban settlements in some regions and approachingly
uniform distribution of urban settlements in other regions. Regional distribution of urban settlements and their growth have
been explained in context of region's geographical, economic and industrial frameworks. 相似文献
3.
K. D. Sharma Surendra Singh Nepal Singh D. N. Bohra 《Journal of the Indian Society of Remote Sensing》1989,17(4):55-59
Traditional grazing lands in the Indian arid zone can be identified and mapped, reliably and reasonably within ±10% accuracy, through Landsat TM false colour composite of bands 2,3,4. Comparative study of Landsat TM and the Survey of India topographical maps revealed reduction in the areal extent of the grazing lands in the Jodhpur district up to 9 to 30% over a period of 28 years, between 1958 and 1986, due to the human activity like cultivation and urbanisation resulting in the desertification of the adjoining agriculturallands. 相似文献
4.
V. S. Prasad K. J. Ramesh A. K. Bohra R. C. Bhatia 《Meteorology and Atmospheric Physics》1998,68(3-4):197-212
Summary TOVS temperature profile data (SATEM) at its full resolution (85 km) has now become available in India on experimental basis. An attempt is made in this study to examine the quality and impact of this on the medium range forecasts over India and neighbourhood. For this purpose, a seven day period starting from 15 March 1996 is chosen to study the impact of the data on the global analysis-forecasting system operational in India. Though one week data is utilized for the impact study, the complete data of march 1996 is used for examining quality, representativeness and consistency of the retrievals. In the operational system of the National Centre for Medium Range Weather Forecasting (NCMRWF), all types of data, including coarse resolution (500 km) global TOVS retrievals-coarse grid SATEM (CGS) data, received on GTS at hourly intervals are used in the assimilation cycle. For the present study the assimilation cycle is repeated for the above period by including high resolution data over the geographical regions covered by the New Delhi's high resolution picture transmission (HRPT) station and simultaneously removing coarse resolution SATEM data. The analysis and forecast fields thus generated are compared with the corresponding operational archives. The impact of the data is examined in terms of various objective scores and through circulation characteristics.The study reveals that the quality of high resolution SATEM (HRS) data is satisfactory and is such that it can be utilized in the global data assimilation system on real-time basis. A general improvement in the RMSE and ACC scores of the medium range forecasts is found over the data void equatorial sectors of the Indian Ocean after the incorporation of the HRS data fields in the assimilation cycle. With regard to a typical easterly wave activity of moderate intensity during the period of experimentation a marginal modulation in low level vorticity and divergence forecasts is found to be improving the precipitation magnitudes over the south peninsular India as well.With 11 Figures 相似文献
5.
Himalayan rangelands, the crucial but by and large the neglected ecosystems, are an integral part of mountain farming systems. The present investigation is based on the extensive survey and collection of mid-altitude range plants from Almora and Champawat districts of Kumaun division in the Uttarakhand Himalaya in India, from September 2003 to June 2007. The rangelands studied were oak types, chirpine types, grass types and mixed ones. Some 300 species of grasses, other herbaceous plants, trees and shrubs were found in the mid-altitude rangelands. A sizeable number of species belonged to the family of Poaceae. The grass-dominated rangelands especially harboured a variety of grass species of good fodder value. The diversity of fodder plants is a proportion of the enormous biodiversity occurring in the parts of the Himalaya. A panorama of the biodiversity emerged in this study, which is of both intangible value and direct value for the livestock- and rangeland- dependent mountain communities, suggests a very high scope of the utilization of this natural and uncultivated biodiversity for supporting livestock- based livelihoods of the region. This biodiversity also has enormous bearing on the cultivated area of the region. 相似文献
6.
Archna Bohra B S Kotlia Amzad H Laskar M G Yadava 《Journal of Earth System Science》2014,123(3):603-616
A relict fluvio-lacustrine sediment of an 8 m thick section exposed at Kilang Sarai along Yunam river, near Baralacha La shows presence of cycloids or pseudonodules, ball and pillow structures, flame-like and pocket structures, sand dyke injections, bed dislocation/faulting and flow folds. Within this section four deformed levels of soft sediment structures have been identified which were dated ca. 25 ka BP at level 1 (～0.4 m from the modern river level (mrl), 20.1 ka BP at level 2 (～1.8 m mrl), 17.7 ka BP at level 3 (～2.56 m mrl) and 12.2 ka BP at level 4 (～4.25 m mrl)). Detailed study of these soft sediment structures allow us to demonstrate that deformation level 3 is not related to seismic trigger, but remaining three deformation levels (1, 2 and 4) are ascribed to seismic origin. From compilation of earlier palaeoseismological studies using soft sediment deformational structures (SSDS) in the palaeolake deposits in the adjoining area, suggest that the deformational events identified in the present study are regional in nature and thus tectonic process plays an important role in the evolution of landform in the Spiti region. 相似文献
7.
Archna Sagdeo S. K. Rai Gyan S. Lodha K. P. Singh Nisha Yadav R. Dhawan Umesh Tonpe M. N. Vahia 《Experimental Astronomy》2010,28(1):11-23
X-ray reflectivity measurements were performed on several thin foil gold mirrors fabricated in TIFR for a Soft X-ray Imaging
Telescope. The mirrors were made from thin aluminum foils with a reflecting layer of sputtered gold transferred from a smooth
glass mandrel using an epoxy. X-ray reflectivity measurements were performed on a sample of randomly selected mirrors using
CuK
α
(8.05 keV), CrK
α
(5.41 keV) X-rays and also at several energies in the energy range of 155–300 eV using the synchrotron source Indus-1. It
was found that the roughness of the low-density top gold layer as obtained from the fitting of X-ray reflectivity data for
CuK
α
radiation is relatively more as compared to that obtained from the CrK
α
radiation. This indicates that in the mirrors made by this process, the upper surfaces are smoother as compared to the deeper
layers. It was also observed that the critical angle almost vanishes in the very low energy range of 290–300 eV due to strong
absorption effects of the low density material sitting on top of these mirrors. Due to this absorption effect, efficiency
of these mirrors reduces in this energy range. This is first time that reflectivity measurements are being reported for very
soft X-rays (≤ 300 eV) for mirrors made for any X-ray astronomy mission. 相似文献
8.
Nepal Singh B K Sharma P C Bohra 《Journal of the Indian Society of Remote Sensing》2000,28(2-3):79-92
Visual interpretation ofIRS-LISS-II (1:50,000 Scale) FCC, band 2, 3 and 4 was carried out for the Industrial effluence assessment on soils (21900 ha) along the Bandi river course in Pali district of arid Rajasthan. Very severe (4378 ha), severe (3427 ha), moderate (5856 ha) and slight (1388 ha) categories of anthropogenic salt affected soils with the varied image characteristics in conjunction with ground truth Have been identified and delineated from satellite imagery. The morphological and physico-chemical characteristics revealed that very severe category soil has thick salt crust dominantly in light gray color at surface, manifestation of strong sub-angular to angular blocky structure, extra-ordinary hardness, high ECe, SAR and ESP but low pHs. Severe category soils have light brownish gray colour at surface, manifestation of strong angular to columnar structure, high Ece, pHs, SAR and ESP but slightly lower than very severe category.Moderate category soils have light brownish gray colour at surface, moderate to strong manifestation of prismatic structure, low ECe but high pHs, moderate to high SAR and ESP.Slight category soils have pale brown colour and hard crust at surface, moderate hardness with the tendency to form weak prismatic structure in subsoil, low ECe (<4dSm-) but moderate pHs. The cations and anaions in saturation extract was in the order of Na+>Ca++ > Mg++ > K+ and Cl- > SO4 -- > HCO3 -- > CO3 --, respectively and salinity/sodicity was Sodium-Chloride-Sulfate type. Dynamics of salt accumulation, available nutrient status and amelioration measures required for their reclamation and improvement has been discussed in this paper. 相似文献
9.
P. L. Kulkarni A. K. Mitra S. G. Narkhedkar A. K. Bohra S. Rajamani 《Meteorology and Atmospheric Physics》1997,64(1-2):61-82
Summary In this paper, a procedure for the computation of the divergent part of wind from Outgoing Longwave Radiation (OLR) data is described. This divergent part is included in the global analysis scheme and its impact is studied by computing the vertical velocity, velocity potential etc., using the analysed fields with and without modifying the divergent part and also making 24 hr and 48 hr rainfall forecasts.Results show that magnitudes of vertical velocity were increased when the divergent part was modified in the wind analysis. There were also changes observed in the analysed wind field over convective regions and the changes over the oceanic regions were higher, suggesting that the impact of divergent part is more pronounced over data sparse regions. Marginal increase was observed in 24 hr and 48 hr rainfall forecast over the Indian region. The area averaged rainfall forecast at each time step in the first 6 hours of model integration was also higher in the case when the wind field contained the divergent part.To sum up, it can be stated that the inclusion of the divergent part from OLR data in the initial wind field has brought out positive impact on the wind analyses and rainfall forecast.With 12 Figures 相似文献
10.