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1.
Contrasting Signals of Glacier Changes in Zanskar Valley,Jammu & Kashmir,India Using Remote Sensing and GIS 总被引：1，自引：0，他引：1
Swagata Ghosh A. C. Pandey M. S. Nathawat I. M. Bahuguna Ajai 《Journal of the Indian Society of Remote Sensing》2014,42(4):817-827
The study of advancement and recession of the glaciers in the Himalayas is essential due to their contrasting response towards climatic change. In the present study, Survey of India (SOI) topographical maps of 1962, IRS: LISS-III image of 2001 and LANDSAT-5: TM (Thematic Mapper) image of 2009 were used to analyze the glacier fluctuations in a part of Zanskar valley. The analysis carried out on 212 glaciers indicated decrease of 57 km2 (8 %) of glacier area over many glacier which was partly compensated with area increase by 42 km2 (6 %) in other glaciers, resulting an overall glacier area decrease by only 15 km2 (2 %) from 1962–2001. Due to glacier fragmentation the number of glaciers increased from 212 in 1962 to 238 by 2001. Although majority of glaciers (88 %) exhibited retreat (up to 13 my?1), minor advancement (<15 my?1) also took place in few glaciers during this period. Advancement took place mainly in larger glaciers (2–5 km2 and >5 km2) located over wider altitudinal range (700 m–1,000 m) whereas smaller glaciers (<2 km2) with narrow altitudinal range (100 m–500 m) exhibited retreat. The supraglacial debris analysis indicated that percentage of debris cover over glaciers ranges from 1.43 % to 18.15 %. Smaller glaciers (<2 km2) were debris free in comparison to the larger glaciers (>5 km2). During 2001–2009 majority of the glaciers were apparently stable in terms of their area and snout position indicating less impact of climate forcing in parts of Zanskar valley as compared to other parts of the Himalaya. 相似文献
2.
P. Jayaprasad B. Narender S. K. Pathan Ajai 《Journal of the Indian Society of Remote Sensing》2008,36(4):313-322
Digital elevation model (DEM) and the derived terrain parameters e.g. contour, slope, aspect, drainage pattern, etc are required
for natural resources management, infrastructure planning and disaster management. The present paper aims at generating DEM
from ERS tandem pair using interferometric technique supported by differential GPS measurements (DGPS) and multispectral optical
data. Validation of DEM has been carried out by DGPS measurements. Ground Control Points (GCP) established by DGPS measurements
have been used to georeference the IRS-1D optical data that has finally been co-registered with SAR amplitude image. Optical
data, co-registered with ERS - I SAR data has helped in locating the GCP’s and check points, precisely, for refinement of
DEM and its validation. 相似文献
3.
K. Nageswara Rao N. Sadakata Vasant Shinde A. S. Rajawat Ajai 《Frontiers of Earth Science》2010,4(4):410-416
The present study is an attempt to estimate the rates of subsidence in the Holocene sediments of the Godavari delta along
the east coast of India. Two boreholes dug at Panangipalli village in the delta revealed Early Historic culture material such
as potsherds including Coarse Red ware, Red-Slipped ware, Coarse Grey ware, and Black and Red ware, between 3.5 m and 9.0
m below the surface level. This suggests that the location was a human settlement of Andhra Satavahana period which flourished in the region between 3rd century BC and 3rd century AD. The fossil shells of Anadara sp. recovered from the borehole further downward at 11.5 m below the surface are considered to represent the intertidal swampy/lagoonal
environment. The age of the shells was determined through AMS 14C dating as 6400 cal a BP. The presence of about 2.5m thick intertidal swampy/lagoonal material between 9.0 m and 11.5 m depth,
suggests post-depositional subsidence at an average rate of less than 1.0 mm·a−1. However, a higher rate of subsidence of about 2.0 mm to 4.0 mm·a−1 is estimated for the upper 9.0 m thick floodplain sediment unit which embeds the Early Historic culture remains. The increased
rates of subsidence during the last two millennia when compared to the earlier period in this part of the Godavari delta could
be due to anthropogenic activity of deforestation and agriculture leading to accelerated soil erosion in the catchment and
increased sedimentation in the delta. 相似文献
4.
A detailed water quality analysis was carried out in the quaternary aquifer system of the marginal alluvial plain (Ganga Plain)
in Bah Tahsil, Agra district, India. The electrical conductivity of 50 samples each from dug wells, hand pumps and tube wells
was analysed for the study of salinity levels in shallow, intermediate and deep aquifers. Out of 50, 20 samples of each were
also analysed for other chemical constituents such as Na+, K+, Cl−, F− and TDS. The analyses show drastic changes in the salinity levels of shallow, intermediate and deep aquifers. The deep aquifers
are more saline compared to the shallow and intermediate aquifers. On the contrary, the concentration of chemical constituents
such as Na+, K+, Cl− and F− was more in the shallow aquifers compared to the deep aquifers. Moreover, there is an indication that the salinity and concentration
of the above chemical constituents also escalate with time in each aquifer. The chemical constituents such as Na+, K+, Cl−, F− and TDS range from 51 to 165 mg/l, 1 to 14 mg/l, 224 to 1,459 mg/l, 0 to 1.5 mg/l and 750 to 2,650 mg/l, respectively. Over
a 3-year period, the salinity levels have sharply increased and the average F level has increased by 0.1–0.3 mg/l. An attempt
has been made here to discuss the factors causing the variation and escalation of chemical constituents and salinity in the
water of the three aquifers. 相似文献
5.
Neogene deep sea benthic foraminiferal diversity in the Indian Ocean: Paleoceanographic implications
The species diversity indices, as defined by the number of species,S; Shannon-Wiener index,H(S) and Buzas-Gibson index,É, of DSDP sites 219, 220, 237 and 238 were measured to determine the benthic foraminiferal diversity patterns in the Indian Ocean deep sea sequences during the Neogene. The Time-Stability hypothesis could satisfactorily explain the observed diversity patterns. The general patterns of diversity suggest environmental stability during the Neogene. However, few small fluctuations in diversity during the Middle Miocene (c.14·8 Ma), Late Miocene (c.6·0 Ma) and Late Pliocene (c.2·0 Ma) may possibly be the effects of Antarctic Bottom Water (AABW) activity in this region. The benthic foraminiferal diversity in the tropical Indian Ocean is more than the high latitudinal areas with comparable depths. 相似文献
6.
Sujay Dutta S.A. Sharma A.P. Khera Ajai M. Yadav R.S. Hooda K.E. Mothikumar M.L. Manchanda 《ISPRS Journal of Photogrammetry and Remote Sensing》1994,49(6)
The accuracy of cotton crop classification using satellite data has been assessed with respect to a detailed land cover map prepared by field survey. The effect of spatial resolution on classification accuracy was studied using LISS-I (spatial resolution 72.6 m) and LISS-II data (spatial resolution 36.25 m) of the Indian remote sensing satellite IRS-1B. The performances of the maximum likelihood and the minimum distance to mean as classifiers have also been assessed. LISS-II data have been found to give a higher classification accuracy. The estimate of cotton acreage using LISS-II data was closer to that obtained from the base map. The maximum likelihood classifier (MXL) and the minimum distance to mean (MDM) classifier performed equally well. 相似文献
7.
Field studies were conducted on differentially irrigated wheat (Cv. ‘Sonalika’), on a sandy loam soil at Indian Agricultural Research Institute, New Delhi to evaluate the surface energy balance evapotranspiration (ET) models which use remotely sensed canopy temperature as an input. Four energy balance ET models were used in this study viz. Jackson et. al. (1977) approach; Bartholic et. al. (1970) and stability corrected and uncorrected aerodynamic resistance forms of models. To test the model, ET was estimated using remotely sensed canopy temperatrue, with the remaining to ET measured by water depletion method. Aerodynamic resistance forms of ET models performed well as compared to other models. Results indicate that remotely sensed canopy temperature as an input to surface energy balance models, offers a potential method of estimating ET from a cropped surface. 相似文献
8.
Canopy temperature in differentially irrigated and fertilized wheat plots were collected by hand held infrared thermometer from seedling emergence to maturity for two growing seasons (1981–82 and 1982–83). Canopy temperature indices like stress degree day (SDD) and crop water stress index (CWSI) based four-parameter (crop growth stage partitioned) and two-parameter (Non-partitioned) yield models suitable for remote sensing application were developed and tested with observed yield data. From statistical analysis of the models it was concluded that crop growth stage partitioned CWSI or SDD yield model was better than non-partitioned SDD models for predicting wheat grain as well as biological yields. 相似文献
9.
Ice sheets investigation is important with regard to climate change and contribution to the sea level rise or fall. Radar altimetry in complement with laser altimetry can serve as a suitable candidate for precise monitoring of ice sheet evaluations. SARAL due to higher observation into the polar region (up to 82.5°N) can cover nearly 100% of the Greenland ice sheet. Continuous ice tracking mode retracker can provide useful information about ice surfaces, that is, determining the snow coverage, ice sheet transaction margin, and the evolution of snow depth during winter more accurately. This study present the results obtained with SARAL satellite Altika radar altimeter over the Greenland ice sheet region. The altimeter high rate waveforms products are used for utilizing the full capability of the instrument. High resolution DEM (1 km) generated using ICESAT/GLAS altimeter has been used for selecting the good quality data over the study region. Four different retrackers—Ocean, ICE-1, ICE-2, and Sea-Ice—were tested on the SARAL altimeter data set and compared with the DEM extracted ice sheet elevations. Three different data analysis—region of interest (ROI), track analysis, and cross-over analysis—were performed for in-depth analysis of the ice height changes and back scattering coefficient variability. ROI's (1° × 0.5°) were selected based on accumulation dry snow zone, percolation zone, wet snow zone, and ablation zone. Finally to observe the effect of Ka band, SARAL results has been compared with the Envisat altimeter in terms of back scatter and error in the height retrieval due to penetration problem within the ice sheet layer. The new SARAL data set confirms the potential of ice altimetry and provides a new opportunity to monitor the ice sheet surface topography evolution. 相似文献
10.
Region-specific atmospheric range correction maps are generated over the Indian tropical region from Jason-1 & Jason-2 radar altimeters data. Seasonal and spatial variability of wet tropospheric correction (WTC), ionospheric correction (IC), dry tropospheric correction (DTC), and sea state bias (SSB) correction are analyzed over the Bay of Bengal and the Arabian Sea. Two year atmospheric range correction data from JASON-1 (2008) & JASON-2 altimeters (2009) has been analyzed where each Jason cycle is exactly 9.9156?days repeat. The monthly and yearly mean variation of the range correction parameters has been studied over the Indian continent. For precise study, four different regions were selected as the Region of Interest in the North & South of the Arabian Sea and Bay of Bengal. WTC, Significant Wave Height (SWH), Wind Speed (WS) and SSB show the higher values during monsoon months. The yearly mean WTC over Indian Tropical region was 26.22?cm in 2008 and 26.20?cm in 2009. SSB Correction values mainly depend on the SWH and wind speed. The yearly mean SSB correction over Indian Tropical region was 6.87?cm in 2008 and 7.02?cm in 2009. DTC values are less during monsoon season and it shows a high value in the month of January. The yearly mean DTC over Indian Tropical region was 230.42?cm in 2008 and 230.43?cm in 2009.The IC values mainly depend on frequency and total electron content (TEC) in the ionosphere which further depends on the solar activity. The yearly mean IC over Indian Tropical region was higher in 2008 (2.98?cm) in comparison to mean IC in 2009 (2.29?cm). This study is useful to understand the variability of atmospheric correction parameters especially over Indian continent. 相似文献