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P. Kotoky M. K. Dutta R. Goswami G. C. Borah 《Journal of the Geological Society of India》2011,78(2):175-183
The bank sediments along the extremely meandered Dhansiri River channel, a south bank tributary of the mighty Brahmaputra
River, with erosion potentiality have been investigated to evaluate its certain geotechnical characteristics. The study has
shown that the bank sediments are basically composed of CL and ML types of soil. These types of sediments are very much prone
to liquefaction which in turn related to erosion susceptibility. The bank stability analysis has differentiated the studied
stretch into unstable, at risk and stable zones. Most of the erosion affected zones along the channel reach under study are
located within the unstable or at risk zones. The field study around Butalikhowa, Barguriagaon, Golaghat and Duchmuagaon areas
along the channel with active erosion activity has supported our contention and practical utility of the present study. It
is expected that such type of study will help in providing certain inevitable baseline information for various channel management
practices for this extremely flood prone areas of Northeast India. 相似文献
3.
Having recognized that it is the tropospheric temperature (TT) gradient rather than the land–ocean surface temperature gradient that drives the Indian monsoon, a new mechanism of El Niño/Southern Oscillation (ENSO) monsoon teleconnection has been unveiled in which the ENSO influences the Indian monsoon by modifying the TT gradient over the region. Here we show that equatorial Pacific coralline oxygen isotopes reflect TT gradient variability over the Indian monsoon region and are strongly correlated to monsoon precipitation as well as to the length of the rainy season. Using these relationships we have been able to reconstruct past Indian monsoon rainfall variability of the first half of the 20th century in agreement with the instrumental record. Additionally, an older coral oxygen isotope record has been used to reconstruct seasonally resolved summer monsoon rainfall variability of the latter half of the 17th century, indicating that the average annual rainfall during this period was similar to that during the 20th century. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
4.
Subhas Dutta 《Pure and Applied Geophysics》1962,52(1):20-26
Summary The possibility of propagation of Rayleigh waves in a transversely isotropic medium resting on (i) a rigid base and (ii) a yielding base has been studied in this paper. In the former case the relation between the wave velocity and ratio of wave length to thickness has been found and in the latter case the frequency equation and its possible solutions are obtained. 相似文献
5.
A Case Study on Forewarning of Yellow Rust Affected Areas on Wheat Crop Using Satellite Data 总被引:2,自引:0,他引:2
Sujay Dutta Suresh Kumar Singh Mukesh Khullar 《Journal of the Indian Society of Remote Sensing》2014,42(2):335-342
Objective of this study was to identify stripe rust affected areas of wheat crop as well as evaluation of remote sensing (RS) derived indices. Moderately low temperature and high humidity favour the growth of yellow rust. Most affected areas of Punjab are the foothill districts such as Gurdaspur, Hoshiarpur and Ropar. Occurrence of yellow rust is possible when maximum temperature for day is below 15 °C and Temperature difference of day’s maximum and minimum temperature is less than 5 °C during the early growth of wheat. Forecast of the infestation was done using 3 days forecast of weather data obtained from Weather Research and Forecasting (WRF) model at 5 km resolution. Weather forecast used was obtained from Meteorological and Oceanographic Satellite Data Archival System (MOSDAC) site and post infestation, identification of specific locations were done using multi-date IRS AWiFS data. It is an attempt for early detection through 3 days advance forewarning of weather which will be handy tool for planners to expedite relief measures in case of epidemic with a more focused zones of infestation as well as for crop insurers to know the location and extent of damage affected areas. 相似文献
6.
Arpita Sharma Ananya Saikia Puja Khare D K Dutta B P Baruah 《Journal of Earth System Science》2014,123(6):1439-1449
In Part 1 of the present investigation, 37 representative Eocene coal samples of Meghalaya, India were analyzed and their physico-chemical characteristics and the major oxides and minerals present in ash samples were studied for assessing the genesis of these coals. Various statistical tools were also applied to study their genesis. The datasets from Part 1 used in this investigation (Part 2) show the contribution of major oxides towards ash fusion temperatures (AFTs). The regression analysis of high temperature ash (HTA) composition and initial deformation temperature (IDT) show a definite increasing or decreasing trend, which has been used to determine the predictive indices for slagging, fouling, and abrasion propensities during combustion practices. The increase or decrease of IDT is influenced by the increase of Fe2O3, Al2O3, SiO2, and CaO, respectively. Detrital-authigenic index (DAI) calculated from the ash composition and its relation with AFT indicates Sialoferric nature of these coals. The correlation analysis, Principal Component Analysis (PCA), and Hierarchical Cluster Analysis (HCA) were used to study the possible fouling, slagging, and abrasion potentials in boilers during the coal combustion processes. A positive relationship between slagging and heating values of the coal has been found in this study. 相似文献
7.
Evolution of a homogeneous, isotropic Universe with flat geometry filled with a viscous fluid is investigated in presence
of a variable cosmological Λ. A non-singular solution leading to a variable deceleration parameter is obtained which reduces
to the solution of Murphy in the ‘no Λ limit’ and to the recent solution of Vishwakarma in the context of ‘a Machian model
of dark energy’ in the ‘no viscosity’ limit. 相似文献
8.
Automatic change detection of land cover features using high-resolution satellite images, is a challenging problem in the field of intelligent remote sensing data interpretation, and is becoming more and more effective for its applications viz. urban planning and monitoring, disaster assessment etc. In the present study, a change in detection approach based on the image morphology that analyses change in the local image grids is proposed. In this approach, edges from both the images are extracted and grid wise comparison is made by probabilistic thresholding and power spectral density analysis for identifying change area. One of the advantages of the proposed methodology is that the temporal images used in the change analysis need not be radiometrically corrected as analysis is based on edge extractions. The grid-based analysis further reduces the error, which might have been introduced by image mis-registration. The proposed methodology is validated by finding the temporal changes in the linear land cover features in parts of Kolkata city, India using three different image data-sets from LISS IV, Cartosat-1 and Google earth having varied spatial resolutions of 5.8 m, 2.5 m and about 1 m, respectively. The overall accuracy in identifying changes is found to be 64.82, 73.86 and 80.93% for LISS IV, Cartosat-1 and Google earth data-set, respectively. 相似文献
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