Application of remote sensing techniques in snow and ice hydrology     

C. P. Vohra  N. K. Agarwal  G. S. Srivastava 《Journal of the Indian Society of Remote Sensing》1981,9(1):49-57

The contribution of snow and ice melt towards the water discharges of most of the Himalayan rivers is highly significant. It is, therefore, necessary to monitor the snow accumulation and depletion, and study the melting processes to help in efficient management of water resources. It is also important to compile a glacier inventory for the purpose. The snow bound areas in the Himalaya lie at high altitudes where the terrain is rugged and inaccessible. This renders the conventional methods of study not only difficult but hazardous as well. Remote sensing techniques, therefore, have a vital role to play in these studies for quick results with much less cost. Visual interpretation of Landsat imagery in Beas river basin and use of aerial photographs for glacier inventory in Baspa river basin have been cited as case studies. To perfect the methodology used in various remote sensing techniques, a pilot project approach has been suggested.  相似文献   

A possible explanation of conductivity anomalies near Ujjain and Jaipur     

Agarwal  A K 《Journal of Earth System Science》1981,90(3):237-244

Journal of Earth System Science - Short-period events such as bays and SSCs have been analysed to investigate the nature of conductivity anomalies at two Indian magnetic observatories: Ujjain (UJJ)...  相似文献   

A generalized concept of resultant gradient to interpret potential field maps     

R.K. Shaw  B.N.P. Agarwal 《Geophysical Prospecting》1997,45(6):1003-1011

The existing concept of the gradient of the potential field anomaly over a 3D source has been generalized. An observed anomaly is modified through a filter based on an assumed source geometry. The first-order derivatives of this modified anomaly in three mutually orthogonal directions form the components of a vector termed the resultant gradient. The gravity anomaly over a point mass, a vertical line mass and the gravity/magnetic anomaly reduced-to-pole over a bottomless right rectangular prism have been suitably modified to yield a specific shape for the amplitude of the resultant gradient in order to decipher the depth of the source centroid/corner. The applicability of the proposed technique is demonstrated by the analyses of a simulated example over a composite source and a real example from published literature with drill-hole information.  相似文献   

Accuracy of mustard and wheat inventory at village-level using liss-II digital data in pali district, Rajasthan     

N L Purohit  F K Joshi  D S Sankhla  N Ravi  Sudha Ravindranath  V K Dadhwal 《Journal of the Indian Society of Remote Sensing》1997,25(3):163-168

A study was carried out to estimate the accuracy of crop discrimination and area inventory for wheat and mustard using IRS LISS-II digital data of two acquisition dates D1 (Dec. 28, 1994) and D2 (Feb. 10, 1995) over a test site (1413 ha) comprising of two villages in Pali district, Rajasthan, The D1 and D2 were optimal acquisitions for mustard and wheat respectively with deviations in aereage estimates of less than five per cent in comparison to field survey. The percent correctly classified pixels ter training site for optimal dates of each crop ranged between 85 and 86 per cent and they were much lower for other dates. These results with lower accuracies than reported earlier for sites with single dominant crop are indicative of accuracies for discrimination and area inventory fot sites having two crops and also sensitivity to acquisition period.  相似文献   

District-level mustard crop estimation for rajasthan: improving precision by in-season digital stratification     

D S Sankhla  N L Purohit  F K Joshi  N Ravi  Sudha Ravindranath  V K Dadhwal 《Journal of the Indian Society of Remote Sensing》1997,25(3):169-175

The acreage and yield of mustard crop in Rajasthan shows year to year variation. In the present study CAPE, analysis by incorporating digital stratification with current season data and comparison of coefficient variation (CV) at district level using conventional stratification with previous season data was undertaken. The stratification approach using current year’s data for mustard acreage estimation was adopted during 1994-95 and 1995-96 crop seasons and regional CV of less than 2 per cent was attained. A comparison of CV at district level for the years 1994-95 and 1995-96 with those obtained in previous two seasons (1992-93, 1993-94) indicated considerable improvement in precision (lower CV) is 7 out of 11 study districts. Mustard acreage estimate for Bharatpur (1995-96) had CV of 10.1 percent when conventional approach (past year data) for stratification was used. However, with the use of current year data for stratification CV reduced to 4.4 per cent The study suggests that use of in-season data for stratification improves precision for acreage estimation of crops like mustard which has high year to year variation in area.  相似文献   

Global Positioning System measurements of strain accumulation and slip transfer through the restraining bend along the Dead Sea fault system in Lebanon   总被引：1，自引：0，他引：1  

Francisco Gomez  Gebran Karam  Mohamad Khawlie  Simon McClusky  Philippe Vernant  Robert Reilinger  Rani Jaafar  Charles Tabet  Kamal Khair  Muawia Barazangi 《Geophysical Journal International》2007,168(3):1021-1028

  相似文献   

Drive-Control System for the TACTIC Gamma-Ray Telescope     

A. K. Tickoo  R. Koul  S. K. Kaul  I. K. Kaul  C. L. Bhat  N. G. Bhatt  M. K. Kothari  H. C. Goyal  N. K. Agarwal  S. R. Kaul 《Experimental Astronomy》1999,9(2):81-101

A PC-based drive-control system has been developed for the altitude-azimuth mounted TACTIC -ray telescope to control the speed and direction of motion of its 2-axes. Details of various hardware components chosen for the telescope, including hybrid-stepper motor, 16-bit absolute encoder and CAMAC-based programmable stepper motor controller, are discussed in this paper. The telescope-control strategy, based on the position-loop with a proportional type control for the source-seek mode and the on/off type control for the tracking mode, is explained in detail. Some important performance features of the telescope, including its blind-spot size, drive-system backlash and encoder-error compensation, are also presented. The drive system has been extensively field-tested and has been operating satisfactorily during observation campaigns carried out since March 1997 with the TACTIC Imaging Element. A tracking accuracy of ±3 arc-minutes has been achieved. A test report of its performance, with regard to its tracking accuracy on the basis of successful detection of TeV -rays from the active galaxy Markarian 501 in April–May 1997, is also presented.  相似文献   

Toxicity of Pesticides to Fecundity,Hatchability and Survival of Young Snails of Lymnaea acuminata     

D. K. Singh  R. A. Agarwal 《洁净——土壤、空气、水》1986,14(2):191-194

The effects of carbaryl and phorate on the fecundity and hatchability of the snail Lymnaea acuminata, the survival of young snails were studied. It was observed that the fecundity of Lymnaea acuminata was reduced only at the 11.00 mg/l concentration of carbaryl and phorate, whereas a time- and dose dependent reduction in the hatchability of exposed eggs and the survival of young snails was observed.  相似文献   

Synergistic Effect of Sulfoxide with Carbaryl on the in vivo Acetylcholinesterase Activity and Carbohydrate Metabolism of the Snail Lymnaea acuminata     

D. K. Singh  R. A. Agarwal 《洁净——土壤、空气、水》1986,14(4):421-427

The synergistic effects of sulfoxide on the effects of carbaryl in the snail Lymnaea acuminata were studied. Snails were exposed to 40 % and 80 % of 48 h LC⁵⁰ doses of synergist, carbaryl mixture (5 : 1). While the concentration of carbaryl present in the mixture would not bring about any change in carbohydrate metabolism, there was a marked decrease in the AChE activity, glycogen levels and an increase in lactic acid and a reduction of sugar levels when the snails were exposed to a carbaryl synergist mixture. Sulfoxide alone also caused a decrease in glycogen levels and an increase in lactic acid levels. These changes, however, were smaller as compared to those resulting from exposure to the mixtures.  相似文献   

Primary and secondary structures in the polymetallic ores of Rajpura-Dariba,Rajasthan, India     

N. G. K. Nair  N. K. Agarwal 《Mineralium Deposita》1976,11(3):352-356

The Precambrian Rajpura-Dariba polymetallic deposits of Rajasthan, associated with black schists, quartzite and calcsilicate rocks, exhibit several primary structures, suggesting a syn-sedimentary origin. The secondary features of the sulphides are attributed to the effects of metamorphism.  相似文献