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51.
This paper aims at examining how the data for the geomechanical properties of slope material and for groundwater condition can be precisely and quickly collected, evaluated, and best used for optimum slope design in a block of phosphorite in an open cast mine. It is also directed at determining the influence of all the slope design parameters on the safety factor by using sensitivity analysis, which indicates that the effect of groundwater and friction angle is prominent in the slope. Suitable remedial measures, e.g., proper drainage and design of high slopes with relatively safe slope angle, have been planned for the critical slopes after sensitivity analysis. Monitoring of the designed slopes has revealed no movement. 相似文献
52.
A quick and simple procedure has been developed for evaluating maximum point rainfall for different return periods for any location in the plains of north India. According to this procedure, 2-year one-day rainfall of a location is estimated from the 2-year generalized chart of the region. Average district rainfall ratios for higher return periods of 5, 10, 25 and 50 years to 2-year return period are obtained with the help of (i) district average ratio map of 100/2 and (ii) frequency interpolation nomogram. The magnitudes of 5, 10, 25, 50 and 100-year rainfall are then obtained by multiplying the 2-year value by the corresponding district average ratios pertaining to different return periods. The estimates of point rainfall obtained by this procedure are quite comparable with those obtained directly by the Gumbel method. By using the procedure given in this study, a design engineer or a hydrologist can estimate point rainfall of different return periods for any station in north Indian plains without undertaking elaborate statistical calculations. 相似文献
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The concentration of dissolved Ba in a number of rivers having their drainage almost entirely in Deccan Trap basalts has been
measured. These results along with available data on the abundances of major elements in these waters, and on Ba and major
elements in bed sediments of these rivers provide a measure of (i) the relative mobility of Ba during chemical weathering
and erosion of basalts, particularly with respect to alkaline earths, Mg, Ca and Sr, and (ii) the flux of Ba out of the Deccan
and its global significance. The concentration of dissolved Ba ranges from 8 to 105 nM. The average Ba/Mg*, Ba/Ca* and Ba/Sr
(* is concentration corrected for atmospheric contribution) in waters is lower than the corresponding mean ratios in Deccan
basalts, though they overlap within errors. Majority of the water samples, however, have ratios less than that in basalts.
These findings can be interpreted as a cumulative effect of limited release/mobility of Ba during chemical weathering and
erosion of basalts and its reactive behaviour in waters which promote its association with clays and oxy-hydroxides of Fe.
These results also indicate that during chemical erosion of Deccan basalts, Ba is the least mobile among the alkaline earth
elements. The abundance of Ba in sediments and their Ba/Al ratios relative to basalts are consistent with the above conclusion.
Ba/Mg and Ba/Ca ratios in water and in sediments from the same location are strongly correlated; however, the mean ratios
in waters are far less than those in sediments. This is a result of limited Ba mobility, effectively 5–6 times lower than
that of Mg. The annual flux of dissolved Ba out of the Deccan Traps is ~1 × 107 moles, ~ 0.2% of its global riverine transport to oceans. The contribution of dissolved Ba from Deccan Traps, seem lower
than its aerial coverage, ~ 0.5% of the global drainage area; the potential causes for this could be the lower abundance of
Ba in basalts relative to “average continental crust”, and its behaviour during chemical weathering and erosion. 相似文献
56.
Anil V. Kulkarni Sunil Dhar B. P. Rathore Babu Govindha Raj K. Rajeev Kalia 《Journal of the Indian Society of Remote Sensing》2006,34(1):39-46
Himalayas possess one of the largest resources of snow, ice and glaciers that act as a huge freshwater reservoir. Monitoring
the glaciers is important to assess the overall reservoir health of the Himalayas. Samudra Tapu is one of the largest glaciers
in Chandra basin of district Lahaul and Spiti, Himachal Pradesh. Based on the field investigations and the remote sensing
techniques. features such as accumulation area, ablation area snowline/equilibrium line, moraine-dammed lakes and permanent
snowfields were mapped. The glacial terminus was identified using moraine-dammed lake, as lake is located at down streamside
of the terminus. The total recession of glacier during the period of 38 years (1962–2000) is about 742 m with an average rate
of 19.5 m/yr. In addition, glacial extent is reduced from 73 to 65 km2 between 1962 and 2000. suggesting overall deglaciation of 11%. During field investigation. three stages of glaciation using
terminal moraine were identified. These moraines were mapped by merging LISS-II1 and PAN data. At the peak of glaciation.
the glacial terminus was extended 3.18 km downstream of terminus position in year 2000. Total area during peak of glaciation
period has been observed to be 77.67 km2, which is 12.67 km2 higher than the present glacier extent. 相似文献
57.
Dipnarayan Ganguly Anirban Mukhopadhyay Rahul Krishna Pandey Debasish Mitra 《Journal of the Indian Society of Remote Sensing》2006,34(4):431-435
Study of landforms in Sundarbans deltaic estuary is necessary in regular basis due to its importance and impact on ecology,
climate and economy. Remote sensing has proved as an important tool to study this. Multi-temporal satellite data helps to
delineate the various geomorphic classes in different time domain and also provide inputs to study the coastal erosion and
accretion. Finer spatial and better temporal resolution will be an added adventure for this kind of study. 相似文献
58.
P Gupta V Khanna T Onong Thirunadha Rao N Dube D Dhar R Ramakrishnan K L Majumder 《Journal of the Indian Society of Remote Sensing》2002,30(1-2):7-13
In this paper, we have described a model to parallelize the resampling routine, which is used in the geometric correction of data provided by remote sensing satellites. Our model is a typical master-slave model consisting of N machines termed as hosts out of which one is designated as the master. The input image data resides on the master. Processing of the input image data is done in parallel on the N machines. Issues related to load-balancing and various error conditions that may occur during execution like one of the machines going down have been studied and are incorporated in the model. It also provides the flexibility to add or delete the hosts during the execution of the resampling routine. The serial version of this routine involves huge amount of computations and takes substantial amount of time even for an image of 473 MB. We have implemented our model with the help of PVM which is most often used in distributed computing environment. Our approach has been tested for geometric correction on LISS-III 4 band data of size 473 MB. It is found that if one uses 2, 3 or 4 hosts the overall execution time is reduced by 33%, 42% and 49%, respectively. 相似文献
59.
S. Dhar A. V. Kulkarni B. P. Rathore R. Kalia 《Journal of the Indian Society of Remote Sensing》2010,38(1):133-141
Peri-glacial studies of the Samudra Tapu glacier reveal three stages of well preserved moraines which are also marked by fluvial
overprinting. The signatures of fluvial outwashes over the otherwise morainal deposits have been utilized in estimating the
extent of palaeo-lake in the valley of Samudra Tapu glacier of the Chandra basin. Distance and thickness of snout of the glacier
and its morainal deposits is estimated by the Laser Range Finder. With the change in the position of the snout there is a
change in the extent and orientation of the lake. Recent expedition to the glacier confirms this process to be continuing.
The study is important in reconstructing formation of the lake with respect to snout position of the glacier. Based on ground
truth, fast melting of the snout is confirmed from year 2004 onwards, with the development of fresh end/terminal moraine.
The study reveals that the snout region of the Samudra Tapu glacier is thinning and retreating at an alarming rate and is
enlarging the lake extent. The development of fresh terminal moraine has the potential to impound the fast melting glacial
waters which in turn can pose serious threat to the downstream regions of the Chandra valley. 相似文献
60.
A. van Geen Z. Aziz A. Horneman B. Weinman R.K. Dhar Y. Zheng S. Goodbred R. Versteeg A.A. Seddique M.A. Hoque K.M. Ahmed 《Journal of Geochemical Exploration》2006,88(1-3):157
The extremely heterogeneous distribution of As in Bangladesh groundwater has hampered efforts to identify with certainty the mechanisms that lead to extensive mobilization of this metalloid in reducing aquifers. We show here on the basis of a high-resolution transect of soil and aquifer properties collected in Araihazar, Bangladesh, that revealing tractable associations between As concentrations in shallow (< 20 m) groundwater with other geological, hydrological, and geochemical features requires a lateral sampling resolution of 10–100 m. Variations in the electromagnetic conductivity of surface soils (5–40 mS/m) within a 500 m × 200 m area are documented with 560 EM31 measurements. The results are compared with a detailed section of groundwater As concentrations (5–150 μg/L) and other aquifer properties obtained with a simple sampling device, “the needle-sampler”, that builds on the local drilling technology. By invoking complementary observations obtained in the same area and in other regions of Bangladesh, we postulate that local groundwater recharge throughout permeable sandy soils plays a major role in regulating the As content of shallow aquifers by diluting the flux of As released from reducing sediments. 相似文献