Permeability of Layered Soils: An Extended Study

The coefficient of permeability of stratified soil deposits, when the flow is normal to the orientation of the bedding planes, has been observed to deviate from the value calculated theoretically. This deviation has been successfully explained in the past for a two-layer soil system by considering the coefficient of permeability of the exit layer as the controlling factor. The present technical note deals with the results from the study of permeability behavior of three-layer soil system. This study reinforces the point that the coefficient of permeability of a layered soil system, when the flow is normal to the orientation of the bedding planes, depends upon the relative positioning of the layers with different values of coefficient of permeability in the system.     

Change in entropy of non-spinning black holes w.r.t. the radius of event horizon in XRBs

The present research paper discusses the derivation for the change in entropy of Non- spinning black holes with respect to the change in the radius of event horizon applying the first law of black hole mechanics ( $\delta M = \frac{\kappa}{8\pi} \delta A + \varOmega\delta J - \upsilon\delta Q$ ) with the relation for the change in entropy δS=8πMδM. When the work is further extended with proper operation, the entropy of black hole is obtained almost the same as the Bekenstein-Hawking entropy of black hole. This is the entirely new method to obtain the change in entropy of Non-spinning black holes w.r.t. the radius of event horizon and Hawking entropy of black hole. We have also calculated their values for different types of test non-spinning black holes having masses 5–20M _⊙ found in X-ray binaries (Narayan, gr-qc/0506078v1, 2005).     

Effects of soil layering on the characteristics of basin-edge induced surface waves

This paper presents the effects of soil layering on the characteristics of basin-edge induced surface waves and associated strain and aggravation factor. The simulated results revealed surface wave generation near the basin-edge. The first mode of induced Love wave was obtained in models having increasing velocity with depth and a large impedance contrast between the soil layers. Amplitude amplification or de-amplification of body waves was proportional to the impedance contrast between the soil layers. The average aggravation factor was inversely proportional to the impedance contrast between the soil layers in case of increasingvelocity models and proportional in case of decreasing-velocity basinedge models. On the other hand, the maximum strain was inversely proportional to the impedance contrast between the soil layers in both cases. On the average, strain was greater in case of increasing-velocity models but the average aggravation factor was greater in case of decreasingvelocity models.     

An anomalous high-velocity layer at shallow crustal depths in the Narmada zone, India

The Narmada zone in central India is a zone of weakness that separates the region of Vindhyan (Meso-Neoproterozoic) deposition to the north from Gondwana (Permo-Carboniferous–lower Cretaceous) deposits to the south. The reinterpretation of analogue seismic refraction data, acquired during the early 1980s, using 2-D ray-tracing techniques reveals a basement (velocity 5.8–6.0 km s⁻¹ ) topography suggesting that the Narmada zone, bounded by the Narmada North and Narmada South faults is a region of basement uplift. A layer of anomalously high velocity (6.5–6.7 km s⁻¹ ) at depths between 1.5 and 9.0 km appears to be present in the entire region. Within the Narmada zone this layer occurs at shallower depths than outside the Narmada zone. At two places within the Narmada zone this layer is at a depth of about 1.5 km. This layer cannot be considered as the top of the lower crust because in this case it should have produced large positive gravity anomalies at the shallowest parts. Instead, these parts correspond to Bouguer gravity lows. Furthermore, lower crust at such shallow depths has not been reported from any other part of the Indian shield. Therefore, this layer is likely to represent the top of a high-velocity mafic body that has different thicknesses in different places.     

Spatio-temporal shift of western bank of the Ganga river,Allahabad city and its implications

Ganga is one of the largest rivers of the world which supports millions of population on its banks. It is a tectonically controlled Himalayan river which also creates havoc due to perennial floods every year. Like most large river systems, it also shifts its course in the Gangetic plains in space and time. The present study measures the variable shift in a selected flood-prone stretch of the Allahabad city lying on the western bank of the Ganga river, taking into account the historical, annual to monthly data (including pre- and post-monsoon shifts) to show the ongoing changes in the river course with possible causes and futher implications. It also discusses for the first time the down stream effect of the Tehri dam on the Ganga river course after it became functional.     

Ri-μi/μm-Ci dependent oblateness of deformed pebbles in the Baraitha conglomerate,Central India and tectonic implications

Strain analysis of the Baraitha conglomerate is attempted by direct measurements on extracted pebbles and by micrometric analysis. The overall deformation is of flattening type, with thek value lower by more than half in the matrix than in the pebbles. The viscosity contrast between pebbles and matrix (μ _i/μ_m) is in the ratio of 2:1 and the bulk deformation appears to be strongly controlled by C_i (concentration of pebbles expressed as percentage). The total shortening (≃35%) in the Baraitha conglomerate is comparable with the shortening accomplished in the folding of the overlying Bijawar Group volcanosedimentary sequence. The bulk strain axesX _t, Y_t andZ _t, as determined from the analysis of the deformed conglomerate, are unsymmetrically oriented with reference to folds formed by oblique flexural-slip with neitherX _t norY _tcoincident with the fold hinges. The lack of transection of folds by cleavage again suggests flattening deformation. The extension in theY _tdirection is greater in the matrix than in the pebbles.     

Quality characterization of groundwater in Koilsagar project area,Mahabubnagar District,Andhra Pradesh,India

Studies of groundwater chemistry in the Koilsagar project area of Andhra Pradesh indicate that the waters are sodium bicarbonate, sodium chloride, mixed cationic-mixed anionic, mixed cationic Na dominating bicarbonate, and mixed cationic Ca dominating bicarbonate types. Of them, sodium bicarbonate and mixed cationic Mg dominating bicarbonate types of waters are more prevalent.Isocone mapping of specific conductance indicates that the ionic concentration increases from east to west in the area. Graphical treatment of chemical data reveals that, in general, the area has basic water, whereas the left flank canal area is dominated by secondary alkaline water, and Pallamarri and Pedda Rajmur villages have strongly acidic waters. Ion-exchange studies show that cation-anion exchanges exist all over the area except for two places, which have a base exchange hardened type of water.Graphical representation further shows that most of the area has medium salinity-low sodium (C₂S₁) water useful for irrigation purposes. High salinity-low sodium (C₃S₁) and high salinity-medium sodium (C₃S₂) waters are present in some areas, which need adequate drainage to overcome the salinity problem.     

Estimation of heavy and opaque mineral contents of beach and offshore placers using rock magnetic techniques

Exploration for placer deposits involves heavy and opaque mineral data that are conventionally obtained using toxic and expensive chemicals and time-consuming and tedious microscopic counting of a large number of grains. In this investigation, we have used rock magnetic properties to obtain estimates of heavy and opaque mineral contents of placers from the SW coast of India. Magnetic susceptibility and other magnetic properties show strong correlations with heavy and opaque (r > 0.87 andr > 0.94; significant at the 1% level) mineral contents. As one or more types of magnetic minerals are invariably present in placers, magnetic properties may be used as a proxy for heavy and opaque mineral contents. This simple, rapid, inexpensive, and nondestructive method may be adopted by those involved in placer exploration to rapidly scan a large number of samples and delineate economically important pockets for more detailed investigations. This method saves considerable time and tedium. Using magnetic properties, rather than radioactivity, as a proxy for heavy and opaque mineral contents is more advantageous because one or more magnetic minerals are always present, but a radioactive mineral may not always be present in placers. An important limitation is that the ratio of magnetic to heavy/opaque mineral contents should not vary widely.