Remote Sensing Analysis of Agroforestry in Bathinda and Patiala Districts of Punjab using Sub-pixel Method and Medium Resolution Data     

R. H. Rizvi  Ram Newaj  P. S. Karmakar  A. Saxena  S. K. Dhyani 《Journal of the Indian Society of Remote Sensing》2016,44(4):657-664

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Remote sensing techniques in establishing geomorphic-soil relationships     

R. S. Murthy  R. M. Pofali  R. K. Saxena 《Journal of the Indian Society of Remote Sensing》1982,10(2):1-11

Landform constitutes one of the important factors in establishing a firm relationship between soil development and pertinent morphological characteristics. Therefore, an understanding of the geomorphological processes helps to initiate studies in the characterisation of soil scapes. Landscape-soil relationships also assist in mapping soils rapidly and accurately. Remote sensing data products like aerial photographs and satelite imagery help in the recognition, delineation and satellite imagery help in the recognition, delineation and classification of landforms for genetical studies. Five sample areas selected from heterogeneous climatic environments distinctly reveal geomorphic-soil linkages. In the humid, highly weathered, sedimentary hilly terrain of Tripura, Udalfs, Ochrepts and Orthents are common while in the valleys Aqualfs, and Aquepts occur dominantly. In the arid and hilly terrain of Kutch, shallow Orthents and Orthids form the dominant soils but in the plains, deep Salorthids and Natrargids take a dominant place. The semihumid Malwa plateau and Nagpur consists of Ochrepts and Usterts.  相似文献   

Aquifer chemistry of the Puga and Chumatang high temperature geothermal systems in India     

V.K. Saxena  Franco D'Amore 《Journal of Volcanology and Geothermal Research》1984,21(3-4)

Results of a chemical study of the fluids from drill holes and hot springs of Puga and Chumatang areas in the northwestern part of the Himalaya are presented and discussed in this paper. The thermal waters of Puga and Chumatang are of Na-HCO₃-Cl and Na-HCO₃ types, respectively. A comparison between these waters, their chemical classification and activity studies suggest a flow path within a quartzitic-schistose basement, containing quartz, K-feldspar and illite, and in clayey terrains containing montmorillonite and illite.The chemistry of thermal waters also indicate their association with magmatic activity. The chemical geothermometers indicate the possible existence of a geothermal reservoir at Puga with temperature ≈250°C. The Chumatang area has a comparatively cooler reservoir with a temperature of 150–180°C.  相似文献   

Kinetics of Fe2+-Mg distribution in aluminous orthopyroxenes     

S. K. Saxena  V. Tazzoli  M. C. Domeneghetti 《Physics and Chemistry of Minerals》1987,15(2):140-147

Kinetic studies of isothermal heating experiments (600–800° C) on aluminous pyroxenes (Mg_0.942Fe _0.880 ²⁺ Fe _0.068 ³⁺ Mn_0.016Ca_0.010Al_0.084) (Si_1.848Al_0.152) permit the determination of rate constant of isothermal disordering as 2.5457 E13(±1.4 E13) min^?1. The activation energy is determined as 278 (±23) kJ/mol. Data on two other aluminous pyroxenes at 700° C indicate that the rate constant decreases significantly with increasing amount of trivalent cations. There is a similar but reverse correlation between the concentration of trivalent cations and the Fe²⁺-Mg equilibrium distribution between sites. The site distribution coefficient increases with increasing concentration of trivalent cations at constant temperature.  相似文献   

Assessment of land degradation hazards,etah district,uttar pradesh using landsat data     

RK Saxena  KS Verma  AK Barthwal 《Journal of the Indian Society of Remote Sensing》1991,19(2):83-94

To understand the nature of land degradation and factors responsible for it, investigations were carried out in Etah district with an area of 4.45 lakh hectares. For identification of soil/land degradation problems, multidate Landsat, TM spectral bands and FCC were used. It is observed that salt-affected soils are sharply depicted by light and dark gray mixed tone on band 3, while they are not clear on band 4. Flood plain and waterlogged soils are clearly observed on band 4. Band 6 (10.3 – 12.5 µm) helps in separation of broad zones of coarse and fine-textured soils, active flood plain of rivers, and eroded and gullied lands. The confusion between coarse-textured droughty soils and salt-affected areas in TM FCC (2, 3, 4) could be eliminated by use of band-6 data in combination with FCC. For delineation of problematic areas, two approaches were followed viz. (i) physiographic approach, and (ii) direct approach. In the physiographic approach landscape map associated with image characteristics was prepared. Further the image interpretation units were interpreted for land degradation hazards. With this approach physiography and soil relationship and the degradation problems vis-a-vis soil units could be established and ameliorative measures as per soil condition can be suggested. In direct approach, the problematic areas as per predetermined key were demarcated. Out of 4.45 lakh ha of the area, 1.99 lakh ha is affected by various soil degradation problems, like droughty soils, flooding hazard and salinity and alkalinity which cover 22.1%, 50.0% and 27.9%, respectively. To study the distribution of a salt-affected lands, major physiographic boundaries were superimposed over the land degradation map prepared by direct approach. It is observed that 81.5% of the salt-affected areas lie in the old alluvial plain while 18.5% is in recent flood plain.  相似文献   

Melting of wüstite and iron up to pressures of 600 kbar     

Guoyin Shen  Peter Lazor  Surendra K. Saxena 《Physics and Chemistry of Minerals》1993,20(2):91-96

The effect of pressure on melting temperature of wüstite and iron has been measured with laser-heated diamond anvil cell. The temperature was determined by measuring the thermal radiation emitted by the sample as a function of wavelength in the range from 600 nm to 900 nm to which Planck's radiation function was fitted; the pressure was measured by ruby-fluorescence technique. The melting curve of wüstite in this study when extrapolated to low pressures agrees with Lindsley's (1966) data. Our data are similar to the recent data of Boehler (1992) and close to that of Ringwood and Hibberson (1990) at pressure of 160 kbar, but the melting temperature does not rise as rapidly with increasing pressure as reported by Knittle and Jeanloz (1991). If tungsten emissivity is used in the temperature calculation, the melting curve of iron matches those of Boehler et al. (1990). Use of emissivity of iron in the temperature calculation results in somewhat higher temperatures than those reported by Boehler et al. (1990).  相似文献   

X-ray diffraction study of Fe2+-Mg order-disorder in orthopyroxene. Some kinetic results     

S. K. Saxena  M. C. Domeneghetti  G. M. Molin  V. Tazzoli 《Physics and Chemistry of Minerals》1989,16(5):421-427

Kinetic rates of Fe²⁺-Mg disordering in three orthopyroxenes (mean value of X_Fe = Fe²⁺/(Fe²⁺+Mg) = 0.175,0.482,0.770 respectively) have been determined employing heating experiments and single crystal X-ray structural refinements. Disordering rate constants \((\vec K)\) (550800° C) for two pyroxenes are given by: ln \((\vec K)\) = 27.107(±5.177)?32062(±783)T^?1(X_Fe = 0.175) ln \((\vec K)\) = 16.142(±0.057)?18227(±423)T^?1(X_Fe = 0.770) The distribution coefficients K_D (representing a steady state of disordering Fe_M2 + Mg_M1 ? Fe_M1 + Mg_M2) are given by: ln K_D = 5.016(±0.223)-7033(±1473) T^?1(X_Fe = 0.175) ln K_D = 1.988(±0.122)-3809(±913)T^?1(X_Fe = 0.770) These distribution coefficients provide the constraint of the disordering reaction on the value of the equilibrium constant for Fe²⁺-Mg order-disorder. Until the low temperature dependence of K_D is well constrained, the calculation of cooling rates of pyroxenes and host rocks cannot be done reliably.  相似文献   

Activity-composition relations in feldspars     

S. K. Saxena  P. H. Ribbe 《Contributions to Mineralogy and Petrology》1972,37(2):131-138

Seck's (1971a) compositional data on coexisting feldspars in the Or-Ab-An ternary at 650° C and 1 kb were used to calculate the activity-composition relations in binary alkali feldspar and binary plagioclase. The energy constants in Guggenheim's expression for excess free energy of mixing are A ₀=3920 and A ₁=657 cal/mole for alkali feldspar, in excellent agreement with values obtained by Thompson and Waldbaum (1969), and 1320 and 373 cal/ mole for plagioclase. Using Orville's (1972) data from ion-exchange experiments between plagioclase and Na—Ca chloride solutions at 700° C and 2 kb, we obtained 967 cal/mole for A ₀ and 715 cal/mole for A ₁ in the plagioclase crystalline solution.Activity-composition relations for plagioclase are interpreted in terms of a continuous, random substitution of CaAl for NaSi across the high structural state plagioclase series. This interpretation is consistent with that obtained from a consideration of lattice parameters.  相似文献   

Three-dimensional semi-idealized model for tidal motion in tidal estuaries     

Mohit Kumar  Henk M. Schuttelaars  Pieter C. Roos  Matthias Möller 《Ocean Dynamics》2016,66(1):99-118

In this paper, a three-dimensional semi-idealized model for tidal motion in a tidal estuary of arbitrary shape and bathymetry is presented. This model aims at bridging the gap between idealized and complex models. The vertical profiles of the velocities are obtained analytically in terms of the first-order and the second-order partial derivatives of surface elevation, which itself follows from an elliptic partial differential equation. The surface elevation is computed numerically using the finite element method and its partial derivatives are obtained using various methods. The newly developed semi-idealized model allows for a systematic investigation of the influence of geometry and bathymetry on the tidal motion which was not possible in previously developed idealized models. The new model also retains the flexibility and computational efficiency of previous idealized models, essential for sensitivity analysis. As a first step, the accuracy of the semi-idealized model is investigated. To this end, an extensive comparison is made between the model results of the semi-idealized model and two other idealized models: a width-averaged model and a three-dimensional idealized model. Finally, the semi-idealized model is used to understand the influence of local geometrical effects on the tidal motion in the Ems estuary. The model shows that local convergence and meandering effects can have a significant influence on the tidal motion. Finally, the model is applied to the Ems estuary. The model results agree well with observations and results from a complex numerical model.  相似文献   

Seismotectonic zones demarcation in the Shillong Plateau using the microearthquakes and radon emanation rate     

Devesh Walia  Andrew C. Lyngdoh  Atul Saxena 《Acta Geophysica》2010,58(5):893-907

The Shillong Plateau signifies the intense tectonic processes that the region has experienced during the Tertiary Indo-Tibetan and Indo-Burman collisions. An attempt has been made to study the microearthquake and radon emanation rate to understand and identify the seismotectonic zones.  相似文献