Soil Loss Mapping for Sustainable Development and Management of Land Resources in Warora Tehsil of Chandrapur District of Maharashtra: An Integrated Approach Using Remote Sensing and GIS     

M. S. S. Nagaraju  G. P. Obi Reddy  A. K. Maji  Rajeev Srivastava  P. Raja  A. K. Barthwal 《Journal of the Indian Society of Remote Sensing》2011,39(1):51-61

The study area is characterized by low and fluctuating rainfall pattern, thin soil cover, predominantly rain-fed farming with low productivity coupled with intensive mining activities, urbanization, deforestation, wastelands and unwise utilization of natural resources causing human induced environmental degradation and ecological imbalances, that warrant sustainable development and optimum management of land resources. Spatial information related to existing geology, land use/land cover, physiography, slope and soils has been derived through remote sensing, collateral data and field survey and used as inputs in a widely used erosion model (Universal Soil Loss Equation) in India to compute soil loss (t/ha/yr) in GIS. The study area has been delineated into very slight (<5 t/ha/yr), slight (5–10 t/ha/yr), moderate (10–15 t/ha/yr), moderately severe (15–20 t/ha/yr), severe (20–40 t/ha/yr) and very severe (>40 t/ha/yr) soil erosion classes. The study indicate that 45.4 thousand ha. (13.7% of TGA) is under moderate, moderately severe, severe and very severe soil erosion categories. The physiographic unit wise analysis of soil loss in different landscapes have indicated the sensitive areas, that has helped to prioritize development and management plans for soil and water conservation measures and suitable interventions like afforestation, agro-forestry, agri-horticulture, silvipasture systems which will result in the improvement of productivity of these lands, protect the environment from further degradation and for the ecological sustenance.  相似文献   

Relationship between abundance and morphology of benthic foraminifera <Emphasis Type="Italic">Epistominella exigua</Emphasis>: Paleoclimatic implications     

R. Saraswat  A. Deopujari  R. Nigam  P. J. Heniriques 《Journal of the Geological Society of India》2011,77(2):190-196

The relationship between abundance (relative as well as absolute abundance) and morphology (size of the shell, number of chambers and proloculus size) of benthic foraminifera Epistominella exigua has been studied in a core to understand the influence of changing environmental conditions on its morphology and distribution. A total of 50 samples from the top 100 cm section of a gravity core collected from the southern Bay of Bengal Fan were used. The changes in abundance of E. exigua match well with variation in average proloculus size of E. exigua. An opposite relationship however, is observed between the abundance and size of E. exigua shells. The higher abundance corresponds with smaller E. exigua shells. Similarly, the increased E. exigua abundance matches with a decrease in the number of chambers. The increased abundance of E. exigua shows favourable conditions for its growth and survival. Thus the study indicates that during favourable conditions, while the number of chambers in the shells and the size of the shells of E. exigua decreases, more number of specimens have a larger proloculus. Since asexual reproduction results in megalospheric specimens with larger proloculus, smaller size and less number of chambers, it is inferred that E. exigua prefers an asexual mode of reproduction during favorable conditions. The findings can be used to apply morphological characteristics of E. exigua as a proxy to infer past climatic conditions.  相似文献   

Dark energy models with anisotropic fluid in Bianchi Type-VI 0 space-time with time dependent deceleration parameter     

Anirudh Pradhan  Rekha Jaiswal  Kanti Jotania  Rajeev Kumar Khare 《Astrophysics and Space Science》2012,337(1):401-413

We present two dark energy (DE) models with an anisotropic fluid in Bianchi type-VI ₀ space-time by considering time dependent deceleration parameter (DP). The equation of state (EoS) for dark energy ω is found to be time dependent and its existing range for derived models is in good agreement with the recent observations. Under the suitable condition, the anisotropic models approach to isotropic scenario. We also find that during the evolution of the universe, the EoS parameter for DE changes from ω>−1 to ω=−1 in first model whereas from ω>−1 to ω<−1 in second model which is consistent with recent observations. The cosmological constant Λ is found to be a positive decreasing function of time and it approaches a small positive value at late time (i.e. the present epoch) which is corroborated by results from recent type Ia supernovae observations. The cosmic jerk parameter in our derived models is also found to be in good agreement with the recent data of astrophysical observations. The physical and geometric aspects of both the models are also discussed in detail.  相似文献   

A fossil palm leaf impression from ∼11.2 Ma old,Siwalik deposits of Kangra Valley,Himachal Pradesh     

Ram Ratan Singh  Rajeev Patnaik 《Journal of the Geological Society of India》2012,79(1):85-88

We report here, a fossil palm leaf from Lower Siwalik sediments, tied to nearby palaeomagnetically dated 11.2 Ma old beds exposed in the Baner Khad, near Ranital, Himachal Pradesh. The palm fossil leaf impression has been placed in the genus Palmacites sp. (Family: Arecaceae) based on its diagnostic features such as large palmate leaf without hastula and costa (midrib), showing coriaceous texture, leaflets diverging from the base of the lamina with prominent midrib and parallel venation. This finding may indicate presence of tropical to subtropical climatic conditions in the Himalayan foothills around Kangra Valley in the Middle Miocene time.  相似文献   

Linkage between Seasonal Insolation Gradient in the Tropical Northern Hemisphere and the Sea Surface Salinity of the Equatorial Indian Ocean during the Last Glacial Period     

Saraswat RAJEEV  Nigam RAJIV  Mackensen ANDREAS  Weldeab SYEE 《《地质学报》英文版》2012,86(5):1265-1275

Paired stable oxygen isotope and Mg/Ca analyses in calcite tests of the mixed-layer-dwelling planktic foraminifer Globigerinoides ruber has been used to reconstruct equatorial Indian Ocean δ18O of seawater (δ18Osw) over the last ~137 thousand years. On the basis of ice-volume-corrected δ18Osw (δ18Osw–ivc), relative changes in sea surface salinity (SSS) have been estimated. The SSS estimates suggest three episodes of higher SSS (131–113 thousand years before present (kyr BP), 62–58 kyr BP, and 30–24 kyr BP) within the last glacial period as compared with the present. SSS comparison between interglacial episodes reveals that the surface seawater over the core site was significantly saltier during the penultimate interglacial than the Holocene. We suggest that the evolution of a seasonal insolation gradient between the Indian monsoon areas and the equator over the investigated time interval was instrumental in shaping the strength of the Indian winter and summer monsoons that left their imprints on the equatorial Indian Ocean SSS via freshwater input and wind-induced mixing. The study shows that the insolation difference between northern latitudes and the equator during winter affects monsoon strength in the Indian region, especially during cold intervals.  相似文献   

New type of possible high-pressure polymorphism in NiAs minerals in planetary cores     

Przemyslaw Dera  Jawad Nisar  Rajeev Ahuja  Sergey Tkachev  Vitali B. Prakapenka 《Physics and Chemistry of Minerals》2013,40(2):183-193

The nickel arsenide (B8₁) and related crystal structures are among the most important crystallographic arrangements assumed by Fe and Ni compounds with light elements such as Si, O, S, and P, expected to be present in planetary cores. Despite the simple structure, some of these materials like troilite (FeS) exhibit complex phase diagrams and rich polymorphism, involving significant changes in interatomic bonding and physical properties. NiP (oP16) represents one of the two principal structure distortions found in the nickel arsenide family and is characterized by P–P bonding interactions that lead to the formation of P₂ dimers. In the current study, the single-crystal synchrotron X-ray diffraction technique, aided by first principles density functional theory (DFT) calculations, has been applied to examine the compression behavior of NiP up to 30 GPa. Two new reversible displacive phase transitions leading to orthorhombic high-pressure phases with Pearson symbols oP40 and oC24 were found to occur at approximately 8.5 and 25.0 GPa, respectively. The oP40 phase has the primitive Pnma space group with unit cell a = 4.7729(5) Å, b = 16.6619(12) Å, and c = 5.8071(8) Å at 16.3(1) GPa and is a superstructure of the ambient oP16 phase with multiplicity of 2.5. The oC24 phase has the acentric Cmc2₁ space group with unit cell a = 9.695(6) Å, b = 5.7101(9) Å, and c = 4.7438(6) Å at 28.5(1) GPa and is a superstructure of the oP16 phase with multiplicity of 1.5. DFT calculations fully support the observed sequence of phase transitions. The two new phases constitute logical next stages of P sublattice polymerization, in which the dilution of the P₃ units, introduced in the first high-pressure phase, decreases, leading to compositions of Ni₂₀(P₃)₄(P₂)₄ and Ni₁₂(P₃)₄, and provide important clues to understanding of phase relations and transformation pathways in the NiAs family.  相似文献   

Tectonic and magmatic evolution of the eastern Karakoram,India     

Rajeev Upadhyay  Anshu K. Sinha  Rakesh Chandra  Hakim Rai 《Geodinamica Acta》2013,26(6):341-358

Abstract

The Shyok suture zone separates the Ladakh terrane to the SW from the Karakoram terrane to the NE. Six tectonic units have been distinguished. From south to north these are; 1. Saltoro formation; 2. Shyok volcanites; 3. Saltoro molasse; 4. Ophiolitic melange; 5. Tirit granitoids; 6. Karakoram terrane including the Karakoram batholith. Albian—Aptian Orbitolina-bearing lime-stones and turbidites of the Saltoro formation tectonically overlie high-Mg-tholeiites similar to the tectonically overlying Shyok volcanites. The high-Mg tholeiitic basalts and calcalkaline andesites of the Shyok volcanites show an active margin signature. The Saltoro molasse is an apron-like, moderately folded association of redgreen shales and sandstones that are interbedded with ~ 50 m porphyritic andesite. Desiccation cracks and rain-drop imprints indicate deposition in a subaerial fluvial environment. Rudist fragments from a polygenic conglomerate of the Saltoro molasse document a post-Middle Cretaceous age. The calcalkaline andesites of the Shyok volcanites are intruded by the Tirit granitoids, which are located immediately south of the Ophiolitic melange and belong to a weakly deformed trondhjemite-tonalite-granodiorite-granite suite. These granitoids are subalkaline, I-type and were emplaced in a volcanic arc setting. The subalkaline to calcalkaline granitoids of the Karakoram batholith are I-and S-type granitoid. The I-type granitoids represent a typical calcalkaline magmatism of a subduction zone environment whereas the S-type granitoids are crustderived, anatectic peraluminous granites. New data suggest that the volcano-plutonic and sedimentary successions of the Shyok suture zone exposed in northern Ladakh are equivalent to the successions exposed along the Northern suture in Kohistan. It is likely that the o istan and Ladakh blocks evolved as one single tectonic domain uring the Cretaceous-Palaeogene. Subsequently, collision, suturing and accretion of the Indian plate along the Indus suture (50–60 Ma) together with tectonic activity along the Nanga Parbataramosh divided Kohistan and Ladakh into two arealy distinct magmatic arc terranes. The activity and a dextral offset along the Karakoram fault (Holocene-Recent) disrupted the original tectonic relationships. © 1999 Éditions scientifiques et médicales Elsevier SAS  相似文献   

Seismic stability of two interconnected steel structures freely standing on the floor     

A. Saraswat  G. R. Reddy  C. Umashankar  Y. M. Parulekar  A. K. Ghosh 《Bulletin of Earthquake Engineering》2016,14(11):3259-3282

Nuclear fuel fabrication and reprocessing facilities have glove boxes that are extensively used as a primary containment for radiological material. These equipment are maintained under negative pressure using ventilation system and possess high degree of leak tightness. Sometimes, they are used as a standalone structure and many a times, interconnected to each other. Normally, they are not anchored to the floor, which raises serious concerns about their seismic performance. To check seismic stability of the glove boxes and evaluate safety margins in design, tri directional fullscale shake table experiments of two interconnected glove boxes had been carried out. Two configurations were compared; in first, both the boxes were connected through flexible linkage (material transfer tunnel) and in second both were rigidly connected via structural members. Objective of experiments was to observe effects of seismic excitation on leak tightness, structural integrity and overall stability of two interconnected glove boxes. Subsequently, nonlinear finite element analysis was carried out to establish and develop analysis methodology. Experimental results were utilized for model benchmarking. Furthermore, a numerical method was developed to determine safe upper bounds on sliding displacements. This paper highlighted critical findings emanated from experimental results and examined their effect on seismic stability. Enhanced seismic stability in case of rigidly connected boxes was observed. Rigid body motions (mainly sliding and low magnitude rocking) dominated the response with very limited effect of elastic motions. Methodology used for modelling and analyzing glove boxes under seismic loading using finite element methods was also presented.  相似文献   

A Study of Early/Slow VLF Perturbations Observed at Agra,India     

Uma Pandey  Ashutosh K. Singh  Om P. Singh  Birbal Singh  Vibhav K. Saraswat 《Acta Geophysica》2016,64(3):755-771

We present here the results of sub-ionospheric VLF perturbations observed on NWC (19.8 kHz) transmitter signal propagating in the Earth-ionosphere waveguide, monitored at our low latitude station Agra. During the period of observation (June-December 2011), we found 89 cases of VLF perturbation, while only 73 cases showing early character associated with strong lightning discharges. Out of 73 events, 64 (~84%) of the early VLF perturbations are found to be early/slow in nature; the remaining 9 events are early/fast. The onset duration of these early/slow VLF perturbations is up to ~ 5 s. A total of 54 observed early events show amplitude change lying between ± 3.0 dB, and phase change ± 12 degree, respectively, and found to occur mainly during nighttime. One of the interesting results we found is that the events with larger recovery time lie far away from the VLF propagation path, while events with smaller duration of recovery are within the ± 50–100 km of signal path. The World Wide Lightning Location Network (WWLLN) data is analysed to find the location of causative lightning and temporal variation. The lightning discharge and associated processes that lead to early VLF events are discussed.  相似文献   

Differential behaviour of a Lesser Himalayan watershed in extreme rainfall regimes     

Pankaj Chauhan  Nilendu Singh  Devi Datt Chauniyal  Rajeev S Ahluwalia  Mohit Singhal 《Journal of Earth System Science》2017,126(2):22

Climatic extremes including precipitation are bound to intensify in the global warming environment. The present study intends to understand the response of the Tons sub-watershed in Lesser Himalaya, in 3 years with entirely different hydrological conditions (July 2008–June 2011) in terms of discharge, sediment flux and denudation rates. Within an uncertainty limit of ±20%, the mean interannual discharge (5.74 ± 1.44 m ³ s ^?1) (±SE), was found highly variable (CV: 151%; 0.8–38 m ³ s ^?1). In a normal rainfall year (2008–2009; ～1550 mm), the discharge was 5.12 ± 1.75 m ³ s ^?1, whereas in a drought year (2009–2010), it reduced by 30% with the reduction in ～23% rainfall (CV: 85%). In an excessive rainfall year (once-in-a-century event) (2010–2011; ～3050 mm), discharge as well as total solid load was ～200% higher. Monsoon months (July–September) accounted for more than 90% of the annual solid load transport. The ratio of dissolved to suspended solid (C/P ratio) was consistently low (<1) during monsoon months and higher (1–7) during the rest of the dry period. C/P ratio was inversely (R ²=0.49), but significantly (P <0.001) related to the rainfall. The average mechanical erosion rate in the three different rainfall years was 0.24, 0.19 and 1.03 mmyr ^?1, whereas the chemical erosion was estimated at 0.12, 0.11 and 0.46 mmyr ^?1, respectively. Thus, the average denudation rate of the Tons sub-watershed has been estimated at 0.33 mmyr ^?1 (excluding extreme rainfall year: 1.5 mmyr ^?1). Our results have implications to understand the hydrological behaviour of the Lesser Himalayan watersheds and will be valuable for the proposed and several upcoming small hydropower plants in the region in the context of regional ecology and natural resource management.  相似文献