Assessment of future climate variability and potential adaptation strategies on yield of peanut and Kharif rice in eastern India     

Halder  Debjani  Kheroar  Shyamal  Srivastava  Rajiv Kumar  Panda  Rabindra Kumar 《Theoretical and Applied Climatology》2020,140(3):823-838

Theoretical and Applied Climatology - Temperature and CO2 are the two most important climate parameters that affect crop yield directly. In this study, the impact of these two parameters on the...  相似文献   

AMO’s structure and climate footprint in observations and IPCC AR5 climate simulations   总被引：1，自引：1，他引：0  

Argyro Kavvada  Alfredo Ruiz-Barradas  Sumant Nigam 《Climate Dynamics》2013,41(5-6):1345-1364

This study aims to characterize the spatiotemporal features of the low frequency Atlantic Multidecadal Oscillation (AMO), its oceanic and atmospheric footprint and its associated hydroclimate impact. To accomplish this, we compare and evaluate the representation of AMO-related features both in observations and in historical simulations of the twentieth century climate from models participating in the IPCC’s CMIP5 project. Climate models from international leading research institutions are chosen: CCSM4, GFDL-CM3, UKMO-HadCM3 and ECHAM6/MPI-ESM-LR. Each model employed includes at least three and as many as nine ensemble members. Our analysis suggests that the four models underestimate the characteristic period of the AMO, as well as its temporal variability; this is associated with an underestimation/overestimation of spectral peaks in the 70–80 year/10–20 year range. The four models manifest the mid-latitude focus of the AMO-related SST anomalies, as well as certain features of its subsurface heat content signal. However, they are limited when it comes to simulating some of the key oceanic and atmospheric footprints of the phenomenon, such as its signature on subsurface salinity, oceanic heat content and geopotential height anomalies. Thus, it is not surprising that the models are unable to capture the majority of the associated hydroclimate impact on the neighboring continents, including underestimation of the surface warming that is linked to the positive phase of the AMO and is critical for the models to be trusted on projections of future climate and decadal predictions.  相似文献   

Fluoride contamination of groundwater in parts of eastern India and a preliminary experimental study of fluoride adsorption by natural haematite iron ore and synthetic magnetite     

Suresh C. Patel  Rajiv Khalkho  Subhagya K. Patel  Janisar M. Sheikh  Duryadhan Behera  Sanjeev Chaudhari  Naraga Prabhakar 《Environmental Earth Sciences》2014,72(6):2033-2049

Incidence of high fluoride (F^?) in groundwater (>1.5 mg/L) in two tribal belts of eastern India, one around Chukru in the Palamau district of Jharkhand and the other around Karlakot in the Nuapada district of Odisha, has been studied. The maximum concentration of F^? in groundwater from dug wells and tube wells is 10.30 mg/L in Chukru and 4.62 mg/L in Karlakot. The groundwaters are mildly alkaline with pH ranges of 7.52–8.22 and 7.33–8.20 in Chukru and Karlakot, respectively. The F^? concentration is positively correlated with pH, electrical conductivity and SO₄ ^2? in both areas. The high F^? in groundwater resulted mainly from dissolution of biotite and fluorapatite in quartzofeldspathic gneiss. The ionic dominance pattern (in meq/L) is mostly in the order Ca²⁺ > Na⁺ > Mg²⁺ > K⁺ among cations and HCO₃ ^? > SO₄ ^2? > < Cl^? > F^? among anions in the Karlakot groundwater. Preliminary adsorption experiments were conducted on natural haematite iron ore and synthetic magnetite to evaluate their potential for F^? removal from water. Effects of different parameters such as contact time, pH, adsorbent dose and initial F^? concentration on the adsorption capacity of these materials were investigated. Strong dependence of F^? removal on pH was observed for both the adsorbents. With natural haematite iron ore, the maximum F^? removal of 66 % occurred at an initial pH of 3.2 for a solution with F^? concentration of 3 mg/L, adsorbent dose of 7 g/L and overnight contact time. The haematite iron ore was observed to increase the pH of the F^? solution. Adsorption equilibrium was not achieved with this adsorbent even after a contact time of 45.2 h. In the case of synthetic magnetite, 84 % F^? removal was achieved after 2 min of contact time for a solution with F^? concentration of 6 mg/L, adsorbent dose of 10 g/L and initial pH of 7. The results indicate high potential of both natural haematite iron ore and synthetic magnetite as adsorbents of F^? in water.  相似文献   

Design Charts for Selecting Minimum Setback Distance from Side Slope to Horizontal Trench System in Bioreactor Landfills     

Rajiv K. Giri  Krishna R. Reddy 《Geotechnical and Geological Engineering》2014,32(4):1017-1027

The primary objective of bioreactor landfill is to achieve adequate and rapid distribution of moisture in landfilled municipal solid waste (MSW) to accelerate the anaerobic biodegradation of the organic fraction within MSW. A horizontal trench system (HT) is commonly adopted for leachate distribution in MSW under pressurized conditions. However, this approach should be implemented carefully due to the potential instability of landfill slopes that comes from the generation and distribution of excessive pore fluid pressures. In this study, HT design charts are presented that determine the optimal location of horizontal trench systems from the side slope (i.e., minimum lateral setback distance) under continuous leachate addition with maximum applied injection pressures, for which the landfill slopes remain stable [factor of safety (FOS) where FOS ≥ 1.5]. Use of any higher injection pressure and/or shorter lateral setback distance of HT than the one presented in the design charts would result in an unacceptable design of the bioreactor side slope (FOS < 1.5). The design chart was developed based on a parametric study that used a numerical two-phase flow model that involved different slope configurations and landfill waste depths. MSW heterogeneity and anisotropy, as well as unsaturated hydraulic properties, were taken into consideration in these simulations. Transient changes in pore water and gas pressures due to leachate recirculation were accounted for dually in the slope stability computations. The importance of these design charts is illustrated using a practical example. Site-specific conditions and the expertise and prior experience of a designer or operator must also be adequately considered and utilized with the design charts presented here for the safe design of a horizontal trench system in a bioreactor landfill.  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   

Formulation of Time Series Vegetation Index from Indian Geostationary Satellite and Comparison with Global Product     

Rahul Nigam  Bimal Kumar Bhattacharya  Keshav R. Gunjal  N. Padmanabhan  N. K. Patel 《Journal of the Indian Society of Remote Sensing》2012,40(1):1-9

To study impact of climate change on vegetation time series vegetation index has a vital role to know the behaviour of vegetation dynamics over a time period. INSAT 3A CCD (Charged Couple Device) is the only geostationary sensor to acquire regular coverage of Asia continent at 1 km × 1 km spatial resolution with high temporal frequency (half-an-hour). A formulation of surface reflectances in red, near infrared (NIR), short wave infrared (SWIR) and NDVI from INSAT 3A CCD has been defined and integrated in the operational chain. The atmospheric correction of at-sensor reflectances using SMAC (Simple Model for Atmospheric Correction) model improved the NDVI by 5–40% and also increased its dynamic range. The temporal dynamics of 16-day NDVI composite at 0500 GMT for a growing year (June 2008–March 2009) showed matching profiles with reference to global products (MODIS TERRA) over known land targets. The root mean square deviation (RMSD) between the two was 0.14 with correlation coefficient (r) 0.84 from 200 paired datasets. This inter-sensor cross-correlation would help in NDVI calibration to add continuity in long term NDVI database for climate change studies.  相似文献   

Controlled blasting in a limestone mine using electronic detonators: A case study     

Arvind K. Mishra  Y. K. Nigam  Deepanshu R. Singh 《Journal of the Geological Society of India》2017,89(1):87-90

Except for very deep-seated deposits, open cast mining method has been recognized as the safest and most productive mode for mining minerals. Ever growing demand in minerals and coal has compelled the mine operators to increase the size of mine, which has resulted in an increasing trend towards large capacity open cast projects. Explosives and blasting techniques play a significant role in efficient opencast mining operations. There have been constant technological developments towards safer, faster, economical and more efficient blasting systems. Further, globally increased competitiveness has necessitated to carryout blasts in such a way that the desired degree of fragmentation is achieved in the primary blast, with minimum undesired side effects such as ground vibration, air blast/noise, flyrock, generation of oversize boulders, formation of toe, and over break or back break. Hence, the ultimate objective of the blasting engineer is to ensure that the blasts are carried out in an eco-friendly manner. This paper presents a case study of limestone mine where a controlled blasting was conducted near a green structure of wagon tippler (at 2 m) being constructed for foundation work of belt conveyor as the mine management wants to double the existing production. This paper deals with controlled blast design and its implementation using electronic detonators with signature hole technique.  相似文献   

Horizontal trench system effects on leachate recirculation in bioreactor landfills     

Krishna R. Reddy  Hanumanth S. Kulkarni  Rajiv K. Giri  Milind V. Khire 《Geomechanics and Geoengineering》2017,12(2):115-136

Horizontal trenches (HTs) are constructed during the waste filling for leachate recirculation in bioreactor landfills. Leachate distribution depends on HT configuration (i.e., spacing between successive HTs), leachate injection rate, modes of injection, and hydraulic properties and MSW heterogeneity. Presently, the effects of these variables on the moisture distribution have not been studied systematically. This study provides a systematic evaluation of the effect of the HTs variables on the moisture distribution and pore fluid pressures. A two-phase flow model is used to model a bioreactor landfill having an HT leachate injection system. It quantifies the effects of the unsaturated hydraulic properties and MSW heterogeneity, trench configuration, leachate injection flux, and mode of injection on hydraulic behaviour. The results show that unsaturated hydraulic conductivity and MSW heterogeneity significantly shape the zone of influence and excess pore pressures. Under heterogeneous-anisotropic conditions, the leachate migrates more laterally and the developed pore-pressures are lower than for homogeneous MSW. A closely-spaced, multi-level, staggered HT system is found to provide uniform and adequate moisture distribution in MSW. An intermittent mode of injection that alternates between the shallow and deep trenches with a higher leachate injection flow rate is found to be effective to control the excess pore pressures.  相似文献   

Development of a Two‐Tier Fibrous Membrane by Sequential Electrospinning for Effective Air Filtration          下载免费PDF全文

Sowndarya Ramachandran  Sheeja Rajiv 《洁净——土壤、空气、水》2018,46(6)

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On the photo-gravitational restricted four-body problem with variable mass     

Amit Mittal  Rajiv Agarwal  Md Sanam Suraj  Monika Arora 《Astrophysics and Space Science》2018,363(5):109

This paper deals with the photo-gravitational restricted four-body problem (PR4BP) with variable mass. Following the procedure given by Gascheau (C. R. 16:393–394, 1843) and Routh (Proc. Lond. Math. Soc. 6:86–97, 1875), the conditions of linear stability of Lagrange triangle solution in the PR4BP are determined. The three radiating primaries having masses \(m_{1}\), \(m_{2}\) and \(m_{3}\) in an equilateral triangle with \(m_{2}=m_{3}\) will be stable as long as they satisfy the linear stability condition of the Lagrangian triangle solution. We have derived the equations of motion of the mentioned problem and observed that there exist eight libration points for a fixed value of parameters \(\gamma (\frac{m \ \text{at time} \ t}{m \ \text{at initial time}}, 0<\gamma\leq1 )\), \(\alpha\) (the proportionality constant in Jeans’ law (Astronomy and Cosmogony, Cambridge University Press, Cambridge, 1928), \(0\leq\alpha\leq2.2\)), the mass parameter \(\mu=0.005\) and radiation parameters \(q_{i}, (0< q_{i}\leq1, i=1, 2, 3)\). All the libration points are non-collinear if \(q_{2}\neq q_{3}\). It has been observed that the collinear and out-of-plane libration points also exist for \(q_{2}=q_{3}\). In all the cases, each libration point is found to be unstable. Further, zero velocity curves (ZVCs) and Newton–Raphson basins of attraction are also discussed.  相似文献