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Extreme Rainfall Events and Associated Natural Hazards in Alaknanda Valley, Indian Himalayan Region 总被引：2，自引：0，他引：2
JOSHI Varun KUMAR Kireet 《山地科学学报》2006,3(3):228-236
Introduction The Himalaya is considered to be the youngest mountains on the earth, and is tectonically very active, and hence inherently (geologically) vulnerable to hazards. Extreme rainfall events, landslides, debris flows, torrents and flash floods due… 相似文献
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Rainfall variability and indices of extreme rainfall-analysis and perception study for two stations over Central Himalaya,India 总被引：1，自引：1，他引：0
The analysis of rainfall pattern and indices of extreme rainfall events is performed for two meteorological stations located in the Central Himalayan Region which is highly vulnerable to rain-induced hazards. The records of these rain-induced disasters suggest that such events are generally observed in later part of monsoon season, when soil is saturated after monsoon rains. An attempt is made here to test trends of 19 different extreme rainfall indices that have been widely used in the literature, using daily rainfall data for two urban centres (Nainital and Almora) over the period 1992–2005. We have used statistical tools such as Sen’s method and Mann–Kendall test for detection of trend in annual rainfall, monsoon rainfall, number of rainy days and 1-day extreme rainfall. Principal component analysis gives the correlation between different extreme rainfall indices. Time series of principal components are representing the trends of extreme indices, their variation and interrelation between different indices. The perception study conducted in the same sites indicates that extreme rainfall events and change in rainfall amount and timing are well perceived by the local people. 相似文献
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Geomagnetism and Aeronomy - We consider fast sausage solitons and super nonlinearity in straight homogeneous magnetic tubes having coronal parameters. The solitonic behavior is described by the... 相似文献
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The transient response of large embedded foundation elements of length-to-diameter aspect ratio D/B=2–6 is characterized by a complex stress distribution at the pier–soil interface that cannot be adequately represented by means of existing models for shallow foundations or flexible piles. On the other hand, while three-dimensional (3D) numerical solutions are feasible, they are infrequently employed in practice due to their associated cost and effort. Prompted by the scarcity of simplified models for design in current practice, we here develop an analytical model that accounts for the multitude of soil resistance mechanisms mobilized at their base and circumference, while retaining the advantages of simplified methodologies for the design of non-critical facilities. The characteristics of soil resistance mechanisms and corresponding complex spring functions are developed on the basis of finite element simulations, by equating the stiffness matrix terms and/or overall numerically computed response to the analytical expressions derived by means of the proposed Winkler model. Sensitivity analyses are performed for the optimization of the truncated numerical domain size, the optimal finite element size and the far-field dynamic boundary conditions to avoid spurious wave reflections. Numerical simulations of the transient system response to vertically propagating shear waves are next successfully compared to the analytically predicted response. Finally, the applicability of the method is assessed for soil profiles with depth-varying properties. The formulation of frequency-dependent complex spring functions including material damping is also described, while extension of the methodology to account for nonlinear soil behavior and soil–foundation interface separation is described in the conclusion and is being currently investigated. 相似文献
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In this study, we have investigated the seasonality and long-term trends of major biomass burning (BB) sources over South and Southeast Asia (S-SE Asia). The activities of BB and related emissions show bi-modal seasonality in S-SE Asia. From January to May period, the BB dominates in the northern hemisphere parts of S-SE Asia. From July to September, the activities shift to the southern hemisphere where the emissions from Indonesian and Malaysian islands make largest contributions. Overall, the activities of BB are lowest during October–December period in S-SE Asia. The seasonality of BB intensity and rain are just opposite in the phase over India. The climatological (1997–2008) emissions of carbon monoxide (CO), oxides of nitrogen (NOx) and non-methane hydrocarbons (NMHCs) show strong spatio-temporal variation. The trends show large inter-annual variations with highest and lowest values during years 1997 and 2000, respectively. In the southern hemisphere parts of S-SE Asia mainly in Indonesia, the intensity of biomass fires has been modulated by the large scale climatic phenomena like El Niño and Southern Oscillation (ENSO). The annual emissions of trace gases in southern hemisphere region during the El Niño years exceed to those for the normal years. The estimates for northern hemisphere region during the La Niña years were significantly higher than those for the normal years. The Model for Ozone And Related Chemical Tracers (MOZART) simulations of columnar CO and NOx tend to capture the prominent features of BB emissions in S-SE Asia. The impacts of extensive fires in Indonesia during El Niño year of 2006 compared to a normal year of 2005 were clearly seen in the MOZART-4 simulations of both CO and NOx. 相似文献
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Ajeet Kumar Vishwakarma Rajendra Prasad Dileep Kumar Gupta Pradeep Kumar Varun Narayan Mishra 《Journal of the Indian Society of Remote Sensing》2018,46(6):973-980
The present study describes the ground based bistatic scatterometer measurements of ladyfinger crop at its various growth stages in the specular direction with the azimuthal angle (\( \phi = 0 \)) for the angular incidence angle ranging from 20° to 60° at the interval of 10° at HH and VV polarization. An outdoor ladyfinger crop bed of an area 4 × 4 m2 was specially prepared for the ground based bistatic scatterometer measurements. The crop growth variables like vegetation water content, leaf area index, fresh biomass, and plant height were also measured at the time of each bistatic scatterometer measurement. The specular bistatic scattering coefficients were found to be decreasing with the crop growth variables up to the maturity stage and then after it increased slightly. The linear regression analysis was carried out between specular bistatic scattering coefficient and crop growth variables at all the incidence angles for HH and VV polarization to select the optimum angle of incidence and polarization for the estimation of crop growth variables. The potential of subtractive clustering based adaptive neuro-fuzzy inference system was applied for the estimation of crop growth variables. The estimated values for different crop growth variables were found almost close to the observed values. 相似文献