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81.
Netra Prakash Bhandary Ranjan Kumar Dahal Manita Timilsina Ryuichi Yatabe 《Natural Hazards》2013,69(1):365-388
Landslide susceptibility assessment is a major research topic in geo-disaster management. In recent days, various landslide susceptibility and landslide hazard assessment methodologies have been introduced with diverse thoughts of assessment and validation method. Fundamentally, in landslide susceptibility zonation mapping, the susceptibility predictions are generally made in terms of likelihoods and probabilities. An overview of landslide susceptibility zoning practices in the last few years reveals that susceptibility maps have been prepared to have different accuracies and reliabilities. To address this issue, the work in this paper focuses on extreme event-based landslide susceptibility zonation mapping and its evaluation. An ideal terrain of northern Shikoku, Japan, was selected in this study for modeling and event-based landslide susceptibility mapping. Both bivariate and multivariate approaches were considered for the zonation mapping. Two event-based landslide databases were used for the susceptibility analysis, while a relatively new third event landslide database was used in validation. Different event-based susceptibility zonation maps were merged and rectified to prepare a final susceptibility zonation map, which was found to have an accuracy of more than 77 %. The multivariate approach was ascertained to yield a better prediction rate. From this study, it is understood that rectification of susceptibility zonation map is appropriate and reliable when multiple event-based landslide database is available for the same area. The analytical results lead to a significant understanding of improvement in bivariate and multivariate approaches as well as the success rate and prediction rate of the susceptibility maps. 相似文献
82.
Sujeewa Malwila Herath Priyantha Ranjan Sarukkalige Van Thanh Van Nguyen 《水文科学杂志》2013,58(11):2061-2070
ABSTRACTDownscaling of climate projections is the most adapted method to assess the impacts of climate change at regional and local scales. This study utilized both spatial and temporal downscaling approaches to develop intensity–duration–frequency (IDF) relations for sub-daily rainfall extremes in the Perth airport area. A multiple regression-based statistical downscaling model tool was used for spatial downscaling of daily rainfall using general circulation models (GCMs) (Hadley Centre’s GCM and Canadian Global Climate Model) climate variables. A simple scaling regime was identified for 30 minutes to 24 hours duration of observed annual maximum (AM) rainfall. Then, statistical properties of sub-daily AM rainfall were estimated by scaling an invariant model based on the generalized extreme value distribution. RMSE, Nash-Sutcliffe efficiency coefficient and percentage bias values were estimated to check the accuracy of downscaled sub-daily rainfall. This proved the capability of the proposed approach in developing a linkage between large-scale GCM daily variables and extreme sub-daily rainfall events at a given location. Finally IDF curves were developed for future periods, which show similar extreme rainfall decreasing trends for the 2020s, 2050s and 2080s for both GCMs.
Editor M.C. Acreman; Associate editor S. Kanae 相似文献
83.
This paper presents the analysis of creep settlement of pile groups for line pile groups, square pile groups, and rectangular pile groups undergoing creep settlements over a period of time. The soil is treated as a viscoelastic material and is modeled using a three-parameter viscoelastic model. The damping component (dashpot) takes care of the permanent time-dependent deformations in three-parameter viscoelastic model. An approach suggested by Mindlin has been employed to calculate the stress distribution along the pile length in a group. The viscoelastic problem is converted into an elastic problem by the application of Laplace transform. Results in the form of variation of interaction factors for parameters such as pile length to diameter ratio, pile spacing, Poisson's ratio, and modulus ratio have been presented. Comparison has been made between interaction factors for piles groups undergoing immediate settlements and creep settlements. Finally, a typical predictive example has been presented for a 3 × 3 pile group showing creep settlement. The load rearrangement due to creep settlements causes about 5% to 35% increase in base resistance over time. Interaction factors for pile groups (2 × 1, 3 × 1, 2 × 2, and 3 × 2) undergoing creep settlement is about 15% to 55% higher than the interaction factors considering only the immediate settlements for pile group spacing less than or equal to 5d. 相似文献
84.
Marcus Bursik Matthew Jones Simon Carn Ken Dean Abani Patra Michael Pavolonis E. Bruce Pitman Tarunraj Singh Puneet Singla Peter Webley Halldor Bjornsson Maurizio Ripepe 《Bulletin of Volcanology》2012,74(10):2321-2338
Data on source conditions for the 14 April 2010 paroxysmal phase of the Eyjafjallaj?kull eruption, Iceland, have been used as inputs to a trajectory-based eruption column model, bent. This model has in turn been adapted to generate output suitable as input to the volcanic ash transport and dispersal model, puff, which was used to propagate the paroxysmal ash cloud toward and over Europe over the following days. Some of the source parameters, specifically vent radius, vent source velocity, mean grain size of ejecta, and standard deviation of ejecta grain size have been assigned probability distributions based on our lack of knowledge of exact conditions at the source. These probability distributions for the input variables have been sampled in a Monte Carlo fashion using a technique that yields what we herein call the polynomial chaos quadrature weighted estimate (PCQWE) of output parameters from the ash transport and dispersal model. The advantage of PCQWE over Monte Carlo is that since it intelligently samples the input parameter space, fewer model runs are needed to yield estimates of moments and probabilities for the output variables. At each of these sample points for the input variables, a model run is performed. Output moments and probabilities are then computed by properly summing the weighted values of the output parameters of interest. Use of a computational eruption column model coupled with known weather conditions as given by radiosonde data gathered near the vent allows us to estimate that initial mass eruption rate on 14 April 2010 may have been as high as 108?kg/s and was almost certainly above 107?kg/s. This estimate is consistent with the probabilistic envelope computed by PCQWE for the downwind plume. The results furthermore show that statistical moments and probabilities can be computed in a reasonable time by using 94?=?6,561 PCQWE model runs as opposed to millions of model runs that might be required by standard Monte Carlo techniques. The output mean ash cloud height plus three standard deviations??encompassing c. 99.7?% of the probability mass??compares well with four-dimensional ash cloud position as retrieved from Meteosat-9 SEVIRI data for 16 April 2010 as the ash cloud drifted over north-central Europe. Finally, the ability to compute statistical moments and probabilities may allow for the better separation of science and decision-making, by making it possible for scientists to better focus on error reduction and decision makers to focus on ??drawing the line?? for risk assessment. 相似文献
85.
86.
D. V. Phani Kumar A. K. Patra Y.-S. Kwak K.-H. Kim G. Yellaiah 《Astrophysics and Space Science》2009,323(3):225-233
In this paper, we attempt to identify the driving forces responsible for the generation of low-latitude E-region field-aligned
irregularities (FAIs). It is evident that the low-latitude E-region FAIs occur both during the day and night with preferential
occurrence being most during local sunrise period. Simultaneous measurements are made with Gadanki radar and nearby located
Ionosonde for understanding the low-latitude Es–FAIs relationship. The observations suggest that the occurrence and SNR of
FAIs have a close relationship with f
t
E
s
−−f
b
E
s
. Finally, using the past electron density profiles and reasonable values of electric field, we have shown that it is generally
difficult with the gradient drift instability to explain low-latitude E-region FAIs when electric field alone is considered
as driving agency. We hypothesize that neutral winds play important role for the generation of irregularities at low latitudes
outside the electrojet belt either by forming sharp Es layers or by enhancing the differential drift of electrons and ions
or by both. 相似文献
87.
Sankar Narayan Patra Gautam Bhattacharya Koushik Ghosh Probhas Raychaudhuri 《Astrophysics and Space Science》2009,324(1):47-53
The solar irradiance data plays a very important role for understanding of Solar internal Structure and the solar terrestrial
relationships. The Total Solar Irradiance (TSI) is integrated solar energy flux over the entire spectrum which arrives at
the top of the atmosphere at the mean sun earth distance. TSI has been monitored from several satellites, e.g. Nimbus 7, Solar
Maximum Mission (SMM), The NASA, Earth Radiation Budget Satellite (ERBS), NOAA9, NOAA10, Eureca and the Upper Atmospheric
Research Satellite (UARS) etc. From these observations it reveals that the total solar irradiance varies about a small fraction
of 0.1 over solar cycle being higher during maximum solar activity condition. In the present paper we have analysed the solar
irradiance data from ERBS during the time period from October 15, 1984 to October 15, 2003. First filtering the data by Simple
Exponential Smoothing we have applied the Rayleigh Power Spectrum Analysis on the processed data in order to search for its
time variation. Study exhibits multi-periodicities on these data around 7, 11, 42, 80, 104, 130, 160, 254, 536, 752, 1142,
1388, 2474 and 4951 days with very high confidence levels (more than 95%). Apart from these strong periods there are some
other weak periods around 22, 47, 53, 67, 69, 149, 167, 365, 489 and 683 days. These periods are significantly similar with
the periods of other solar activities which may suggest that solar irradiance may be associated with other solar activities. 相似文献
88.
Pawan Kumar Singh Arvind Kumar Mishra Deepanshu Ranjan Singh 《Journal of the Geological Society of India》2017,89(3):307-314
Indian coal mining industry is in transition phase with the growing demand of coal and is likely to escalate further with the need of ultra-mega power projects as well as announcement of smart cities projects. Although, there exist sufficient coal reserves in India, continuous acquisition and possession of coal bearing land is required to minimize the existing gap prevailing between coal demand and supply.The solution of the problem lies not only in modification of laws and policies of industry, but also in modification of mining engineering practices towards sustainable development. This paper critically examines the cause of the problem in the light of Indian laws and practices of the industry. In this paper a method of exact reclamation of post-mining land has been designed as a solution to make easier land acquisition by way of proposing a system of returning back the exact reclaimed land to its owners under corporate social responsibility activity of the industry. The proposed conceptual model of interlinking corporate social responsibility with land exchange will encourage sustainable development practice by mining engineers, and may turn around the public image of the industry. 相似文献
89.
An analytical method has been proposed to predict the ultimate uplift capacity of single vertical piles embedded in sand considering
arching effect. The present analysis takes into consideration of various pile and soil parameters such as length (L), diameter (d) of the pile, angle of internal friction of soil (ϕ), soil pile friction angle (δ) and unit weight of soil (γ). A modified value of coefficient of lateral earth pressure in uplift has been developed considering the arching effect of
soil. A comparative assessment of the uplift capacity of piles predicted by using proposed theory and the existing available
theories is made with the existing field and model test results. It has been observed that the present model considering the
arching effect predicts the results closer. 相似文献
90.
Natural Hazards - It has been found that the less care is shown while constructing the water retention structures as compared to the amount of care shown in designing for it. This is more often in... 相似文献