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91.
Natural Resources Research - Unlike in coastal and sedimentary basins, regional-scale exploration of groundwater resources using only geophysical methods is costlier in consolidated rocks such as...  相似文献   
92.
In this study, a novel approach of the landslide numerical risk factor(LNRF) bivariate model was used in ensemble with linear multivariate regression(LMR) and boosted regression tree(BRT) models, coupled with radar remote sensing data and geographic information system(GIS), for landslide susceptibility mapping(LSM) in the Gorganroud watershed, Iran. Fifteen topographic, hydrological, geological and environmental conditioning factors and a landslide inventory(70%, or 298 landslides) were used in mapping. Phased array-type L-band synthetic aperture radar data were used to extract topographic parameters. Coefficients of tolerance and variance inflation factor were used to determine the coherence among conditioning factors. Data for the landslide inventory map were obtained from various resources, such as Iranian Landslide Working Party(ILWP), Forestry, Rangeland and Watershed Organisation(FRWO), extensive field surveys, interpretation of aerial photos and satellite images, and radar data. Of the total data, 30% were used to validate LSMs, using area under the curve(AUC), frequency ratio(FR) and seed cell area index(SCAI).Normalised difference vegetation index, land use/land cover and slope degree in BRT model elevation, rainfall and distance from stream were found to be important factors and were given the highest weightage in modelling. Validation results using AUC showed that the ensemble LNRF-BRT and LNRFLMR models(AUC = 0.912(91.2%) and 0.907(90.7%), respectively) had high predictive accuracy than the LNRF model alone(AUC = 0.855(85.5%)). The FR and SCAI analyses showed that all models divided the parameter classes with high precision. Overall, our novel approach of combining multivariate and machine learning methods with bivariate models, radar remote sensing data and GIS proved to be a powerful tool for landslide susceptibility mapping.  相似文献   
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94.
Alaa A. Masoud 《水文研究》2013,27(20):2987-3002
Eighteen groundwater well sites located in Kafr Al‐Zayat (Egypt) were sampled monthly from January 2009 to November 2011 for microbial content, Mn+2, Fe+2, total dissolved solids (TDS), total hardness, NO3?, and turbidity. The data were analyzed combining the integrated use of factor and cluster analyses as well as the geostatistical semi‐variogram modeling. The prime objectives were to assess the groundwater suitability for drinking, to document the factors governing the spatio‐tempral variability, and to recognize distinctive groundwater quality patterns to help enable effective sustainability and proactive management of the limited resource. The groundwater microbial, Mn+2, Fe+2, TDS, and total hardness contents violated the drinking water local standards while the turbidity and the nitrate content complied with them. Factor analysis indicated that the microbial content is the most influential factor raising the variability potential followed, in decreasing order, by Mn2+, Fe2+, TDS, NO3?, turbidity, and finally the total hardness. Turbidity resulting from urban and agricultural runoff was strongly associated with most of the quality parameters. Quality parameters fluctuate sporadically without concrete pattern in space and time while their variability scores peak in November every year. Three spatially distinctive quality patterns were recognized that were consistent with and affected by the cumulative effects of the local topography, depth to water table, thickness of the silty clay (cap layer), surface water, and groundwater flow direction and hence the recharge from contaminated surface canals and agricultural drains. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   
95.
Natural Resources Research - It is of a high importance to introduce intelligent systems for estimation and optimization of blasting-induced ground vibration because it is one the most unwanted...  相似文献   
96.
Natural Resources Research - Offshore oil and gas reservoirs comprise a significant portion of the world’s reserve base, and their development is expected to help close a potential gap in the...  相似文献   
97.
Estimation of pillar stress is a crucial task in underground mining. This is used to determine pillar dimensions, room width, roof conditions, and general mine layout. There are several methods for estimating induced stresses due to underground excavations, i.e., empirical methods, numerical solutions, and currently artificial intelligence (AI). AI based techniques are gradually gaining popularity especially for problems involving uncertainty. In this paper, an attempt has been made to predict stresses developed in the pillars of bord and pillar mining using artificial neural network. A comparison has also been done to compare the obtained results with the boundary element method as well as measured field values. For this purpose, a multilayer perceptron neural network model was developed. A number of architectures with different hidden layers and neurons were tried to get the best solution, and the architecture 5-20-8-1 was found to be an optimum solution. Sensitivity analysis was also carried out to understand the influence of important input parameters on pillar stress concentration.  相似文献   
98.
The entire land of Southern Iran faces problems arising out of various types of land degradation of which vegetation degradation forms one of the major types. The Qareh Aghaj basin (1 265 000 ha), which covers the upper reaches of Mond River, has been chosen for a test risk assessment of this type. The different kinds of data for indicators of vegetation degradation were gathered from the records and published reports of the governmental offices of Iran. A new model has been developed for assessing the risk of vegetation degradation. Taking into consideration nine indicators of vegetation degradation the model identifies areas with “Potential Risk” (risky zones) and areas of “Actual Risk” as well as projects the probability of the worse degradation in future. The preparation of risk maps based on the GIS analysis of these indicators will be helpful for prioritizing the areas to initiate remedial measures. By fixing the thresholds of severity classes of the nine indicators a hazard map for each indicator was first prepared in GIS. The risk classes were defined on the basis of risk scores arrived at by assigning the appropriate attributes to the indicators and the risk map was prepared by overlaying nine hazard maps in the GIS. Areas under actual risk have been found to be widespread (78%) in the basin and when the risk map classified into subclasses of potential risk with different probability levels the model projects a statistical picture of the risk of vegetation degradation.  相似文献   
99.
GPS Solutions - Ionosphere and its spatial and temporal gradients play an important role in positioning and navigation using global navigation satellite systems (GNSS). This study intends to...  相似文献   
100.
A unique zircon was studied in the gneiss samples collected from the Wadi Abu Rusheid psammitic gneiss using electron scanning microscope and electron probe microanalyses. This zircon can be categorized into two types according to the texture and trace element content: (l) magmatic zircon slightly enriched in HfO2 with ordinary zone. (2) Overgrowths of zircon occur as two species, the first species being highly enriched in HfO2 with irregular zoning. The second species is highly enriched in HfO2 forming a rim around the second species with a very sharp thinner boundary. The first type shows a distinct oscillatory internal zoning pattern without change in shape of this zone and has conspicuous inclusion-free zircon overgrowths with distinct poor concentrations in Y, Hf, Th, U, Nb, and Ta in both rim and core. The second type shows two species, the first one displays distinct irregular interval zoning and irregular overgrowth with abrupt change in composition of these zones with distinct enrichment in Y, Hf, Th, U, Nb, and Ta in the rim relative to the core. The second species is forming a rim around the first species also with distinct enrichment in Y, Hf, Th, U, Nb, and Ta content. These indicate that two events (crystallization environment) have played an important role in the formation of this zircon and largely reflect differences in whole-rock trace element contents between the successive generations of this zircon. The first event is believed to be of magmatic origin giving rise to normal composition of magmatic zircon. The second event shows an intense successive process of metasomatic activity during the formation of the Abu Rusheid radioactive gneiss. Electron microprobe analysis indicates that oscillatory zoned zircon shows poor content of Y, Hf, Th, U, Nb, Ta, and rare earth elements (REE) in the rim and core, while overgrowths of zircon are slightly enriched by these elements. Also, these analyses indicate that the Abu Rusheid psammitic gneiss has been significantly enriched by the thorite mineral (Th content up to 54.72% ThO2) and columbite-bearing minerals (Nb content up to 64.74% Nb2O5, Ta content up to 9.32% Ta2O5). The poor content of REE in overgrowths of zircon indicates mobilization of REE during the metamorphism processes of gneiss.  相似文献   
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