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61.
Amvrossios C. Bagtzoglou Faisal Hossain 《Stochastic Environmental Research and Risk Assessment (SERRA)》2009,23(7):933-945
This paper investigates three techniques for spatial mapping and the consequential hydrologic inversion, using hydraulic conductivity
(or transmissivity) and hydraulic head as the geophysical parameters of concern. The data for the study were obtained from
the Waste Isolation and Pilot Plant (WIPP) site and surrounding area in the remote Chihuahuan Desert of southeastern New Mexico.
The central technique was the Radial Basis Function algorithm for an Artificial Neural Network (RBF-ANN). An appraisal of
its performance in light of classical and temporal geostatistical techniques is presented. Our classical geostatistical technique
of concern was Ordinary Kriging (OK), while the method of Bayesian Maximum Entropy (BME) constituted an advanced, spatio-temporal
mapping technique. A fusion technique for soft or inter-dependent data was developed in this study for use with the neural
network. It was observed that the RBF-ANN is capable of hydrologic inversion for transmissivity estimation with features remaining
essentially similar to that obtained from kriging. The BME technique, on the other hand, was found to reveal an ability to
map localized lows and highs that were otherwise not as apparent in OK or RBF-ANN techniques. 相似文献
62.
Pollutant dispersion characteristics in Dhaka city, Bangladesh 总被引:1,自引:0,他引:1
Air pollution is a major environmental concern in major cities around the world. The major causes of air pollution include rapid industrialization/urbanization and increased non environment-friendly energy production. This paper analyses the atmospheric pollutant such as carbon monoxide (CO) and particulate matter (PM) dispersion characteristics of Dhaka city. The yearly and diurnal variations of pollutant concentration are described by taking into consideration of both meteorological and emission source parameters highlighting washout effect due to rainfall and inversion phenomena. Concentration of PM (both PM2.5 and PM10) and CO in the ambient air are measured for a period of one year with Airmetric Minivol air samplers and Gas Chromatographic (GC) technique, respectively. The trend over the year shows an increase in the monthly average hourly PM and CO concentrations in winter months (November to March) when both PM10 and PM2.5 annual average concentrations (about 130 and 95 ??g m?3, respectively) exhibit levels exceeding World Health Organization (WHO) guidelines as well as exceed more than twice the national standards of annual PM10 (50 ??g m?3) and PM2.5 (15 ??g m?3) concentrations. Such high pollutant concentrations may have significant health implications for residents of Dhaka city. It is also found that the PM concentration increases with the increase of wind speed during dry winter season and is also influenced by transboundary air pollution. The data and subsequent recommendations can be useful in formulating air quality management strategies for the Dhaka city. 相似文献
63.
The Rashidpur structure is located in the southern part of the Surma Basin, Bangladesh. This paper presents an integrated
interpretation of seismic and other geophysical data considering the available geologic information in terms of hydrocarbon
potential of this structure. The study area lies within a gravity high and a high magnetic intensity. Fifteen seismic sections
of the study area have been analyzed to interpret the subsurface geology, structure and stratigraphy. Based on the analysis
of seismic sections and correlation with well data, four prominent reflecting horizons have been identified. The litho-stratigraphy
of the Rashidpur structure is prepared on the basis of well information. The lithological sequences encountered in the Rashidpur
structure range in age from Miocene to Plio-Pliestocene. The gas producing sands of the structure are within Bokabil to Bhuban
Formations of the Miocene age. The seismic study indicates that the Rashidpur structure is a narrow, NS elongated anticline
affected by a major reverse fault on the eastern flank. It is an asymmetrical anticline with the axis swinging slightly to
the east on the northern plunge and thus attaining a slight concavity to the east. There are various geophysical indications
of hydrocarbons in this structure. 相似文献
64.
Ahmed Nasir Bodrud-Doza Md. Islam S. M. Didar-Ul Choudhry Manzoor Ahmad Muhib Md. Iftakharul Zahid Anwar Hossain Shahadat Moniruzzaman Md. Deb Nipa Bhuiyan Md. Abdul Quaiyum 《中国地球化学学报》2019,38(3):440-455
Acta Geochimica - To investigate the hydrogeochemical characteristics of groundwater 23 shallow, 30 intermediate and 38 deep wells samples were collected from Sylhet district of Bangladesh, and... 相似文献
65.
Analysis of travel time,sources of water and well protection zones with groundwater models
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This study compares numerical models with analytical solutions in computing travel times and radius of protection zones for a pumping well located in an unconfined aquifer with uniform recharge and in a semi-confined aquifer. Numerical models were capable of delineating protection zones using particle tracking method in both cases. However, protection zones defined by travel time criterion can only protect small percent of source water to the well; large percent of source water is not protected which may pose a risk of pollution of source water to the well. The case study of Leggeloo well field in the Netherlands indicates that although a well field protection area was enforced in 1980s, elevated nitrate concentration has been monitored in the abstracted water since 1990s. The analysis of protection areas shows that the current protection area only protects 37.4% of recharge water to the well field. A large protection area must be adopted in order to safeguard the sustainable water supply for the local community 相似文献
66.
The Permian–Triassic boundary (PTB) is a world‐wide event characterized by the most extensive mass extinction in the history of life. In the Persian Gulf, the rock record of this time interval host one of the most important hydrocarbon reserves in the world: the South Pars Gas Field and its southern extension, the North Dome (or North Field). These carbonate and evaporite successions were sampled in eight wells for petrographic, geochemical and porosity–permeability studies. An important characteristic of the Dalan and Kangan formations is the centimetre‐scale lithological heterogeneities caused by facies changes and diagenetic imprints that led to the compartmentalization of these reservoirs. These Permian–Triassic (P‐T) sediments were deposited in a shallow marine homoclinal ramp. The PTB in this hydrocarbon field is represented by a reworked coarse‐grained intraclastic/bioclastic grainstone facies deposited during a marine transgression. Prolonged subaerial exposure in the P‐T transition caused hypersaline and meteoric diagenesis, including extensive cementation, dolomitization and some dissolution, influencing reservoir characteristics of bordering units. Both δ18O and δ13C values in this succession mirror worldwide excursions typical of other P‐T sections, with some variations due to diagenetic alterations. A pronounced decline in 87Sr/86Sr values, reflective of global seawater geochemistry for most of the Permian is evident in our data. Reservoir quality declines through the late Permian, as a result of facies change and diagenesis. The Late Permian is succeeded by a Triassic transgressive facies and decline in reservoir quality. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
67.
Hooshang H. Asadi Atefeh Sansoleimani Moslem Fatehi Emmanuel John M. Carranza 《Natural Resources Research》2016,25(4):417-429
The Salafchegan area in central Iran is a greenfield region of high porphyry Cu–Au potential, for which a sound prospectivity model is required to guide mineral exploration. Satellite imagery, geological geochemical, geophysical, and mineral occurrence datasets of the area were used to run an innovative integration model for porphyry Cu–Au exploration. Five favorable multi-class evidence maps, representing diagnostic porphyry Cu–Au recognition criteria (intermediate igneous intrusive and sub-volcanic host rocks, structural controls, hydrothermal alterations, stream sediment Cu anomalies, magnetic signatures), were combined using analytic hierarchy process and technique for order preference by similarity to ideal solution to calculate a final map of porphyry Cu–Au potential in the Salafchegan area. 相似文献
68.
The Ilam Formation (Santonian–Campanian in age), part of the Bangestan Group, is disconformably overlain by the Sarvak Formation and underlain by the Gurpi Formation in the Tang-E Rashid, Peyon area, Izeh (Zagros), southwest of Iran.Facies analyses indicate that the Ilam carbonates formed in four microfacies belts: tidal flat, lagoon, shoal and open marine, in a platform ramp environment. Major and minor elements and carbon and oxygen isotope values were used to determine the original carbonate mineralogy of the Ilam Formation. Petrographic evidence and elemental and oxygen and carbon isotope values indicate that aragonite was the original carbonate mineralogy in the Ilam Formation. The elemental and isotopic compositions of the Ilam carbonates also illustrate that they have stabilized in the marine phreatic environment. Variations of Sr/Ca and δ18O values versus Mn suggest that diagenetic alteration occurred in a closed system. Temperature calculation based on the oxygen isotope value of the least-altered sample indicates that the very early shallow burial fluid temperature was around 28 °C.Recognition of the exact boundary between the Ilam and Sarvak Formations is difficult, due to similar lithologies and the absence of the Surgah Formation in the study area. However, elemental and oxygen and carbon isotope analysis were used to determine the boundary between these formations. The δ18O and δ13C values, along with elemental results, clearly indicate a subaerial exposure surface, below which meteoric diagenesis affected the sediments. 相似文献
69.
70.
Jason Hill Faisal Hossain Bellie Sivakumar 《Stochastic Environmental Research and Risk Assessment (SERRA)》2008,22(1):47-55
The correlation dimension (CD) of a time series provides information on the number of dominant variables present in the evolution
of the underlying system dynamics. In this study, we explore, using logistic regression (LR), possible physical connections
between the CD and the mathematical modeling of risk of arsenic contamination in groundwater. Our database comprises a large-scale
arsenic survey conducted in Bangladesh. Following the recommendation by Hossain and Sivakumar (Stoch Environ Res Risk Assess
20(1–2):66–76, 2006), who reported CD values ranging from 8 to 11 for this database, 11 variables are considered herein as indicators of the
aquifer’s geochemical regime with potential influence on the arsenic concentration in groundwater. A total of 2,048 possible
combinations of influencing variables are considered as candidate LR risk models to delineate the impact of the number of
variables on the prediction accuracy of the model. We find that the uncertainty associated with prediction of wells as safe
and unsafe by LR risk model declines systematically as the total number of influencing variables increases from 7 to 11. The
sensitivity of the mean predictive performance also increases noticeably for this range. The consistent reduction in predictive
uncertainty coupled with the increased sensitivity of the mean predictive behavior within the universal sample space exemplify
the ability of CD to function as a proxy for the number of dominant influencing variables. Such a rapid proxy, based on non-linear
dynamic concepts, appears to have considerable merit for application in current management strategies on arsenic contamination
in developing countries, where both time and resources are very limited. 相似文献