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One-third of the population of Oman depends upon groundwater extracted from the alluvium of the Batinah Plain, on the coast
of the Gulf of Oman. Deep geophysical exploration techniques were used to determine the depth and nature of the alluvium and
the boundaries of the aquifer. The base and structural controls of the alluvial basin at its contact with Tertiary marine
sediments and Cretaceous ophiolite were mapped with seismic reflection data, recorded originally for oil exploration. The
base of the alluvium dips northward from the foothills of the Northern Oman Mountains, reaching a maximum depth of 2000 m
at the coast. The varying facies of the alluvium are grossly characterised by different, overlapping ranges of electrical
resistivity, depending largely on the clay content and degree of cementation. Resistivities near the coast are reduced by
saline intrusion. These variations of resistivity were mapped with time-domain electromagnetic sounding along 400 km of profile,
to distinguish among the three zones of the alluvial aquifer. The wedge of saline intrusion was also delineated, up to 10 km
from the coast. The thickness of the saturated gravel aquifer ranges from 20–160 m in an area greater than 600 km2.
Received, April 1997 · Revised, January 1998 · Accepted, April 1998 相似文献
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Thirty two geochemical reference samples have been analysed for their iodine contents by a pyrohydrolysis extraction technique, followed by colourimetry. In spite of the existence of few reported values for iodine, limiting comparison with results from this study, the four available "reference" values show good agreement with the work reported here. 相似文献
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Single and binary adsorption of lead and cadmium ions from aqueous solution using the clay mineral beidellite 总被引：1，自引：0，他引：1
Beidellite, a low-cost, locally available and natural mineral was used as an adsorbent for the removal of lead and cadmium
ions from aqueous solutions in batch experiments. The kinetics of adsorption process was tested for the pseudo first-order,
pseudo second-order reaction and intra-particle diffusion models. The rate constants of adsorption for all these kinetic models
were calculated. Comparison amongst the models showed that the sorption kinetics was best described by the pseudo second-order
model. Langmuir and Freundlich isotherm models were applied to the experimental equilibrium data for different temperatures.
The adsorption capacities (Q°) of beidellite for lead and cadmium ions were calculated from the Langmuir isotherm. It was found that adsorption capacity
was in the range of 83.3–86.9 for lead and 42–45.6 mg/g for cadmium at different temperatures. Thermodynamic studies showed
that the metal uptake reaction by beidellite was endothermic in nature. Binary metal adsorption studies were also conducted
to investigate the interactions and competitive effects in binary adsorption process. Based on the optimum parameters found,
beidellite can be used as adsorbent for metal removal processes. 相似文献
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Manoj Yadav M. P. Sharma R. Prawasi Rajeev Khichi Pavan Kumar V. P. Mandal Abdul Salim R. S. Hooda 《Journal of the Indian Society of Remote Sensing》2014,42(2):343-352
Haryana has emerged as an important state for Rice & Wheat production in India contributing significantly in the central pool. Mechanized combine harvesting technologies, which have become common in Rice Wheat System (RWS) in India, leave behind large quantities of straw in the field for open burning of residue. Besides causing pollution, the burning kills the useful micro flora of the soil causing soil degradation. There is no field survey (Girdawari) data available with the Government for the areas where stubble burning is taking place. The present paper describes the methodology and results of wheat and rice residue burning areas for three districts of Haryana namely Kaithal, Kurukshetra and Karnal for the year 2010 using complete enumeration approach of multi-date IRS-P6 AWiFS and LISS-III data. In season ground truth was collected using hand held GPS and used to identify area of burnt wheat/rice residues, associated crops and land features. After geo-referencing the satellite images, district images were masked-out and multi-date image data stacks were created. Normalized Difference Vegetation Index (NDVI) of each date was generated and used at the time of classification along with other spectral bands. The non-agricultural classes in the image included: forest, wasteland, water bodies, urban/settlement and permanent vegetation etc. The vector of these non-agriculture classes were extracted from the land use, imported and mask was generated. During the classification non-agriculture area was excluded by using mask of these classes. From this the agricultural area could be separated out. The area was estimated by computing pixels under the classified image mask. In season multi-date AWiFS data along with available single-date LISS-III data between third week of April to last week of May are found to be useful for estimation of wheat residue burning areas estimation. The data between second week of October to last week of November is useful for estimation of rice residue burning areas estimation at district level. 相似文献
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Fast economic growth of a country contributes to the increase of activities that can also bring negative impacts on the rivers. Contamination of rivers, sedimentation, coastal erosion, decrease of aquatic life, and also flooding are some of these universal impacts. There are several rivers around the world, which are categorized as very polluted and require cleaning‐up operations. Several factors have been identified to be influencing factors in the success or otherwise of the implementation and operation of these projects. This study examined the factors related to the steps taken to clean‐up and rehabilitate these rivers and deduce by utilizing factor analysis the most critical success factors from the results obtained. A responsible river community is by far the most effective way to keep a river basin clean. Very often, however, cleaning‐up operations are necessary to revive and maintain the quality of the river so that it can be save to use as an important source of water for human consumption. It was found that community awareness was the most critical cluster of factors determining the success of the clean‐up work. 相似文献
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GPS Solutions - Until recently, the real-time IGS precise orbit and clock corrections were only available for the predicted part of the ultra-rapid solution. Whereas the accuracy of the ultra-rapid... 相似文献
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We implemented the Princeton Ocean Model to study the seasonal circulation patterns in the Gulf of Khambhat and surrounding oceans on the northwestern continental shelf of India. Simulated currents are used in General NOAA Operational Modeling Environment to track a past oil spill event in this region. The model's performance is evaluated against the Synthetic Aperture Radar (SAR) and in situ measurements. Mean currents, computed by subtracting tidal components from the simulated currents, are used together with satellite images of Chlorophyll-a to describe spatial patterns of the circulation. Mean-flow patterns inside the gulf are characterized with strong along-channel flow during southwest monsoon and spring seasons, which are weak during winter and autumn seasons. On the proximity of the gulf mouth currents are northwestward throughout the year except the southwest monsoon when the circulations are southwestward. Coastal boundary currents parallel to the 60 m isobath are prominent during the inter-monsoon and weak during the monsoon periods. Slope currents, near the shelf-break, are strong during southwest monsoon and spring periods. Numerical experiments suggest that ocean current is the main driver of the net transport of spilled oil in this region and other factors such as direct wind drift play negligible role. 相似文献
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Ibtissem Ladlani Larbi Houichi Lakhdar Djemili Salim Heddam Khaled Belouz 《Meteorology and Atmospheric Physics》2012,118(3-4):163-178
Estimation of reference evapotranspiration (ET0) is needed to support irrigation design and scheduling, and watershed hydrology studies. There are many available methods to estimate evapotranspiration from a water surface, comprising both direct and indirect methods. In the first part of this study, the generalized regression neural networks model (GRNN) and radial basis function neural network (RBFNN) are developed and compared in order to estimate the reference ET0 for the first time in Algeria. Various daily climatic data, that is, daily mean relative humidity, sunshine duration, maximum, minimum and mean air temperature, and wind speed from Dar El Beida, Algiers, Algeria, are used as inputs to the GRNN and RBFNN models to estimate the ET0 obtained using the FAO-56 Penman-Monteith equation (PM56). The performances of the models are evaluated using root mean square errors (RMSE), mean absolute error (MAE), Willmott index of agreement (d) and correlation coefficient (CC) statistics. In the second part of the study, the empirical Hargreaves-Samani (HG) and Priestley-Taylor (PT) equations are also considered for the comparison. Based on the comparisons, the GRNN was found to perform better than the RBFNN, Priestley-Taylor and Hargreaves-Samani models. The RBFNN model is ranked as the second best model. 相似文献
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