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1.
The Sultanate of Oman is located in the south-eastern part of the Arabian Peninsula and covers the larger part of the southern coasts of the Arabian Peninsula in both arid and semi-arid environments except for the southern part which is swept by the monsoon affecting the Arabian Sea during the period from June to September. The summer rainfall over Oman shows year-to-year variability, and this is caused by oceanic and atmospheric influences. In the present study, we tried to explore the influence of El Niño on the rainfall over Oman using different data sets. The empirical orthogonal function (EOF) technique employed to the zonal wind at 850 hPa for the 30-year period shows that the second and third modes of EOF are showing high variability over the Oman regions. The corresponding PCs were subjected to FFT analysis, and it showed a peak about 5–6 years. In addition to this, the zonal wind over the Oman regions is correlated with the global zonal wind and found a significant correlation (1 % significant level). It has already been proved that the wind and rainfall during summer monsoon is in phase. Moreover, the spectral analysis of rainfall at Masirah station and the Niño3.4 index show the similar mode of variability indicating a direct relationship. The correlation between rainfall and the Niño3.4 index is also showing a positive significant value, and therefore, it can be concluded that the El Niño in the Pacific favours rainfall over the Oman region.  相似文献   
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3.
The contamination of aquifers by fluoride and arsenic is a major cause of concern in several parts of India. A study has thus been conducted to evaluate the extent and severity of fluoride contamination and also its seasonal variability. Two blocks (Purulia-1 and Purulia-2) were considered for this purpose. Twenty groundwater samples (in each season) were collected from tube wells during the pre-monsoon and post-monsoon seasons. In addition to fluoride, groundwater samples were also analyzed for major cations, anions, and other trace elements. The concentration of fluoride shows significant seasonal variation and ranges between 0.94–2.52 and 0.25–1.43 mg/l during the pre-monsoon and post-monsoon seasons, respectively. In pre-monsoon season, more than 40% of the water samples show fluoride concentrations higher than the WHO limit. However, during the post-monsoon season, none of the groundwater sample shows fluoride concentrations higher than the WHO limit. Lesser concentration during the post-monsoon season is attributed to the dilution effect by the percolating rainwater, which has also been reflected in the form of a decrease in concentrations of other elements. The petrographic studies of the rock samples collected from the study area show that the rocks are mainly composed of plagioclase, orthoclase, and quartz with abundant biotite. The weathering and dissolution of biotite plays an important role in controlling the fluoride concentrations in the groundwater of the study area.  相似文献   
4.
Bangladesh experiences frequent hydro-climatic disasters such as flooding.These disasters are believed to be associated with land use changes and climate variability.However,identifying the factors that lead to flooding is challenging.This study mapped flood susceptibility in the northeast region of Bangladesh using Bayesian regularization back propagation(BRBP)neural network,classification and regression trees(CART),a statistical model(STM)using the evidence belief function(EBF),and their ensemble models(EMs)for three time periods(2000,2014,and 2017).The accuracy of machine learning algorithms(MLAs),STM,and EMs were assessed by considering the area under the curve-receiver operating char-acteristic(AUC-ROC).Evaluation of the accuracy levels of the aforementioned algorithms revealed that EM4(BRBP-CART-EBF)outperformed(AUC＞90％)standalone and other ensemble models for the three time periods analyzed.Furthermore,this study investigated the relationships among land cover change(LCC),population growth(PG),road density(RD),and relative change of flooding(RCF)areas for the per-iod between 2000 and 2017.The results showed that areas with very high susceptibility to flooding increased by 19.72％between 2000 and 2017,while the PG rate increased by 51.68％over the same period.The Pearson correlation coefficient for RCF and RD was calculated to be 0.496.These findings highlight the significant association between floods and causative factors.The study findings could be valuable to policymakers and resource managers as they can lead to improvements in flood management and reduction in flood damage and risks.  相似文献   
5.
The Earthquake Model of Middle East (EMME) Project aimed to develop regional scale seismic hazard and risk models uniformly throughout a region extending from the Eastern Mediterranean in the west to the Himalayas in the east and from the Gulf of Oman in the south to the Greater Caucasus in the North; a region which has been continuously devastated by large earthquakes throughout the history. The 2014 Seismic Hazard Model of Middle East (EMME-SHM14) was developed with the contribution of several institutions from ten countries. The present paper summarizes the efforts towards building a homogeneous seismic hazard model of the region and highlights some of the main results of this model. An important aim of the project was to transparently communicate the data and methods used and to obtain reproducible results. By doing so, the use of the model and results will be accessible by a wide community, further support the mitigation of seismic risks in the region and facilitate future improvements to the seismic hazard model. To this end all data, results and methods used are made available through the web-portal of the European Facilities for Earthquake Hazard and Risk (www.efehr.org).  相似文献   
6.
Geohistory analysis was carried out on block 10 in the Say??un-Masilah Basin. The present study is based on the analysis of the well logs of six exploration wells. In the Middle Jurassic to the Middle Eocene, Say??un-Masilah Basin exhibited a complex subsidence history over a period of about 155?Ma. Backstripped subsidence curves are constructed by removing the effects of decompaction to the water column and sediment loads. In the Middle Jurassic, slow subsidence was driven under the effect of sediment load as Kuhlan and Shuqra Formations were deposited as pre-rift deposits. The average total subsidence value of the basement during the deposition of Shuqra Formation was 276?m. The highest subsidence rates during this time are observed northeast of the study area. Rapid subsidence initiated in the Upper Jurassic driven by mechanical extension of the rift, resulting in the deposition of Madbi and Safer Formations, or the so-called Syn-rift deposits. The average tectonic subsidence value of the basements during the deposition of Madbi Formation was 368?m. The highest subsidence rates during this time are observed southwest of the study area. Mechanical extension ceased at about 145?Ma, being replaced by a phase of post-rift subsidence, resulting in more widespread uniform sedimentation, with reduced tectonic subsidence rates forming post-rift deposits represented by Nayfa Formation, Sa??ar Formation, Biyad Formation, and Mahra Group. The total subsidence value of the basement during the deposition of the post-rift sediments increases gradually due to the increase of the sediment load as the rate of deposition was high especially northeast of the area.  相似文献   
7.
In this study uranium and thorium contents and depositional characteristics of ay rhan bituminous shales（ BS）, west of Ankara（central Anatolia）, are investigated. Samples used were collected from boreholes opened by Park Holding Ltd. A total of 25 samples were taken from bituminous shale levels in boreholes drilled at 6 different locations in the study area. The H rka formation which hosts bituminous shale deposits is a volcanosedimentary sequence and all lithofacies indicate that a lacustrine environment where the water level was continuously changed. In addition to hydrocarbon generation potential, bituminous shales also accumulate significant amount of radioactive elements such as uranium and thorium. The average uranium and thorium concentrations of BS（1.83/2.62 ppm） are much lower than averages of UC, NASK and PAAS（uranium： 2.70/2.66/3.10 ppm; thorium： 8.50/12.30/14.60 ppm）. Low uranium contents in comparison to those of similar lacustrine environments might be attributed to that waters of depositional environment of BS contain low concentration of dissolved uranium and redox conditions were of oxic and dioxic character. Correlation data indicate that U and Th have a similar source and are associated predominantly with clays and phosphates and dominantly with organic material. Radioactive elements in the basin might be derived from Paleozoic granites and metamorphites（e.g. gneiss, schist） which comprise the basement and volcanism which was active in the region throughout the Miocene period. These elements are probably associated with uraniferous phosphate minerals（e.g. autunite, torbernite） which occur in granite, gneiss and schist. BS with average TOC content of 10.96 % shows very good/perfect source rock potential. Positive correlations between Gamma-Ray values and U, Th and K concentrations imply that radioactivity might be originated from these three elements.  相似文献   
8.
Preventive protection of surface waters against pollution and the guarantee of the best quality water are the major challenges to provide a sustainable supply of drinking water for the future generations. In this article, we present a hazard mapping application for water contamination of the dam “9 April 1947” located in the northwest of Morocco. This study was motivated by the proliferation of many pollution sources in the study area knowing that the dam feeds the region of Tanger-Asilah that has over 3 million inhabitants. The methodology used was applied for the first time in the city of Freiburg-Ebnet in Germany under the TECHNEAU project funded by the European commission and based on weighting of the different sources of contamination according to three indices: the toxicity index, quantity index, and probability index. The multiplication of the three indices has given us a hazard index named HI varying between 0 and 120 depending on the harmfulness of hazard; the later index has been used to create the final contamination hazard map. The hazard map shows 65% of the watershed area is witnessing a very low danger, 22% of the watershed area is witnessing a low danger, 10% of the watershed area is witnessing a the high danger, and 3% of the watershed area is witnessing a moderate.  相似文献   
9.
Seawater intrusion and its spreading rate are the challenging problems in over-pumped coastal aquifers of arid zones like the Batinah region of Oman. The study delineates the saline plume, identifies saline/freshwater zones, and estimates the migration rate of the plume in the Al Khabourah area of the Batinah coast. Time domain electromagnetic surveys, aided by vertical electrical sounding surveys, and seismic refraction methods have defined the locus of the saline/freshwater interface in the area. The current (2007) interface position, when compared with that determined during 2002, indicates a prominent recession in the saline plume and suggests an average annual recession rate of 120 m. This recession may be attributed mainly to the recharging dam of Wadi Al Hawasinah, constructed in 1995, and the enforcement of new water resources legislation. This study reveals the shielding role of the recharging dam to counter advancing saline intrusion.  相似文献   
10.
The estimation of the monthly mean flow is a critical issue in many water resource development projects. However, in practice the mean flow is not easily determined in ungauged and poorly gauged basins. Therefore, in the literature, various flow estimation methods have been developed recently for mountainous regions which are generally ungauged or poorly gauged basins. In this study a fuzzy logic model based on the Mamdani approach was developed to estimate the flow for poorly gauged mountainous basins. This model was applied to the Solakli Basin which is located in the Eastern Black Sea Region of Turkey. Limited rainfall and flow data are available for this basin. In addition to these variables, the stream and time coefficients were introduced and used as variables for modeling. The data was divided into training and testing phases. The model results were compared with the measured data. The comparison depends on seven statistical characteristics, four different error modes and the contour map method. It was observed that the fuzzy model developed in this study yielded reliable results.  相似文献   
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