Drought risk assessment using remote sensing and GIS techniques   总被引：1，自引：0，他引：1  

Abdel-Aziz Belal  Hassan R. El-Ramady  Elsayed S. Mohamed  Ahmed M. Saleh 《Arabian Journal of Geosciences》2014,7(1):35-53

Beginning with a discussion of drought definitions, this review paper attempts to provide a review of fundamental concepts of drought, classification of droughts, drought indices, and the role of remote sensing and geographic information systems for drought evaluation. Owing to the rise in water demand and looming climate change, recent years have witnessed much focus on global drought scenarios. As a natural hazard, drought is best characterized by multiple climatological and hydrological parameters. An understanding of the relationships between these two sets of parameters is necessary to develop measures for mitigating the impacts of droughts. Droughts are recognized as an environmental disaster and have attracted the attention of environmentalists, ecologists, hydrologists, meteorologists, geologists, and agricultural scientists. Temperatures; high winds; low relative humidity; and timing and characteristics of rains, including distribution of rainy days during crop growing seasons, intensity, and duration of rain, and onset and termination, play a significant role in the occurrence of droughts. In contrast to aridity, which is a permanent feature of climate and is restricted to low rainfall areas, a drought is a temporary aberration. Often, there is confusion between a heat wave and a drought, and the distinction is emphasized between heat wave and drought, noting that a typical time scale associated with a heat wave is on the order of a week, while a drought may persist for months or even years. The combination of a heat wave and a drought has dire socio-economic consequences. Drought risk is a product of a region’s exposure to the natural hazard and its vulnerability to extended periods of water shortage. If nations and regions are to make progress in reducing the serious consequences of drought, they must improve their understanding of the hazard and the factors that influence vulnerability. It is critical for drought-prone regions to better understand their drought climatology (i.e., the probability of drought at different levels of intensity and duration) and establish comprehensive and integrated drought information system that incorporates climate, soil, and water supply factors such as precipitation, temperature, soil moisture, snow pack, reservoir and lake levels, ground water levels, and stream flow. All drought-prone nations should develop national drought policies and preparedness plans that place emphasis on risk management rather than following the traditional approach of crisis management, where the emphasis is on reactive, emergency response measures. Crisis management decreases self-reliance and increases dependence on government and donors.  相似文献   

Simulation of the lately injected dykes in an Iranian porphyry copper deposit using the plurigaussian model     

Hassan Talebi  Omid Asghari  Xavier Emery 《Arabian Journal of Geosciences》2014,7(7):2771-2780

Ore deposits are usually composed of rock units or facies with different grade distributions and complex spatial structures. Being able to simulate the spatial layout of these facies are essential to have a comprehensive mining plan and an accurate resources and reserves evaluation. Modelers are faced with a set of challenges when creating the facies model such as: reproducing the facies proportions and spatial continuity as well as the topological contacts between facies, capturing post depositional overprinting, and honoring the data obtained from drill holes. Plurigaussian simulation (PGS) is a geostatistical approach that allows covering these challenges. This study addresses the application of PGS to Sungun porphyry copper deposit (Iran), in order to simulate the layout of three facies: mineralized porphyry and skarn and non-mineralized dykes. The aim of this study is to construct numerical models in which the dyke structures reflect the evolution observed in the geology.  相似文献   

Log-derived petrophysical characteristics and oil potentiality of the Upper Qishn Clastic Member,Masila Basin,Yemen     

Awad A. Omran  Nabil M. Alareeq 《Arabian Journal of Geosciences》2014,7(5):1733-1748

The Lower Cretaceous Qishn Formation at Masila Basin, Yemen, contains substantial amounts of proven crude oil. It is divided into a lower shaly silisiclastic member and an upper carbonate member. In the present work, detailed formation evaluation of the Upper Qishn Clastic Member was carried out using the digitized well logging data from 12 wells, via computer-assisted analysis, to accomplish its reservoir characteristics and oil potentiality. Accordingly, the true resistivity (R _t), porosity (total φ _t and effective φ _e), shale content (V _sh), permeability (K), water saturation (S _w), hydrocarbon saturation (S _h) (movable “S _hm” and residual “S _hr”) and lithologic composition in each well were estimated, analyzed, and illustrated versus depth on litho-saturation cross-plots. Likewise, the areal distribution of such parameters alongside the member in the investigated area and their relations to geological setting were defined from the constructed isoparametric contour maps. Based on the obtained results, the components of Upper Qishn Clastic Member of Masila Basin are mainly shaly sandstone and minor calcareous sandstone with considerable amount of shale. Regionally, the Member was deposited on an inner neritic to shallow-marine platform setting. It is interpreted as a good-quality reservoir rock which has been established from high total porosity (15–22 %), good effective porosity (8–13 %), and variable shale volume (24–31 %). A number of high hydrocarbon saturation zones (exceeding 55 %) are detected through intervals having S _w?<?60 % and S _hm?>?20 % which have been considered as economic oil producers. The storage and pay capacities of the reservoir intervals have been resolved. The obtained results were confirmed from the available data of core analyses and production tests. The Upper Qishn Clastic Member reveals promising reservoir characteristics which should be taken into consideration during future development of the oilfields in the area.  相似文献   

A Neuro-Fuzzy modeling for prediction of solar cycles 24 and 25     

Abdel-Fattah Attia  Hamed A. Ismail  Hassan M. Basurah 《Astrophysics and Space Science》2013,344(1):5-11

The paper presents a Neuro-Fuzzy model to predict the features of the forthcoming sunspot cycles 24 and 25. The sunspot time series were analyzed with the proposed model. It is optimized based on Backpropagation scheme and applied to the yearly smoothed sunspot numbers. The appropriate number of network inputs for the sunspots data series is obtained based on sequential forward search for the Neuro-Fuzzy model. According to the model prediction the maximum amplitudes of the cycles 24 and 25 will occur in the year 2013 and year 2022 with peaks of 101±8 and 90.7±8, respectively. The correlation and error analysis are discussed to ensure the performance of the proposed Neuro-Fuzzy approach as a predictor for sunspot time series. The correlation coefficient between Neuro-Fuzzy model forecasted sunspot number values with the actual ones is 0.96.  相似文献   

Partitioning of Se, As, Sb, Te and Bi between monosulfide solid solution and sulfide melt - Application to magmatic sulfide deposits   总被引：1，自引：0，他引：1  

Hassan M. Helmy  Chris Ballhaus  Raúl O.C. Fonseca 《Geochimica et cosmochimica acta》2010,74(21):6174-6179

The chalcogenes (S, Se, Te), semimetals (As, Sb) and the metal Bi are important ligands for noble metals and form a wide range of compositionally diverse minerals with the platinum-group elements (PGE). With the exception of S, few experimental data exist to quantify the behavior of these elements in magmatic sulfide systems. Here we report experimental partition coefficients for Se, Te, As, Sb, and Bi between monosulfide solid solution (mss) and sulfide melt, determined at 950 °C at a range of sulfur fugacities (fS2) bracketed by the Fe-FeS (metal-troilite) and the Fe_1−×S-S_x (mss-sulfur) equilibria. Selenium is shown to partition in mss-saturated sulfide melt as an anion replacing S²⁻. Arsenic changes its oxidation state with fS₂ from predominantly anionic speciation at low fS₂, to cationic speciation at high fS₂. The elements Sb, Te, and Bi are so highly incompatible with mss that they can only be present in sulfide melt as cations and/or as neutral metallic species. The partition coefficients derived fall with increasing atomic radius of the element. They also reflect the positions of the respective elements in the Periodic Table: within a group (e.g., As, Sb, Bi) the partition coefficients fall with increasing atomic radius, and within a period the elements of the 15th group are more incompatible with mss than the neighboring elements of the 16th group.  相似文献   

Stratigraphy,deposition, and structural framework of the cretaceous (review) and 3D geological model of the lower cretaceous reservoirs,Masila oil field,Yemen     

Hassan S. Naji  Mohammad H. Hakimi  Mohammed Khalil  Farooq A. Sharief 《Arabian Journal of Geosciences》2010,3(3):221-248

The Masila area is located in the Hadhramaut region in east central Yemen. Oil was first discovered in the area in late 1990 with commerciality being declared in late 1991. Oil production began in July 1993. By the end of December 1999, the daily production rate was set at 210,000 stock tank barrels/day (STB/D) of very low gas–oil ratio (GOR) oil under partial to full water drive. About 90% of the reserves are found in the Lower Qishn Clastics Member of the Qishn Formation. This paper focuses on the detailed 3D geological modeling of the Lower Cretaceous Sequence conducted through an integrated study. There are three critical areas in the process of modeling reservoirs that involve geological and geophysical modeling, reservoir characterization, and reservoir flow modeling. This paper presents methodologies found useful during the modeling of these reservoirs including field case histories for the Lower Cretaceous reservoir in the Masila oilfield.  相似文献   

Steel rings as seismic fuses for enhancing ductility of cross braced frames     

Farhad Behnamfar  Saeid Arman  Hassan Zibasokhan 《地震工程与工程振动(英文版)》2022,21(4):1103-1117

A new remedy is proposed in this study to increase the ductility of cross-braced frames to a level comparable with ductile moment frames. The suggested system consists of one or two concentric steel rings installed in the cross-braced bay vertically. The steel rings are designed such that they fail in bending sooner than failure of the braces in compression.Then the rings act as seismic fuses with multiple bending plastic hinges. Using nonlinear static analysis, it is shown that the proposed sys...  相似文献   

Numerical Evaluation of Local Site Effects on Amplification of the 2017 Mw 7.3 Sarpol-e-Zahab,Iran, Earthquake Waves Using Near and Far-Field Records     

Sharafi  Hassan  Raeisi  Niloofar 《Geotechnical and Geological Engineering》2022,40(6):3007-3037

Geotechnical and Geological Engineering - This is the first study to quantitatively evaluate the local site effects in the most severely affected neighborhoods of Sarpol-e-Zahab city following the...  相似文献