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851.
Ahmed M. Youssef Hasan M. Al-Harbi Francisco Gutiérrez Yasser A. Zabramwi Ali B. Bulkhi Saeed A. Zahrani Alaa M. Bahamil Ahmed J. Zahrani Zaam A. Otaibi Bosy A. El-Haddad 《Hydrogeology Journal》2016,24(3):625-644
Approximately 60 % of the 2,150,000 km2 area of Saudi Arabia is underlain by soluble sediments (carbonate and evaporite rock formations, salt diapirs, sabkha deposits). Despite its hyper-arid climate, a wide variety of recent sinkholes have been reported in numerous areas, involving significant property losses. Human activities, most notably groundwater extraction, have induced unstable conditions on pre-existing cavities. This work provides an overview of the sinkhole hazard in Saudi Arabia, a scarcely explored topic. It identifies the main karst formations and the distribution of the most problematic sinkhole areas, illustrated through several case studies covering the wide spectrum of subsidence mechanisms. Some of the main investigation methods are presented through selected examples, including remote sensing, trenching and geophysics. Based on the available data, the main causal factors are identified and further actions that should be undertaken to better assess and manage the risk are discussed. 相似文献
852.
853.
Magmatism at continental passive margins inferred from Ambient‐Noise Phase‐velocity in the Gulf of Aden
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Félicie Korostelev Sylvie Leroy Derek Keir Cornelis Weemstra Lapo Boschi Irene Molinari Abdulhakim Ahmed Graham W. Stuart Frédérique Rolandone Khaled Khanbari Ali Al‐Lazki 《地学学报》2016,28(1):19-26
Non‐volcanic continental passive margins have traditionally been considered to be tectonically and magmatically inactive once continental breakup has occurred and seafloor spreading has commenced. We use ambient‐noise tomography to constrain Rayleigh‐wave phase‐velocity maps beneath the eastern Gulf of Aden (eastern Yemen and southern Oman). In the crust, we image low velocities beneath the Jiza‐Qamar (Yemen) and Ashawq‐Salalah (Oman) basins, likely caused by the presence of partial melt associated with magmatic plumbing systems beneath the rifted margin. Our results provide strong evidence that magma intrusion persists after breakup, modifying the composition and thermal structure of the continental margin. The coincidence between zones of crustal intrusion and steep gradients in lithospheric thinning, as well as with transform faults, suggests that magmatism post‐breakup may be driven by small‐scale convection and enhanced by edge‐driven flow at the juxtaposition of lithosphere of varying thickness and thermal age. 相似文献
854.
Al Jabal al Akhdar (Green Mountain) in arid northern Oman has freshwater resources that had supported small communities for hundreds of years. Jabal Akhdar receives more rainfall (300-400 mm) when compared to the desert plains. In the last few years, this region had undergone enormous changes due to rapid development. The resident and transient populations have increased and their activities exert severe stress on the water resources. There are 24 retention reservoirs in the area, but most are eutrophic and the nutrient loading is due to input of animal fecal matter via surface run-off. As expected, these waters contaminated with coliform bacteria and some have pathogenic Escherichia coli. Drinking water needs of all the villages met by groundwater extraction. Because of poor quality, the surface water in the reservoirs is under-utilized. A low-cost low-maintenance treatment system designed, constructed and operated in one village to clean the reservoir water for non-drinking human use. The treatment unit improved the water quality parameters. A survey among the adult male population of the village showed their eagerness to adopt this system and use the treated reservoir water for uses other than agriculture. Establishment of these treatment units in other villages should reduce the pressures on groundwater extraction. 相似文献
855.
856.
Mesoscale analysis of failure in quasi‐brittle materials: comparison between lattice model and acoustic emission data
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David Grégoire Laura Verdon Vincent Lefort Peter Grassl Jacqueline Saliba Jean‐Pierre Regoin Ahmed Loukili Gilles Pijaudier‐Cabot 《国际地质力学数值与分析法杂志》2015,39(15):1639-1664
The purpose of this paper is to analyse the development and the evolution of the fracture process zone during fracture and damage in quasi‐brittle materials. A model taking into account the material details at the mesoscale is used to describe the failure process at the scale of the heterogeneities. This model is used to compute histograms of the relative distances between damaged points. These numerical results are compared with experimental data, where the damage evolution is monitored using acoustic emissions. Histograms of the relative distances between damage events in the numerical calculations and acoustic events in the experiments exhibit good agreement. It is shown that the mesoscale model provides relevant information from the point of view of both global responses and the local failure process. © 2015 The Authors. International Journal for Numerical and Analytical Methods in Geomechanics published by John Wiley & Sons Ltd. 相似文献
857.
Drought risk during the early growing season in Sahelian Sudan 总被引:1,自引:0,他引:1
Nadir Ahmed Elagib 《Natural Hazards》2015,79(3):1549-1566
858.
859.
Mallick Javed Islam Abu Reza Md. Towfiqul Ghose Bonosri Islam H. M. Touhidul Rana Yousuf Hu Zhenghua Bhat Shakeel Ahmed Pal Subodh Chandra Ismail Zulhilmi Bin 《Theoretical and Applied Climatology》2022,147(1-2):307-324
Theoretical and Applied Climatology - The rise in the frequency and magnitude of extreme temperature phenomena across the globe has led to the recurrent incidence of global climate hazards, which... 相似文献
860.
Solla Mercedes Buceta-Bruneti Gonzalo Elseicy Ahmed Nieto-Muñiz Breogán 《Surveys in Geophysics》2022,43(5):1587-1606
Surveys in Geophysics - This paper deals with the application of the Ground Penetrating Radar (GPR) method in the assessment of stone monuments. Compilation of published works and a discussion of... 相似文献