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1.
Hatem A. Ewea Amro M. M. Elfeki Jarbou A. Bahrawi Nassir S. Al-Amri 《Arabian Journal of Geosciences》2016,9(5):424
Runoff peak and volume in flood studies are estimated relying on temporal rainfall distribution from various storm patterns. Usually, SCS distributions types (I, II, III, IA) are commonly used. Using these distributions in runoff calculations assume that the in situ temporal rainfall pattern typically behaves as the one described by the SCS-type distribution, which is due to cyclonic frontal storms and actually developed in temperate environment. To what extent such assumption is valid in the arid environment? How much the impacts of rainfall temporal patterns are reflected in runoff volumes and peaks? The aim objectives of the current study are to answer the above two questions and clarify the validity of aforementioned assumption and exemplify such effect. Real rainfall data collected from rain gauges of Makkah Al-Mukkramah region over a period of more than 20 years are utilized. Temporal rainfall patterns and their parameters are deduced. Many hydrological simulations are performed and comparisons, in terms of runoff volume and peak flows, are made to show the effects of the common rainfall storm patterns and the developed rainfall storm patterns in the region based on the current study. Results indicate that major bursts of the design rainfall storm pattern are located in the first time of the storm period in the two quartiles which is mainly due to convective rainfall type in thunderstorms unlike the commonly used by SCS types relying on frontal cyclonic storms. Makkah Al-Mukkramah temporal rainfall pattern does not behave as the “typical pattern” assumed by SCS distributions that are deduced from different environments. The impacts of the temporal pattern reflected as an overestimate in the runoff peak reached to 68 %. The developed hyetographs and tables presented in the current study are recommended to enhance economical and rational design practice in watersheds of Makkah Al-Mukkramah region. 相似文献
2.
Hatem A. Ewea Nassir S. Al-Amri Mohamed A. Dawoud Amro M. Elfeki 《Natural Hazards》2018,94(2):801-817
Forecasting and monitoring extreme floods in arid regions like Saudi Arabia (SA) are a big challenge for engineers and hydrologists. It is difficult to derive reliable flood estimates at any site without adequate flood measurements. Therefore, envelope curves were developed for reliable estimates of flood peaks. Relaying on recorded flood events in SA, Francou–Rodier approach is used to develop the Regional Maximum Flood (RMF) for some wadis and for SA as a whole. A total of 3121 flood events in 32 arid basins of sizes varying from 99 to more than 4500 km2 are collected and analyzed. Results show that established regional coefficients (K) range between 2.76 and 5.5. The RMF formula for the Saudi regions is Q?=?251 A0.45. The flood-frequency analysis showed that the Log-Pearson Type III is best. The extreme observed floods for the envelope curve for K?=?5.5 accommodate floods of recurrence interval ranging between 1000 and 100,000 years. The study results provide more realistic runoff peaks for a design of flood protection works for SA watersheds and for the similar environment. Consequently, it is recommended to use the developed envelope curves and models for efficient, safe and precise hydraulic structures design in SA. 相似文献
3.
Development of storm hyetographs for flood forecasting in the Kingdom of Saudi Arabia 总被引：1，自引：0，他引：1
This paper presents the derivation of the design storm hyetograph patterns for the Kingdom of Saudi Arabia based on real rainfall events from meteorological stations distributed throughout the Kingdom. Two thousand twenty-seven rainfall storms for a 20–28-year period were collected and analyzed covering 13 regions of the Kingdom. Four distinct dimensionless rainfall hyetograph patterns have been obtained over the Kingdom, while two patterns have been obtained for each individual region because of the lack of data for long-duration storms in individual regions. The resulting dimensionless rainfall patterns for each region can be used to develop storm hyetographs for any design duration, total rainfall depth and return period. It has been shown that the developed storm hyetographs have different features from other storm patterns that are commonly used in arid zones. The study recommends using these curves for the design of hydraulic structures in Kingdom of Saudi Arabia and regions alike. 相似文献
4.
N. Wassif A. M. Kafafy E. M. Abdel Aal A. Abdeldayem H. Odah R. Mostafa 《Arabian Journal of Geosciences》2014,7(9):3455-3466
Ore microscopic study was carried out on a great number of samples collected from four well-dated alkaline rock masses (ring complexes), namely Gabal Mishbeh, Gabal Nigrub El Fogani, Gabal Nigrub El Tahtani, and Gabal El Gezira located in the Eastern Desert of Egypt. These rings consist mainly of wide variety of rock types ranging from basic to acidic and from under saturated to quartz bearing. The opaques of the basic rocks consist mainly of various ilmenite–magnetite intergrowths and differ essentially from those of the acidic rocks where minor amount of titanomagnetite is present. Numerous exsolution, replacement, and deformational textures were described. The distribution of opaque minerals and their intergrowths in the four well-defined ring complexes is described. Systematic rock magnetic measurements such as natural remanent magnetization intensity and initial susceptibility, Curie point, saturation magnetization, and coercive force were carried out, and their results were discussed in the light of opaque mineralogical studies. 相似文献
5.
Modeling of surface water quality based on a deductive approach is highly non-linear, varies with time, is spatially distributed and is difficult to incorporate as part of decision-support systems. A Neural Networks (NNs) procedure provides a reliable analysis in several science and technology fields. NNs are often applied to develop statistical models for intrinsically non-linear systems. In this investigation, NNs are used in the induction of a water quality model from available field measurements for the Bahr Hadus drain in the Eastern Egyptian Delta. Two models, namely, feed-forward back propagation (BP) and cascade correlation (CC), were used. It is concluded that the CCNN model produced slightly more accurate results and learned very quickly compared with the BP procedure. The results indicated that the NNs model could be used as a non-linear dynamic system model to encapsulate site-specific knowledge and emulate the temporal sequence of one-dimensional flow systems. This NNs model undoubtedly will reduce the cost and save time in this class of problems. 相似文献
6.
T. Abdallatif A.E. El Emam M. Suh I.A. El Hemaly H.H. Ghazala E.H. Ibrahim H.H. Odah H.A. Deebes 《Geophysical Prospecting》2010,58(2):307-320
The main outbuildings of the Amenemhat II pyramid complex in Dahsour were yet to be discovered due to a very long subjection of the area to the military authorities and also the demolition of the pyramid itself. We describe the discovery of some of these outbuildings using near‐surface magnetic investigations. A gradiometer survey was conducted in the area east of the pyramid to measure the vertical magnetic gradient with a high resolution instrument at 0.5 m sampling interval. The data showed some undesirable field effects such as grid discontinuities, grid slope, traverse stripe effects, spikes and high frequencies originating from recent ferrous contamination. These undesirable effects were addressed to produce an enhanced display. We have successfully detected four main structures in the area east of the pyramid; the causeway that connected the mortuary temple with the valley temple during the Middle Kingdom of the 12th Dynasty, the mortuary temple and its associated rooms, ruins of an ancient working area and an Egyptian‐style tomb structure called a Mastaba. An improved recognition for these structures was accomplished by using the analytic signal and Euler deconvolution techniques. Excavation of a small part within the study area has proven the reliability of magnetic discoveries and the shallowness and composition of the detected features. 相似文献
7.
High‐resolution gamma ray spectrometry was exploited to locate the potential radioactive targets at Kab Amiri granite pluton, Central Eastern Desert, Egypt. The Kab Amiri pluton forms a concentric granitic body of monzogranite to syenogranite composition intruded into mafic‐ultramific rocks. To identify and detect anomalous concentrations of natural radioactive elements in the study area, contour maps of equivalent uranium (eU ppm), equivalent thorium (eTh ppm), potassium (K%) and their geochemical ratios (eU/Th, eTh/K and eU‐eTh/3.5) as well as standard deviation map of uranium were constructed and interpreted. Qualitative and quantitative interpretations of the spectrometric survey data revealed the presence of seven radioactive anomalies in the south of the studied area. These anomalies could be related to the prevailing faulting directions NE and ENE fault trends. The southernmost anomalous zone is related to high episyenitization and uranium concentrations. It exhibits a sharp increase in the eU concentrations reaching 370 ppm resulting in a high eU/eTh ratio reaching 4.5 and characterized by oval shape trending in the NE direction. Constructing the contour map of the (eU‐eTh/3.5) was helpful in defining the trends of uranium migration and enabling the delineation of the limit between the negative contours (leaching) and positive contours (deposition). 相似文献
8.
Evaluation of hydrocarbon pollution in marine sediments of Sfax coastal areas from the Gabes Gulf of Tunisia,Mediterranean Sea 总被引：1，自引：0，他引：1
Hatem Zaghden Monem Kallel Boubaker Elleuch Jean Oudot Alain Saliot Sami Sayadi 《Environmental Earth Sciences》2014,72(4):1073-1082
The Tunisian environmental legislation that follows the EC Directives requires monitoring of persistent, toxic and bio-accumulated substances commonly considered as hazardous substances. In order to comply with this requirement, samples of sea water, sediment and biota from the urbanized and industrialized coast line of Sfax city are investigated. This study presents the results of petroleum hydrocarbon content, distribution and probable origin (anthropogenic and/or biogenic) in 16 intertidal sediments of Sfax coastal area. Alkane distribution indices and hydrocarbon distribution patterns are used to identify natural and anthropogenic input. Non-aromatic hydrocarbons present a high concentration with a range varying from 180 to 1,400 μg/g of dry sediment. The total concentrations of polycyclic aromatic hydrocarbons (PAHs) varied from 0.41 to 5.6 μg/g dry weight. These concentrations are comparable to other marine areas that receive important inputs. n-Alkanes with carbon number ranging from 15 to 35 are identified to be derived from both biogenic and anthropogenic sources in varying proportions. Pristane/phytane ratio shows values lower than 1.4 suggesting the presence of petroleum contamination. This is confirmed by the presence of a large group of unresolved complex mixture and the identification of hopanes with predominant C29 and C30 compounds and steranes with predominance of C27 over C28 and C29 compounds. Ratios of selected PAH concentrations indicate petrogenic and pyrolytic origin of hydrocarbons. Anthropogenic hydrocarbon inputs were more apparent at sites associated with industrial discharges, shipping activities and sewage outfalls. 相似文献
9.
Hatem Gasmi Essaïeb Hamdi Nejla Bouden Romdhane 《Rock Mechanics and Rock Engineering》2014,47(4):1393-1409
Homogenization in fractured rock analyses is essentially based on the calculation of equivalent elastic parameters. In this paper, a new numerical homogenization method that was programmed by means of a MATLAB code, called HLA-Dissim, is presented. The developed approach simulates a discontinuity network of real rock masses based on the International Society of Rock Mechanics (ISRM) scanline field mapping methodology. Then, it evaluates a series of classic joint parameters to characterize density (RQD, specific length of discontinuities). A pulse wave, characterized by its amplitude, central frequency, and duration, is propagated from a source point to a receiver point of the simulated jointed rock mass using a complex recursive method for evaluating the transmission and reflection coefficient for each simulated discontinuity. The seismic parameters, such as delay, velocity, and attenuation, are then calculated. Finally, the equivalent medium model parameters of the rock mass are computed numerically while taking into account the natural discontinuity distribution. This methodology was applied to 17 bench fronts from six aggregate quarries located in Tunisia, Spain, Austria, and Sweden. It allowed characterizing the rock mass discontinuity network, the resulting seismic performance, and the equivalent medium stiffness. The relationship between the equivalent Young’s modulus and rock discontinuity parameters was also analyzed. For these different bench fronts, the proposed numerical approach was also compared to several empirical formulas, based on RQD and fracture density values, published in previous research studies, showing its usefulness and efficiency in estimating rapidly the Young’s modulus of equivalent medium for wave propagation analysis. 相似文献
10.
Natural Hazards - Urbanization of watersheds is known to increase the flood risk potentials. Since 1970, eastern Jeddah, Saudi Arabia, underwent rapid urbanization due to the high rate of... 相似文献