Structural patterns in river network organization at both infra‐ and supra‐basin levels: the case of a granitic relief     

Christophe Cudennec  Youssef Fouad 《地球表面变化过程与地形》2006,31(3):369-381

Within a landform, the channelized water path from any point to the corresponding outlet is split into successive components within the Strahler ordering scheme. The probability density functions (pdf) of the length L of the whole channelized path and of the lengths of the components are studied as multi‐level structural functions. We have considered a granitic area and studied both its main basin and the set of its 48 constituent basins. With respect to the main basin, the pdf of the component lengths exhibit a strong scaling property, except for the highest orders, due to a hierarchical constraint; hence, the pdf of sum L has no particular shape. We have nevertheless identified an underlying structural pattern at particular infra‐ and supra‐basin levels, where the hierarchical constraint is weaker. This identification process entails noting structurally emerging patterns based on multi‐level variables and distributions, which satisfy the general self‐similarity of networks. The fairly good fit of an analytical gamma law with most of these emerging patterns can prove to be a positive step towards both a general modelling approach to the geomorphometric functions and a stronger geomorphological basement of hydrological transfer functions. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

Book reviews     

Gwyn Rowley  Mushtaqur Rahman  Fouad Ibrahim  Günther Schlee  Eckart Ehlers  Yola Verhasselt  Andreas G. Koestler  G. L. Kamukala  Wolf Tietze 《GeoJournal》1995,36(1):102-96

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Cultural change and the chances of reintegration after remigration to home areas — the case of the southern Sudanese dislocated population in Greater Khartoum     

Fouad N. Ibrahim 《GeoJournal》1995,36(1):103-107

About three million indigenous southern Sudanese have been dislocated as a result of the civil war which has been going on since 1955, with an interruption of only eleven years. The 1.5 million dislocated southern Sudanese in Khartoum are currently suffering from hunger and religious, social, political and economic discrimination. This paper argues, however, that a considerable number of them would prefer to keep living in the North, when the civil war comes to an end. After many years of separation from the South, it will be difficult, especially for those who came as young children to Khartoum, to reintegrate into the completely different environment of a war-wrecked South.  相似文献   

Use of two-dimensional electric resistivity and ground penetrating radar for archaeological prospecting at the ancient capital of Egypt     

Fouad F Shaaban  Fathy A Shaaban   《Journal of African Earth Sciences》2001,33(3-4)

Two-dimensional (2-D) resistivity and ground penetrating radar (GPR) surveys facilitate tracing of buried archaeological relics at the archaeological site of the Tell El Rabi'a, southwestern Cairo. These surveys also provide information on variations in depth of the groundwater table, which affect both exhumed and buried archaeological remains. The 2-D electrical resistivity profiles obtained show some high anomalies (up to 6900 Ω m). Based upon on-site calibration at partly exhumed sites, such anomalies are interpreted as pillar crowns and wall-like structures of hard limestone of the Hathour temple. The low background resistivities are interpreted to represent riverine deposits with differing moisture (or saturation) characteristics. The results of the GPR survey show three forms of high-amplitude radar anomalies, denoted as “P, H and R”. The “P” anomalies have semi-hyperbolic shapes, which suggest the presence of thin buried walls. The second, near-horizontal group of anomalies, “H”, may be either due to the presence of thick buried walls or arise from coincidental parallel alignment of survey lines with buried linear structures. The third group of GPR anomalies “R” is composed of chaotic reflections, and interpreted to depict buried stone-filled chambers. Some un-exhumed parts of the study area show weak radar reflections with occasional highly attenuated radar signals. These phenomena are ascribed to differing compaction and moisture characteristics of riverine soil layers. Recommendations with regard to archaeological site-excavation, preservation of archaeological relics, and soil conservation are submitted.  相似文献   

Comment on “Update on terrestrial ages of Antarctic meteorites” by K. Nishiizumi, D. Elmore and P.W. Kubik     

Derek W.G. Sears  Fouad A. Hasan  Benjamin M. Myers  Hazel Sears 《Earth and Planetary Science Letters》1990,99(4)

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Book reviews     

Fouad N. Ibrahim  G. Kunkel  David H. Miller  A. Wallner  R. O. Whyte  W. U. Ehrmann  Matthias Kuhle  Robert Giepel  Pieter Lukkes  B. K. Roy  W. R. Stanley  Paul Mosely 《GeoJournal》1986,12(4):464-469

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Lands at risk in the third world: local level perspectives     

Fouad Ibrahim 《GeoJournal》1986,12(2):220

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Microearthquake studies in Egypt carried out by the geological survey of Egypt     

Fouad K. Boulos  Paul Morgan  Tousson R. Toppozada 《Journal of Geodynamics》1987,7(3-4)

Extensive microearthquake studies have been conducted in Egypt as a joint project between scientists from the Egyptian Geological Survey and Mining Authority (EGSMA) and U.S. scientists. At this stage, a great part of the data has been analyzed and two intensively active areas have been located: one in the Abu Dabbab area of the Eastern Desert, the second at the mouth of the Gulf of Suez near Gubal Island (Daggett et al., 1980). Both sites have been reported to be the epicenters of large earthquakes in 1955 and 1969, respectively. A few scattered earthquakes have also been located in the northern part of the Red Sea, some of which lie along its median axis (Daggett et al., 1986) adding to evidence for the medial opening of the northern Red Sea. After the occurrence of an earthquake (M = 5.5) in the Aswan region on 14 November 1981, continuous recording of the many aftershocks was carried out by EGSMA for about seven months from December 1981 to July 1982, when the temporary network was replaced by a network of telemetered seismographs installed and operated by Helwan Institute of Astronomy and Geophysics in cooperation with scientists from Lamont and Doherty Geological Observatory (LDGO). The majority of epicenters are concentrated in the vicinity of G. Marawa about 65 km upstream of Aswan Dam, along the E-W Kalabsha fault. The observed focal mechanism is consistent with a right-lateral strike-slip motion on the Kalabsha fault. Analysis of Aswan microearthquakes has been done by EGSMA in cooperation with scientists from California Division of Mines and Geology (CDMG).  相似文献   

The role of women peasants in the process of desertification in Western Sudan     

Fouad N. Ibrahim 《GeoJournal》1982,6(1):25-30

Women peasants in the Sudan are both agents of and sufferers from the process of desertification which is taking place in the arid and semi-arid zone. The researchwork done by the author on the problem of desertification in the west of the Republic of the Sudan convinced him that women there suffer much more than men do from the decrease of land productivity. Paradoxically enough, women themselves have actively taken part in desertifying their environment in their desperate attempt to keep their families living. This paper endeavours to highlight the role of peasant women in areas prone to or already stricken by desertification. Especially in the transitional phases following drought disasters and loss of live-stock the whole brunt of catering for the family falls on the shoulders of peasant women. Three main issues are being tackled: Millet production as essentially women's task, rainfall variability and its impact on women cultivators, the settlement of nomads and semi-nomads as a new burden laid on women. Finally, some suggestions are made to improve the conditions of women's work to provide nutrition for their families without doing much destruction to the fragile environment and its limited resources.  相似文献