Contribution of remote sensing and GIS to analysis of the risk of flooding in the Zat basin (High Atlas-Morocco)

Natural Hazards - Despite the controversy regarding their use, school buildings are often assigned as emergency evacuation shelters, temporary accommodation and aid distribution hubs following...     

Field study on the behavior of pre-bored grouted planted pile with enlarged grout base

This paper presents the results of field tests performed to investigate the compressive bearing capacity of pre-bored grouted planted (PGP) pile with enlarged grout base focusing on its base bearing capacity. The bi-directional O-cell load test was conducted to evaluate the behavior of full scale PGP piles. The test results show that the pile head displacements needed to fully mobilize the shaft resistance were 5.9% and 6.4% D (D is pile diameter), respectively, of two test piles, owing to the large elastic shortening of pile shaft. Furthermore, the results demonstrated that the PHC nodular pile base and grout body at the enlarged base could act as a unit in the loading process, and the enlarged grout base could effectively promote the base bearing capacity of PGP pile through increasing the base area. The normalized base resistances (unit base resistance/average cone base resistance) of two test piles were 0.17 and 0.19, respectively, when the base displacement reached 5% D_b (D_b is pile base diameter). The permeation of grout into the silty sand layer under pile base increased the elastic modulus of silty sand, which could help to decrease pile head displacement under working load.

     

Flood hazard and risk analysis in the southwest region of Bangladesh

Flood hazard and risk assessment was conducted to identify the priority areas in the southwest region of Bangladesh for flood mitigation. Simulation of flood flow through the Gorai and Arial Khan river system and its floodplains was done by using a hydrodynamic model. After model calibration and verification, the model was used to simulate the flood flow of 100‐year return period for a duration of four months. The maximum flooding depths at different locations in the rivers and floodplains were determined. The process in determining long flooding durations at every grid point in the hydrodynamic model is laborious and time‐consuming. Therefore the flood durations were determined by using satellite images of the observed flood in 1988, which has a return period close to 100 years. Flood hazard assessment was done considering flooding depth and duration. By dividing the study area into smaller land units for hazard assessment, the hazard index and the hazard factor for each land unit for depth and duration of flooding were determined. From the hazard factors of the land units, a flood hazard map, which indicates the locations of different categories of hazard zones, was developed. It was found that 54% of the study area was in the medium hazard zone, 26% in the higher hazard zone and 20% in the lower hazard zone. Due to lack of sufficient flood damage data, flood damage vulnerability is simply considered proportional to population density. The flood risk factor of each land unit was determined as the product of the flood hazard factor and the vulnerability factor. Knowing the flood risk factors for the land units, a flood risk map was developed based on the risk factors. These maps are very useful for the inhabitants and floodplain management authorities to minimize flood damage and loss of human lives. Copyright © 2005 John Wiley & Sons, Ltd.     

Microseismicity and tectonics of Sinai

Five microearthquake seismographs were used at 11 sites in northern Sinai in the period February 1987 to February 1988 to study the microseismicity of the area around the Maghara coal mine for mine-development studies. A total of 270 events were recorded on 850 records. The magnitude, epicenter and depth of each event were calculated using suitable software for an Egyptian Geological Survey and Mining Authority's (EGSMA) XT computer. The interpretation of the seismic activity in the area is given in view of plate tectonics, the Sinai subplate boundary follows the Gulf of Aqaba and the Dead Sea. The plate and subplate boundaries are presently active, and there seems to be a diffuse zone of deformation between “NW Africa” and “Nubia” affecting the Cairo-Suez district.     

Net radiation over the Aswan High Dam Lake

Summary Net radiation is an essential parameter for estimating evaporation from large water surfaces by energy balance method. Net radiation has been measured for the first time over the Aswan High Dam Lake on the Nile River for 132 days including warm and cold seasons. A high multiple linear correlation coefficient of 0.98 was obtained between the measured net radiation on the one hand and the global solar radiation measured at Aswan and the difference between water and air temperatures measured over the Lake on the other hand.Seven different empirical formulae for estimating the effective outgoing radiation have been applied on the average data measured over the Lake for days of clear sky. It has been found that the Swinbank formula is the best one suitable for the location of the Aswan High Dam Lake.With 2 Figures     

A structural synthesis of the Proterozoic Arabian-Nubian Shield in Egypt

Detailed structural geological and related studies were carried out in a number of critical areas in the Proterozoic basement of eastern Egypt to resolve the structural pattern at a regional scale and to assess the general characteristics of tectonic evolution, orogeny and terrane boundaries. Following a brief account of the tectonostratigraphy and timing of the orogenic evolution, the major structural characteristics of the critical areas are presented. Collisional deformation of the terranes ended about 615-600 Ma ago. Subsequent extensional collapse probably occurred within a relatively narrow time span of about 20 Ma (575 – 595 Ma ago) over the Eastern Desert and was followed by a further period of about 50 Ma of late to post-tectonic activity. The regional structures originated mainly during post-collisional events, starting with those related to extensional collapse (molasse basin formation, normal faulting, generation of metamorphic core complexes). Subsequent NNW-SSE shortening is documented by large-scale thrusting (towards the NNW) and folding, distributed over the Eastern Desert, although with variable intensity. Thrusts are overprinted by transpression, which was localized to particular shear zones. Early transpression produced, for example, the Allaqi shear zone and final transpression is documented in the Najd and Wadi Kharit-Wadi Hodein zones. Two terrane boundaries can be defined, the Allaqi and South Hafafit Sutures, which are apparently linked by the high angle sinistral strike-slip Wadi Kharit-Wadi Hodein shear zone with a tectonic transport of about 300 km towards the W/NW. In general, the tectonic evolution shows that extensional collapse is not necessarily the final stage of orogeny, but may be followed by further compressional and transpressional tectonism. The late Pan-African high angle faults were reactivated during Red Sea tectonics both as Riedel shears and normal faults, where they were oriented favourably with respect to the actual stress regime.     

Uplift in seismic response of pile supported buildings

To resist seismic overturning moments piles are often designed for tensile forces which require pile connection to the cap and sometimes, socketing. For typical buildings, this paper theoretically examines the effect of these measures on seismic response, forces and pile loading in dependence on pile numbers, configuration and tip conditions.     

Geographic analysis of manufacturing industry in Saudi Arabia

The study focuses on the analysis of manufacturing industry in Saudi Arabia by examining development, structure and spatial distribution. The analysis has shown that Saudi manufacturing is basically of recent development and is highly capital- and energy-intensive, particularly the hydrocarbon-based groups. Perhaps the most conspicuous weakness of Saudi industrialization is the almost total dependence on expatriate labour. Foreign capital and expertise share in the building and development of the industrial sector by providing technical, managerial, and marketing skills. Saudi industry is heavily subsidized by the government, and the public sector plays a commanding role in industrial development. Large-scale basic industries are owned and run by the government, while light manufacturing of the import-substitution type is dominated by the private sector. One of the main characteristics of manufacturing industry is that it is scantily diversified, modestly concentrated and remarkably linked geographically but not functionally or structurally. Although the authorities are exerting tremendous efforts to achieve a regional balance in industrial development, Saudi manufacturing industry is significantly polarized, urban-oriented and highly associated with the major axes of population scatter. Like all developing countries beginning to industrialize, Saudi manufacturing industry faces certain problems which have to be resolved so as to lay the foundations for a sound and prosperous industrial future. The paper goes on to indicate problems and to suggest solutions.