Volume 2 ,2000

Geo-environrnental themes including topography, geomorphology, lithology, structure, mineral resources, natural hazards (flash flooding, earthquakes, sand drift and landslides), soil cover, and natural protected areas (reserves) of the Sohag-Lake Nasser stretch are defined, mapped and automated by applying Geographic Information System (GIS) functions and operations. The prepared geo-environmental database (input) is used to obtain derivative (interpretational) maps for resource evaluation, risk zonation of natural hazards, and suitability for urban development.

The rapid urban extension towards the east Cairo area and the presence of several trunk wadis direct attention to the study of the drainage basins of the area in detail. Using satellite images and aerial photographs, the morphometric parameters and the influence of structures and lithology on the hydrographic basins of the area were determined. The study indicated that the drainage net is dominantly trellis in nature, coarse, well developed, highly integrated, consistent and dense. Streams are deeply incised and are structurally controlled. The main valleys are controlled by the main fault system (NW-SE) whereas the directions of their tributaries are mainly controlled by the resulting fault blocks (cuestas) characterizing the local landforms. With respect to flood hazards, the basins rank as highly dangerous to dangerous. On the bases of previously recorded climatic conditions, the area may face strong cloudbursts in the next few years. Sulphurous water is recorded in some locations in the study area indicating reducing environment and hence deep-seated fault effect. Earthquake records show that the area is still seismically active.

Southern Sinai rocks, between the Gulf of Suez and Gulf of Aqaba, predominated by Precambrian basement, are highly tectonized. It is to be noted that the basement rocks of Egypt are hitherto not comprehensively investigated geomorphologically. Genesis of southern Sinai landforms is basically related to morphostructural types initiated by structures, followed by denudation. Lithological control plays an important role in the mechanical and chemical weathering which govern the development of the landforms as depicted on Landsat TM images. These landforms are clearly shown on images of original scale 1:250,000. The main landforms identified include: a structural suite which was differentiated according to lithological control and degree of weathering, as well as fluvial, eolian and coastal landforms.

Geomorphologic features have been interpreted on Landsat TM images (bands 2, 4 and 7) of the southern part of the Eastern Desert of Egypt. These features could be classified into: landforms of structural denudation origin, landforms due to fluvial deposition, features of aeolian origin, and coastal forms. Color, tone and texture as reflected in the used thematic map help in the determination of the type of rocks and sediments constituting mapped landforms. Identification of geomorphologic units could be used as criteria for ground water prospection, mineral exploration and hazard mitigation.

The drainage system of Wadi El-Barud, Wadi El-Ambagi and Wadi El-Alam threaten the Red Sea coastal towns of Safaga, Quseir and Marsa el Alam respectively, as well as the highways connecting and crossing them. The drainage nets of these basins are external, well developed, highly integrated and significantly affected by geological structures and rock type. These basins originate mainly from mountainous highland of basement rocks, which are flanked further east by a relatively low-lying sedimentary strip. The morphometric parameters of the basins defined point out to moderate to high peaked discharges and low to moderate recharging. Suggested management and flash flood alleviative measures include: construction of heaped-stone dykes (and/or versatile gabions) at key locations in the upper and middle reaches of the basins as well as diversions, in cases to protect already existing human activities at the lower reaches. With proper study and management, Quaternary alluvial plains in the upper and middle reaches of complex basins particularly in the basement terrain may be usable, in addition to the fans of the lower reaches, for development purposes as they, beside having good soil, may host considerable trapped groundwater in sinks of shallow unconfined aquifers.

The drainage networks, affecting Ras Gharib and Hurghada towns, were defined and traced on Landsat-TM images by computer-assisted routines. These routines were also applied to delineate basin boundaries and variables, as well as their morphometric parameters. These latter are used to assess flash flood probability and groundwater potentiality. Geomorphological, lithological and structural setting of the drainage basins were studied. Spatial distribution of Quaternary fluviatile deposits within the basins was emphasized because of their potential as desert arable lands. Land-use maps, basically based on newly acquired aerial photographs (scale 1: 10,000), were prepared for Ras Gharib and Hurghada and their environs. Flash flood vulnerable sites were delineated, appraised, and sorted out according to degree of risk into three categories: high, moderate and slight. Recommended mitigative measures include piling stone dykes and /or gabion stacks at critical sites in the middle and lower reaches of the drainage basins. These have the dual objective of reducing flood velocity, thus increasing infiltration rate with concomitant reduction in the carrying capacity of solid load, and recharging the unconfined wadi aquifers.

Remote sensing data can be used as an important tool to evaluate and monitor land-use and land-cover changes. Global coverage, high spatial resolution and revisit capabilities of modem remote sensing satellites, provide us with a large amount of valuable data for accurate land-use estimation. In this study land- use change detection of Al-Ain City, United Arab Emirates (UAE), within approximately ten years period was conducted. Three landsat images of different dates (1984, 1989, 1993) were processed and analyzed, geometrically corrected (registered) and digitized to extract more detailed information and differences. Based on the combined use of multitemporal satellite imagery and ancillary data, such as topographic maps, aerial photographs and field check (ground truth) data, land-use maps with different classes were prepared, showing the substantial rate of change, and usefulness of Landsat data in detailed mapping and in land-use change detection studies.

Since the last two decades, major national development projects have been accomplished in Egypt, in particular around the Gulf of Suez, Red Sea. These include construction of roads, power stations, ports, industrial plants, mineral exploration and beach resorts and villages construction. This study was carried out to provide data to evaluate the present status and monitor the marine and coastal environment of one of the important coastal power plant in the region. This has been done through studying different oceanographic parameters (i.e. bathymetry, water quality, sedimentological and ecological characteristics) of the coastal zone of Al-Sukhna area, located along the western coast of the Gulf of Suez. Field, satellite data and laboratory analyses show that the cross-shore profiles marked three distinctive slopes; the beach face, intertidal flat, and subtidal zone. The beach is composed of medium sand (mean grain size = 0.34 to 0.46 mm) with an average carbonate content of 70.2 %. Sediments, including muddy sand and sandy mud, cover the intertidal flat, while mud and sandy mud cover the subtidal area, both are rich in carbonate contents yielding averages of 58.02 and 48.80%, respectively. The spatial pattern of grain size to beach and bottom sediments shows fining towards the offshore. Factors influencing the process of sedimentation in the nearshore area include shoreline orientation and geometry, seabed gradient, tidal fluctuation, direction of the incoming waves, and sediment input, both natural and anthropogenic. Hydrographic and water quality of the coastal water lie within the expected normal levels, which characterize the northern part of the Gulf of Suez, not affected by human interventions. High concentrations of TSM are attributed to sediment discharging from human activities at Al-Sukhna area. As a result of the ongoing development projects (i.e. dredging activities) at Al-Sukhna area, the biodiversity of the fauna and flora is very poor. The wide intertidal flat is partly covered with shell fragments and coral debris. In general, the subtidal region is biologically deteriorated, as most of the observed molluscan and foraminefral shells are broken with very few living specimens.

Multiple data sets including both remotely-sensed imagery and field measurements are integrated using GIS techniques to delineate the optimal sites of industrial granite at Wadi Sanad area. The data sets encompass the geological and structural parameters which control the suitability of granite for quarrying. The accomplishment of integration process involves the assignment of weighting factors to these parameters, then producing a priority map. The obtained map shows three ranks of industrial granite; the first rank granite is represented by old biotite granite (monzogranite). It has pinkish color and coarse-grained texture, and is composed mainly of plagioclase, alkali feldspar, quartz and biotite. Moreover, selected twelve prospect sites, both newly discovered sites and previously opened quarries, are located in the study area. Only one new site and one quarry could be classified as a first rank quality, whereas the others are assigned as second to third rank.

This research aims at integrating airborne radiometric and remote sensing data to prospect for radioactive materials in the Central Eastern Desert of Egypt. The study recorded uranium mineralization for the first time along NW-SE trending fault zones, within the Miocene clastic-carbonate sediments. These occurrences are associated with iron ochre (Um Greifat) and Pb-Zn mineralization (Abu Gherban, Um Ghieg, Wizr, Essel). Gamma ray spectrometer measurements for samples representing these localities indicate the presence of U up to 0.0584 % in Urn Greifat ochre deposits and up to 0.0152 % at the Wizr fault zone cutting the Miocene sediments. Results demonstrate the accuracy of airborne radiometric data, as well as the suitability of remote sensing techniques for use in exploration for radioactive materials

An aerial shuttered camera without an exposure control system is controlled manually to adjust opening of a diaphragm according to the ambient light level. The correct adjustment in the mean time according to the change of ambient light level is an important issue to obtain good results. In many cases the follow-up of such adjustment cannot be fulfilled during the mission itself. Therefore, the diaphragm always keeps its initial adjustment and the produced film is more probable out of the correct exposure (either over-exposed or under-exposed). An aerial shuttered camera must be equipped with such capability to verify better results.

Determination of lithology from well logs is the subject of interest of many geologists. The method introduced in this paper gives an automatic determination of lithology from well logs using a 1-nearest neighbor classifier. The I-nearest neighbor rule (I-NNR) with editing and condensing techniques training data set has been obtained from a key well in Abu Garadig oil field. This well has a suitable suite of logs and a continuous core as a geological reference. The designed classifier is tested on other wells in the same field. Analysis of the experimental results demonstrates that all the obtained lithologies are in accordance with the geological references.

Geologic rock units mapping using Landsat-TM images of different bands and band ratios, for the Gabal Igla Al-Ahmar and Ash Shaykh Salim areas, was carried out to get an accurate spatial distribution of the different rock units exposed in the two areas. Landsat-TM images of scales 1:90000, 1:213000 and 1: 200000 original scenes were generated, processed and prepared at Free University of Berlin and Technical University-Bergakademie Freiberg, Germany. The images were generated using bands (7, 4, 2) and band ratios (5/7, 5/1, 4/5x3/4) and (1- 4, 2-5, 3-6) for Igla AI Ahmar area. On the other hand, bands (7, 3, 1) and band ratios (1/4//2/5, 3/4//5/7, 4/5//1/3), (3/1 5-4, 5/7, 3/5) and (3/5, 5/7, 3/15-4) were generated for Ash Shaykh Salim area. The study proves that both image bands (7, 4, 2) and band ratio R4 (5/7, 5/1, 4/5x3/4) are the best combinations to delineate geological units with precision on regional and semi-regional scales.