Volume 5 ,2003

In this paper, different pixel-based fusion techniques have been examined for enhancing the low spatial resolution of bands 2,4&7 of Landsat- 7 ETM+ image covering a sample area of north-west part of Gulf of Suez, Egypt, by using the high resolution band of the same data (band 8). The techniques considered in this study are Multiplicative, Color Normalization (CN), Intensity Modulation (IM), Filter, PCA, HIS and Wavelet. The proposed scheme in this study is based on cascaded (hybrid) transforms incorporating both PCA and Wavelet transforms. The ability to preserve spectral characteristics of the low resolution bands while enhancing the spatial resolution has been examined in each technique. An evaluation of the fused output has been performed based on both visual and statistical analysis. The statistical evaluation measures include mean, standard deviation, RMS, correlation, entropy, and the percentage of pixels with no change. Quantitative assessment of the output fused images demonstrates that the proposed Cascaded transforms scheme not only improves the spatial quality, but also preserves the spectral characteristics in different bands.

The Advanced Space-borne Thermal Emission and Reflection Radiometer (ASTER) is a multi-spectral imaging system that was launched in December 1999 onboard the Terra satellite. It has 14 bands in different parts of the electromagnetic spectrum; 3 in the visible and near infrared (VNIR) with 15 m spatial resolution, 6 in short wave infrared (SWIR) with 30 m spatial resolution, and 5 in thermal infrared (TIR) with 90 m spatial resolution. Compared to the Enhanced Thematic Mapper Plus (ETM+), ASTER has better spectral range and better spatial resolution in the VNIR. ASTER false-color and band-ratio images are compared to equivalent ETM+ images that have proven to be useful for geological mapping in arid regions. Remote sensing data covering part of the Neoproterozoic Allaqi suture in southern Egypt were used to evaluate the usefulness of ASTER false- color composite and band-ratio images for geological mapping in arid regions. The Allaqi suture is defined by ophiolites, shelf sediments, arc volcanics and granites that are deformed by S-verging fold and thrust belt. 7-3-1 false-color composite ASTER image is equivalent to 7-4-2 TM image (ARAMCO combination). This ASTER image is useful for outlining lithological units, as well as structural and morphological features. 4/7-4/1-2/3*4/3 ASTER image is equivalent to 5/7-5/1- 3/4*5/4 TM (Sultan's combination) and 4/7-3/4-2/1 ASTER image is equivalent to 5/7-4/5-3/1 TM image (Abram's combination). Both ASTER band-ratio images are quite useful in defining lithological units specially serpentenite, granites and marbles. In addition, the authors qualitatively evaluated the spectral curves of the rock types common in the Allaqi suture, to introduce new ASTER band-ratio images to be used for geological mapping in arid regions. 4/1-3/1-12/14 ASTER image is recommended because of the presence of diagnostic spectral features in these bands. This band-ratio image has the highest Optimum Index Factor (OIF) compared to other selected ASTER band-ratio images. Moreover, the 4/1-3/1-12/ 14 ASTER image incorporates bands from the VNIR, SWIR and TIR regions of the electromagnetic spectrum. Visual geological interpretation of this band-ratio image is in good agreement with published regional geological maps, field data and detailed geological mapping conducted by the authors

The aim of this study is to delineate the surface and subsurface structural lineaments of the Dihmit district, South Eastern Desert, Egypt, using in an integrated way, three data acquisition media, namely, space imagery, aeroradiometry and aeromagnetometry. To enable discrimination of the lithologic rock units and the surface manifested lineaments a Landsat- 7 ETM+ satellite image was used. The utilization of the two-dimensional power spectrum technique to determine the depths of the causative magnetic bodies within the basement revealed that the causative magnetic bodies are aggregated at two disturbing interfaces having average depths of 0.85 and 1.75 km. Filtering combined with the analytical downward continuation at the two assigned interfaces could simply assist in discriminating the shallow (near-surface or residual) and deep (deep-seated or regional) causative bodies. Four maps were drawn, two at each interface: one for the regional component of the magnetic field and the other for the residual one. Besides, the normalized total and horizontal magnetic vectors (gradients) of the field intensity and the variations of the total and horizontal phase angles were calculated at the two assigned interfaces to assist in the construction of the magnetic basement structural map. These were aided by the available geological information of the study area and interpretation of Landsat- 7 ETM+ imagery. The results show that the major structural trends affecting the studied area: are NW-SE (Gulf of Suez- Red Sea trend), NNW- SSE (Wadi Attala trend), NNE- SSW (Gulf of Aqaba trend), ENE-WSW (Syrian arc or Qattara trend), WNW-ESE (Najd trend), NE-SW (Trans-African trend), and N-S (Meridional or East Africa trend) arranged in decreasing order of significance. The statistical analysis of the extracted lineaments from the Landsat- 7 ETM+ data and the aeroradiometric total count data shows that the radioactivity of Gabal Dihmit area mainly follows the surface predominant NW, NNW and WNW trends. These trends were also registered over most of the geophysical maps, which reflect the presence of structures trending in these directions at the surface, near-surface and deep-seated levels. This could be used as guide to delineate potential radioactive occurrences along fractures of these trends particularly hosted in younger granite masses.

Listwaenites are recorded as gold-bearing alteration zones in the Eastern Desert of Egypt. Landsat TM ratio images and supervised classification method could distinguish between the different rock units and the alteration zones exposed in the Eastern Desert. The application of TM-ratioing enhancement and supervised classification methods with field verification in Urn Khasila district, revealed presence of old workings for gold at Wadi Um Shao (a tributary of Wadi Garf), and existence of extensive listwaenite alteration zones. Um Khasila district is occupied by ophiolitic-ultramafic rocks (serpentinites, talc carbonates and listwaenites) and island arc rocks (metavolcano-sedimentary, metaconglomerates, metavolcanic and gabbro-diorites). The serpentinites occur as a WNW stretched belt, thrusting over the island arc rocks, with abundant talc-carbonates and listwaenites along the thrust planes. The geochemical analysis for samples from Wadi Garf listwaenites recorded presence of relatively high contents of Au, Ag, As, Cr, Ni, and Co elements. The gold (Au) content reaches up to 2.72 g/t, silver (Ag) up to 15.4 g/t, chromium (Cr) up to 4300 ppm, nickel (Ni) up to 300 ppm and cobalt (Co) up to 150 ppm. The associated quartz veins contain up to 7.72 g/t Au and up to 4.9 g/t Ag. The mineralogical studies using ore microscope and SEM confirm presence of native gold, chromite, cobaltite, and pentlandite. This study indicated that the listwaenites and associated quartz veins in this district are promising targets for gold and silver mineralizations.

The Gulf of Suez catchment is a part of the Red Sea rift zone and is characterized by contrasting relief, landforms and geological manifestations. Rocks exposed range in age from Precambrian to Recent, including igneous, metamorphic and sedimentary varieties. The coastal strip varies in width and is characterized by a multitude of touristic attractive natural features. Major industrial facilities and oil fields stud the coastal area and extend into the water of the Gulf. At present, the region is under intensive development involving the construction of new maritime, industrial, and touristic facilities. Protection of these enterprises mandates a comprehensive study of the flash flood potential of the salient drainage basins debouching into the Gulf. In the last few years, recurrence of cloudbursts and heavy rainfall caused short period flash floods that were so strong to cause substantial local damage and havoc. In the light of this, it became inevitable to launch an integrated, geologic, geomorphic and morphometric study of all drainage basins in the Gulf of Suez catchment to assess their flash flood potential, and suggest mitigative precautionary measures that may, in the same time lead to water conservation. The study involves 138 drainage basins of different sizes and having a cumulative area of 32,000 km2 . These basins range in area from 3 km2 to 3684 km2 . They are classified into 6 size categories; namely: very large (>1500 km2 , 4 basins), large (> 600-1500 km2 , 11 basins), medium (> 300-600 km2 , 10 basins), small (> 100-300 km2 , 25 basins), very small (> 50-100 km2 , 31 basins) and minute basins (> 50 km2 , 57 basins). These measurements were based on topographic maps of 1: 100,000 scale. Each of these basins has its own geologic and geomorphologic characteristics. The most common feature among them is their being elongate and rather perpendicular to the Gulf. This study led to the delineation of the hazardous sites along the coastal highways on both sides of the Gulf. Plausible alleviative measures, mainly involving cost-effective flow retardation dykes, are recommended.

The capability of the space-borne, multi-frequency and multi-polarization Shuttle Imaging Radar (SIR-C/X) Synthetic Aperture Radar (SAR) for penetrating dry soil has been utilized in mapping subsurface drainage network (fossil rivers) and structures in the Kom Ombo -Aswan area, Southern Egypt. The area has been selected for its potential natural resources required for the sustainable development, including mineral and water resources, in addition to cultural heritages such as archeological sites. Furthermore, the vicinity of some wide plains of Wadis Kharit, Shait (in the eastern side of the Nile) and Wadi Kobbania (in the western side of the Nile) offer a good opportunity for agricultural development. Investigation of Enhanced Landsat TM and SIR-C/X-SAR images covering the area shows some drainage features and structural lineaments, which are not obvious in Landsat data alone. These drainages, which cross the Nile from east to northwest (e.g. Wadis Abu Subeira and Kobbania), indicate that rainfall was once plentiful and surface water prevailed in the region before the Nile has carved its present course. Some of that water would have seeped through the underlying porous rocks to be stored as fossil groundwater. Therefore, identification and mapping paleo-drainages in that area is important exercise if the groundwater resources are to be located. Moreover, the mapped paleo-channels provide a spectacular confirmation of the hypothesis that an older, local drainage system associated with the Red Sea Hills of the Eastern Desert, was fundamentally reorganized in the Middle Pleistocene time by appearance of a southerly-sourced, more continental drainage now known as the Nile.

Lead-zinc deposits in Miocene host rocks, located in seven drainage basins in the coastal plain of the Red Sea, Egypt, have been subjected to important mining activities. These basins cover an area of 2100 km2 . The basins were analysed to estimate the effect of flash flood in the transportation of these ore minerals. Fourteen soil samples and fifteen plant samples were collected from sites located in the basins and also in neighboring area. In the basins including Pb/Zn mines, soils include Pb contents reaching 3490 ppm with an average of 1950 ppm and average Zn values of 7625 ppm, Mn values of 1265 ppm and MgO of 4.0%. In the surrounding basins, however, the average Pb content is 860 ppm, Zn 3440 ppm, Mn 800 ppm and MgO 4.0 %. This soil derived from drainage of hills including Pb/Zn mines have a relatively high content of the above mentioned minerals than soils produced in other basins. Plants in mine basins also include high contents of these minerals. Capparis spinosa include Zn 0.02 % and Pb 0.013 %, Heliamthemun lippii include Zn 0.016 % and Pb 0.014% and Balanites aegyptiace include Zn 0.024% and Pb 0.11 %, while plants in other basins such as Salvadura persica include Zn 0.0011 %and Pb 0.0001 %. Some plants are grown in evaporite soil such as Oligomeris linifolia and Kohautia caespitose. Ca reaches up to 4.68 % in Balanites aegyptiaca, 6.6 % in Salvadura persica, 10.34 % in Kohautia caespitose and 4.1 % in Cleome drosifolia.

Decorative stones embrace a range of durable raw materials of attractive appearance and include dimension stones, ornamental stones, building stones, marble facing and terrazzo chips. Present-day ever-increasing structural and building operations in the United Arab Emirates (UAE) create large demands for these place-value products. This work deals with delineation of new occurrences of decorative stones in the UAE by using Landsat images and aerial photographs, corroborated with field investigation and laboratory studies. Most of these rocks are part of the Semail Ophiolitic Nappe of the Oman Mountains that crop out, with practically no overburden, forming huge rock masses with attractive colors, textures and grain sizes. Marble that crops out at Dibba, Wadi Ham and Hatta zones, including white and banded types, can be used to produce terrazzo products for finishing and fabrication. Large reserves of yellowish-beige, medium-hard to soft limestone occur in the sedimentary cover, particularly in Ruus Al Jebal, Jabal Al Faya and Jabal Hafit. Substantial quantities of these limestones are suitable as facing stones for external use.

The use of low quality water for irrigating either the old cultivated areas or the newly reclaimed desert areas is of prime importance due to the increasing of water demands. But, the uncontrolled application of such water must have many restricted effects on both soils and the plants grown, especially in the long-term use. The hazard effects are mainly related to the soil properties and water quality, beside the kinds of the crops grown. Twenty-three soil samples (0-20 cm) from Elgabal Elasfar region were taken which represent the soils irrigated with sewage water for different periods (about 20, 40, 80 years) and virgin soil. Chemically available Fe, Zn, Cu, Co, Ni and Pb, pH, O.M. content, and CaCQ3 content were determined. The target of the present study is to construct a suitability model map for soil contaminated with heavy metals in the Elgabal Elasfar area. To achieve this target the Geographical Information System (GIS) techniques were applied. The ARC/INFO and the IDRISI software's modules were used to create and process the different GIS layers for the heavy metals and some characteristics. The resulting GIS layers have several classes, where the statistical and topological relationships between these layers were determined as well as the weighting of each layer. The result of the overlaying of these different layers led to the suitability model map for the soil contaminated with the heavy metals in the concerned area. This suitability model map shows the distribution of the heavy metals in the study area that is irrigated with sewage water for different periods. Approximately, 1573 feddan of the studied area contained excess amounts of Cu and Co, which are beyond the permissible limit