Volume 6 ,2003

This study aims at supporting sound planning for sustainable ecotourism development of Ras Banas area along the Red Sea Coast, Egypt. This area is characterized by unique coastal ecosystems and fragile environment. Landsat Thematic Mapper (TM) data have been used as a source of information for the preparation of different thematic geo-environmental maps of the coastal area through visual or digital image interpretation. A digital database for the area was established and the essential derived maps representing data layers on the spatial distribution of different types of terrestrial ecosystems have been used for building a Geographic Information System (GIS) model. The thematic maps include: (1) land cover classification with emphasis on the coastal formations (sabkha, coral reefs, coastal islands and mangroves), (2) shore line, (3) drainage network and (4) basins and flash flood hazard map. In addition, topographic sheets at scale of 1:50,000 were digitized and transformed to GIS digital maps that include two layers for coordinate grid and contour lines with spot heights. A spatial model has been developed and constructed for analyzing large spatial data in a GIS environment. The development of the model scenarios aimed at quantifying the impacts of different derived layers that required an assessment of different factors influencing the model. Different layers have been given different weights, based on their anticipated contributions to the model. The model was subjected to various dynamic trials related to its layer components and weights. An environmental sensitivity index map was prepared, where the coastal zone was classified, on the basis of its relative sensitivity to anthropogenic activities, into high, medium and low sensitivity classes. Sensitivity classification, has been used for the delineation of the suitable sites for potential sustainable ecotourism development. This derivative mapping and integrated modeling has added a significant new dimension to the database by combining existing data with knowledge of interplay between different environmental factors.

Sol Hamid area is chiefly occupied by Neoproterozoic rocks, partly covered by Miocene sediments and Recent sand sheets and dunes. The Neoproterozoic rocks include ophiolitic-ultramafic to mafic rocks, metavolcano-sedimentary rocks, metavolcanics, gabbro-diorite rocks, granodiorites, biotite granites and alkali granites. Magnesite, chromite, iron ores, manganese and barite ore deposits are hosted in different rocks at the study area. ERS-2 SAR data enabled to obtain an image that reveals some buried fluvial features beneath the surface cover of desert sand. These features are not observable in Landsat TM images of similar resolution. In this work, Principal Component Analysis (PCA) technique was used for merging ERS-2 SAR and Landsat TM images to make use of the potential of data fusion technique of image processing in the interpretation of geological features. This procedure has resulted in enhancing subsurface structures such as faults that control distribution of several deposits in the study area. This study represents an example to demonstrate the utility of merging various remote sensing data for exploring mineral deposits in arid region.

Integration of Landsat-Thematic Mapper (TM), aeromagnetic data, structural geology along with the known mineralization occurrences in the area are mainly the factors used to recognize favorable sites for structurally controlled mineralization at the northern part of the south Eastern Desert of Egypt. Two knowledge-driven models were constructed based on a conceptual gold exploration model. The Density of Lineament Intersection (DLI) results from this study along with Dempster-Shafer (D-S) Belief approach show good results in delineating favorable mineralization areas. The basic assignment probability maps for the heat source, strong magnetism, hydrothermal alteration, geologic structure, and known mineralization occurrences in the area are the main D-S Belief approach recognition criteria components used for mineral exploration in the study area. The DLI method is maximizing the use of Landsat remote sensing data that could be used efficiently in the exploration for structurally controlled hydrothermal related mineralization. The DLI method results show higher resolution and accurate results for gold and base metals exploration. The high favorability areas by using the DLI method is 2196 Km2 which are concise area than the D-S Belief approach for about 3976.5 Km2 . These results are useful to be a strong base for planning accurate exploration program. The potential favorability maps of gold and base metals ore deposits from the northern part of the South Eastern Desert predicted the known areas of mineralization as well as identified high potential areas not known before with mineralization for future exploration

The utilization of the Landsat-7 ETM+ imagery and scanned aerial photographs for mapping hydrothermal alteration zones at the Haimur gold mine area, south Eastern Desert, Egypt and the production of large scale geologic image map, scale 1:20.000, using fusion technique are the main tasks of this article. The study area lies at the conjunction of two shear zones, namely the Allaqi shear zone (NW -SE) and the Haimur shear zone (NE-SW). The basement rocks covering Haimur gold mine area include ophiolitic blocks and sheets that were tectonically thrusted over and mixed within a matrix of island arc rocks. Principal Component Analysis (PCA), band ratios and data fusion are the main remote sensing techniques applied in the present work. The eigenvalue of the first principal component (PC1) includes 95.9 % of the information content of the image whereas PC2 and PC5 mark 3.03 % and 0.10 %, respectively. The PC5 image was found to represent the highly altered. rocks in the study area (serpentinites and carbonates), which display dark image signatures. The metagabbros and metapyroclastics can be easily discriminated on the PC1:R, PC2:G and PC5:B false color composite image in which they have dark red and blue image signatures, respectively. The talc carbonates and the serpentinites have bright image signatures on 5/7 band ratio image whereas metapyroxenites have dark image signatures. The talc carbonates are composed mainly of talc, magnesite and calcite with subordinate amounts of fibrous antigorite. These minerals have absorption features near 2.35 m which lead to increase 5/7 band ratio value. The false color composite ratio image 5/7:R, 4/5:G and 3/1:B was merged with scanned high spatial resolution aerial photograph using IHS transformation method. The resultant fused image was then used to delineate the hydrothermal alteration zones, as well as listwaenite ridges exposed at the Haimur gold mine area

Safsaf area is located in the southwestern part of Egypt. It lies between latitudes 22° 56' and 22° 59' N, and longitudes 29° 18' and 29° 42' E. The studied area represents a small and inconspicuous oasis characterized by scattered natural vegetation and some cultivated or wild palm trees. The oasis lies within the hyper arid zone. Bir Safsaf area has been analyzed using SAR images acquired during the Shuttle Imaging Radar (SIR) missions A-C to possess optimal conditions for demonstrating the use of space-borne SAR in sand penetration and mapping features of geomorphologic, pedologic and hydrographic importance in the south Western Desert of Egypt. Acquired SAR images of Bir Safsaf and vicinity from ERS-1/2 have been mosaicked and were used as C-band base maps in the field. They have been interpreted in conjunction with the multi-frequency (C/X-band) Synthetic Aperture Radar (SIR-C/X-SAR) images for portraying lithic contacts and associated fracture zones and mapping old streams "paleo drainage" in weathered granite rocks below a thin cover of wind-blown sand, at Bir Safsaf. Landsat ETM+ image was used to map surface features .Using integrated SAR and TM imagery data enabled us to define and map geomorphologic and pedologic features as well as identifying secondary features that include (1) north- trending bedrock lineament system of eolian origin discriminated specifically at X-band, (2) portrayal of local late Quaternary channels on images acquired at all three radar bands (X-, C-, and L). Natural resources that are represented by land and water have been assessed. Buried channels and vicinities have been classified into four Radar classes namely 1-Radar deltaic stage of river terraces, 2-Radar island, 3-Radar river and 4- Radar river terraces

The main geomorphologic and drainage characteristics of the Tushka area were . delineated through the interpretation of Landsat TM image. The study area displays physiographic features indicative of previous wet climatic conditions. The Nubia aquifer system in the region has a wide extension in the study area and rests unconformably on the Precambrian rocks. The River Nile has its own bearing on the hydrogeological regime of the Tushka and neighbouring areas of Lake Nasser. Comparison of the available data concerning the water levels of Lake Nasser above its submerged bottom (which involves elevations ranging from 50 to 90 m a. s. 1.) according to the recorded data between 1964 and 1996, with the static water levels of the groundwater wells reaching the deeper horizons of the Nubia Sandstone aquifer system in the Tushka basin area, suggests that the River Nile acts mostly as an influent stream. However, in some cases, when the static water levels of some deep water-bearing horizons reach levels above those of the bottom of the lake, water flows from the groundwater reservoirs towards the river which acts as an effluent stream. Other wells have low static water levels compared to those of the bottom of the lake, and the waters of the River Nile most probably recharge the groundwater of these deeper water-bearing horizons of the Nubia aquifer. The prepared equipotentiometric contour map confirms this conclusion as it indicates that the maximum potentiometric level is attained in the north western part of Lake Nasser (at contour 80, near Well No. 12) whereas the minimum potentiometric level is encountered in a small area around Well No.6 (at contour 50). Hence, the groundwater flow is generally towards Lake Nasser. However, in some instances, it is also moving in an adverse direction. The hydrogeological condition of the study area was conducted based on the variation in lithology, areal extent, recharge and productivity. The study revealed that the Nubia aquifer system in the area is mainly moderately to low productive and the groundwater could be used for the planned future developmental activities.

The impact of land cover/land use on groundwater can be critical. Land cover / land use maps give an early warning for planners and developers to protect groundwater resources from depletion and preserve its sustainabi1ity. These land cover / land use maps can be used for the planning of groundwater development to prevent the deterioration of the aquifer. The Research Institute for Groundwater of Egypt (RIGW) has carried out hydrogeological studies, in 1990, to evaluate the potentiality of groundwater in Luxor area in southern Egypt close to the Nile Valley. The region is characterized by a rapid and continuous increase in land reclamation and development on the fringes which surround the already heavily cultivated land within the Nile Valley. This presented a need for continuous monitoring and information updating over a vast region in a short time and at a reasonable cost. This study illustrates how remote sensing techniques can be effectively used for monitoring changes in land cover / land use in an effort to aid groundwater management. Landsat Thematic Mapper (TM) data collected in 1984 and 2000 were processed and analyzed over the study area to produce land cover/ land use maps. The Normalized Difference Vegetation Index (NDVI) technique is used for Landsat TM images to quantify areas which are covered by vegetation. Results indicated significant increase in cultivated areas. Remote sensing results are compared with iso-piezometric maps and iso-salinity maps that were produced in 1984 and 2000. Comparison of these maps indicates groundwater depletion and salinity increase from 1984 to 2000. We relate this to the increase of the area being cultivated.

Geologically, Wadi Araba is a horst, but its topography may misleadingly suggest that it is a graben-shape, as it appears as a depression surrounded by two high walls rising at about 1 000 m above its mid-ground. The main geomorphic features found in the area are: plateaus, cuestas, fault scarps, slopes, badlands, alluvial fans (upper and lower), terraces and wadi deposits and a coastal plain. The analysis of the geological setting, geomorphology and structure of Wadi Araba suggests that the evolution of its topography proceeded in several stages (cycles): a pre-Jurassic cycle, a Cretaceous cycle of folding, a pre-Eocene phase of tectonic movements, an Eocene stage of sedimentation, an Oligocene cycle of weathering and a post- Miocene cycle (with Pliocene and Quaternary sedimentation).

Three major Precambrian basement inliers are exposed in the South Western Desert of Egypt between Long. 29° E and the River Nile within the Uweinat-Bir Safsaf-Aswan E-W uplift system. These are Bir Safsaf, Gabal EI-Asr and Gabal Umm Shaghir areas. Smaller outcrops include Gabal EI-Gara EI-Harnra and Gabal EI-Gara EI-Soda, Gabal Siri, GabaI EI-Fantas and Aswan-Kalabsha area, as well as the scattered outcrops around Darb EI-Arbain road. Band ratios 5/7, 5/1, 4 of Landsat TM images were applied to delineate the borders, the lithologic units and structural features of low relief basement outcrops within the surrounding flat lying sedimentary rocks and sand plains. These basement rocks comprise orthogneisses (assumed by many authors as related to old continent pre Pan- African rocks), G1 tonalite-granodiorite, and G2 monzogranite-alkali feldspar granite intruded by variable dykes. The boundaries between the basement exposures and the sedimentary rocks are marked by nonconformity surfaces or sets of faults. Both basement and sedimentary rocks are intruded by Mesozoic syenite-G3 granites, rhyolite, trachytic plugs and Upper Cretaceous to Tertiary basalts. The basement exposures are structurally controlled by major E-W fault system. Their vertical uplifting is overprinted by folding the overlying sedimentary rocks. This study revealed that the different basement exposures in the SE of the Western Desert of Egypt are similar in appearance and field relations to the Pan-African basement rocks extending towards the east of the River Nile and exposed everywhere in the Eastern Desert of Egypt

A database for the classification and description of basic geomorphologic landform units has been prepared for establishing geomorphologic maps in Egyptian terrains. This database includes morpho-structural, lithological, denudational and depositional units. The database is included in tables with proper coding to be used for establishing automatically the color, symbols and legend of the maps. Also the system includes description of various geomorphic units. The system is designed to be used with the ARC Map software. The AUTOCAD 2000 software has been used to trace the maps. The database has been applied to produce five new geomorphologic maps with a scale of 1:100 000. These are: Wadi Feiran Sheet, Wadi Kid Sheet, Gabal Katherina Sheet in South Sinai, Shelattein area (South Eastern Desert) and Baharia Oasis area (Western Desert)

Landsat Thematic Mapper (TM) data for Al Hasa Oasis area was processed for delineating characteristic land features represented mainly by sand dunes, sabkhas, cultivated land and urban areas using procedures that take advantage of distinctive spectral reflectance of these land features. The method employs a color ratio technique based on comprising different ratios 2/3, 2/4, 3/4, 3/5, 4/5, 5/6, and 5/7. A number of ratio triplets were processed using a three colored composite ratio. The ratio images (3/4, 3/5, 5/6, and 5/7) succeeded to distinguish the main land features in the studied arid region and generate detailed maps over wide area by using quantitative reproducible mapping criteria and helping in identifying the characteristics of the different land features

This article presents rock art paintings in an area located at the scarp face of Wadi Abraq (Latitude 23° 28' N and Longitude 34° 45' E). The site is a sandstone protruding ledge rising about 30m. above the ground level. The Gebel Abraq paintings depict a tropical fauna including Elephants, Giraffes, Cows and Ostrich denoting that the area was previously subjected to intensive rainfall during the last pluvial periods. The result was a savana type of land. During recent times, the climate became dry and the communities were forced to move to other areas where natural springs are still flowing such as Ain Abraq and Bir Abu-Safa. The present founding of the prehistoric paintings (Graffiti) has revealed a mass of evidence that many of the concepts regarding Sahara rock art should be studied.