Volume 11 ,2009

The manual delineation of drainage networks and catchments from topographic maps has widely been replaced by the automatic extraction from Digital Elevation Model (DEM) using different processing algorithms. The automatic extraction requires first removing all the sinks (depressions) in the DEM by filling their elevation to the nearest neighbouring cells. The sinkholes are true inherited landscape in the karstified Marmarica Limestone Plateau covering the northwestern coast of Egypt. Following the traditional methods of automatic extraction, all the catchments outlets are located on the Mediterranean coast, but the centripetal catchments on the plateau surface cannot be delineated. A new technique is presented on how to delineate these centripetal catchments along with the coastal catchments, by masking the true sinks layer derived from topographic maps and satellite images from the DEM throughout the delineation process. The analysis of Tropical Rainfall Monitoring Mission (TRMM) data reveals that these centripetal catchments of the study area receive more precipitation than the coastal ones in contrary of the previous extrapolated isohyets maps. The runoff and soil potential for one of these centripetal catchments were initially assessed. The estimated average annual surface runoff is 1.8 million m3 and the soils are moderate to marginally suitable for citrus, peach, olives, wheat, sunflower and alfalfa.

Alexandria is the second largest urban governorate in Egypt and has seen significant urban growth in its modern and contemporary history. This study investigates the urban growth phenomenon in Alexandria, Egypt, using the integration of remote sensing and GIS. The urban physical expansion and change were detected using Landsat satellite images. The satellite images of years 1984 and 1993 were first georeferenced, achieving a very small RMSE that provided high accuracy data for satellite image analysis. Then, the images were classified using a tailored classification scheme with accuracy of 93.82% and 95.27% for 1984 and 1993 images respectively. This high accuracy enabled detecting land use/land cover changes with high confidence using a post-classification comparison method. One of the most important findings here is the loss of cultivated land in favour of urban expansion. If the current loss rates continued, 75% of green lands would be lost by year 2191. These hazardous rates call for an urban growth management policy that can preserve such valuable resources to achieve sustainable urban development. Modelling techniques can help in defining the scenarios of urban growth. In this study, the SLEUTH urban growth model was applied to predict future urban expansion in Alexandria until the year 2055. The application of this model in Alexandria of Egypt, with its different environmental characteristics is the first application outside USA and Europe. The results revealed that future urban growth would continue along the edges of the current urban extent. This means that the cultivated lands in the east and the southeast of the city will be decreased. To deal with such crisis, there is a serious need for a comprehensive urban growth management programme that can be based on the best practices in similar situations.

The current study aims at using remote sensing (RS) and Geographic Information System (GIS) techniques for optimum land-use planning of the area located north Ismaillia - south Port Said Governorates on the western side of Suez Canal. It is bounded by longitudes 32° 10' and 32 °20' E and latitudes 30° 41' and 31° 00' N. Great part of this area is under reclamation and suffering from improper land-use. Ten geomorphologic units were recognized i.e. clay flats, decantation basins, overflow basins, sand sheets, gypsiferous flats, old river terraces , sand flats , turtle backs, lake beds, and recent river terraces. Using US Soil Taxonomy, two soil orders could be identified; Entisols and Aridisols which are represented by ten great groups: Typic Haplosalids, Typic Haplogypsids,Typic Toriorthents, Vertic Argigypsids,Vertic Torrifluvents, Vertic Natrargids ,Typic Torripsamments,Typic Torrifluvens, Aquic Torriorthents and Typic Psammaquents. Surface and ground water with respect to salinity and alkalinity hazards were investigated ,where surface water of the main canals was classified as C2-S1, C3-S1,C4-S2 and C4-S4, meanwhile the ground water was classified as C3-S1, C3 -S1,C4-S2, C4-S1 and C4-S4 .Optimum land-use planning of the studied area includes three approaches i.e., physical planning, optimum cropping pattern and other uses. Physical planning includes designing of three geospatial models.1-treatment plant site selection model, 2-central village site selection model, and 3- shortest path for new canal model. Current cropping pattern was obtained by matching the crop requirements with soil characteristics, where soils of high sand flats and low gypsiferrous flats are currently highly suitable (S2) for sugar beet, alfalfa and cotton, soils of low sand flats are currently highly suitable (S2) for olive, citrus and melon, soils of low recent river terraces are currently highly suitable (S2) for sugar beet, cotton, corn and rice ,soils of moderately recent river terraces are currently highly suitable (S2) for wheat, melon, potato and rice, soils of high recent river terraces are currently highly suitable (S2) for wheat, melon, rice and cotton, soils of high gypsiferrous flats are currently highly suitable (S2) for corn, cotton, and citrus, soils of decantation basins are currently highly suitable (S2) for wheat, rice, corn, cotton, soils of turtle backs are currently highly suitable (S2) for melon, potato, cotton , soils of overflow basins are currently of moderate suitability (S3) for olive, citrus, peach, soils of sand sheets and old river terraces are currently of moderate suitability (S3) for olive, citrus, peach, soils of clay flats and lake bed are currently very severe suitability (S5) for all selected crops. Optimum cropping pattern was obtained by selecting the highly suitable classes from the current suitability status to be used in the optimum land-use of the investigated area. The main limitations of the above-mentioned soils are soil texture (t) , sodium content increase (a) , carbonate increase (c) and salinity increase (s).

Multi-temporal Landsat Thematic Mapper (TM) and Enhanced Thematic Mapper Plus (ETM+) data were utilized in a Geographic Information System (GIS) to evaluate changes in land use /land cover in the area surrounds the Suez Canal, Egypt. The area is bounded by the Great Bitter Lake from the south, El Qantara city from the north, Nile Delta from the west, and Sinai Peninsula from the east. The area witnessed a rapid development in the past three decades, and the environmental changes were very remarkable. The data collected by Landsat sensors, TM (1984) and ETM+ (2000) were used to conduct a change detection and land use analysis over the area of study. Both images were spatially registered and band four (Near Infra-Red) was radiometrically normalized to eliminate the atmospheric and sun luminance variation. Band algebra techniques were implemented to generate a reflectance difference image. On the other hand, the images were classified with supervised (maximum likelihood) technique with the help of ground truth data to provide the land use maps for 1984 and 2000 periods. These maps were converted to GIS environment and final land use changes have been provided.

Jabal Al-Wask ophiolite complex is the largest ophiolitic ultramafic-mafic rock association in the Arabian Shield (50 X 25 Km) which has been tectonically emplaced over the volcano-sedimentary rocks of the Farri Group and overlain unconformably by Hadiyah Group volcano-sedimentary sequence. The serpentinites are hydrothermally altered to listwaenite along the tectonic contact with the volcano-sedimentary rocks. The main task of the present study is to utilize the Landsat ETM+ data for mapping the listwaenite exposures along the southern margin of Jabal Al-Wask serpentinites. Only serpentinites can be easily discriminated on the FCC principal components imagery in which they have sky blue image signature. On the 3/1 band ratio image, listwaenite exposures have white image signature which may be due to the oxidation of magnesite and sulphides (the main constituents of listwaenite). Serpentinites and listwaenite have bright and dark grey image signatures respectively on 4/5 band ratio image. Absorption near band-4 leads to the lowering of 4/5 value and yields dark grey image signature to listwaenite. The false-color composite ratio image 3/1:R, 4/5:G, 5/7:B was generated and merged with high spatial resolution panchromatic band 8 using Intensity, Hue & Saturation (IHS) transformation method. The resultant fused image proved to be useful in delineating the listwaenite occurrences and generating 1:50,000 geological image map for Jabal Al-Wask ophiolitic complex. This study presents, for the first time, a "Listwaenite Discriminatiom Model" (LDM) that works under modeler environment of PCI image processing package. This study successfully proved the use of remote sensing technique for mapping listwaenite and other hydrothermally altered zones.

The Advanced Space-borne Thermal Emission and Reflection Radiometer (ASTER) is an advanced multi-spectral imager that was launched onboard NASA's TERRA Spacecraft in December 1999. ASTER covers a wide spectral region with 14 bands from the visible to thermal infrared, with high spatial, spectral and radiometric resolutions. An additional backward looking near-infrared band provides stereo- coverage. The spatial resolution varies with wavelength; 15 m in the visible and near- infrared (VNIR, 3 bands), 30 m in the short wave infrared (SWIR, 6 bands), and 90 m in the thermal infrared (TIR, 5 bands). Each ASTER scene covers an area of 60X60 km.

In the present study the 3 VNIR and the 6 SWIR bands have been used to discriminate the Oligocene sands and gravels from the surrounding rock units that are exposed near the mouth of Wadi Ghoweiba, at the northwestern side of the Gulf of Suez. Spectral reflectance curves of 9 rock units were extracted from ASTER data and were subsequently examined. The spectral reflectance curve for the Oligocene sands and gravels shows a spectacular unique behavior compared to the spectral reflectance curves of the other 8 rock units. Based on the spectral reflectance behavior, ASTER bands 1, 2 and 5 are found to be the most suitable bands for discriminating the Oligocene sands and gravels from the surrounding 8 rock units. Therefore, the highest percentages of information of these bands were quantitatively extracted from the principal component (PC) analysis using eigen matrix. The highest percentages of information contributed by bands 1, 2 and 5 were found to be in PC2, PC6 and PC9, respectively. A principal component color image (PC2, PC6 and PC9 in B, G, R) showed the Oligocene sands and gravels in a characteristic orange color. This result was verified using the available geological maps followed by field check.

The method used here is effective for exploring new sites of the Oligocene sands and gravels that are being extensively used as raw materials for concrete and other building purposes.

Muscat Governorate is the main governorate in the Sultanate of Oman and at the same time, it is the capital of the country. The urban of Muscat expanded on the area rapidly. So, the process of the growth, the controlling factors and the side problems which become apparent need to be highlighted. In order to determine the urban growth between 1960 and 2003, multi data sources and techniques have been used under a GIS environment. This research aims to measure and to model the urban expansion of Muscat Governorate using the combined technologies of Geographical Information System (GIS) and Remote Sensing (RS). Based on the detailed datasets and knowledge of historical land use maps, attempts were made to simulate future growth patterns of the city. The outcome of this exercise was the design of six urban growth maps covering the years 1960, 1970, 1980, 1990, 2000 and 2003. The results show that the total urban expansion reached more than 650% between 1960 and 2003, with an annual growth rate of approximately 20%. A combination of human and physical factors controlled this rapid growth. The paper discusses also the current urban problems resulting from this rapid growth, as well as its future spatial trends.

The Allaqi-Heiani suture in southeastern Egypt represents the western part of the main Allaqi-Heiani-Onib-Sol Hamed-Yanbu suture that is exposed in Egypt, Sudan and Saudi Arabia as one of the Neoproterozoic ophiolite-decorated, arc- arc sutures in the Arabian-Nubian Shield (ANS). The Egyptian part of the suture extends for ca. 250 km from the north-trending Hamisana shear zone in the east to the Nile River in the west. It separates the ca. 750 Ma south Eastern Desert terrane in the north from the ca. 830-720 Ma Gabgaba terrane in the south. The suture zone is defined by a deformational belt made up of ophiolitic gabbros, serpentinites and mafic volcanics, which are imbricated with syn-tectonic granitoids and metasediments. The whole rock suite is intruded by post-tectonic granitoids and gabbros. The suture zone suffered a poly-phase structural deformation that led to a complex structural pattern.

For precise lithological mapping and delineation of geological structures along the suture zone, we utilized digital image processing techniques to enhance Landsat 7 Enhanced Thematic Mapper Plus (ETM+) data to produce high quality images suitable for photogeological interpretation. These techniques included false color band composition (7, 4, 1 in R, G, B), principal component analysis (PC1, PC2, PC3 in R, G, B) and band-ratios (5/7, 5/1, 5/4*3/4 in R, G, B and 5/7, 7/5, 5/ 4*3/4 in R, G, B). Density slicing of the implemented four band ratios (5/7, 7/5, 5/1 and 5/4*3/4) has been used to produce a photogeological map. The mapped rock units were checked in the field and the attitudes of both planar and linear structures were measured and subsequently analyzed for better understanding of the structural setting of the central Allaqi-Heiani suture zone. The serpentinites and related ophiolitic rocks were followed along strike to identify the structural continuity and changes in strike direction.

Photogeological interpretation and field studies indicate that the central part of the Allaqi-Heiani suture zone is dominated by WNW-ESE striking low angle thrusts that are associated with asymmetrical folds whose axial planes are parallel to these thrusts. Folds are verging towards SSW. Additionally, a series of NNW-SSE oriented parallel folds are dominated in the eastern part.

Structural analysis indicates that the central part of the Allaqi-Heiani suture zone has undergone a poly-phase structural deformation involving, at least, two phases. Each phase has its own structural style and stress regime. The first phase (D1) was associated with an overall N-S or NNE-SSW shortening that produced SSW- verging folds and thrusts. The second phase (D2) was associated with an overall ENE-WSW shortening, which produced NNW-SSE oriented folds in the central and eastern parts of the study area and reactivated the older thrusts with oblique- slip reverse fault movement.

The present work aims at monitoring soil degradation process within the last two decades in the northern part of Nile Delta .The investigated area lies between longitudes 31o 00' and 31o 15' E and latitudes 31o 00' and 31o 37' N, covering an area of about 344584.01 feddans. Detecting soil degradation and recognizing its various types is a necessity to take the practical measures for combating it as well as conserving and keeping the agricultural soil healthy. Land degradation was assessed by adopting new approach through the integration of GLASOD/FAO approach and Remote Sensing / GIS techniques .The main types of human induced soil degradation observed in the studied area are salinity, alkalinity (sodicity), compaction and water logging .On the other hand, water erosion because of sea rise is assessed. The obtained data showed that areas that were affected by compaction increment have been spatially enlarged by 40.9 % and those affected by compaction decrease have been reduced by 22.6 % of the total area, meanwhile areas that have been unchanged were 36.5% of the total area. The areas that were affected by water logging increase have been enlarged by 52.2 % and those affected by water logging decrease have been reduced by 10.1 % of the total area, meanwhile the areas which have been unchanged were 37.7 % of the total area. Areas that were affected by salinity increase have been enlarged by 31.4 % of the total area and those affected by salinity decrease have been reduced by 43.3 % of the total area. An area represented by 25.2 % of the total area has been unchanged. Alkalinization (sodicity) was expressed by the exchangeable sodium percentage (ESP).Areas that were affected by sodicity increase have been enlarged by 33.7 %, meanwhile those affected by sodicity decrease have been reduced by 33.6 % of the total area. An area represented by 32.6 % of the total area has been unchanged. Multi-dates satellite data from Landsat TM & ETM+ images dated to 1983 and 2003 were used to detect the changes of shoreline during the last two decades. The obtained results showed that the eroded areas were determined by 547.4 feddans, meanwhile the accreted areas were detected by 476.5 feddans during the twenty years period. Soil improvement program was adopted in the investigated area.

The present study deals with investigating some significant geomorphic features in the Farafra Oasis area such as natural caves and white desert which display remarkable landscapes of high esthetic value and very important sites for ecotourism. The study aims to produce a GIS-ready database for registration of the natural caves with stalactites and stalagmites and a set of printed thematic maps for the above mentioned features with an explanatory notes for the features considered. To achieve these goals remote sensing and GIS techniques have been used, verified by field trip and GPS instrument for correct locations. The used thematic maps are: topographic maps for roads and tracks and main cities, and geologic maps. The study is illustrated by numerous field photos. The description of the considered features and including significant photographs is presented on a CD.