Volume 10 ,2008

Elevation Zones of the Egyptian Terrain produced from SRTM data, (M.N. Hegazy and H. A.Effat, 2007)

A GIS-Based Tool for Mapping a Coastal Highway's Sensitivity Index : A Case Study of the Mediterranean Coastal Highway in Egypt

The objective of this study is to assess, in a qualitative and quantitative approach, the mutual environmental impacts between a coastal highway and its landscape. The study aims at highlighting the efficiency of using remotely sensed data and GIS in environmental management of highways.

The construction of the International Coastal Highway that extends parallel to the Mediterranean shore of Egypt east to west, from Rafah in the east to El Salloum. The highway has its positive and negative influences on the environment. Passing through various land features such as wetlands, lagoons, sand dunes, towns, national parks and ports, the road is under pressure from rapid growth of touristic villages especially in the north-western coastal area. The existence of the highway has environmental impacts on the natural coastal environment. The coastal environment in its turn, affects the performance and functionality of the road.

A land use/land cover map (LU/LC) was produced from the Landsat ETM+data and used to provide an inventory of the sensitive areas that are liable to be affected and in need of a management plan. Buffering function was applied to detect the zones of the land cover classes that are subject to undesirable changes along a sector of the coastal highway. Those land cover zones are weighted according to their relative importance. A simple relation was developed by multiplying the land class distance-from highway and the LU/LC class relative importance. The relation quantifies the impacts of the highway on its surrounding lands, in terms of an impact index. The terrain characteristics of the landscape were studied, elevation zones, slope and aspect maps were used to produce the highway's sensitivity map. The resulting impact index is an indicator that points out the priorities for a required management plan while the highway's sensitivity map defines the zones in need of an adequate management plan.

The results indicated that the wetlands have an index of management priority of 60 in the 100 meters and an index of 50 in the 200 meters buffer zones. Water bodies score a priority index of 60 in the 100 meters buffer zone, suggesting a first priority in any control plan. Cultivated lands score a management priority index of 45 in the 100 meters buffer zone, indicating a second order priority in control plans. Environmental impact indices for any planned extensions to the existing roads that may intersect the highway have an index of 45 suggesting a high priority index necessitating urgent control actions. The limestone quarries activities surrounding the highway would certainly constitute a threat to the highway construction unless thoroughly controlled.

The elevation map shows that in the studied sector, with only some exceptions, most of the highway is located on a relatively higher elevation than its surroundings. The elevation of the highway and its neighboring landscapes range from -3 meters to 33 meters above sea level. The slope of the highway is gentle ranging from zero to 6 degrees. The result of the aspect model (slope direction) shows that most of the lands surrounding the highway and falling in the vicinity of the northern part are oriented in the northwest direction between 315 and 360 degrees in El-Hammam and El-Omayed sectors. This trend changes making a northeastern direction in El-Alamein sector. The sensitivity map is produced to show the highway sectors of high, medium and low sensitivity.

The present study shows that the establishment of sensitivity maps with adequately chosen criteria and the estimation of management priority indices for different areas provide an indispensable guideline for highway management plans to insure sustainable development. Utilizing the potentials of remote sensing and GIS techniques in the analysis provided a wider vision for land use management and control.

Investigation of new proposed Sohag - Hurghada highway across the Egyptian Eastern desert using Geographic Information Systems and Remote Sensing Techniques

In mountainous environment such as the area between Sohag and Hurghada, a vital highway has been proposed. Mapping and evaluating the complex geographical, geomorphological, geological, and environmental impact processes, using remote sensing and GIS techniques have been implemented in this study, to predict the more favorable path for the proposed highway. Different types of thematic, environmental, and economic data records, extracted from satellite images, aerial photo mosaics, topographic and geologic maps and field investigations were analyzed and integrated. Paths 1, 4, and 5 for sections 1, 2, and 3 respectively have the lowest possible degree for flash floods, curvature degree, rock obstacles, as well as economical problems. Some additional engineering measures can be proposed, to mitigate any other probable hazards along the selected path.

Exploring the Egyptian Terrain characteristics from space using SRTM data for strategic planning

Shuttle Radar Topographic Mission (SRTM) data have been used in this study for mapping the terrain characteristics for Egypt. The SRTM 30 Arc. Second (=900 meter) resolution data is found to be the most suitable for national-scale mapping. Using the DEM produced by the SRTM, different GIS layers were created using the ARC/GIS 9.0 software. These layers include all the necessary base map layers for terrain analysis, namely contour, elevation zones, slope angle, aspect, drainage network and basins. Each layer map gives a clear idea about one parameter of the terrain as elevation zone map displays the topography distribution, highest and lowest altitudes. Slope angle map shows the distribution of steep and gentle slope areas in Egypt. Aspect map explains the direction of the land surface slope differentiating, as example, areas facing north from others facing south. Maps of the drainage network and basins outline the Egyptian terrain into different watersheds regarding the surface runoff and consequently point out areas vulnerable to flash flood hazard and others capable for ground water recharge. The relative moisture index was derived from the catchment areas and the slope layers. Using the available land cover map of Egypt, the loose sand and sand dunes class was selected and overlaid on the elevation and slope maps in a GIS model to point out the hot spots for unstable more active loose sand bodies. Various parameters affect the sand dune movement are known to be the prevailing wind directions and speed, humidity, vegetation, soil moisture, etc. This paper is concerned only with three parameters affecting the sand movement which are relative moisture index, terrain surface elevation and slope variables. The study of terrain characteristics is essential for strategic planning and pre-planning decisions and for environmental management for sustainable development. An application of the physical environment base map layers, produced from our work, was used to explore some locations of the road network in the Egyptian terrain that are subjected to active, less stable sand bodies.

Influence of DEM source and resolution on the hydrographical simulation of Wadi Keed Catchment, Sinia, Egypt

The analysis of topological and geometrical relationships (morphometry) of catchment drainage network has widely been used in the hydrological modelling. Drainage networks can be derived form a variety of sources including topographic maps, aerial photographs, field survey, satellite images and recently from Digital Elevation Models (DEM). The manual extraction of drainage networks is a very inconsistent process even within the same network. Recently, conventional cartographic representation of topography has been gradually replaced by digital representation using DEM. This is driven by the increasing availability of DEM and the increase in computing power, which make the derivation process faster and more objective than traditional manual techniques applied to topographic maps. Sets of drainage networks were automatically extracted from DEMs of various sources and resolution for Wadi Keed catchment, Sinia, Egypt. The comparison between these sets and a reference drainage network digitised from 1: 50,000 topographic maps revealed a high degree of spatial and morphometrical coincidence. This is implying the quality of the DEMs used in the hydrological analysis, and the insensitivity of the automatic extraction process to the source or resolution high-quality DEMs.

Spatial investigation of water quality of lake Manzala using GIS techniques

Water quality parameters such as salinity, total suspended matter (TSM), dissolved oxygen, biochemical oxygen demand (BOD), ammonia and phosphates have been used to assess the health of Lake Manzala water body. Based on the statistical analysis and methods of Geographic Information System (GIS), this study developed procedures to investigate water quality of Lake Manzala; Then, a conversion vector values to a raster format resulted in regionalized images showing spatial characteristics of water quality, where interpolation techniques were performed within the ILWIS GIS package. The critical spatial distribution areas of each parameter were calculated for the whole area allover the Lake Manzala for each season (winter, spring, summer, autumn) and a comparative study was conducted in order to know the overall seasonal trend of water quality inside the Lake. Based on the study, the following conclusions are made:(1) GIS graphical representation shows increase of salinity and TSM values especially at the northern site and the lowest mean value of salinity was observed in winter and highest mean value of TSM was in spring; (2) images of dissolved oxygen and BOD shows tendency towards a relative decrease in oxygen content at the western and south-western sides of the lake and lowest value was recorded in autumn and increase BOD levels indicating the presence of a high load of organic matter in the water especially in winter; (3) the nutrients concentration revealed a high eutrophic condition of the lake allover the year.

Remote Sensing and GIS to assess the soil suitability for crops in north Saini, Egypt

The main objective of this study is to integrate land qualities with Landsat ETM images and digital elevation model (DEM) into a geographic information system (GIS) to produce the soil map and assess the current and potential suitability for crops in El-Tina Plain – South El-Kantara Shark area, north Saini. ArcGIS 9.0 software was used to produce digital elevation model from the digitized topographic map and elevation points of the area. Digital elevation model and Landsat ETM+ images were used in ERDAS Imagine 8.5 software, to define the land use / land cover and the physiographic units in the studied area. Geomorphologically, the main landscape in the area includes marine plain (311.69 km2), fluvio-marine plain (288.13 km2) and aeolian plain (730.00 km2). Fourteen soil profiles were taken to represent the different mapping units in the area; morphological description and soil sampling were collected for laboratory analyses. The main land qualities of the different mapping units and crops requirements were rated and matched to obtain the current and potential land suitability using Automated Land Evaluation System (ALES). Requirements of 30 crops were matched with the main land characteristics of the area. Only 11 crops have a moderate to marginal suitable, the rest of crops are omitted as they currently are not suitable and potentially are marginal suitable. The obtained data indicate that the main limiting factors are salinity and soil depth in El- Tina Plain area, while soil fertility and texture in South El-Kantara Shark area. The potential suitability classification of the studied area indicate that the most promising crops are Rice, Wheat, Sugar beet, Corn, Melon, Potato, Sunflower, Alfalfa, Peach, Citrus and Olive.

Quantitative assessment of soil degradation in cultivated areas of El-Sharkeiya governorate, Egypt

Most forms of degradation are man-made problems, although there are some physical environmental factors involved, but misuse and mismanagement are important factors. Quantitative assessment of human-induced land degradation and monitoring the changes in land qualities in El-Sharkiya Governorate during the period of 1975 to 2006 are the main objectives of this study. Geometrically- corrected physiographic-soils map of scale 1: 100.000 reduced to scale 1: 250.000 was produced for the studied area. The comparison between the data extracted from the Research Institute of Soil and Water (RISW) reports (1975) and the data of this study was carried out to determine the rate of land degradation. Aerial photo-interpretation, fieldwork and laboratory analysis data were used to produce the physiographic-soil map of El- Sharkiya Governorate. Land degradation rate, relative extent, degree and severity level in the study area were assessed. The results indicate that the most active land degradation features are; water logging, salinization, alkalinization and compaction. The main causative factors of human - induced land degradation types in the studied area are over irrigation, human intervention in natural drainage, improper time use of heavy machinery and the absence of conservation measures.

Statistical analysis of surface structural lineaments and radioactivity of the alkaline rocks province, South Eastern Desert, Egypt

The alkaline rocks province in the South Eastern Desert of Egypt is of limited distribution and is found mainly south of Latitude 25o N. The present work deals with the analysis of all structural lineaments in five unit areas (A1 to A5), and their effects on the emplacement of the ring complexes and radioactivity.

Based on Landsat images, the predominant trends of structural lineaments in 22.5o wide sectors are the NW, NE, NNW and ENE trends, constituting 67.06% of the total number and 69.88% of the total length of all lineaments. While the main trends of all structural lineaments in 10o wide sectors can be classified into two groups of trends. The first group (N20o- 50oW) includes N35oW, N45oW and N25oW trends, constituting 26.50% of the total number and 30.88% of the total length of all lineaments. This group of trends can be considered as fault trends because of the increase in length ratio than the number ratio of all lineaments. While the second group (N40o - 70oE) of trends is represented by the N55oE, N65oE and N45oE trends, constituting 26.58% of the total number and 24.69% of the total length of all lineaments. From the previous works, it is found that these two groups of trends are responsible for the emplacement of the ring complexes in the examined areas according to Garson and Krs (1976), and they play an important role in the distribution of radioactive mineralizations in all discovered localities.

Using Remote Sensing Techniques in the Geology and gold mineralization at al Faw - Eqat area, South Eastern Desert, Egypt.

Al Faw- Eqat area is made up of metamorphic and magmatic late Proterozoic rock assemblages. The metamorphic suite consists of ophiolitic ultramafics thrusted over metavolcanosedimentary schists of intermediate to basic composition. The magmatic suite comprises syn- to late-tectonic calc-alkaline granites of less deformed tonalite and monzogranites. These magmatic rocks were intruded by post-tectonic potassic calc-alkaline granite exposed at Gabal Eqat. Applying some digital image processing techniques such as false color composite, band ratio and Principal Component Analysis (PCA) of Landsat ETM+ data, produced detailed images with good discrimination of exposed rocks enabling to accurately map the geologic and structural features in the area. Another image processing technique based on band ratios helped in tracing alteration zones possibly gold bearing.

The effect of digital work flow on color digital maps data when exported using Geological Information System

The coloring values of digital maps is exposed to change due to different working stages, because we do not use suitable work flow, suitable digital formats and suitable resolution enhanced through different machines and monitors. Monitors don't use the color management system to keep coloring value without changes, because coloring degree represents geographical information and any change in color value will lead to a wrong output color data.

In this research we create a test file consists of map and standard color bar into the geological information system program. This file works by some different digital work flows, with applying color management system. Then measuring color gamut after printing standard color bar, to reach the best digital work flow which lead to best color gamut for printed digital maps.