An Analysis of the Geomorphological Map of 'Agiba Area
Using GIS and Remote Sensing
Summary
Situated on the Mediterranean coast, 18 km to the west of Marsa Matruh, the studied area is bounded by Wadi Umm Ashtan to the east, Wadi al-'Asi to the west, the watersheds of the wadis discharging into the Mediterranean to the south, and the Mediterranean coast to the north. In terms of absolute location, the studied area lies between latitudes 31° 18' 32" & 31° 28' 25" N and longitudes 26° 49' 02" & 27° 02' 31" E. The maximum north-south extension attains 37.8 km., and the east-west width is 35.5 km., giving rise to an area of 269.8 sq. km.
Chapter One deals with the natural geographical characteristics of the studied area, including the geological characteristics of the formations and the structure. The study has shown that formations are of sedimentary rocks ranging in age from the Middle Miocene (21.8 %) to the Pliocene (33.3 %) in addition to the surface deposits belonging to Pleistocene (6.6 %) and Holocene (5.3 %). The area is dissected by a range of surface cracks which are almost limited in the region trending NE & NW, and a series of NE / SW anticlines and synclines, the latter are filled with the waters of the bays. Chapter One deals also with the characteristics of terrain: the heights, the micro-reliefs and the slopes. The terrain rises progressively southwards, from the coastline, which is represented by Kantor line zero in most sectors, to the plateau surface (90– 125 m.), in line with the water division of the drainage basins sloping line over the edge of the Miocene plateau. The climatological study reveals that the climate is temperate in summer and warm and rainy in winter, with N & NW winds; the rain is almost of the cyclonic type. Water resources in the study area are surface water and groundwater, and rain is considered the main source for both of them.
Chapter Two deals with the slopes in the study area: the techniques of studying them, the geographical distribution of their transects, the morphometric analysis including the angles of slope, the length of transects, the curvature, the types of slopes and the factors shaping them. The study shows that the gentle slopes are the dominant feature (62.7 % of the total length of the measured transects), due to the variability in lithology that gives rise to variability in the angles of slope and in the length respective to each angle. The concave shape is more common (54.7 %) than the convex (43.4 %)— something that indicates the role of running water in shaping the slopes.
Chapter Three deals with the geomorphology of the coastal belt: the characteristics of the coastline, its morphology, direction and depth; the changes affecting the coastline in the period 1985 – 2013, as it is eroded in some sectors by as much as an annual mean of 3.18 m, and accreted in other sectors by 11.2 m. The other marine factors shaping the coastline are: waves, tides, currents. The continental factors comprise: running water, wind, mechanical and chemical weathering, and mass movement. The chapter deals also with the landforms that evolved as a result of both marine erosion and deposition.
Chapter Four investigates the geomorphological map of the studied area by identifying the main geomorphological units that were studied. These include: the surface of the plateau, its edge, and the coastal plain. Additionally, the landforms related to erosion by water were studied, including wadis, wadi gorges, knickpoints, wadi terraced shapes, alluvial fans, isolated hills, the landforms resulting from wind action such as sand dunes and nebkas, and the landforms resulting from coastal erosion such as cliffs and sebkhas. Equally, the phenomena resulting from mechanical and chemical weathering were dealt with.
Chapter Five deals with the applied geomorphology of the studied area, defining the geomorphological hazards and prescribing how to mitigate them. Additionally, some applied aspects of the area were reviewed, including the potentials of the studied area and how they can be best exploited so as to add to the map of the development in Egypt's Northwestern Coast through the agricultural, touristic, industrial and urban development.
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