Document Type

Article

Publication Date

3-4-2009

Abstract

Satellite images have consistently Improved our understanding of the surface features of the Earth. They can be processed in numerous ways to emphasize particular terrain characteristics, Examples are given of image processing for transformation, enhancement, mosaic-king, classification and the detection of changes In space and time. The various products allow mapping of drainage patterns, analysis of structural fealures, idenlification of thermal anomalies, classification of geomorphic patterns, and mapping of vegetation patterns that may indicate water availability. The space- borne data are particularly useful in the case of desert terrain, where surface patterns are clearly revealed in different ways by various sensors. This includes using satellite data to: (a) identify the variety of exposed rocks, soils and sand by multi: spectral images; (b) reveal sand-buried features by radar images, because radar waves ponetrafe the desert sand cover to unveil courses of former rivers and streams; and (c) depict slope gradients and define the flow directions of the dry channels using the Shuttla Radar Topography Mission (SRTM) data, Two examples are given in the eastern Sahara of North Africa, which exemplifies the driest places on Earth. In this desert, former river and stream courses lead to topographic depressions where lakes were formed. Lake deposits within these depressions indicate that water stagnated for thousands of vears above the old sandstone substrate. Because the latter formation is porous, it has the capacity of holding vast amounts of water. As shown by the first example, the East Uweinat region of southwest Egypt, over 500 wells have been drilled for agricultural farms. The proven sweet aroundwater resources in this region are capable of supporting the production of wheat, chickpeas and peanuts over 150,000 acres of land for 100 years. The second former lake is represented by a depression in northwestern Sudan, just across the border of southwest Egypt. Thus, it is assumed that the Northern Darfur depression would also enclose groundwater resources. The United Nations plans to take this intc account in future groundwater exploration to alleviate water shortages and help establish a sustainable peace in this troubled region of northwestern Sudan.

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