الفهرس 
D HYDROGEOCHEMISTRY ANWATER QUALITYOnly 14 pages are availabe for public view
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Abstract
evelopment of agriculture and urban areas has demanded rapid exploitation of groundwater resources, which requires suitable assessment and prioritization of measures for their sustainable use. Indeed, overuse of groundwater without proper management has caused serious environmental issues, especially in arid areas. Such a chain of environmental issues has occurred in the Dakhla Oasis. Typical issues include a rapid declining of water level in the northern parts of the area as a result of overexploitation of groundwater. In addition, the rising of groundwater level to the ground surface after irrigation in the central and southern parts as a result of lack drainage network induces intense soil salinization and enhances shallow aquifer salinity, leading to deteriorated quality and productivity of affected resources. Degradation of the groundwater quality in salinized soil areas originates from complex interactions of groundwater chemical properties with soil and rock compositions, hydrometeorology, topography, drainage system efficiency, anthropogenic activities, and other artificially imposed conditions. The prime objectives of this research are to investigate and document the factors controlling groundwater and soil quality degradation and their inter-relationships through the integration of groundwater and soil chemistry data. A combination of multivariate and geostatistical analyses was used to clarify these relationships with a special emphasis on the relationships between groundwater and soil chemistries and between major and trace element concentrations. Moreover, geoelectrical resistivity measurements were integrated and compiled with hydrochemical data to establish successful pictures of groundwater development and monitoring programs. Furthermore, the efficiency of applying remote sensing and GIS techniques were implemented to examine the relation between the change detection of land use/land cover and the degradation of groundwater and soil salinization in the study area. Dakhla Oasis is a natural depression located in the heart of Western Desert of Egypt. The study area covers approximately 323 km2 situated along the settlements Balat and Teneida in the eastern part of the Oasis. The area is characterized by hot and dry climate with almost no annual rainfall, a high rate of evaporation, and strong solar irradiation. The area is strongly suffered from aridity and considered as a part of the most hyper arid region in the world as there is essentially no precipitation. The study area is composed of three main geomorphological units, a high plateau in the north, a depression in the middle, and a structural plain in the south. The high plateau bounds the Dakhla depression to the north and is characterized by a wide rough surface and a precipitous escarpment dipping northward. The surface of the depression where cultivation practices dominate is a lowland formed by geodynamics and erosion, which contains different landforms represented by the piedmont plain, residual hills, and piedmont flats. The structural plain originated from merging of the Dakhla depression into an extensive elevated plain sloping northward.