Groundwater can be a problem in desert areas, especially if its level is raising. In this book we are addressing such issues by geophysical, geotechnical and geochemical investigations in the urban center of 15th May City and Al-Mokattam area,Cairo and in the Osireion of Abydos, Egypt. Ground penetrating radar was applied in both areas. In Abydos the results show a channel underneath the Temple of Seti I and irregularities inside and outside the Temple of Seti I. While in urban,results show structural discontinuities in the subsurface (joints and faults and caves), which could be part of the geotechnical problems observed in the study areas. XRD results show that the soluble salts are mainly halite and gypsum. Water-intake tests show that the rocks are composed of halite, gypsum, calcite and clay minerals, which are critical as smectite swells and [...] concentration of Arsenic and Chromium among the trace elements in the study area is four times the world health limit. The Strontium isotope signature suggests a hydraulic connection between the karstified Eocene and Miocene sediments of the study areas.