Geophysics’ Role in Investigating and Mitigating Groundwater Hazards on Archaeological Sites: Case Studies from “Sphinx-Giza, Kom Ombo Temple-Aswan and Hawara Pyramid-Fayoum”

Ancient Egypt left behind numerous landmarks such as pyramids, temples, statues, tombs spread along the shores of the River Nile, most of which are invaluable man-made archaeological treasures. Placed at uniquely chosen archaeological sites and having survived several millennia, they are increasingly devastated by the rising water table, soil composition, and subsurface water flows that have a destructive impact on their foundations and structural integrity. Much of that change took place over the past few centuries due to intensive farming, irrigation plans, climate change, growing urbanization, malfunctioning sewer systems, and changing environmental and soil conditions in the surrounding areas. In particular, intense irrigation, increasing plantation and deficiency of the drainage networks in the vicinity of the archaeological sites are the most significant risks and a major cause for recorded deterioration of subsurface structures across the past fifty years. The problem has been exasperated by rising groundwater containing high dissolved salts that chemically interact with and affect subsurface bases. In dry seasons water evaporates, condensed salt crystallizes and creates multiple pore holes that, following prolonged exposure, cause stone blocks to disintegrate. Geophysical studies emerged, in recent decades, as critical for the diagnostic investigation of subsoil and hydrogeological conditions of archaeological sites and mapping subsurface structures and water flows. Several geophysical techniques are used as non-intrusive methods to generate multiple datasets for underground water management and determining mitigation and dewatering plans. This paper provides a detailed empirical study using essential geophysics methods and applications for three major archaeological sites in Egypt with distinctive groundwater threats and environmental conditions and prevention plans. These include Sphinx-Giza, Kom Ombo Temple-Aswan and Hawara Pyramid-Fayoum. Three geophysical methods have been used to highlight the characteristics of underground water flows and impact and provided a roadmap for solutions and dewatering plans in each case.