Coupling of field investigations and remote sensing data for karst hazards in Egypt: case study around the Sohag City
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ORIGINAL PAPER
Coupling of field investigations and remote sensing data for karst hazards in Egypt: case study around the Sohag City Ahmed M. Youssef 1,2 & Abdel-Hamid El-Shater 1 & Mohamed H. El-Khashab 1 & Bosy A. El-Haddad 1
Received: 15 June 2016 / Accepted: 14 May 2017 # Saudi Society for Geosciences 2017
Abstract Karst rocks cover a wide area of Egypt. These rocks include soluble sediments such as carbonate rock formations, evaporites, and sabkha deposits that are characterized by karstification features. Karst features could affect many current and developing projects (urban areas and infrastructure). The areas covered by the rocks susceptible to karstification need detailed studies to examine the presence of karst features and/or sinkholes. The current work provides a detailed evaluation of the karst and/or sinkhole hazards around the city of Sohag, Egypt. This research is rarely done in Egypt, using field investigation and remote sensing application to determine the main karstic rock formations and the distribution of the most problematic sinkhole areas. In this work, different types of the subsidence mechanisms were investigated. Our results indicated that field investigations help in finding different features related to karstification including small-scale versus large-scale features and empty caves versus filled caves. In addition, remote sensing techniques succeeded in predicting and locating the sinkhole areas, and those determinations were verified in the field. Finally, fundamental considerations are discussed to better evaluate and manage the hazard of karst and/or sinkholes.
* Ahmed M. Youssef [email protected] Bosy A. El-Haddad [email protected] 1
Geology Department, Faculty of Science, Sohag University, Sohag, Egypt
2
Geological Hazards Department, Applied Geology Sector, Saudi Geological Survey, P.O. Box 54141, Jeddah 21514, Kingdom of Saudi Arabia
Keywords Karst . Geohazards . Detection . Investigation . Egypt
Introduction Karst is a geomorphologic feature that is formed in soluble rocks and/or sediments by widening existing fractures or cavities through the dissolution activities (Youssef et al. 2016). Amin and Bankher (1997) indicated that the dissolution of karst units forms sinkholes that represent subsidence hazards in Saudi Arabia. The dissolution process of the subsurface materials causes collapse of the overburden materials resulting in the formation of sinkhole depressions (White 1988). Ford and Williams (2007) mentioned that the surface and subsurface rock dissolution mechanism largely overrules the mechanical erosion mechanism, leading to a distinctive morphology and hydrology in karst areas. Karst systems are distinct from non-karst systems because of the processes of karst dissolution and the presence of a well-developed and open subsurface (Gunn 2004). White (2002) indicated that karst processes, along underground pathways, may give rise to the formation of three-dimensional systems of conduits, sometimes forming huge, long, and extremely complex caves. Whi
