Mosul and Haditha Dams are the largest dams on the Tigris and Euphrates Rivers in Iraq, respectively. Both dams are of earthfill type and constructed on sedimentary rocks, but have different geological conditions. Both of them suffer from karstification problems. The former; however, suffers from intense karstification, which has endangered the stability of the dam and possible failure. The karstification in both sites is of different origins, types, shapes, sizes and depths, as well as in different rocks and geological formations. In Mosul Dam site, the highly dissolved gypsum beds of the Fatha Formation has formed solution type sinkholes with cavities of different shapes and sizes at different depth; attaining to about 250 m upon which the foundations of the dam are located. In Haditha Dam site, the karstification occur in the limestone beds of the Euphrates Formation, the developed sinkholes are of collapse type with regular shapes; either circular or oval apertures. The thickness of the karstified sequence in the foundations is not more 50 m. This research work is to highlight the role of the geological conditions, especially when the karstification in the safety of both dams is concerned and its effect on the foundations of the dams
Keywords: Mosul Dam; Haditha Dam; Dam site geology; Karstification, Gypsum and Limestone beds.
ISSN: 1792-9040 (Print)