Geophysical and Geological investigation of the Delga proposed Dam Site, Qala Diza, Sulaimani City, Kurdistan Region, NE-Iraq

Abstract

The use of two geophysical methods and geological study in the investigation of the
 geological setting is aimed at evaluating the feasibility of the area for establishing a dam
 foundation and reservoir. 2D resistivity tomography was conducted on abutments while
 GPR was used on the river terraces in the trough of the valley. The framework and
 mutual relations of the geophysics, stratigraphy, lithology, structure, hydrologeology and
 geotechnique are used to study feasibility of a segment of river valley for dam building.
 The study is aided by detail and uptodate geological maps and geological cross sections
 which are all base on field data and geophysical measurements. This proposed dam is
 located at the southeast Delga village and about 20.0 km upstream of Dokan reservoir on
 little Zab River and about 19.5 km from the Iraqi-Iranian border. The dam site and
 surround areas are located in the Imbricated Zone which characterized by southwest
 overturning of the folds. The dam site is located on one of the overturned syncline in which
 Shiranish and Kometan Formations are exposed and the foundation and abutments of the
 dam are located on latter formation. The trend of the dam axis is N80W and the dip of the
 strata of the Kometan Formation is nearly parallel to the dam axis. This structure relation
 with dam axis improves water tightness and stability of the dam abutments against sliding
 and collapse. The 2D resistivity tomography and GPR survey showed that there are
 underground week zones (cavern and fractured zones) in restricted limited area. The site
 is water tight as the river descended inside fresh Kometan and Shiranish Formation.