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

Volume 15 , Issue 1 , December 2013 , Pages 95-115

Authors

¹ Faculty of Science and Science Education , University of Sulaimani

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.

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