Mapping the Fractured Zones Affecting Qanawat Dam Area, Syria: A Geoelectric Application

By

 Salah El-Deen A. Mousa¹, Mohamed A. El-Melhem¹

(1) Ain Shams University, Cairo, Egypt

 Qanawat Dam was built on basaltic bedrock, and is designed to collect and store about 3,000,000 m3 / year of run off water received from Qanawat basin, which covers an area of about 350 km2, and is located to the south west of Syria. A considerable amount of water loss is recorded due to seepage and percolation through fractured basalt. Mapping of these fractured basaltic zones based on geoelectric resistivity assessment of these zones, is the main target of this work.

Geoelectric resistivity surveys have been carried out in two phases, conducting Schlumberger 4-electrode array with maximum current electrode spacing of 1000m. The first phase have been achieved by carrying out 12 Vertical Electrical Sounding stations (VESes), distributed along Qanawat basin to delineate the main geoelectric charactersitics. The second phase is conducted by 64 VESes distributed in 8 profiles and concentrated in an area of 4 km2 , surrounding the Dam. The depth and thickness of massive basalt, the bedrock of the Dam, is determined.

Geoelectric profiles and panel diagram, have been constructed to follow up the massive and disconnected fractured basaltic zones. The depth to this zone is varying from 3.8m to 25.6m. It exhibits a thickness ranging from 3.5m to 33.3m. Fracture distribution map was constructed. The location of seepage water areas from the lake and the body of the Dam was delineated.