Abstract

AL-FARES, Walid  and  AL-HILAL, Mohamed. Integration of electrical resistivity tomography with electromagnetic and soil radon measurements for characterizing the leakage problem in Afamia B dam, Syria. Geofís. Intl [online]. 2018, vol.57, n.4, pp.275-287. ISSN 2954-436X.

Three complementary techniques, including Electrical Resistivity Tomography (ERT), Electromagnetic (EM) and soil gas radon measurements were applied in order to propose a conceptual model that may describe the main causes of water leakage in Afamia B dam. The survey was accompanied by extensive geologic and tectonic field investigations which assisted the delineation of certain pathways for possible water leakage from the basin of the lake’s dam. Significant weak zones including subsurface tectonic lineaments, fractured bedrock, eroded surfaces, and some other deformed structures were characterized. Further analysis of the resultant data indicates that the underlying geological structure of the dam basin is primarily composed of a successive lithological bedding consisting of permeable layers (sands and gravels) alternating with impermeable calcareous marl beds. The heterogeneous composition of such lithofacies may provide an additional reason which could effectively enhance the water losses through the permeable units along the shoulders of the main valley. The overall results of the combined techniques have shown a positive correlation between the applied methods, and they confirmed the usefulness of such approach for mapping out hidden deformed structures and weak zones. Moreover, the existence of numerous archeological ruins such as graves and wells distributed throughout the dam basin may greatly increase the water leakage from the lake. Consequently, it has been found that the eroded bedrock, the heterogeneity of alternating beddings and other detected subsurface features are all playing a crucial role in the subhorizontal and vertical leakage processes that occurring within the Neogene formations and passing down to deep-seated karstified carbonate rocks of Cretaceous age.

Keywords : Geophysical techniques; ERT; EM; Soil radon survey; Water leakage; Afamia dam; Syria.

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