ABSTRACT
The Syrian capital Damascus obtains its drinking water from several sources: inner-city wells, the Figeh Spring and the Barada Spring with its surrounding wells. The catchment of the Barada Spring consists of limestone and dolomite outcrops at the core of two Palmyrides folds. The thickness of these formations can exceed 1000 m. The Serghaya Fault to the east of the springs is the fundamental tectonic feature in this area. It is a branch fault of the Dead Sea Transform Fault. A sinistral movement along this fault has been active since the Neogene period. Tectonic measurements and the analysis of high resolution remote sensing data show the transform fault network and block rotation in the surroundings of the main fault and the Horst structures. These can be explained by the Riedel model for simple shear. The estimated angles of block rotation rise to 53° in a counter-clockwise direction. In the vicinity of the Barada Spring the formations are intensively faulted and block rotated, whereas the south is less faulted and lacks this tectonic feature. Surrounding the Barada Spring four tracer injections, three Very Low Frequency-ElectroMagnetic (VLF-EM) soundings, two geoelectrical profiles and one geoelectrical tomography in the dried spring lake have been carried out by different authors. A VLF (Very Low Frequency) sounding carried out in 2007 and an Audio Magneto Telluric (AMT) investigation in 2004. Geophysical structures trend in south east to north west and west to east directions and possess high electrical conductivities, indicating the probability of a water-bearing structure. An intersection of both trends occurs in the Barada Spring Lake. In combination, almost all methods show a dependency of possible groundwater flow towards the main faults in the vicinity of the spring. Further investigations are to be done to delineate the borders of the catchment. AMT is the most efficient geophysical method for the deep water table in the carbonatic rocks. Ancillary geoelectrical methods yield interpretable results within shallow water tables. All geophysical and remote sensing methods in combination with in situ measurements of strike and dip give an understanding of faults, fissures and discontinuities. A proved flow direction can only be estimated, field measurements of the head of the water table could lead to a more precise interpretation.
