An integrated approach for identifying aquifers in transcurrent fault systems: The Najd shear system of the Arabian Nubian shield

Groundwater potentials were assessed for major transcurrent fault systems in basement complex terrains using the Najd transcurrent Shear System of the Arabian Nubian Shield as a test case. Spatial analysis, within a geographical information system environment, of relevant data sets (field, remote sensing, geophysical, and digital elevation) revealed a spatial correlation between existing well locations and distribution of Najd transcurrent Shear System structural elements (i.e., faults, shear zones, mélange, dykes) within highly fractured domains suggesting a causal relationship. Specifically at: (1) intersection of Najd brittle shear zones and fault systems, (2) intersections of two or more fault systems, (3) intersections of Najd-related dykes with the main streams within catchment areas, and (4) within tectonic mélange. For each of the former aquifer types, aquifer-specific field and satellite-based characteristics were identified and used in conjunction with complementary data (e.g., watershed morphology, precipitation, soil moisture) to target aquifers of similar settings. Postulated well locations were then successfully tested and refined using Very Low Frequency technologies. Results could potentially highlight the important role of major transcurrent fault systems in providing settings conducive for hosting and transmitting groundwater and could potentially serve as a replicable model for regional assessment of groundwater potentials in similar tectonic and hydrologic settings.