The influence of geoelectrical parameters on the Quaternary aquifer and its protectivity and contamination: a case study from the Khanasser Valley Region, Northern Syria

Abstract

Abstract The technique of vertical electrical sounding (VES) is used here to evaluate the influence of several geoelectrical parameters of reflection coefficient (RC), fractured constant (FC), anisotropy (λ) of the subsurface hydrogeological layers and protecting layers (hOverb) which affect the overburden protective capacity (OPC) of the Quaternary aquifer in the Khanasser Valley region, Northern Syria. RC varies between a minimum of −0.89 and a maximum of 0.92 with an average of −0.28. FC varies between a minimum of 0.057 and a maximum of 25 with an average of 1.89. λ varies between a minimum of 0.72 and a maximum of 2.31 with an average of 1.24. The overburden-protecting layer (hOverb) varies between a minimum of 1.1 m and a maximum of 28.9 m with an average of 5.36 m. OPC varies between a minimum of 0.01 Ω−1 and a maximum of 13.75 Ω−1 with an average of 0.94 Ω−1. The statistical correlation matrix computed for those parameters highlights the mutual relationships between them. Different empirical equations are consequently established between the mentioned treated parameters and the OPC one. Three different trends of negative exponential function are revealed between anisotropy λ and OPC, indicating the presence of different hydraulic systems. The alteration sequence of impermeable and permeable layers as proven by the available lithological descriptions control the mentioned parameters and their values. The presence of sufficiently thick overburden impermeable layer helps in protecting the Quaternary aquifer from the surficial contamination, and acts as a natural filter slowing and retarding the fluid percolation. The approach developed in this paper with its different established empirical relationships is applied for the first time in Syria, and can be easily undertaken worldwide to assess the different conditions controlling the aquifers protectivity.