Abstract
Similarities in both water and electric current flows allow the relation of hydraulic and geoelectric parameters of porous aquifers. Based on this assumption and the importance of the hydraulic parameters for groundwater analyses, this study aimed to estimate hydraulic conductivity (K) and transmissivity (T) with vertical electrical sounding (VES) in the porous aquifer at the experimental farm of the University of Brasilia, Brazil. VES is a geophysical technique that provides electrical resistivity (ρ, Ω m) and thickness (h) of the subsurface layers. The ρ and h aquifer data, associated with lithology, water table level (WTL), and groundwater electrical resistivity (ρw, Ω m), allowed the calculation of complementary geoelectric parameters (formation factor, F, and Dar Zarrouk parameters) and the relation with K and T, determined via slug test. VES data allowed the elaboration of geoelectric models, with mean absolute percentage error (MAPE) below 6% compared to field data, and the identification of the aquifer in each VES station. Significant exponential regression models (R2 > 0.5 and p-value < 0.05) showed the possibility of using geoelectric parameters to estimate hydraulic parameters. This study allowed the verification of the applicability of consolidated models and the identification of appropriate empirical relationships for hydrogeological characterization in the Brazilian tropical porous aquifers. The results of this work, besides the rapid sampling and low cost of performing vertical electrical sounding (VES), may justify the use of this geophysical technique for preliminary porous aquifer characterization, especially in regions absent of or with insufficient monitoring wells.
Highlights
The resolution of flow and transport problems in aquifers depends on information about the hydraulic parameters, which influence the occurrence and movement of groundwater
The inversion of the vertical electrical sounding (VES) data together with lithological and water table level (WTL) data resulted in geophysical-lithological models composed of five geoelectric layers, with mean absolute percentage error (MAPE) below 6% (Table 1, Figure 3)
Significant exponential regression models showed the possibility of using geoelectric parameters, obtained indirectly, to estimate hydraulic parameters (K and T) in porous aquifers
Summary
The resolution of flow and transport problems in aquifers depends on information about the hydraulic parameters, which influence the occurrence and movement of groundwater. Considered the most important parameter in hydrogeological studies, hydraulic conductivity (K) indicates the ability of aquifers to conduct water [1,2]. Determining aquifer hydraulic parameters requires the use of field hydrogeological methods (e.g., pumping or slug test) characterized by a high demand for time and financial resources [5,6,7]. Geoelectric measurements from the soil surface by DC (direct current) electric geophysical method, applied especially through the vertical electrical sounding (VES) technique, enable a non-invasive and relatively inexpensive hydrogeological characterization [2,8,9,10,11,12,13,14]. In addition to applications for identifying soil moisture content, lithological structures, and water table level (WTL) [15,16,17,18], surface geoelectrical measurements have allowed indirect estimation of K and T, reducing the need to drill boreholes [12,13,14,17,19,20,21,22]
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