Investigation of Harşit cayi-Baglarbasi (Gümüshane Centre) groundwater potential by electrical resistivity method

The study conducted along the Harşit River in Bağlarbaşı District is based on a geological structure consisting of granitoid, sedimentary, and volcanic rocks. The Paleozoic-aged Gümüşhane Granitoid forms the base of the study area, over which the Şenköy Formation, exhibiting volcanic-sedimentary characteristics, and the Berdiga Limestone are conformably found, respectively. The Gümüşhane Granitoid is composed of granite and granodiorite, characterized by fractures and fault structures. The volcanic rocks of the Şenköy Formation are andesite. The Berdiga Limestone is primarily composed of calcite mineral. Geophysical measurements were conducted in the study area using a Schlumberger electrode configuration with expansion geometries at 10 different points. Vertical Electrical Sounding (VES) and Electrical Resistivity Tomography (ERT) methods were employed in the study area to investigate the subsurface structures. The VES measurements were conducted at ten distinct locations using the Schlumberger electrode configuration, while the ERT data were acquired along two profiles using the Wenner-Schlumberger array. These complementary geophysical methods enabled the assessment of the spatial distribution and electrical resistivity variations of subsurface formations, providing valuable insights into the geological and hydrogeological characteristics of the area. Specifically, areas with low resistivity were found to represent clay-rich and impermeable units, while high resistivity areas were identified as sandy-gravel layers, which could correspond to potential groundwater levels (GWL). It is predicted that wells to be drilled in the regions corresponding to these high-resistivity values in the ERT profiles will yield high water flow rates. Furthermore, zones with resistivity values ranging from 50 to 300 ohm-meters, showing continuity in depth, were found to be suitable for a sustainable water supply. The data obtained provided a critical foundation for sustainable groundwater management in the study area. By accurately delineating subsurface resistivity variations and hydrogeological conditions, the study facilitated the selection of optimal drilling locations based on scientific principles rather than empirical or arbitrary methods.