Integrated vertical electrical sounding and hydrogeological approach for detailed groundwater pathways investigation: Gökpınar Dam Lake, Denizli, Turkey

Abstract

Understanding the hydrodynamic systems in the dam lake surroundings is of great importance to protect the lakes feeding zones and maintain their water level. In this study, a combination of hydrogeological and geophysical surveying processes was carried out in order to distinguish the Gökpınar dam lake's recharge ways. The Gökpınar dam lake area is characterized by a very complicated hydrogeological system causing difficulty at distinguishing the groundwater flow pathways feeding the lake. Therefore, a detailed vertical electrical sounding survey was performed in accordance with the Shlumberger array in the surroundings of the Gökpınar dam lake. Results obtained from the resistivity measurements were processed using a partial curve matching technique then inverted in order to build 2D and 3D resistivity models which in their turn were corelated with the geology of the study area. In addition to the geoelectrical measurements 44 boreholes were drilled in order to confirm the vertical electrical sounding results. Data collected from these boreholes were also used for the plotting process of the water table contour map in the study area which highly correlated with the resistivity contour maps. Resistivity data evaluation led to the differentiation between water bearing and dry zones. Results showed that the Gökpınar dam lake is fed by several groundwater flows, deriving from South-West, North-West, and South-Eastern parts of the study area. These flows are generally more important near the surface than they are deeper toward the impermeable bedrock.