Investigation of dolines, karstic voids and underground water flow system with hydrogeophysical studies, and examination of hydrochemical properties of water: The case of Şahinkaya member, Çalköy/Trabzon/Türkiye

The study areas covered by this thesis are located within the Şahinkaya Member, which outcrops around the Çal Cave and its vicinity, situated between the Çayırbağı/Çalköy neighborhoods in the Düzköy district of Trabzon province. The Şahinkaya Member is composed of neritic limestones. Over time, the karstification of these limestones led to the formation of dolines, karstic cavities, and the Çal Cave, through which an underground river flows. The underground waters are generally fed by rainwater and surface waters seeping underground through pores or passing through karstic formations to reach saturated zones. It is possible to detect such karst formations using hydrogeological and geophysical methods. This is the aim of this thesis. As a result of the analysis of the waters collected from the various points on the surface and from the underground river within the Çal Cave, it was determined that these waters were fed from the same member and were of Ca-HCO3 water type. Among the physical parameters, it was determined that the average values of EC, Ph and DO amounts varied between 108.3-338 μS/cm, 7.31-9.11 and 7.56-9.96 mg/l, respectively. The limestones forming the Şahinkaya Member were investigated for the first time using geophysical methods. In this context, three study areas with a total surface area of approximately 3.2 km² were identified. ERT, SP, SRT, MASW, and GPR data were collected, leading to the identification of karstic cavities, water-saturated zones, and dolines within the limestones. Additionally, the priority and effective usage sequence of the five geophysical methods were determined, and their results were compared based on the collected data.