Karst hydrogeological investigation of the Tecer Mountain (Sivas) [Tecer Da?inin (Sivas) karst hidrojeolojisi incelemesi]

Abstract

Tecer Mountain, located about 40 km to the southeast of Sivas city is formed of Maestrichtian-Thanetian aged limestone (Tecer Limestone). This study aims to determine the hydrogeological, hydrochemical and water quality characteristics of the Tecer Limestone aquifer. Tecer Limestone is densely fractured, jointed and karstified. Karrens, dolines, ponors, underground channels and caves are among the karstic features observed in the unit. Groundwater circulation within the karstified Tecer Limestone occurs mainly along the fractures, joints and solutional conduits, as concentrated (conduit) flow. The flow rate of the springs discharging from the Tecer Limestone in the study area ranges between 0.5 and 565 l/s. The discharge of the Beşgözeler Spring, the largest karst spring in Tecer Limestone, ranges between 150 and 565 l/s. The electrical conductivity (EC) and hardness of the spring waters that issue from the Tecer Limestone range between 215 and 585, ?S/cm, and 10 and 20°F (French Hardness), respectively. The spring waters are of a calcium bicarbonate type. The spring waters plot in medium saline-low sodium water (C2-S1) class in the U.S. Salinity Laboratory Diagram. EC and hardness values of the Tecer River waters range between 630 and 885 ?S/cm, and 30 and 45°F, respectively. Field observations on karstic features and joint systems, and studies of air photographs and satellite images have revealed that karstification has developed in Tecer Limestone as an affect of the surface drainage, joints and faults. There is a rather strong correlation between the fracture traces, densely jointed zones, faults and the intensively karstified zones.