Hydrogeology of Karstic Springs in Saldoran Anticline, Chahar Mahal and Bakhtyari Province

Determining the groundwater flow direction in karts terrains is very important to understand the hydrogeological conditions. Saldoran Anticline is located in Chahar-Mahal and Bakhtyari province. The presence of highly karstified limestone and the relatively high mean annual rainfall in this region lead to the evolution of major karst springs such as Sarab-Baba heydar, Bagh-Rostam and Pir-e-Ghar. Studying the physical and chemical features of these springs together with determining the ground water flow direction are vital to characterize Saldoran karstic aquifer. The rate of mean annual precipitation is higher than 600 mm which occurs dominantly in the form of snow. The mean discharge and EC values are 1.9 and 438 in Pir-e-Ghar, 3 and 475 in Bagh-Rostam and 0.98 m3/s and 347 µmhos/cm in Sarab-e-Baba Heydar springs, respectively.Two different recession coefficients (α1 (0.002) and α2 (0.003))were recognized from the recession curves of the springs. The α1 regimen takes about 4 months, during which the major conduits discharge the infiltrating snow melt water. The α2 regimen which represents the discharge through the narrow fractures and joints (diffuse flow) continues for about 2 months. There is an inverse relation between discharge and EC values. The highly variable values indicate high degrees of karstification. The main flow directions in Saldoran anticline was estimated from north west to south east according to the hydrogeological and geomorphological parameters such as karst valley, sinkhole, fault, fracture, dip and elevation.