Characteristics of karst springs in Aydincik (Mersin, Turkey), based on recession curves and hydrochemical and isotopic parameters

We evaluate the hydrogeology of the area around the Soguksu spring in the Aydincik district, Mersin, Turkey, with a focus on the groundwater and aquifer systems. An increasing population and the expansion of agricultural land have resulted in increasing demand for water in the Aydincik area. The Soguksu spring, discharging from the Aydincik aquifer, is the major source of water for Aydincik and the surrounding area. To establish a sustainable water management plan for the region it is essential to determine the characteristics of the hydrogeological structure of the area. Water samples taken from the Soguksu spring and other small springs in the Aydincik area were analysed and the spring recession curve, hydrochemistry, stable isotopes (delta O-18, delta H-2), and tritium isotopes (H-3) were used to characterize the aquifer. The master recession coefficient obtained from analysis of the spring discharge data for 1999-2012 indicates one exponential term. Analysis of the groundwater composition identified two groups, the Ca-HCO3 and Ca-Mg-HCO3 groups, based on the major cation and major anion in the sampled water, as expected from karstic carbonate aquifers. The stable isotopes demonstrate the predominance of low-elevation precipitation. High tritium concentrations between 2.32 and 4.25 TU suggest recent recharge of groundwater from rainfall.