Characterization of Karst Springs from Zagros Mountain in southwestern Iran

Karst groundwater resources in the Zagros Mountains are vital for supplying different demands in the region which need sustainable management and protection. Quantitative and qualitative characterization of karst aquifers in this region was understudied due to a lack of site-specific logging data and speleological investigations. In this study, state-of-the-art statistical methods developed to characterize karst aquifer based on analyses of the spring recession hydrograph and spring water quality are presented. These methods include Mangin's method for the classification of karst aquifers, relationships of precipitation and discharge data, groundwater quality index (GQI), hydrochemical diagrams (Piper, Durov, and Gibbs), and calcite and dolomite saturation indices, Chloro-Alkaline indices (CAI), and 10 bivariate plots of hydrochemistry of spring waters. 42 major karst springs mainly located in folded part of the Zagros region (western Iran) are selected for application of the reviewed methods. Results indicated that the saturated zone exerts almost the main control over the discharge of 76% of the studied springs. The base-flow contributes between 80.0 and 100% of total water storage in the study aquifers. 78.5% of the studied aquifers have a high karstification degree. An insignificant lag time is observed between the precipitation on the karst basin and spring discharge. The hydrochemical diagrams show that the waters are dominated by HCO3 and Ca and the majority of the waters are alkaline, originating from carbonate rocks-water interaction through the ion exchange process. Moreover, the water sources of the studied springs are young and feed through precipitation (during the rainy season) and drainage from the upper karst setting (during the dry season). Such repeatable methods adopted in this study can provide crucial information for the karst aquifers, especially those suffering from scarcity of aquifer hydrodynamic data.