CHARACTERISTICS OF KARST AQUIFER AS INDICATED BY TEMPORAL CHANGES OF THE SPRINGS PHYSICO-CHEMICAL PARAMETERS

Gar, Barm-Firooz and Mor mountains are located northwest of Shiraz in the Zagros. The Mounts are mainly composed of calcareous Sarvak Formation, sandwiched between two impermeable shaly formations, namely Pabdeh-Gurpi at the top and Kazhdomi at the bottom. The main karst feature of the area is the presence of 259 sinkholes in the Sarvak Formation which, along with the other superimposed secondary structures such as joints and fissures, direct the rain and snow-melt water into the aquifer. The main discharge point is Sheshpeer spring. To study the characteristics of the aquifer, the major ions, electrical conductivity, temperature, and discharge were measuped for a period of eighteen months. Moreover, caroon dioxide partial pressure and saturation index of calcite and dolomite were calculated using a hydrochemical model.. The recession curve of the spring is indicative of presence of two different flow regimes. In the first regime the flow is of conduit-diffused type, while in the second, the flow is mainly diffused by the larger channel-ways acting as a drainage system.