Physicochemical time series of karst springs as a tool to differentiate the source of spring water

Abstract

Podenow Anticline is located in the Zagros Mountain Range, southern Iran. This anticline is exposed in an outcrop of Tertiary karstic limestone-dolomite Asmari Formation which is sandwiched between two impermeable marly formations. Part of the Podenow aquifer is discharged by 23 springs on the southern flank. Nineteen of these springs are concentrated in an area less than 0.5 km². The major ions, electrical conductivity, temperature and pH of these springs were measured once every two to three weeks for a period of 17 months. Geological setting, geomorphology, topography, lithology of the karst aquifer and surrounding formations, ratio of SO₄ to total anions, time series of specific conductance, hydrograph of springs, elevation of water level in piezometers and aquifer water balance were used to determine the probable catchment area of the springs. These parameters indicate that the sources of four springs are most probably the southern flanks and the sources of the other springs are both the southern and northern flanks. The time series of specific conductance of the fourteen Atashkadeh springs overlap which implies that all of these springs share a common conduit and the same catchment area. But the catchment area of one of the Atashkadeh springs is different from the other springs, even though it is surrounded by those other springs. A later tracer study confirmed the above discussion.