Characterization of Barmejamal Spring Karst Aquifer Using Physico-Chemical Spring Responses

Barmejamal Spring is located in northeast of Ahwaz, Khuzestan Province, Iran. The catchment area of the spring consists of the northeast and southwest flanks of the Koh-e-Safid anticline, which is made up of karstic calcareous Asmari formations. There are sinkholes, caves, and other karst landforms in the catchment area. The existence of several faults has brecciaed Barmejamal spring karst aquifer that may have caused karstification to occur in parallel fracture systems. For the purposes of this study, pH and water temperature were measured on a weekly basis for a period of 12 months and water samples were analyzed for major anions and cations. Flow rate was measured on a daily basis during the recession, and weekly during the rest of the study period. Using the PHreeqc 2.6 computer model, the partial pressure of carbon dioxide and the saturation index of calcite and dolomite were also estimated. Three distinct periods belonging to three recession coefficients (α1, α2, α3) were observed in the hydrograph of the Barmejamal Spring. No considerable differences were observed between the first and second recession coefficients. Base flow for α1, α2 and α3 constituted 49%, 75.34%, and 100% of the total flow in the first and second recession periods and in the precipitation period, respectively. The variation of specific conductance, calcium and bicarbonate concentrations, and calcite saturation indices were not significant throughout the study period. The morphology and geology of the Barmejamal Spring catchment area and the data from hydrograph and chemographs show that the hydrologic system is of the diffuse-conduit flow type