Hydrogeological properties of Çokrağan - Yukarı Karacahisar (Banaz-Uşak) karstik springs

The Study area covers Cokragan spring and its vicinity which is in Banaz, county of Usak. The oldest rocks of the area is Jurassic aged sandstone schist and recrystallized limestone. These rocks are overlain with unconformity by the Tertiary aged peridotite, serpentinite, dacide tuff, dacide andesite, silicified zone and volcanic conglomerate, sandstone and basic tuff rocks. Quaternary aged alluvial deposits covering the old units with angular uncorfimity. To calculate the Cokragan spring recharge and discharge quantity according to years, montly flow data were taken from State Hydraulic Works (DSI). By using Cokragan spring flow data, dry season inclinations were computed and discharge coefficients were calculated. Cokragan spring?s average discharge coefficient was found by calculating mean of seperatly calculated each dry season discharge coefficients. Each dynamic reserves, at the end of dry season, were calculated and dynamic reserve changes were computed by the difference between dynamic reserves of consecutive years. By using the calculated dynamic reserve change of a water year, the discharge and recharge quantity of Cokragan Spring was found for the calculated water year. Water samples were collected from the area to determine the hydrogeological properties. Hydrogeological properties were determined by using geochemical analyse of selected water samples from the study area. Analyses results were evaluated by plotting on the Piper, Schoeller, Wilcox and USA-Salinity diagrams. Hydrochemical facies type of the water samples are generally calcium-magnesiumsulphate- bicarbonate, calcium-magnesium-sulphate. The geological and the geomorphological properties of Cokragan cave were investigated to define the effects of the tectonic activities, the geomorphological background and the changes in the groundwater level that occured at the study area. According to these investigations, water levels were diclined twice and tectonic activities were not very forcefulness. Furthermore, fissure systems of the rocks that Cokragan cave was formed, are well developed. Keywords: Recharge volume, Discharge coefficient, Hydrogeology, Karst