Assessment of groundwater quality of the Tatlicay aquifer and relation to the adjacent evaporitic formations (Cankiri, Turkey)

One of the most important hydrogeologic problems in and adjacent areas of evaporitic formations is severe quality degradation of groundwaters. These kinds of groundwaters contain high content of dissolved solids and generally have some limitations for use. Tatlicay basin (north-central Turkey) is an example to effects of the evaporites on groundwater quality in the adjacent alluvium aquifer. Gypsum and anhydrites in the two evaporite formations (Bayindir and Bozkir) effect of the groundwater quality in the alluvium adversely, by dissolution of the evaporites by surface drainage and infiltration into the alluvium aquifer (widespread effect) and by infiltration of low quality gypsum springs (local effect) into the aquifer. Evaporitic formations significantly increased EC, TDS, Ca and SO4 parameters in the alluvium aquifer in the central and downstream regions. EC has increased roughly from 500-800 to 1,700-2,000 mu S/cm, Ca has roughly increased from 3-4 to 10 meq/l, SO4 has increased 0.5-1 to 11-12 meq/l. Consequently, three clusters were distinguished in the basin; (1) nonevaporitic waters in low TDS, Na, Ca, Mg, Cl and SO4, (2) diluted waters in high TDS and relatively high Cl, moderate-relatively high Na, Ca, Mg, SO4, (3) gypsum springs in highest TDS, Ca, SO4, but moderate Mg and low Na, Cl.