Investigation of hydrogeology and geothermal properties of Erzincan Basin

This study has been prepared in order to reveal the hydrology, hydrogeology, hydrogeochemistry and isotope properties of groundwater, cold and hot water resources in the Erzincan Basin. Groundwater level maps of the study area were prepared. While the groundwater flow direction is in the same direction with the Çardaklı stream in the west of the plain, and in the same direction with the Euphrates River in the east, the groundwater discharges towards the Euphrates River in the area where the river forms an island. The geological units in the study area were classified according to their hydrogeological characteristics and determined as permeable units (1), permeable units (2), secondary porosity permeable (1) units, secondary porosite permeable (2) units, less permeable units, and impermeable units and were shown on the hydrogeological map. The transmissibility value of the aquifer was calculated in the range of 48,75-3136,25 m2/day, and the permeability value was calculated in the range of 1,21-52,27 m/day. According to the static water levels measured in the plain in 2015 and 2016, the hydraulic gradient was calculated as 0,008 in the west and 0,004 in the east of the plain, and the groundwater flow rate was found to be 2.84x10-5 m/s in the west and 1.6x10-5 m/s in the east. Water samples belonging to rainy and dry periods were taken from wells, springs and geothermal waters in the basin. The results of the analysis were evaluated according to national and international standards and their drinkability and usability were evaluated. In the Piper, Schoeller and Durov diagrams created as a result of the chemical analyzes of the waters, it was determined that there were waters of MgHCO3 facies with the same origin and similar feeding areas. It was observed that in some of the water samples, the limit values determined by national and international standards were exceeded in the amounts of Mg+2, Cr, Ni, Pb, B, Fe and Se. According to the sodium absorption rate, sodium percentage, Wilcox diagram and USA Salinity Laboratory diagrams used in the classification of groundwater irrigation waters, they are in the class of very good, very good, well usable and very good, C3S1 and C2S1 waters, respectively. CAI-I and CAI-II values are calculated with the help of the chemical analysis results of the water samples in the study area, and it shows that there is reverse ion exchange in the two waters, ion exchange in the other waters, and that there is a fundamental exchange between the calcium and magnesium ions in the groundwater and the sodium and potassium ions in the aquifer. Ekşisu thermal water is not saturated with anhydrite, gypsum, halite, siderite, talc and villemite; albite, aragonite, calcite, chalcedony, dolomite, goethite, hematite and quartz were determined to be saturated. According to the results of δ18O and δD analyzes of the water samples, they were determined to be of meteoric origin.