Hydrogeological study of Soke Plain and Bafa Lake surroundings: Geothermal potential, soil and water contamination

This study includes hydrogeological and hydrogeochemical studies of Söke Plain and Lake Bafa environs in the western part of the Büyük Menderes Graben, determination of geothermal potential, and investigation of the present inorganic contaminations for surface and groundwaters and soils in the basin. The rocks belonging to the Menderes Massif form the basis of the geological structure in the study area. These rocks comprising metagranite, schist, marble, recrystallized limestone type rocks with different ages from Precambrian to Eocene, are overlain with an unconformity by Neogene terrestrial sediments. Quaternary alluvium discordantly covers all the units. Alluvium, Neogene lacustrine carbonates and marbles occur as aquifers producing groundwaters from many wells and springs. Within the scope of field work, surface and groundwaters and hot and mineral waters were marked and hydrogeological map was prepared. Along the northern and southern border of the alluvial plain, there are low-temperature saline karstic waters discharged from the marbles belonging to the Menderes Massif. In total, forty water samples were collected for chemical and isotopic analysis: twenty-eight were groundwater (spring, well), seven of them were hot water, and twelve were surface water (sea, lake, stream). By evaluating the chemical and isotopic analysis; the relations between the dominant hydrogeochemical processes and dissolved ions in the field, geothermal system properties and seawater intrusion have determined. Conceptual hydrogeological and geochemical models have developed and contamination processes were investigated. More than seventy percent seawater intrusion to the geothermal waters have been determined. The seawater intrusion is controlled by the Akköy Fault from the sea to Bafa Lake. Potassium, calcium, magnesium, chloride, sulphate, boron, arsenic, iron, manganese, aluminum, selenium, nickel, lead, uranium, selenium were determined above the limit of the value in drinking water. The pollution index of the soil samples were calculated. Contamination was detected in the irrigated areas by Büyük Menderes River.