HYDROGEOCHEMICAL FRAMEWORK AND GROUNDWATER VULNERABILITY MAPPING OF IZMIR BORNOVA PLAIN, TURKEY

This paper aims at studying of groundwater vulnerability mapping by using GOD method and preliminary hydrogeochemical attributes, result of natural and / or manmade conditions, of Bornova plain. It, lying through the Eastern part of Izmir-Turkey, is a coastal-alluvial domain embracing industry plants and was selected for the lack of hydrogeological data. Thereby, hydrogeochemical scrutinies and rapid groundwater vulnerability assessment were accomplished. Former hydrogeochemical studies were mostly concentrated upon collecting and analyzing groundwater samples and evaluating hydrochemical water type by way of Piper, Schoeller Diagrams. Ca²⁺HCO₃^- water type was distinctive attribute of the plain in accordance with results of these studies. Conversely, later hydrochemical studies indicated mixing water type which is widespread in the area. In addition to hydrochemical survey in this study, saturation indices were calculated by using software to develop conceptual model. With regard to electrical conductivity measurement results as a part of hydrogeochemical studies, these are higher in the western part of the plain than the eastern part of that. Besides, Na⁺, Ca²⁺, Mg²⁺, Cl^- content of groundwater increases time dependently. It was presumed that major chemical properties of groundwater and saturation indices indicated sea water intrusion due to unhindered groundwater withdrawal in the plain. Additionally, variously publications used in this study, albeit irregularly, were completed, but heavy metal content of groundwater can be arranged as a following research for the purpose of understanding possible effect of industrialization. Secondly, aquifer properties were used in terms of vulnerability index. GOD method was chosen owing to the lack of data and rapid assessment. Thus, it was shown that higher vulnerability indexes pertained to the western part of the plain. These index values was appropriately considered with hydrogeochemical features indicating sea water intrusion in the coastal zone and intensive industrial facilities which signed potential heavy metal pollution in the western part of the plain.