Stable Isotope Techniques as a Tool in Hydrogeological Conceptualisation of Ayazmant Mine Site (NW Turkey)

Ayazmant mine site is situated in the near vicinity of a dam reservoir being utilized for drinking and irrigation purposes. The mine is planned to be extracted by combination of two methods: open pit mining followed by underground mining. Most part of the operations will take place below the groundwater level. Preliminary hydrogeological assessment has revealed that the groundwater system is in connection with the dam reservoir. Prediction of groundwater inflow to both the open pit and the underground galleries and calculation the ratio of reservoir water in the inflow were the major questions. Numerical modeling was the methodology selected to be followed to achieve these objectives. Reliability of the numerical model is based on the accuracy of the hydrogeological model of the site. Hydrogeological conceptualization requires detailed geological hydrological and hydrogeological information. These studies give sufficient information on the occurrence, potential, availability and flow of groundwater systems. However, knowledge of interactions with different water bodies requires information on the flow path and velocity of a particle in the system. Isotopic constituents of water bodies provides this information. Particularly, stable isotopes are very useful in tracing the origin of the waters, mixing processes and interactions. This technique was used in conceptualization of the hydrogeological system in the mine site. The hydrogeological conceptual model suggested that the groundwater system is recharged mainly from highlands but also in connection with the dam reservoir. The water level fluctuation in the reservoir affects the interaction between the groundwater system in the mine site and the reservoir.