GIS in Hydrogeology: unconfined aquifer of the Chisinau City, Moldova. GIS for hydrogeology is based on the concept of geo-information system capable of both storing large amounts of data (time-dependent, point data, map data, etc.) and processing data is one coherent user-friendly system to evaluate hydrogeological conditions on natural and anthropogenic scale. The power of GIS for hydrogeology system is the coupling between GIS platform and a huge database. The common user of the system only deals with this so-called GUI (Graphical User Interface) and the underlying intricate database and GIS technologies remain invisible and immaterial for the proficient user. Test-side like Chisinau City is representative and well characterized hydrogeologically. Other geographical and meteorological data are available. As a result, proposed model for GIS Hydrogeology solved complex of questions related to water quality: distribution of chemical elements, hydrogeological parameters and equilibrium calculus for the system water-rock. Prepared model is adequate for connection with other software, like Mod Flow and Aqua Chem. Also is flexible for additions and complexity.