GROUNDWATER QUALITY ASSESSMENT FOR DRINKING PURPOSES USING GIS MODELLING (CASE STUDY: CITY OF TABRIZ)

Tabriz is the largest industrial city in North West of Iran and it is developing rapidly. A large proportion of water requirements for this city are supplied from dams. In this research, groundwater quality assessed through sampling 70 wells in Tabriz and its rural areas. The purposes of this study are: (1) specifying spatial distribution of groundwater quality parameters such as Chloride, Electrical Conductivity (EC), pH, hardness and sulphate (2) mapping groundwater quality for drinking purpose by employing Analytic Hierarchy Process (AHP) method in the study area using GIS and Geosatistics. We utilized an interpolation technique of ordinary kriging for generating thematic map of each parameter. The final map indicates that the groundwater quality esaeicni from North to South and from West to East of the study area. The areas located in Center, South and South West of the study area have the optimum quality for drinking purposes which are the best locations to drill wells for supplying water demands of Tabriz city. In critical conditions, the groundwater quality map as a result of this research can be taken into account by East Azerbaijan Regional Water Company as decision support system to drill new wells or selecting existing wells to supply drinking water to Tabriz city.