Assessing the quality of groundwater is important to ensure the sustainable safe use of these resources. However, describing the overall water quality condition is difficult due to the spatial variability of multiple contaminants and the wide range of indicators (chemical, physical and biological) that could be measured. Therefore, in this case study, some water quality parameters including Na, Mg, Cl, K, and pH, SAR, TDS, Th, Co3, HCo3, So4, Ca and EC of 34 wells and 16 qanats have been monitored and analyzed in a 15 year period. After collecting data, the main affecting factors on water quality of wells and qantas were determined separately by factor analysis test. Zoning maps were generated in Arc GIS on the basis of most important effective factors. Dry and wet years were determined based on rainfall data and 7-year moving average. Finally, the temporal trend of principal factors was depicted and water quality variations of wells and qantas were compared. Believing that sodium and chlorine are the most important parameters for water quality of wells and qanats, water quality of wells during dry years is downgraded as the results show. In initial wet year period, water quality is extremely improved but thereafter it is degraded. Results also show that water quality variation in qanats is negligible.
