Assessing Temporal and Spatial Variations of Groundwater Quality (A case study: Kohpayeh-Segzi)

Assessing the quality of groundwater is important to ensure the sustainablesafe use of these resources. However, describing the overall water quality condition isdifficult due to the spatial variability of multiple contaminants and the wide range ofindicators (chemical, physical and biological) that could be measured. Therefore, in thiscase 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 andanalyzed in a 15 year period. After collecting data, the main affecting factors on waterquality of wells and qantas were determined separately by factor analysis test. Zoningmaps were generated in Arc GIS on the basis of most important effective factors. Dry andwet years were determined based on rainfall data and 7-year moving average. Finally, thetemporal trend of principal factors was depicted and water quality variations of wells andqantas were compared. Believing that sodium and chlorine are the most importantparameters for water quality of wells and qanats, water quality of wells during dry yearsis downgraded as the results show. In initial wet year period, water quality is extremelyimproved but thereafter it is degraded. Results also show that water quality variation inqanats is negligible.