Groundwater is one of the major sources of exploitation in arid and semi-arid regions. Thus for protecting
groundwater quality, spatial and temporal distribution of data are important. The objective of this
research was to evaluate interpolation methods for predicting spatial distribution of some groundwater
quality such as TDS, Na+, EC, SAR, Cl- and SO4
-2. Data related to 65 wells in Rafsanjan plain were used
and IDW, kriging and cokriging were studied. After normalization of data, variograme was drawn. For
selecting suitable model for fitness on experimental variograme, less RSS value was used. By using crossvalidation
and RMSE, the best method for interpolation was then selected. Results showed that for interpolation
of groundwater quality, kriging and cokriging methods are superior to IDW method. At last, the
maps of groundwater quality were prepared, using the best interpolation method in GIS environment.