Assessing groundwater quality and selection of the most appropriate spatial interpolation method (Case study: West of Marivan city, Iran)

Groundwater quality assessment and selection of appropriate methods of zoning depends on the region conditions, and data availability. The correct choice is a key milestone and a major step forward in the management of groundwater resources. The aim of this study was to evaluate the quality of groundwater for drinking and irrigation purposes in the west of Marivan city, Iran. For this purpose, data from 1985 to 2011, and the parameters of salinity, chlorine, concentration of dissolved substances, sulfate, water hardness, sodium, sodium adsorption ratio were used. Analysis of variance (ANOVA) and the LDS test was used to compare treatments and the differences between various stations respectively. For determining the most appropriate location and zoning methods for the above parameters, geographical information system was used. For this purpose, a geostatistics method of simple Kriging, and deterministic techniques such as inverse distance weighting, radial basis function, local estimator and general estimates was applied to annual and season data. The results showed that the quality of water in the area is appropriate and acceptable for drinking. Also for the irrigation, most of the study area is located within an acceptable range. Spatial interpolation results according to the root mean squared error (RMSE) and mean absolute error (MAE), among the different methods of interpolation techniques the LP for estimating the parameters of sulfate, soluble solids concentration and salinity, the RBF for for estimating parameters of sodium and sodium absorption ratio, the GPI method for chlorine at annual scale were the most appropriate methods .