Spatial Estimation of Groundwater Quality Parameters Based on Water Salinity Data using Kriging and Cokriging Methods

Groundwater is one of earth’s most vital renewable and widely distributed resources as well as an important source of water supply worldwide. The increased exploitation of groundwater resources can decrease regional water quality as a whole. The estimation of sodium adsorption ratio (SAR) and chloride content, and also, Na, Ca and Mg concentration are much more timeconsuming and expensive than water salinity measurement. Therefore, it is necessary to find a sterategy to estimate SAR and chloride using salinity extent. In this research, kriging and cokriging methods to estimate the parameters including the sodium adsorption ratio (SAR) and the chloride content (Cl) based on groundwater salinity data (EC) in Fasa area were applied. Results obtained from two methods were compared together. Results indicated that cokriging has higher accuracy than kriging method in the estimation of the sodium adsorption ratio (SAR) and the chloride content of groundwater in areas with data restriction. Generally, results of this research showed that the two methods differ slightly and they have suitable accuracy to estimate SAR and Cl based on water salinity parameter. Keywords—Groundwater, sodium adsorption ratio, chloride, geostatistic methods.