Spatial Estimation of Sodium Adsorption Ratio (SAR) and Chlorine in Groundwater Using Geostatistical Methods

Having knowledge of groundwater quality in arid and semi-arid areas can result sustainability of this valuable resource. For this reason, it is necessary to estimate Sodium Adsorption Ratio (SAR) and Chlorine in the groundwater quality accurately. Nowadays, many attentions have been arisen on geostatistical methods to detect spatial variability using same data (Kriging) or using auxiliary variables (Co-kiriging) in groundwater science. The quality of groundwater for agriculture is very important, however its measurement is time consuming and expensive. Therefore, finding solution to estimate SAR and Cl from easily measuring parameters is essential. This study is done in Boukan region using Co-kriging estimator in which water salinity (EC) is considered as an auxiliary variable. The results of Co-kriging and Kriging, were compared and evaluated using RMSE criterion. The results showed that Co-kriging method with high correlation coefficients is more precise than Kriging models in estimating SAR and Cl. RMSE values were 3.07 and 3.82 in estimating SAR and Cl respectively.