Geostatiscal analysis of groundwater quality index (Case study: Marvdasht-Kharameh aquifer, Fars)

One method of groundwater quality assessment is applying Groundwater quality index (GWQI), which is a combinational method of different quality parameters of groundwater. The aim of this study was to estimate the Marvdasht-Kharameh Plain groundwater quality for drinking by employing GWQI along with applying geostatistics technology in GIS environment. For this purpose, the norm of five years quality data of 49 wells were used. GWQI was estimated by applying inverse distance weighting method to quality parameters. Kriging geostatistics pattern was used for assessing spatial changes and mapping the quality parameters and GWQI. Spherical variogram pattern had the best fitting on quality parameters and GWQI. The results illustrated that spherical variogram pattern with 19200 m effective range is appropriate for GWQI. Based on sensitivity analysis, EC, TDS, and Mg had the most and pH, sulphate and TA had the least influence on GWQI. The GWQI range was variable from 47 to 1000. Upon to GWQI map, the north-western parts of Marvdasht-Kharameh Plain aquifer had suitable quality for drinking while it was not suitable to use in southern parts of aquifer.