Qualitative Analysis of Groundwater Quality Indicators Based on Schuler and Wilcox Diagrams: IDW and Kriging Models

Abstract

Introduction: It is generally accepted that groundwater is one of the most vital sources of water for drinking use in cities and rural areas. The water drawn from these sources should be sanitary, have low soluble substances, and be free of any pathogens and microorganisms.

Materials and Methods: In this study, 90 wells were sampled with proper dispersion over the study area to achieve suitable estimation accuracy.

Results: The assessments made based on 10-year averages of water quality in the studied plain showed that according to the Schuler and Wilcox criteria of water quality for drinking and agricultural use, the northern and southern parts of the plain have unsuitable water quality compared to central parts. Interpolation RMSE value of the Inverse Distance Weighting (IDW) model for SO₄^-, TDS, TH, Mg²⁺, Cl^-, Ca²⁺ and HCO₃^- were 8.46, 2615, 246, 6.8, 38.9, 8.3 1.16 also 8.4, 2628, 750.9, 7.0, 39.8, 8.1, 8.1 (mg L^-1) for Kriging, respectively.

Conclusion: The cause of low groundwater quality in northern regions is the high rate of SO₄^-, TH, Cl^-, and TDS, which are of the most important determinants of water quality for drinking. The examination of samples in the assessment of water quality for agricultural use clearly showed a higher value of EC compared to SAR.