Evaluation of Groundwater Quality Indices of Mashhad Plain using Geostatistics and GIS Techniques

Introduction The quality of drinking water resources is closely related to public health. Using GIS, we can easily map the measured quality parameters and provide valuable information to community health services. In the present paper, some important indicators of groundwater resources in the central district of Mashhad city were measured and zoned. Materials and Methods In this research, water quality indicators, including TDS, TH, sulfate, chloride, pH and sodium were analyzed in a zone including 1580 wells. Then the data was entered to GIS Framework and mapped using the Kriging methods. Results The results of the research indicate that TDS and TH exceed in the most acceptable levels of the Iranian national standard in 60% and 81% of the total studied area respectively. In the case of the sodium index, only 3% of the area and in the chloride index, six percent of the area, which is located mainly in the south of Mashhad and small parts in the northwest of Mashhad, have exceeded the standard. Sulfate index is also in unfavorable conditions in more than nine percent of the studied area. The pH index is in suitable condition. Conclusion The outcomes illustrate that the qualitative conditions of underground water resources, particularly in TDS and TH are in the inappropriate condition in the southern parts of Mashhad. It is related to the high population density and the lack of proper drainage. It is needed to restrict over exploitation of groundwater resources in critical hot spots, along with defining alternative safe water sources for urban consumption