Examining Changes Trend of Fluoride Concentration in Groundwater Using Geo-Statistical Technique Case Study: Drinking Water wells in Yazd-Ardakan Plain

Abstract Introduction: Studies have demonstrated that the presence of standard amount of fluoride in drinking water can prevent tooth decay. Meanwhile, higher concentration than permitted amount in drinking water causes bone disease and dental fluorosis. Given the importance of fluoride in drinking water as well as GIS ability in spatial analysis of various factors in the groundwater, this study aimed to evaluate concentration of fluoride in the plain of Yazd-Ardakan using two IDW (Inverse Distance Weighting) and Kriging models. Materials and Methods: In this descriptive study, the applied data on the water quality of underground water of Yazd Regional Water Company and the average annual fluoride in 2014 were related to 76 rural wells and 107 urban wells in the studied area. The fluoride rate in groundwater in rural and urban areas was compared to the standard amount of Institute of Standard and Industrial Researches and then was analyzed via Arc GIS software using IDW and Kriging interpolation methods. Results: The mean concentration of fluoride was 0.68 mg/l in rural areas and 0.7 mg/l in urban areas. With regard to the minimum and maximum concentrations of fluoride as well as standard deviation of 0.364, fluoride concentration fluctuations in rural areas were reported higher than urban areas, For both rural and urban areas, Kriging interpolation method was more efficient than IDW method. Conclusion: The study findings revealed shortage of fluoride in drinking water and the risk of tooth decay within the residents of southern districts of Yazd-Ardekan which necessary management needs to be taken in regard with these areas. It is worth mentioning that Geo-statistical methods can greatly assist in understanding the environmental issues.