Survey on trend changes of drinking groundwater resources quality: A case study in Lordegan

Introduction: Groundwater is the main source of drinking water and the life of many human societies depend on it. Continuous monitoring and assessment of groundwater quality changes are necessary because improvement and decontamination of polluted groundwater is very difficult and costly. The aim of this study was to determine the groundwater quality trend changes in Lordegan city (Iran) during one decade (2002-2012). Materials and Methods: The required data were collected from the results recorded in the years 2002-2012 and analyzed by descriptive and analytical statistics (correlation coefficients). Results: changes of all of them were ascending. In the first and end year of the study period, the number of fecal coliform positive samples were 9(6.25%) and 14(9.75%) and the mean±SD of fecal coliform's MPN in positive samples were 0.24±0.04 and 0.83±0.40 respectively. Also the mean±SD of nitrate (as nitrate, mg/l), total hardness (as calcium carbonate, mg/l) and electrical conductivity (as micromhos/cm) in the first and end year of the study period were 16.6±6.56 and 21.7±10.76, 254±47 and 298±34 and 507±92 and 529±98 respectively. On the basis of spearman's correlation coefficient, the ascending trend of some parameters concentration with time was significant at the level of 95% of confidence limits (α≤0.05). Conclusion: The ascending trend of concentration of all the parameters shows gradual declining of drinking water resources quality. Continuing the ascending trend of the parameters concentration and declining the quality of water resources and incompatibility with Iranian drinking water standard can lead to significant health risks, therefore, tracking the trend changes, investigating the reasons and preventive measures are important. Keywords: Drinking water, Groundwater, Lordegan, Trend changes, Water resources