The Relation between Meteorological Drought and Groundwater Quality in Arid and Semi-arid Climate (Case Study: Isfahan Province)

In this study, for study the effect of rainfall changes on groundwater quality in dry and semi-arid climate of Isfahan province, six basins with high concentration of wells and meteorological stations were selected. Data from 72 meteorological stations of Isfahan province during the statistical period of 2003-2013 and data from 350 wells were used to study the changes in groundwater quality. Subsequently, data with the lowest quality of EC, Ca, Mg, pH, Na, Cl parameters were recorded in Excel software, and ArcGIS software and the changes were zoned. In studying the meteorological drought, rainfall of September as the representative of the driest months of Isfahan, DIP software, analysis of time series 6, 12, 18 and 24-month and the time series with the highest correlation in the zonation were used. Then a correlation time series was zoned in different sections of the six study basins in ArcMap software. The results of Pearson statistical method showed a positive correlation between the drought of meteorology and groundwater quality in the 18-month time series. In summary, with the negative trend of precipitation, the positive trend of salinity, calcium, magnesium, acidity, chlorine and sodium in groundwater was observed from the western areas to the eastern regions. The results show that the minimum variation of millimeters in rainfall from a basin to another basin in Isfahan province affects groundwater quality in each of the six basins and leads to a downward trend in groundwater quality following drought events.