In this study, the impact of ENSO atmospheric and oceanic phenomenon on the groundwater table (GWT) changes was investigated using the Southern Oscillation Index (SOI) in Iran. For this purpose the information of 30 piezometeric wells selected from different points of the country were used. Pearson correlation analysis conducted on relationship between SOI and GWT. Results showed that minimum GWT changes occurred in La Nina phase at 37 % of stations. On the contrary, the maximum GWT changes occurred in El Nino phase at 80% of the stations. Application of Pearson correlation analysis revealed that a negative correlation exists between SOI and GWT fluctuations at more than 93% of the stations. Furthermore, variation of GWT in La Nina phase to neutral phase was 207.3 % which was comparable with 6.8% for the average GWT changes in El Nino phase to neutral phase. Results showed that the percentage changes of GWT in La Nina phase is more than El Nino phase.
