Groundwater as an important sources of water have been rapidly exploited in most parts of the world for domestic and agricultural consumptions, thus groundwater depletion in response to droughts has become increasingly important. Although groundwater is one of the most important water resources in most part of the world, it has not been considered in many drought studies, except the last decade. Iran is located in arid and semi-arid regions resulted in years with less than average rainfall. In last two decades, continuous droughts in Iran have increased the groundwater exploitation for various agricultural, urban and industrial uses. This has exacerbated the drought stress on groundwater resources in most parts of Iran and has caused groundwater level to drop significantly. Analysis and study of the effect of drought on groundwater, using drought indices, is one way of measuring the extend of consequences and building a tool for future prediction. The purpose of this study was to investigate the impact of different types of drought and climate change on the Najafabad aquifer located in Zayanderood basin using drought indices, directly. For this purpose, the data-driven support vector machine (SVM) was used to simulate the Najafabad aquifer. The best combination of model inputs was selected by gamma test from meteorological, hydrological and groundwater drought indices. The model output was selected either the groundwater level or the groundwater volume. Model input parameters were also optimized using particle swarm optimization (PSO). In order to check the generalization ability of the model and to select the appropriate input vector for time series, a five-folded cross validation method was employed. Finally, model’s performance was evaluated using the average percentage error (APE), coefficient of determination (R 2 ) and root mean square error (RMSE). Based on results, for both models the coefficient of determination between the simulation output and the observed values was more than 90% in training, validation and test steps, indicating reliable accuracy of the results. After selecting the best model (model with groundwater volume as the output), the effects of climate change on the Najafabad aquifer were investigated using five general circulation models (GCMs) under two RCP4.5 and RCP8.5 scenarios. For this purpose, GCMs were downscaled using SVM in which the groundwater volume was predicted from 2017 to 2050 using the selected simulation model. After calculating and comparing the precipitation, temperature and groundwater volume changes from 2017 to 2050, no significant trend was observed in precipitation data due to GCMs low accuracy in precipitation prediction. There was also no significant relation between precipitation and groundwater volume. Despite the significant relation between temperature and groundwater volume, the volume under two climatic scenarios did not change significantly compared to the observed period. Therefore, the groundwater volume under two scenarios RCP4.5 and RCP8.5 has changed + 0.49% and -2.09%, respectively, compared to the observed period. As a result, climate changes will not have a significant effect on the Najafabad aquifer in the future. It is suggested that human factors (including aquifer exploitation) need to be further studied and its effects on the groundwater resources should be investigated. Keywords : Groundwater Drought, Support Vector Machine, Climate Change, Najafabad Aquifer