Vulnerability maps of groundwater pollution are basic tools for land use planning. However, some of the parameters taken into account by the different methods of vulnerability assessment may vary over time such as recharge, rainfall, groundwater level, etc. In the present work, through the application of the DRASTIC method to evaluate the intrinsic vulnerability of the porous aquifer R'Mel (Morocco), and using the data of three different years, we showed that intrinsic vulnerability varies from one year to another, i.e. that it is dynamic. For this we compared the years 2000, 2003 and 2005 selected for their different rainfall. The sensitivity maps obtained are different from one year to the next and the errors margins determined for each map are low and slightly different. Furthermore, the sensitivity analysis showed that the effect of parameters on the final vulnerability index changes from one map to another and that all parameters are necessary to apply the DRASTIC method. Analysis of these maps shows great variability in the spatial distribution of the degree of vulnerability, and that the proportions of areas occupied by the different classes vary also from one year to another. These vulnerability maps developed by the application of the model DRASTIC, are dynamic and therefore they can compromise the protection of resources.