Avoiding confusion between pressure front pulse displacement and groundwater displacement: Illustration with the pumping test in a confined aquifer

Two distinct phenomena may be distinguished and defined during a pumping test conducted in a confined aquifer: the pressure front pulse displacement and the groundwater displacement. This Scientific briefing examines and clarifies the difference between the pressure wave displacement and the groundwater displacement, by stating the differences in their respective transit times and velocities. The pressure front pulse displacement is controlled by the diffusivity of the aquifer, whereas groundwater displacement is controlled by the pumping flow rate and the effective porosity of the aquifer. To calculate the transit time and velocity of each type of displacement, several equations are presented and compared. An example is provided to illustrate the differences in velocity between the pressure front pulse displacement and the groundwater displacement.