Determination of Flow Velocities in Groundwaters by the Aid of Tracer Techniques

The present paper, which is part of the implementation of the Project “Evaluation of the Groundwater Resources of Peru”, reports methodologies and techniques developed for on-site artificial tracer aided measurements of groundwater flow velocities. Horizontal flows are computed through labeling of the whole water column which is coated with a holed pipe in its entire length, below the piezometric level. Concentration monitoring inside the well, is performed prior to the experiment. The injection of a tracer in a borehole located in the influence area of the project, allowed the determination of velocity of ground water flow. The basis of the technique relates to the application of a relationship existing between the observed concentration decreases of a tracer solution released into the borehole. Changes in the position of the tracer as a function of time, allow us to draw some conclusions about the direction of flow as well. Satisfactory results show that techniques applied herein are cheap, simple and rapid methods for the determination of groundwater flow characteristics.