Determination of the hydraulic characteristics of a cohesionless soil by means of the multicounter methods

This paper gives a descriptionof a newly developed technique for determination of both groundwater movement and the relative displacement of isotopes through porous media, The device automatically times the drift of a small radioisotope injection over a certain distance by means of four counting tubes. The flow direction is obtained from the time ratio between the peaks in the time-activity record. The velocity can furthermore be deduced knowing the direction and the distance from injection point to the centre of the countinq tubes,distance which is constant. Measurement capability with this device ranges between 1 and 200 cm per day, giving an error within acceptable limits. Field and laboratory tests executed with this device were compared and calibrated by existing methods. Finally, some other applications are given.