Single-well pulse technique

The paper deals with some theoretical and experimental problems of the single-well pulse technique proposed in Israel. The single-well technique is based on a traced injection, pause and pumping. Knowing the thickness of an aquifer as well as the pumping rate, it is possible to find a distance travelled by a tracer during the pause from the measurement of tracer concentration in pumped water. The ratio of distance and duration of the pause gives natural groundwater velocity. It is shown in the paper that the problem may sometimes be solved for a two-layered aquifer. A new method for interpreting the arrival time of the tracer is proposed. It is based on the time of 50% recovery of recovered amount of an injected tracer. This method seems to be essential when very high dispersion of tracer is observed. Many limitations of the technique and an example of complex interpretation are discussed in detail. Final results are compared with those obtained from classical and other tracer methods. A general interpretation of all the data leads to some conclusions and hypotheses which suggest that the main part of water in the investigated aquifer (part of the Vienna Basin) flows very quickly through highly permeable zones and that the movement of water probably takes place mainly in the upper layers of the aquifer. (author)