A tracer test in a fractured aquifer that gave a groundwater flow rate of kilometers per day

摘要

Tracer and dilution tests were done during a borehole injection test in a fractured quartzite aquifer in Windhoek, Namibia. The injection tests formed the basis of a study into artificial recharge to the Windhoek aquifer. During one of the tests, at an injection rate of 17.1 L/s, a tracer was added to the injection water and monitored in a borehole 786 m away. The tracer took 216 minutes to reach the observation borehole, giving a flow velocity of 3.6 m/min. The hydraulic gradient, as a result of injection was approximately 0.01. This paper describes the geology of the Windhoek aquifer, the tracer test and a dilution test on the observation borehole.