Localisation and measurement of flows in boreholes

The identification and measurement of flow patterns in boreholes using artificial tracers is an essential tool in investigating the nature of leaks from reservoirs and lakes. The repair works carried out to reduce or stop such leaks generally consist of reducing the permeability of the geological materials through which groundwater flows. To successfully and cost effectively achieve such a decrease in permeability, it is necessary to identify and determine the exact groundwater flow path that connects the reservoir with the downstream springs. The most direct way of achieving this is by conducting tracer experiments. The techniques, which allow the identification, localisation and measurement of the magnitude of the flows intercepted by boreholes, are described in this chapter. The measurement of vertical profiles of temperature and electrical conductivity, as well as the permeability tests described in Chapter 3 and the geophysical well-logging techniques described in Chapter 4 , are complementary techniques.