Tracer tests

Tracer tests help to verify whether two points are connected by water, generally speaking between a swallow hole or any other infiltration area (a surface leak point, an active karst cave, etc.), or a surface or underground waterway and a spring or a group of springs.
A tracer is defined as any substance whose atomic/molecular, physical, chemical or biological properties make it is easy to be identified. Among the various types of tracers, an important role is played by fluorescent tracers or colouring agents. They are easy to use, show up immediately, are cost-effective and do not affect environmental matrices.
The tracer’s route can be verified at the resurgence point(s) by:

  • using small containers made from a highly permeable netting containing granular activated carbon, known as fluorocaptors
  • installing automatic collectors, known as field fluorometers

For the ALIRHYS project, a total of 6 tests were conducted with tracers by using automatic collectors.