Solute transport in fractured media – analysis of non-reversibility in tracer tests
- 1Earth Sciences Department, Faculdade de Ciências e Tecnologia da Universidade de Coimbra, Largo Marquês de Pombal, 3000-272 Coimbra, Portugal
- 2Civil Engineering Department, Faculdade de Ciências e Tecnologia da Universidade de Coimbra, Rua Luís Reis Santos – Pólo II Universidade de Coimbra, 3030-788 Coimbra, Portugal
- 3Civil Engineering Department, Escola Superior de Tecnologia e Gestão de Leiria, Morro do Lena – Alto do Vieiro, 2411-901 Leiria, Portugal
Abstract. This paper describes several small-scale (laboratory) experiments designed to simulate solute transport through fractured formations. A block of granite was broken to produce a fracture similar to those found in natural environments. Seven holes were drilled in the block to intersect the fracture. Later these holes functioned as either inlet or outlet points. All the possible combinations of pairs of inlet-outlet points were used to set up the tracer tests that provided the data analysed in this paper.
The results indicate that reverse tracer tests do not necessarily provide symmetric results. Under some circumstances, the non-reversibility might be used to detect differences in the morphology of the fracture. The results also indicate that it is possible to estimate reasonably well the volume available for the circulation of the fluid by using transport models that neglect diffusion.