Calibration and Reliability in Groundwater Modelling: From Uncertainty to Decision Making (Proceedings of ModelCARE’2005, The Hague, The Netherlands, June 2005). IAHS Publ. 304, 2006. pp. pp.87–92.

Calibration of hydraulic and tracer tests in fractured media represented by a DFN model

LEONARDO DAVID DONADO1, XAVIER SÁNCHEZ-VILA1, EDUARDO RUIZ2, FRANCISCO JAVIER ELORZA3, CARMEN BAJOS4 & ANTONIO VELA-GUZMAN5

1 Department of Geotechnical Engineering and Geosciences, Technical University of Catalonia, Jordi Girona 1-3, UPC Northern Campus, Building D2, E-08034 Barcelona, Spain

leonardo.david.donado@upc.edu

2 Enviros Spain S. L., Passeig de Rubi, 29-31, E-08197 Valldoreix-Barcelona, Spain

3 Department of Applied Mathematics and Informatics Methods, Technical University of Madrid, Ríos Rosas 21, Building M3, E-28003 Madrid, Spain

4 ENRESA, Emilio Vargas 7, E-28043 Madrid, Spain

5 Spanish Nuclear Security Council (CSN), Justo Jurado 11, E-28040 Madrid, Spain

Abstract A methodology is proposed for interpreting hydraulic and tracer tests in a discrete fracture network (DFN). To start off, an externally generated network of fractures (represented by 2-D disks) is embedded in a 3-D domain. Since each generated DFN is considered as one of the possible outcomes, a stochastic approach is adopted. In each DFN, the connections between the disks define a conductive network, modelled as a suite of 1-D elements. The hydraulic conductivity and specific storage coefficient for each element form the product resulting from an individual value multiplied by a parameter; this is the same for all the elements and corresponds to a disk belonging to a given family. These family parameters are fitted by means of an inverse problem solution using available pumping test data. Tracer tests are also used to inversely calibrate solute transport parameters (mobile and immobile porosities, dispersivity, and diffusion in the fractures and matrix). The methodology is illustrated with hydraulic and tracer tests performed at the El Berrocal site (Spain).

Keywords discrete fracture network; fractured media; hydraulic and tracer test interpretation