Author(s)

L. Colombo, P. Gattinoni, S. Rizzo & L. Scesi

Abstract

The paper deals with the water circulation in rock masses, with particular reference to those karstic/fractured systems in which the porous matrix contribution to flow cannot be neglected. The state of the art proposes different numerical solutions to study dual permeability systems, while analytical solutions are pointed out only for dual porosity model. In this study, three different models were developed to study typical dual permeability systems: a numerical code written in Matlab for solving 1-D partial differential equations of flow in dual permeability system, a Single Continuum Model implemented in MODFLOW-2005, a combined model developed in MODFLOW-2005 using the Conduit Flow Process Package. First, the sensitivity of the model responses to different input parameters was evaluated. Then, the different approaches were applied to the case of Vigolana Massif (Trento, Northern Italy), evaluating their ability to reproduce the response of this typical dual permeability system. Modeling results showed that the Single Continuum Model gives a quite good response with a relatively low cost (in terms of required data and computational time), even if it is not properly representative of the examined phenomenon, because it is not able to return and shape the water transfer between matrix and conduit. On the contrary, the Combined Model, solving two flow equations, is perfectly able to reproduce the response of a dual permeability system, but it obviously requires more detailed parameters, often not easy to define. Finally Matlab 1-D code does not reproduce correctly the delay of the matrix response, due to the mono-dimensionality of flow. Keywords: dual permeability karstic system Italy numerical models.

Keywords

Keywords: dual permeability karstic system Italy numerical models.