Mathematical Modeling of Karst Aquifers

Abstract

The chapter presents an overview of numerical modeling techniques for equivalent porous media (EPM) and conduit flow formulations, including a case study illustrating the value of conduit presentation. The authors provide an overview of basic numerical modeling concepts, including layering and the assignment of boundary conditions. The limitations of using classical MODFLOW EPM for karst aquifers are discussed, and alternative approaches such as the Conduit Flow Process (CFP) are introduced. Different implementations of the CFP are described, including discrete pipe networks and high-conductivity turbulent–laminar layers. While acknowledging the difficulties of numeric modeling of karst systems, the authors present justification for the use of new tools such as the CFP. This includes the ability to simulate sinks, turbulent and laminar flow processes, and two-way water exchange between porous media and conduits. More generally, the authors explain why and how numeric modeling adds value to water resources and site remediation projects of all kinds. The case study compares the results of EPM and CFP numerical modeling approaches for a karstic site in the southeast USA.