The paper "Porous Media Equivalents for Networks of Discontinuous Fractures" by J.C.S. Long, J.S. Remer, C.R. Wilson, and P.A. Witherspoon, published in Water Resources Research in June 1982, explores the conditions under which fractured rock behaves like a homogeneous anisotropic porous medium. The authors use the theory of flow through fractured rock and homogeneous anisotropic porous media to determine when a fractured rock can be modeled as an equivalent porous medium. They review field studies of fracture geometry and develop a realistic, two-dimensional fracture system model. The model considers the shape, size, orientation, and location of fractures in an impermeable matrix as random variables. The results of simulated flow tests show that fractured rock does not always behave as a homogeneous anisotropic porous medium with a symmetric permeability tensor. The behavior of fracture systems more closely resembles that of porous media when the fracture density is increased, apertures are constant, orientations are distributed, and larger sample sizes are tested. The authors conclude that their new tool, when perfected, will enhance the analysis of field data on fractured rock systems and can distinguish between fractured systems that can be treated as porous media and those that must be treated as a collection of discrete fracture flow paths.The paper "Porous Media Equivalents for Networks of Discontinuous Fractures" by J.C.S. Long, J.S. Remer, C.R. Wilson, and P.A. Witherspoon, published in Water Resources Research in June 1982, explores the conditions under which fractured rock behaves like a homogeneous anisotropic porous medium. The authors use the theory of flow through fractured rock and homogeneous anisotropic porous media to determine when a fractured rock can be modeled as an equivalent porous medium. They review field studies of fracture geometry and develop a realistic, two-dimensional fracture system model. The model considers the shape, size, orientation, and location of fractures in an impermeable matrix as random variables. The results of simulated flow tests show that fractured rock does not always behave as a homogeneous anisotropic porous medium with a symmetric permeability tensor. The behavior of fracture systems more closely resembles that of porous media when the fracture density is increased, apertures are constant, orientations are distributed, and larger sample sizes are tested. The authors conclude that their new tool, when perfected, will enhance the analysis of field data on fractured rock systems and can distinguish between fractured systems that can be treated as porous media and those that must be treated as a collection of discrete fracture flow paths.