title: Dip and anisotropy effects on flow using a vertically skewed model grid.
abstract: Darcy flow equations relating vertical and bedding-parallel flow to vertical and bedding-parallel gradient components are derived for a skewed Cartesian grid in a vertical plane, correcting for structural dip given the principal hydraulic conductivities in bedding-parallel and bedding-orthogonal directions. Incorrect-minus-correct flow error results are presented for ranges of structural dip (0 < or = theta < or = 90) and gradient directions (0 < or = phi < or = 360). The equations can be coded into ground water models (e.g., MODFLOW) that can use a skewed Cartesian coordinate system to simulate flow in structural terrain with deformed bedding planes. Models modified with these equations will require input arrays of strike and dip, and a solver that can handle off-diagonal hydraulic conductivity terms.
authors.affiliation: The Pennsylvania State University, Earth and Mineral Sciences Environment Institute, 2217 Earth-Engineering Sciences, University Park, PA 16802-6813, USA. hoaglund@essc.psu.edu
authors.forename: John R
authors.initials: JR
authors.lastname: Hoaglund
authors.forename: David
authors.initials: D
authors.lastname: Pollard
mesh_terms: D008962:Models, Theoretical; D012987:Soil; D014867:Water / Q000737:chemistry; D014872:Water Movements; D014881:Water Supply
chemical_list: D012987:Soil; D014867:Water