Chapter 5 – Spatial Discretization and Parameter Assignment

Discretization of the problem domain into a structured or unstructured finite-difference grid or a finite-element mesh is one of the most important and difficult steps in model design. Selection of horizontal nodal spacing and definition of model layers is guided by the modeling objective. Assignment of material property and hydrologic parameters to cells, elements, or nodes is facilitated by zonation and interpolation of point measurements. Inconsistency between the scale at which parameters are measured in the field and laboratory and the nodal spacing of a grid/mesh introduces scaling errors that contribute to uncertainty in parameter values.