Chapter 3. Elements of an Aquifer Simulation Previous Page Next Page

3.1 The Aquifer

Although, an aquifer is usually a continuous body with the porosity conductivity varying as such; it is necessary to represent an aquifer in discreet terms for BUGS SCRATCHPAD to understand it. BUGS SCRATCHPAD divides the aquifer into discrete elements or cells. It assumes the material properties and concentrations are assumed to be constant throughout each element, but are allowed to differ between separate elements. In this way the program represents a non-homogeneous aquifer as a collection of different homogeneous regions.

BUGS SCRATCHPAD can simulate one and two dimensional aquifers. The coordinate system is limited to the Cartesian coordinate system. Elements are rectangles and are node centered. Node centered means the element is defined by a node which is located at the center of the element. Figure 3.1 depicts a "5 X 4" aquifer mesh.

Figure 3.1 Illustration of a 5 x 4 Aquifer Mesh

Element boundaries reside halfway between nodes. Width of boundary elements equal the distance between the boundary node and its neighbor. If a node lies on an aquifer boundary, it is assumed to be a no-flow, no-flux boundary unless otherwise modified by the user.

The amount of data required to properly represent an aquifer at minimum is the number of nodes in both the X and Y dimensions, and their coordinates.

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Last Updated October 1, 2001