The Grid Spacing dialog box is used to specify the precise locations of grid lines. The Grid Spacing dialog box is displayed by selecting Grid|Specify Grid Lines... In PHAST models, the dialog box has three tabs labeled Columns, Rows, and Layers. In MODFLOW models, there are only two tabs: Columns and Rows. Each tab has a table with the positions of the relevant grid lines and an edit box that can be used to change the number of grid lines. The numbers in the tables represent the distance in the X', Y', or Z directions from the origin of the coordinate system. X' and Y' represent distances in a coordinate system aligned with the grid. If the grid angle is zero, X' = X and Y' = Y. The user can type new values in the table or copy them from a spreadsheet to the operating system clipboard and then paste them in the table. (Pressing the Ctrl and V keys simultaneously will paste the contents of the clipboard into the selected cell in the table and overwrite the existing contents.) The grid-line positions do not need to be in order; they will be sorted into the correct order when the user clicks on the OK button. The cells in the table can be dragged to different positions in the table by clicking-down in the area of the table where the row number is displayed and moving the mouse to a new position before releasing the mouse.
The easiest way to delete a particular grid line in this dialog box is to make the cell where it is specified blank. The grid line will be deleted when the OK button is clicked.
To add new grid lines, increase the number of nodes to the desired number. Each new grid line will be added at a position that is equal to the number in Default spacing further than the previous line in the grid. For example, if the last grid line is at 100 m and the default spacing is 20 m, the next new grid line will be at a position of 120 m.
This method can not be used with Footprint grids because the cell spacing is required to be uniform.
