Troubleshooting Data Set Values

A data set or boundary condition will sometimes take on an unexpected or undesired value at a particular location. When this happens, ModelMuse provides the user with tools both to detect the problem and to understand why it has occurred. The following steps can be used to diagnose why a value is or is not assigned at a particular location.

1.First, the user can check that the column, row, and layer that are being examined are the intended ones. If the cursor is over the grid in the top view, the column and row at the cursor location will be displayed on the status bar. Placing the cursor over the Selection Cube will cause the selected layer to be displayed on the status bar. Similar information can be obtained from the front and side views.

2.Next the user can check what value is assigned to a cell and the explanation for how that value was assigned. To do this, the user first selects Data|Data Visualization|Color Grid... to show the Color Grid pane of the Data Visualization dialog box and colors the grid with the data set or feature of interest. Then the user selects Data|Show Grid or Mesh Values... to show the Grid or Mesh Value dialog box. Both the value and the explanation are shown in the Grid or Mesh Value dialog box.

3.If the value was assigned by the formula of the data set, the user can check the values of each of the other data sets referenced by the formula until one is found that has an unexpected value. If none of the referenced data sets has an unexpected value, the problem may be that the user does not understand exactly what the formula does. To understand the formula, the user can select Data|Edit Data Sets... to display the Data Sets dialog box. Next the user can select the data set of interest and click the Edit Formula... button to display the Formula Editor. The Formula diagram in the Formula Editor can be used to help understand how the formula works. If the formula makes use of any functions, the user can select those functions in the list of functions on the right and click the Function help button to display the documentation for the function.

4.If the data were assigned by interpolation, the problem may be that the user doesn't realize what interpolation method was used or how it works. To determine which interpolation method was used, the user can select Data|Edit Data Sets... to display the Data Sets dialog box. The interpolation method will be displayed. The user can then read the documentation for the selected interpolation method. In addition, the Show or Hide Objects dialog box can be used to show all the objects that set the value of the data set of interest by interpolation. The user can check the formulas for the data set for each of those objects.

5.If the data were assigned by PHAST-style interpolation, the user can select Data|Edit Data Sets... to display the Data Sets dialog box. The interpolation direction, values, and distances or mixture formula. More information about PHAST-style interpolation is available in this help file.

6.If the data were assigned by being enclosed or intersected by an object, the user can check if the object that was used to assign the value was the one that was intended. The user can also check exactly what it means to be enclosed or intersected by an object as documented on the help for the Properties tab of the Object Properties dialog box.

7.If the value was assigned by the wrong object, it could be because the value assigned by the desired object was overwritten by the value assigned by the other object. To check this, the user can first select the other object. The Select Object by Name dialog box may be helpful for this purpose. The user can then display the properties of the object that assigned the values to the data set in the Object Properties dialog box. The user can check the Object order for both the object that was intended to assign a value and the one that actually assigned the value. An object with a higher Object order can overwrite a value assigned by an object with a lower Object order. The Object order can be changed using the Rearrange Objects dialog box or by selecting an object, right clicking on the top, front, or side view, and choosing To Front, To Back, Forward One, or Back One.

8.If the value was assigned by the wrong object it could be because the desired object did not enclose or intersect the cell or element in the third dimension. The user can display the properties of the object in the Object Properties dialog box and check the number of third-dimension formulas and check that the formulas have the intended values. It can also be helpful to use the 3-D view to check that the object encloses or intersects the desired cell or element. To do this, hide all the other objects and then depress the Show 3-D objects button . Examining the other 2-D views can also be instructive. To do this, it is helpful to first set the color of the object in the Object Properties dialog box and then check the other views of the model to check that the object encloses or intersects the desired cell or element. The command Grid|Select Column, Row, or Layer can be helpful when checking a particular location. If the object does not enclose or intersect the desired cell or element in the third dimension and it isn't clear why not, it can be helpful to check the position of the object in the third dimension. To do this, the user creates one or more 2-D data sets. The default formulae for these data sets should be set to the same formulae used to assign the third dimension of the object of interest. The grid can then be colored with the new data set and individual values of cells at locations of interest should be checked. In objects with formulas for a higher and a lower third-dimension coordinate, the user may find that the formula that is intended to give the higher value actually gives a lower value. The Grid or Mesh Value dialog box can also be helpful in determining where an object is located in the third dimension. If only a single object is selected and the checkbox on the Grid or Mesh Value dialog box is checked, the position of the selected object in the third dimension will be displayed on the dialog box in cells enclosed or intersected by the object.

9.If the value of a boundary condition is being examined, the user can check the time for the boundary condition that is being used to color the grid in the Color Grid pane of the Data Visualization dialog box. Then the user can display the properties of the object in the Object Properties dialog box and check that the object assigns boundary conditions at the time that is being used to color the grid.

10.If a boundary condition is being examined, and no value is assigned to a cell or element by the desired object, check in the Object Properties dialog box that the object assigns values to either enclosed or intersected cells or elements.

11.For most boundary conditions, objects used to assign the boundary condition are normally 3-D objects. (The number of third-dimension formulas is one or two.) If a boundary condition is not being assigned properly, check that the object that should be assigning the boundary condition is a 3-D object. The PHAST river boundary is an exception to this rule.

12.In MODFLOW models, the user can check that the top of the cell is above the bottom of the cell.

13.In MODFLOW models, boundary conditions can not be assigned to cells in nonsimulated layers. The user can select Model|MODFLOW Layer Groups... to display the MODFLOW Layer Groups dialog box and check that the selected layer is part of a simulated layer group.

14.The user can select View|Errors and Warnings and see any errors or warnings that are related to the problem.