A Water Surface in Slide refers to either the Water Table (created with the Add Water Table option), or a Piezometric Line (created with the Add Piezometric Line option). When Water Surfaces are added to a model, they must be assigned to the desired materials, in order to be used in the analysis, to calculate pore pressure for the materials.
The Assign Water Surface option in the Properties menu, is an alternative method which can be used to assign water surfaces to materials. It will only be enabled if the Groundwater Method = Water Surfaces, in the Project Settings dialog.
It is important to note that this capability ALSO EXISTS in the Define Material Properties dialog. A water surface can be assigned to an individual material, by selecting from the list of Water Surfaces available for each material in the Define Material Properties dialog.
The Assign Water Surface option offers the convenience of allowing you to assign a selected Water Surface, to ALL the desired materials, at the same time.
By contrast, in the Define Material Properties dialog, this must be done individually for each material. This can be quite slow, if your model uses many materials.
The Assign Water Surface option can be used as follows:
When you initially add a Water Surface to your model (i.e. a Water Table or a Piezometric Line), the Assign Water Surface dialog will AUTOMATICALLY APPEAR, after you have added the boundary.
The title of the dialog will indicate the type of Water Surface you are assigning (i.e. it will indicate whether you are assigning the Water Table, or a Piezometric Line).
The dialog will list all of the material names, and the currently assigned Water Surface for each material (this will indicate None if no Water Surface is currently assigned to a material).
To assign the Water Surface, select the checkboxes for the desired materials, and select OK.
The Water Surface will now be assigned to all materials which were selected in the dialog.
You can verify the assignments by viewing the Define Material Properties dialog. The Water Surface assigned in the Define Material Properties dialog, to each material, will correspond to the selections that you made with the Assign Water Surface dialog.
The Assign Water Surface option can also be used at any later time, after Water Surfaces have been added to a model. To do this:
Select the Assign Water Surface option from the Properties menu.
Now select the desired Water Surface. This is done graphically with the mouse. Left click the mouse on the desired Water Surface, then right click and select Done Selection (or press Enter).
The Assign Water Surface dialog will appear. Use the dialog as described above, to assign the selected Water Surface to the desired materials.
Right Click Shortcut
If you right click the mouse directly ON a Water Surface (e.g. the Water Table), the popup menu which appears will provide a shortcut to the Assign Water Surface dialog.