To define the distributed loading due to Ponded Water (e.g. impounded water against a slope or dam), a specialized option is provided, the Add Ponded Water Load option. This allows you to easily define hydrostatic loading due to Ponded Water by specifying total head boundary conditions on user-selected boundary segments.
Ponded water
Weight of ponded water modeled as an equivalent distributed load
To use this option:
Select Add Ponded
Water Load 
from the toolbar or the Distributed
Loads sub-menu of the Loading
menu.
You will see the Add Ponded Water Load dialog. In this dialog:
Enter a value of Total Head. This value should be numerically equal to the y-coordinate of the water level you are modeling.
The load Orientation for a Ponded Water Load is always Normal to boundary (this cannot be changed).
In a multi-stage model, the water level can be changed at different stages, by selecting the Stage Load checkbox (see below for details about staging).
Select OK in the dialog, and you will be prompted to select the boundary line segment(s) on which to apply the load. In most cases you will be applying a Ponded Water load to segments of the External boundary.
NOTE: in order to define the exact intersection point of the water level with the External boundary, you may need to add a vertex to the boundary. See the note below about Ponded Water location.
When finished selecting, press Enter or right-click and select Done Selection. The Ponded Water Load will be applied to all selected segment(s). Phase2 will automatically create a series of distributed loads on the boundary which are equivalent to the hydrostatic force of the ponded water, as indicated by the display of blue arrows and the magnitudes.
Ponded Water Load Magnitude
When a Ponded Water Load has been added to a model, the load magnitude is defined in terms of the equivalent distributed load values (i.e. force per unit area), applied normal to the boundary. The values of the equivalent load magnitude are derived from:
the value of Total Head (entered in the Add Ponded Water Load dialog)
the elevation of each boundary vertex (relative to the water level)
the value of the Pore Fluid Unit Weight entered in the Project Settings dialog.
Ponded Water Location
Here are some important points to remember when defining Ponded Water Loads.
Adding vertices at the water level
In order to precisely locate the intersection point of the water level with the model boundaries, you should add a vertex at the exact intersection point (i.e. at the y-coordinate corresponding to the Total Head value). This will ensure that the distributed load magnitude is correct (i.e. zero) at that location. If there is no vertex at the water level, then the magnitude and location of the load may be slightly incorrect at that point (i.e. the end of the load will correspond to the nearest mesh node, which may not be located at the water level).
Boundaries
In most cases you will be applying a Ponded Water load to segments of the External boundary. However, you can apply a Ponded Water load to Excavation, Material or Stage boundaries, if the material above the boundary has been excavated (i.e. the boundary represents the current ground surface). This allows you to model a surface excavation which is later filled with water.
Staging Ponded Water Loads
On a multi-stage model, Ponded Water loads can be staged by selecting the Stage Load checkbox in the Add Ponded Water Load dialog (Step 2 above), and selecting the Stage Total Head button. You will see the Stage Total Head dialog, in which you can enter a value of Total Head at each stage.
NOTE:
If you are staging a Ponded Water Load, you should add a boundary vertex (as necessary) corresponding to EACH water level, so that the load is accurately applied to the correct boundary segments at each stage.
If you are staging a Ponded Water Load, and the water level is being RAISED as staging progresses, then in Step 3 (above) you must remember to select ALL segments up to the MAXIMUM water level, so that the water level can rise to the desired level. (If you only select segments corresponding to the lowest water level, then the increasing load will only be applied on those segments).
Ponded Water Loads and Total Head Seepage Boundary Conditions
It is important to note that defining a Ponded Water Load does NOT define the Total Head conditions for a finite element groundwater seepage analysis. This must be done independently with the Set Boundary Conditions option in the Groundwater menu.
And conversely, defining the Total Head boundary conditions for a finite element seepage analysis, does NOT automatically define the loading due to the weight of the Ponded Water. The weight of the Ponded water can only be defined with the Add Ponded Water Load option, as described above.