When a catchment node is created in a schematic, a window appears in which the user is required to select a number of options appropriate for the catchment. In addition to the name and label for the catchment, the user must select a river to which runoff from the catchment will be directed. One and only one river can be selected to direct runoff to for each catchment.
Once a river is selected, the text "Represents Headflow?" and associated toggle box will appear out of shadow, and the user can click this box if the runoff is to represent headflow to this river. The user can also choose a groundwater node to direct infiltration from the catchment to--selecting a groundwater node for infiltration, unlike runoff, is not required, though. Selecting a groundwater node to which to direct infiltration will modify the Soil Moisture model from that of a two soil layer formulation to one layer (see Overview of Catchment Calculation Methods).
Finally, if the catchment is to include irrigated areas, click on the box associated with "Includes Irrigated Areas?". If this box is clicked, a box requesting input of the Demand Priority will appear. Only if this box is selected will the window associated with inputting irrigation variables (such as irrigated fraction) appear for that catchment in the Data view.
The catchment node will then appear in the schematic view, along with an associated Runoff/Infiltration Link that connects the node to the indicated river and, if appropriate, to a groundwater node. If the catchment runoff was selected to represent headflow to the river, the link will terminate at the first node of the river.
Automatically created Runoff/Infiltration Links that do not represent headflow to the river can be moved to another location along the river if desired. If you try to move a Runoff/Infiltration Link that does represent headflow to a river, a dialog box will appear asking if you no longer want this catchment inflow to represent headflow to that river.
Runoff/Infiltration Links can also be created manually by using the drag-and-drop feature. The appropriate details for link will be set accordingly (in General Info).
When you go to the Data view and select, for the first time, from the data tree the created catchment, a dialog box will automatically appear requesting that you select the desired catchment simulation method (such as Rainfall Runoff, Irrigation Demand Only, or Soil Moisture Methods--see Overview of Catchment Calculation Methods).