Clicking the Subcatchment Data button on the Node Datawill bring up a dialog box with the following options: 

Laurenson's Runoff Routing Module (LRRM)

Up to two sub-areas may be defined at each node. When a sub-area is selected a local flow will be calculated using the Laurenson's runoff routing procedure. Each sub-area is treated independently and may have separately defined runoff characteristics. The sum of the local flows at the node will be added to any upstream flows to provide the total input to the top of the link or the input to a storage basin.

The second sub-area is activated by clicking in the check box adjacent to the second sub-catchment button. Data may then be entered for this sub-area. When you exit from the sub-area dialog an 'X' in the check box will indicate that this sub-area is active. If you wish to turn the sub-area off you may click in the check box to disable that sub-area. Note that none of the underlying data is lost when doing this, it is simply not used in the analysis. This data may be re-activated by clicking again in the check box.