Farm Dam Observation Point Node
- Tom Roberts
- Juanita Moolman
- Jin Wang
The Farm Dam Observation Point node has been included in Source to enable backwards compatibility with older Source models built using the original Farm Dams plugin developed by SKM (Jacobs since 2013). This node is not required in later versions of Source where the Farm Dam node has been integrated into Source catchment model functionality.
The Observation Point node is most often used in a Source model in conjunction with (but not limited to) a Farm Dam node.
The functionality of the Observation Point node now can be accessed from Source without the ObservationPointNodeModel plugin.
Similar to the farm dam node, the Observation Point Node can be created by dragging the Observation Point icon 
 from the Node Palette in a Source schematic model or changing an existing node to the Observation Point node type in a Source catchment model.
Right-clicking on an Observation Point node will open the Feature Editor to configure this node (Figure 1).
The inflows into an Observation Point node come from two alternative Sources: (i) overflows from the upstream dam(s)/Observation Point node(s)/subcatchment(s) (ii) local inflow generated by the interstation area between the upstream dam(s)/Observation Point node(s)/subcatchment(s) and the downstream observation point. These interstation inflows are calculated on the basis of a reference timeseries (i.e. at a gauge) that can be scaled down/up. The scaling will reflect (a) the interstation catchment area relative to the reference catchment area and (b) the non-linearity of the relationship between the catchment area and flow.
The parameters include the Scaling Factor and a Reference Timeseries which can be configured as a Value, a Data Source or a Function.
The interstation inflows from an Observation Point node and its upstream flow will be summed and added together to the network flows.
Figure 1 Farm Dams Observation Point editor