ArcToolbox Tools¶
The schematic processor is implemented as two ArcToolbox geoprocessing tools:
- Assign Processing Order – Tags each feature with a number indicating its (upstream to downstream) processing order.
- Process Schematic Network – Processes each feature in the schematic network according to processing order and the behaviors that the user has assigned for each type of node and link feature.
Before running the schematic processor tools, you must create a schematic network. I recommend using the Arc Hydro tools to do this so that the links and nodes are created with the correct connectivity and the HydroID, FromNodeID, ToNodeID, SrcType, and LinkType fields are correctly populated. (Since the schematic processor was created to work with an Arc Hydro Schematic Network, it relies on the connectivity attributes associated with that approach.)
Once the network is created, you should calculate attributes on the nodes or links to represent whatever property you are modeling, such as amount of bacterial load. For example, you could populate a field representing mean annual load generated for watersheds represented by your network nodes. These values represent the starting condition of your system.
Once these fields are populated, use schematic processor to move these values through the network from upstream to downstream. If necessary, write your own processing ops in Python to simulate the phenomenon you are modeling.
A summary of the tools is provided below. For more details about each tool, please see the help documentation presented when you open the tool in ArcToolbox.
Assign Processing Order¶
This tool reads the HydroID, FromNodeID, and ToNodeID in links and nodes to determine processing order for the schematic processor. It assumes the network is dendritic and that flow occurs from nodes identified by FromNodeID to nodes identified by ToNodeID. The result is saved to a field called SortOrder in the node and link feature classes. The field is added if it does not already exist.
Process Schematic Network¶
This tool processes the schematic network, applying behaviors to each type of link and node. In addition to fields prescribed by Arc Hydro and the SortOrder field, links and nodes must possess fields that represent incremental values, total values, and passed values. Incremental values describe the initial condition of the system and are used by the schematic processor to produce total values. The total values and passed values will be overwritten as the tool executes.
Tips¶
Some important things to remember when running these tools are:
- If you are using a selection set, make sure all upstream features are selected or else those features will not be processed.
- The names of processing ops provided to the schematic processor are case sensitive.