Pre 2014 Blogs

Note:  Tributary Area to a Node in InfoSWMM

Here are the steps you neeed to take to calculate the tributary area of a node in InfoSWMM:

Step 1:  Use the DB Editor to get the total area in your model using the Data Statistics Tool.

Step 2:  Use the Process options in InfoSWMM to ONLY simulate surface runoff and flow routing.

Step 3. Copy the Node name and Total Inflow Volume from the Juntion Summary Output Table to Excel

Step 4:  Find the Total Wet Weather Flow during the simulation from the Wet Weather Inflow Row in the Flow Continuity Table.

Dry Weather Inflow   0.000  0.000

Wet Weather Inflow  0.782   0.255

Step 5. Make a new column in Excel to calculate the tributary area.

The Tributary Area of a Node = Total Inflow Volume / Total Wet Weather Flow * Total Subcatchment Area from Step 1.

You will now have the tributary area for each node.  You can verify this number = the total tributary area at the outfalls should equal the Total Subcatchment Area from Step 1.