Channel junctions

I'm a new SWMM user and have a very basic question. When joining two or more open channels at a junction, what is the standard practice for defining the node?

Thank You
Kenneth Cecil

Kenneth,

I follow a few simple rules:

1. Let the goals of your modeling determine the amount of detail (# of nodes) to include.

2. Add nodes where you need stage/surcharge/HGL information.

3. Add a node where there is a need to represent two distinct, adjacent open channel segments. What constitutes a distinct channel segment? See Rule 1 (generally, significant changes in channel slope, Manning's n or other channel geometry).

4. Add a node where there is a need to introduce a static flow input (or loss) or depth of flow.

The node invert will be the invert of the lowest channel and the ground elevation must be higher than the highest channel crown (= depth + offset), regardless of how many channels come together at a single "point". "Point" is in quotes because it may be practical to use a single node to represent several nearby channel confluences. This involves judgement based on Rule 1.

Hope this helps.
Don Waye
NVPDC