Subject: SWMM 5 Arrow Direction Question
A question often asked is what happens to the flow in a SWMM 5 link if the downstream and upstream node names are entered in reverse. The flow will be exactly the same as if the nodes were entered in the right order but the flow in the link will be negative. As long as the inflow to the model is at the same node in both alternate models the node depth, the link upstream depths and upstream cross sectional areas will be the same. For example, the flow out of Nodes 80408A and 80408 will be the same but the flow out of 80408 will be negative and the flow out of 80408A will be positive.