Pre 2014 Blogs

Surcharging occurs in SWMM 5 when water rises above the crown of the highest conduit. The RPT file of SWMM 5 lists the surcharging in hours in the Node Surcharge Summary Table (Figure 1) using the definitions for surcharging shown in Figure 2. Figure 3 shows the relationship between the output columns of the table.

Node surcharging occurs at a node if:

1. The node cannot pond and the node depth is above the highest pipe crown elevation connected to the node, or

2. The node can pond and the node depth is above the highest pipe crown elevation connected to the node and

3. The node depth is below the full depth of the node.

Node Flooding occurs if the water surface elevation is at the rim or above the rim elevation of the node.

Figure 1: Node Surcharge Summary Table

Figure 2: Definition of Surcharging at a Node in SWMM 5.

Figure 3: The definition of the Height above Crown and Depth below Rim columns in the Node Surcharge Table.