The headloss alternative editor allows you to define headloss properties for manhole, catch basin, and conduit elements. The following columns are available, depending on element type:

ID: Displays the unique identifier for each element in the alternative.

Label: Displays the label for each element in the alternative.

Absolute Headloss: Enter the desired value for headloss at the structure. This method ensures that the headloss across the structure will be equal to the value entered here regardless of the actual flows or geometry of the structure. This field is only used when the Headloss Method is set to Absolute.

Headloss Method: Select the method to be used to calculate the headlosses through the associated structure. The option chosen here determines which of the parameter fields will become available.

Flow-Headloss Curve: Specify the previously defined Flow-Headloss curve to be applied to the node, or create a new one by choosing the <Select...> option to access the Flow-Headloss Curves dialog.

Headloss Coefficient (Standard): Enter the headloss coefficient for the structure. The headloss across the structure will be equal to this number multiplied by the exit conduit velocity head. This field is only used when the Headloss Method is set to Standard.

Headloss Coefficient (Upstream): This field is only used when the Headloss Method is set to Generic. The Generic method computes the structure headloss by multiplying the velocity head of the exit pipe by the user-defined Headloss (Downstream) value and then subtracting the velocity head of the governing upstream pipe multiplied by thevalue entered in this field.

Headloss Coefficient (Downstream): This field is only used when the Headloss Method is set to Generic. The Generic method computes the structure headloss by multiplying the velocity head of the exit pipe by the value entered in this field and then subtracting the velocity head of the governing upstream pipe multiplied by the user-defined Headloss Coefficient (Upstream) value.

Entrance Loss Coefficient: Specify the loss coefficient for the entrance of the conduit.

Exit Loss Coefficient: Specify the headloss coefficient for the conduit exit.

Expansion Loss Coefficient: Specify the expansion loss coefficient for the current conduit.

Contraction Loss Coefficient: Specify the contraction loss coefficient for the current conduit.

Average Loss Coefficient: Coefficient for energy losses along the length of the conduit. For use with the SWMM engine only.