Time of Concentration - TR-55 Method

This command calculates the time of concentration (Tc) by the TR-55 method. Time of concentration is the time required for water to flow from the most distant point in the watershed to the measurement point.

The TR-55 method divides the flow into sheet, shallow concentrated and channel types, and Tc is computed by summing all the travel times for consecutive components of the drainage conveyance system. You can have any number of each of the three types of flow: Sheet, Shallow and Channel. For example, you could have two different channel flows in case you had two different types of channels in series. Use the Add button to add flows. You can add Sheet, Shallow and Channel flows individually or all together.

When adding a flow, the Select Flow Line From Screen function allow you to pick a 3D polyline and split it into segments of sheet, shallow and channel flow precisely. The Manning's n for the sheet and channel flow can be chosen from a table by clicking the Select button. Clear button will clear all fields in the dialog for entering new data.

TR-55 method report

Pulldown Menu Location: Watershed -> Time of Concentration > TR-55 Method
Keyboard Command: flowtc
Prerequisite: None