The Time Of Concentration Calculator allows the Time of Concentration to be calculated for the Runoff Generation.


You can select various methods to calculate the amount of time. Click the following links for more information about these methods:

Some of the methods may not be available for your region. For more information, refer to the Regionalisation topic.

Some initial values on the calculator are populated based on the current Inflow:

  • Area - Based on the current inflow's Area.
  • Catchment Slope - Maximum slope derived from the Outline if a surface file is available. If no surface file is used, defaults to 1:200.
  • Catchment Length - The maximum distance between any two points on the outline of the area.
  • Runoff Coefficient - The Preliminary or Runoff Coefficient, depending on where the calculator is launched from. Defaults to 0 if it is not specified.

All of these values can be overwritten in the Calculator without affecting the values on the Inflow.