Time of Concentration - Maricopa County, Arizona
This command calculates the time of concentration (Tc) by the
following equation developed by Papadakis and Kazan in Maricopa
County, AZ. This is due to the extent of imperviousness associated
with urban watersheds and to the fact that the time of
concentration is usually very short.
Tc =
11.4L0.5Kb0.52S-0.31i-0.38
where: Tc = time of concentration, in
hours
L = length of the longest flow path,
in miles
S = watercourse slope,
in feet/mile
Kb = watershed resistance coefficient, see
table taken from design manual
i
= rainfall intensity, in inches/hour
Select Maricopa County Method from Watershed > Time of
Concentration menu. In the dialog, specify the unit of area, flow
length and slope, and the basin surface type. The flow path data
can be obtained from picking a 3D polyline and the program
calculates the length and slope of the flow automatically. Click on
Calculate button to see the result.
Pulldown Menu Location: Watershed -> Time of
Concentration > Maricopa County Method
Keyboard Command: flowtc6
Prerequisite: None
