Drainage Design Manual, Hydrology - Flood Control District of ...

Drainage Design Manual for Maricopa County
Hydrology: Application
Using the above procedure, the K b for each of the Clark subbasins is as follows:
Subbasin
ID
Drainage
Area acres
Percent
Natural
. -- K b .
Percent
Developed Natural Developed Weighted
S2 2816.8 57.76 42.24 0.064 0.018 0.045
S3 2113.3 3.76 96.24 0.067 0.017 0.019
S4 1514.1 0.00 100.00 --- 0.020 0.020
S5 690.8 21.91 78.09 0.079 0.022 0.035
S6 675.0 18.19 81.81 0.079 0.022 0.033
S7 755.7 30.06 69.94 0.078 0.022 0.039
S8 613.2 30.55 69.45 0.080 0.023 0.040
S9 529.0 20.08 79.92 0.082 0.023 0.035
S10 284.2 0.00 100.00 --- 0.025 0.025
S11 1164.9 81.83 18.17 0.073 0.021 0.064
c. Compute Time of Concentration (T c ) as a function of Intensity (i) using Equation (5.5)
Subbasin S2:
T c 11.4L 0.5 0.52 – 0.31
= K b S i
–0.38
T c = ( 11.4) ( 4.11) 0.5 ( 0.045) 0.52 ( 224.5) 0.31
– –0.38
i
–0.38
T c = 0.860i
August 15, 2013 9-53