Page 408 - Planning and Design of Airports

Remarks = 0.015 n See accumulated runoff computed below. Accumulated runoff adjustment negligible.

Tributary Area A, acres 2.88 2.32 8.75 7.24 5.39 4.84

Rainfall Intensity I 3.10 3.15 2.80 2.70 2.65 2.60

Runoff Coefficient C 0.51 0.63 0.39 0.37 0.39 0.44

Time of Concentration, min 31.2 30.0 37.7 38.9 39.9 40.7 Calculation of Example Maximum flow from inlets 5 and 5A will reach inlet 4 in 31.6 and 33.0 min, respectively. All inlet 4 subarea will be contributing to the system only after 37.7 min. Flow from inlets 5 and 5A must be adjusted for 37.7-min time

Flow Time, min 1.8 1.6 1.1 1.0 0.8 0.5

Inlet Time, min 31.2 30.0 37.7 38.9 34.4 30.7

Length of Segment, ft 440 380 420 440 380 330 Flow from inlet 4 subarea = 9.56 Accumulated flow entering inlet 4 in 37.7 min = 17.90 ft 3 /s

Segment 1-outlet Applying these data in the formula Q = CIA: Adjusted flow from inlet 5 = 0.63 × 2.85 × 2.32 = 4.16 Adjusted flow from inlet 5A = 0.51 × 2.85 × 2.88 = 4.18 Flow into inlet 4 from inlets 5 and 5A in 37.7 min = 8.34

Line 5A-4 5-4 4-3 3-2 2-1

Inlet 5A 5 4 3 2 1 Outlet

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