HEC-22 Shallow Concentrated Flow

This equation is declared in Hydraulic Engineering Circular No. 22 (HEC-22) Urban Drainage Design Manual for computing the portion of travel time corresponding to a segment of overland flow with shallow concentration flow conditions.

T_c	Time of concentration (min)
V	Velocity of Shallow Conc. Flow (ft/s)
L	Flow length (ft)
k	Intercept coefficient (from HEC-22 Table 3-3)
S_p	Slope (%)