6.4.1 Basic Flow Equations

The outflow hydrograph at the downstream end is calculated using the following formula.

(24)
where:
(25)
(26)
(27)
(28)
(29)

where:
Q = discharge
K = travel time in seconds
x = weighting factor, 0 <= x <= 0.5
∆x = subreach length
∆t = time interval
q = lateral flow
c = wave celerity

The parameters of K and x are expressed as follows (Cunge, 1969 and Ponce, 1978):
(30)

(31)

where:
B = top width
S = the channel slope.