Table 1 Definition of symbols:

Q = discharge in m3/sec A = channel area (m2)
R = hydraulic radius = A/P where P = wetted perimeter (m) S = slope (m/m)
n = Manning’s roughness C = weir constant (1.7 for high head condition)
B = width of weir (m) H = head (m)
ω = unit stream power (kg m-1 s-1) ωc = critical stream power
Y = mean depth of flow (m) D = median diameter of boulders (m)