Table 5 The characteristics of the upper stream network channel of Khanh waterfall

Width of channel (B)

m

3.00

Height of channel (H)

m

2.00

Left slope of channel (1:m1)

0.50

Right slope of channel (1:m2)

0.50

Roughness coefficient (n)

0.10

Slope gradient (l)

%

0.18

Peak flow (Q)

m³/s

181.5

α

0.80

Cross-sectional area (A)

m²

8.00

A = H{2B + (m1 + m2)H}/2

Wetted perimeter (P)

m

7.47

P = B + H{(1 + m1²)^1/2 + (1 + m2²)^1/2}

Hydraulic radius (R)

m

1.07

R = A/P

Allowable flow (Qmax)

m³/s

3.55

Qmax = I^1/2.R^2/3.A/n

Peak flow/allowable flow

51

Q/ Qmax