Shear velocity and roughness Reynolds number for unobstructed flows that differed in free-stream velocity
U (cm s-1)
.
u* (cm s-1)
.
Re*
.
1.5
0.14
1.1
5
0.22
1.8
10
0.52
4.1
15
0.71
5.7
U (cm s-1)
.
u* (cm s-1)
.
Re*
.
1.5
0.14
1.1
5
0.22
1.8
10
0.52
4.1
15
0.71
5.7
Determination of hydraulic roughness (z0) by regression of ln(z) against velocity yielded an r2>0.95 in all four conditions; where u* is shear velocity, Re* is the Reynolds number and U is free-stream velocity.