studied in the concentration measurements. Results of these measurements 
are shown in Figures 23, 24, 25, and 26, and are tabulated in the appen- 
dix, Table A-5. This relationship was valid for elevations of approxi- 
mately 0.04 foot above the crest of the bed dunes. The relationship below 
this elevation, which would be in the boundary layer, was not determined. 
The turbulent velocity fluctuation distribution was only measured for the 
single-bed roughness described in Section II. 
c. Based on the four turbulent velocity fluctuation distributions 
described above, it was concluded that the rate of turbulent velocity 
decay with elevation above the bed is independent of both the elevation 
and the flow velocity generating the turbulence. The exponential decay 
rate, determined from a least squares curve fitting of the data, for the 
four distributions ranged from -10.38 to -10.86 feet-1, with a mean of 
-10.57 feet™! and a variance of 0.05 foot 2. 
d. The relationship between the flow velocity and the root-mean- 
Square turbulent velocity fluctuation at zero elevation (calculated from 
the empirical relationships) is shown in Figure 27. A linear relation- 
ship is indicated. However, this relationship, which is far from con- 
clusive, is based on only four data points with a significant amount of 
scatter. The qualitative conclusion that the turbulence intensity at 
zero elevation becomes larger with greater flow velocities is not only 
indicated by the data but is logical. 
Ue) 
