SonTek RS5 User Manual (August 2020) 56
Figure 26. Measured Areas Versus Top/Bottom Estimates
Discharge is calculated by summing the edge, measured, and estimated areas. Only
the measured area and edge estimates are measured by the acoustic Doppler profiler.
The top and bottom regions are determined using industry-standard calculations for
extrapolation.
The reasons for dividing the discharge calculation into components result from the
inherent limitations of all acoustic Doppler profilers, and include:
The profiler has a minimum operating depth. At depths lower than this minimum,
the water velocity and therefore the discharge must be estimated based on the
velocity and depth measurements on the edges. The Start and End Edges are
measured in this way.
The mounting depth plus a short distance (referred to as the blanking distance)
from the profiler to the start of the measured velocity profile leave a section of the
water at the surface unmeasured. This area is referred to as the Top Estimate.
Potential data contamination in the last cell (i.e., the cell is partially or fully
“touching” the riverbed), or potential side-lobe interference at the end of the
profile, leaves a section of water at the bottom unmeasured. This area is referred
to as the Bottom Estimate.
Summary of Contents for Sontek River Surveyor RS5
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