Shear Stress Comparison Using ADV Sontek FlowTracker and SonTek 10-MHz ADV

We compared shear stress values obtained from an ADV SonTek FlowTracker to shear stress values from a SonTek 10-MHz ADV in a range of natural streams with the D84 particle size ranging from 0.02 mm-80 mm. Our objective is to determine 1) a correlation between the two pieces of equipment, and 2) how this relationship changes with increasing particle size. Our hypothesis is that with increasing particle size the 10-MHz ADV will result in higher shear stress values than those obtained from the FlowTracker. This result is expected due to the higher roughness heights found in streams with larger particles sizes. The SonTek 10-MHz ADV is able to measure closer to the benthic layer than the ADV Sontek FlowTracker. The SonTek 10-MHz ADV, while capable of measuring closer to the stream bottom, is cumbersome to use compared to the Sontek FlowTracker. The results of these data can be used to adjust shear stress values obtained from the less precise Sontek FlowTracker.