Comparison of Erodibility Parameters for Cohesive Streambank Soils between In Situ Jet Test Device and Laboratory Conduit Flume

Several methods have been developed to estimate critical shear stress tau(c) and the erodibility coefficient k(d) for cohesive stream banks/beds. This research compares estimates of these parameters between an in situ minijet device and a laboratory pressurized conduit flume. Estimates for tau(c) between the two devices for the same soils were in general agreement compared with k(d), especially for shear magnitudes greater than 5 Pa and consolidated soil with moisture contents greater than 20%. However, k(d) erodibility estimates between devices were significantly different. Operation of the minijet device applied a unique multiple-pressure setting (MPS) procedure that accounts for the change in soil properties with depth from the bank face. Both the minijet MPS approach and a conduit flume appeared to reduce the effect of surface subaerial process on erodibility parameter measurements, where tau(c) and k(d) estimates were more similar compared with single-pressure test estimates using the Blaisdell, iterative solution, and scour depth solution computational procedures. Findings suggest tau(c) and k(d) estimates are dependent on the device hydraulics, computational method, and soil properties. (C) 2021 American Society of Civil Engineers.

Automated summary

This study compares estimates of critical shear stress and erodibility coefficient for cohesive stream banks/beds between an in situ minijet device and a laboratory pressurized conduit flume. The results show that the estimates of critical shear stress are generally consistent between the two devices for the same soils, but there are significant differences in erodibility estimates. The minijet device's multiple-pressure setting method provides more accurate estimations by considering the change in soil properties with depth. Both the conduit flume and minijet device show promising results in reducing the influence of surface subaerial processes on erodibility parameter measurements.