Experimental Design of the Submerged Jet Erosion Test for a Soil Erodibility Evaluation

Soil erosion and soil degradation are critical concerns worldwide. Developing comprehensive techniques to assess soil erodibility is in direct response to the need for quantifying this characteristic. Soil erosion rate is commonly estimated by the excess shear stress, the amount of shear stress acting on a soil surface in excess of critical shear stress (τ_c), and conditioned by the erodibility coefficient (K_d). The submerged jet erosion test (JET) is a widely used technique to measure the excess shear stress parameters based upon the impinging jet theory. Recent studies, however, have shown that the JET result is highly dependent on test conditions and jet hydrodynamics. Therefore, this study seeks to investigate the effects of changing test conditions on soil erodibility. We designed a series of experiments using one type of soil and intended to record the resulting scour depth for a narrow range of impinging heights and nozzle velocities. The main objective of the study is to improve the JET methodology and to quantify the effect of variable test conditions. The scour depth was quantified using point gauge reading and photogrammetry technique. Data collected at set time intervals for a maximum of seven hours from the beginning of the JET test. The results demonstrate that current JET methods should be revisited to make them consistent and independent of the test conditions.