Simulation study on the dynamic rill erosion processes: model validation with laboratory experiments

A series of laboratory experiments were conducted to verify the simulation model for the dynamic process of rill erosion and evolution. The experiments focused on the validation of the dynamic processes of rill flow, the spatial variation of hydraulic parameters, the soil detachment, transport and deposition; the verification of temporal and spatial evolution of rill morphology, including rill width, flow epth, as well as the local slope gradients; and the validation of feedback effect of local rill morphology change as affected by erosion and deposition on rill flow. The soil material used was a sandy loam. Three slopes: 3%, 5% and 7% and 3 flow rates: 7.6, 11.4 and 15.2 L/min were used in the experiments. Numerical simulations were made on the same conditions as the experiments for different cases for the model verification. Simulated flow velocity values along the rills, sediment concentrations at the rill end were compared with those from the experiments. The results showed that the model prediction was consistent with the measured patterns of morphological changes as the rill evolved, which suggests that the model itself and the feedback loops in the model between erosion, bed morphological changes, and hydraulics were adequate to describe the trend and characteristics of rill erosion dynamics.