DETACHMENT IN A SIMULATED RILL

The effects of water and sediment inflow to the top of a 25 cm wide rill with a fine sand bed at 5% slope with no rainfall and no infiltration were determined by using a new laboratory apparatus called a rill simulator. A significant sediment feedback effect on the detachment by flow at the top of the flume was determined with data obtained from laser elevation scans. Observations of the detachment that occurred in the rill were thus comparable with those predicted by the detachment equation in the WEPP model (Foster et al., 1995). For low sediment inflow rates, the detachment equation could be adjusted to predict reasonable results of detachment in the rill, but parameter estimation (rill erodibility, critical shear stress, transport capacity) was difficult.

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