Extending the RUSLE with the Monte Carlo error propagation technique to predict long-term average off-site sediment accumulation

ABSTRACT:

To evaluate if the adaptation of the basically two-dimensional Revised Universal Soil Loss Equation (RUSLE) to a three-dimensional reality is appropriate far predicting off-site sediment accumulation, it was extended with the Monte Carlo error propagation technique. This technique generates the true probability distribution of model output and gives the possibility to explain whether the difference between the model output and the field observations is largely due to the uncertainty of the model input or is mainly due to the uncertainty and limitations of the model itself. It was found that the RUSLE was able to accurately predict off-site sediment accumulation in the water reservoir of a study area. The value of the measured sediment input was within the 68% confidence interval around the predicted value, with a difference of only 1.4%. Therefore, the error propagation explained this difference as mainly due to the uncertainty of the model input parameters. Consequently it can be concluded that the topographic factor of the RUSLE model also can be considered as a measure of the sediment transport capacity of the overland flow, although it was originally developed far situations where detachment limits the sediment load.