A simple approach to soil loss prediction: a revised Morgan-Morgan-Finney model

A revised version of the Morgan-Morgan-Finney model for prediction of annua l soil loss by water is presented. Changes have been made to the way soil p article detachment by raindrop impact is simulated, which now takes account of plant canopy height and leaf drainage, and a component has been added f or soil particle detachment by flow. When tested against the same data set used to validate the original version at the erosion plot scale, prediction s made with the revised model gave slopes of a reduced major-axis regressio n line closer to 1.0 when compared with measured values. The coefficient of efficiency, for sites with measured runoff and soil loss, increased from 0 .54 to 0.65. When applied to a new data set for erosion plots in Denmark, S pain, Greece and Nepal, very high coefficients of efficiency of 0.94 for ru noff and 0.84 for soil loss were obtained. The revised version was applied to two small catchments by dividing them into land elements and routing ann ual runoff and sediment production over the land surface from one element t o another. The results indicate that, when used in this way, the model prov ides useful information on the source areas of sediment, sediment delivery to streams and annual sediment yield. (C) 2001 Elsevier Science B.V. All ri ghts reserved.