Parameters for estimating annual runoff and soil loss from agricultural lands in Rhodesia

Cumulative values of rainfall energy, momentum, and precipitation depth were investigated as predictors of annual soil loss and runoff from selected arable and grazing land field trial plots. Energy parameters were the most accurate predictors of soil loss from bare soils, explaining 96.4% of the variation in results from a clay loam and 80.0% from a sandy soil. However, little accuracy was lost by adopting the more practical precipitation depth parameters. There was little to choose between momentum, energy, and precipitation depth parameters as predictors of soil loss from the vegetated plots or as predictors of runoff from both bare and vegetated conditions. Consequently, precipitation depth parameters were selected as being the most practical for soil loss and runoff estimation under the conditions investigated. Percentage vegetal cover was shown to be an additional important variable on grassland.