The historical Universal Soil Loss Equation (USLE) is often adopted to predict

Concept

The Universal Soil Loss Equation (USLE) is an empirical model A = R·K·L·S·C·P. It is built from long-term field-plot data and estimates A, the soil loss averaged over many years, expressed as a mass of soil lost per unit area per year (for example, tonnes per hectare per year). It is a long-term average estimator, not a model of any single storm.

Application

Reading the equation against the question: A is defined as the average annual soil loss per unit area. So the quantity the USLE is adopted to predict is the annual soil loss in tonnes/ha. Each factor (rainfall erosivity R, soil erodibility K, slope-length and steepness L and S, cover-management C, and support practice P) feeds into that single output A.

Cross-check / Contrast

• Annual soil loss in tonnes/ha: this is the definition of the output A — long-term mean annual loss per unit area. This matches the USLE.

• Event-based soil erosion rates: a single-storm estimate is the job of the Modified USLE (MUSLE), which replaces the rainfall factor with a runoff term; the original USLE deliberately averages over years and cannot resolve a single event.

• Sedimentograph: this is a plot of sediment discharge against time at a catchment outlet, an output of routing/hydrograph models, not of the USLE.

• Land degradation Index: a composite indicator that aggregates many degradation processes; the USLE quantifies only erosional soil loss, not a broad degradation index.

Hence the USLE predicts the average annual soil loss in tonnes/ha.