The primary indicator, perhaps, for differentiating process-based from other types of erosion models is the use of the sediment continuity equation discussed below.
Empirical models relate management and environmental factors directly to soil loss and/or sedimentary yields through statistical relationships.
[8] However, determining the P factor has proven to be challenging as there is usually a lack of geospatial information on the specific soil conservation practices in a given region.
Thus, to estimate the P factor value in the RUSLE formula, a combination of land use type and slope gradient is often used, where a lower value indicates more effective control of soil erosion.
[9] Creating field boundaries, such as stone walls, hedgerows, earth banks, and lynchets, effectively prevented or reduced soil erosion in pre-industrial agriculture.
[10] Recently, a novel P-factor model for Europe has been developed from the data retrieved during a statistical survey that recorded the occurrence of stone walls and grass margins in EU countries.
Starting from the assumptions that the construction of field boundaries has always represented an effective method to limit soil erosion and that the efficiency of any conservation measures to mitigate soil erosion increases with the increasing of the slope, a new P factor equation has been developed integrating the HLC within the RUSLE model.