A Process-Based Soil Erosion Model for USDA-Water Erosion Prediction Project Technology

TLDR

The study develops a model to estimate water‑driven soil erosion on hillslopes for USDA erosion prediction technology. The model represents detachment, transport, and deposition using a steady‑state sediment continuity equation, with rill detachment driven by hydraulic shear stress exceeding critical shear stress and sediment load relative to transport capacity, and interrill erosion modeled as a function of rainfall intensity, residue cover, canopy cover, and soil erodibility.

Abstract

ABSTRACT Amodel was developed for estimating soil erosion by water on hillslopes for use in new USDA erosion prediction technology. Detachment, transport, and deposition processes were represented. The model uses a steady-state sediment continuity equation for predicting rill and interrill processes. Net detachment in rills is considered to occur when the hydraulic shear stress of flow exceeds the critical shear stress of the soil and when sediment load in a rill is less than the sediment transport capacity. Net deposition is calculated when the sediment load is greater than the transport capacity. Rill detachment rate is dependent upon the ratio of sediment load to transport capacity, rill erodibility, hydraulic shear stress, surface cover, below ground residue, and consolidation. Rill hydraulics are used to calculate shear stresses and a simplified transport equation, calibrated with the Yalin transport equation, is used to compute transport capacity in rills. Interrill erosion is represented as a function of rainfall intensity, residue cover, canopy cover, and interrill soil erodibility. The model has capabilities for estimating spatial distributions of net soil loss and is designed to accommodate spatial variability in topography, surface roughness, soil properties, hydrology, and land use conditions on hillslopes..