Assessment of soil erosion models for predicting soil loss in cracked vegetated compacted surface layer

Rainfall-induced progressive soil erosion of compacted surface layer (SL) impedes the functioning of cover system (CS) of landfills with high expected design life (≈ 100 years). The existing soil erosion models are not tested extensively for compacted soil with cracks and vegetation. This study evaluated the efficacy of three popular soil erosion models for estimating the soil loss of compacted SL of CS, which is useful for annual maintenance. The interactive effect of rainfall, vegetation and desiccation cracks on erosion of compacted surface layer was investigated under the influence of both natural and simulated rainfall events for one year. Among all, the Morgan, Morgan and Finney (MMF) model was found to be effective in predicting soil erosion of compacted SL. However, the MMF model overestimated soil erosion when the vegetation cover exceeded 60%. The soil loss estimated from Revised Universal Soil Loss Equation (RUSLE) and Water Erosion Prediction Project (WEPP) models was poor for high rainfall intensity (100 mm/h). The RUSLE and WEPP model overestimated the soil erosion for low vegetation cover (≤ 3%) and underestimated for vegetation area > 3%. The mechanism of root reinforcement, strength due to root water uptake-induced soil suction and its effect on soil loss mitigation could not be adequately captured by the existing models for compacted SL. Further studies are needed to improve the existing erosion models for incorporating the effects of desiccation and vegetation on soil loss from the compacted SL.