1 Incorporating rainfall and drying sequences into erodibility assessment

Short-term changes of soil condition are one of the major obstacles to effective dynamic event-based erosion prediction. However, effective process-based erosion modelling is essential to 1) predict the impact of changing environmental conditions without long-term monitoring, 2) simulate extreme events, and 3) assess the off-site effects of low magnitude events. The poor performance of process-based erosion models is largely attributed to a lack of integration of the short-term (minutes to days) interaction between climate and soil resistance to erosion (erodibility). Erodibility comprises the effects of surface roughness, resistance to detachment, entrainment, and transport on erosion. During a growing season, erodibility of agricultural soil changes both within and between storms, reflecting the effects of wetting, seal formation, compaction, erosion, and drying on soil moisture, soil structure, and surface morphology. Due to the complex nature of short-term soil-climate interaction, no physical model to assess erodibility has been developed, and is unlikely to be available for practical purposes in the forseeable future. In this study, process-based analysis of erodibility dynamics during contrasting rainfal