Severe soil erosion during a 3-day exceptional rainfall event: combining modelling and field data for a fallow cereal field

Abstract

Exceptional rainfall events cause significant losses of soil, although few studies have addressed the validation of model predictions at field scale during severe erosive episodes. In this study, we evaluate the predictive ability of the enhanced Soil Erosion and Redistribution Tool (SERT-2014) model for mapping and quantifying soil erosion during the exceptional rainfall event (~235 mm) that affected the Central Spanish Pyrenees in October 2012. The capacity of the simulation model is evaluated in a fallow cereal field (1.9 ha) at a high spatial scale (1 × 1 m). Validation was performed with field-quantified rates of soil loss in the rills and ephemeral gullies and also with a detailed map of soil redistribution. The SERT-2014 model was run for the six rainfall sub-events that made up the exceptional event, simulating the different hydrological responses of soils with maximum runoff depths ranging between 40 and 1017 mm. Predicted average and maximum soil erosion was 11 and 117 Mg ha−1 event−1, respectively. Total soil loss and sediment yield to the La Reina gully amounted to 16.3 and 9.0 Mg event−1. These rates are in agreement with field estimations of soil loss of 20.0 Mg event−1. Most soil loss (86%) occurred during the first sub-event. Although soil accumulation was overestimated in the first sub-event because of the large amount of detached soil, the enhanced SERT-2014 model successfully predicted the different spatial patterns and values of soil redistribution for each sub-event. Further research should focus on stream transport capacity. Copyright © 2014 John Wiley & Sons, Ltd.