Gully erosion might become a larger problem than hitherto anticipated: insights from fieldwork and recent modelling advancements

Abstract

Gully erosion has long been recognized as an important driver of soil loss and land degradation. However, modeling this process—particularly at larger spatial scales—remains challenging. While recent advancements have significantly improved our ability to simulate the spatial patterns of gully occurrence, understanding their activity and the factors controlling their erosion rates remains a much greater challenge. Similarly, the broader impacts of gullies across diverse environments are still poorly understood and under-researched.This talk highlights recent progress in modeling gully erosion from regional to global scales. We demonstrate that gully occurrence and activity are governed by distinct yet complementary sets of factors. For instance, land cover plays a dominant role in determining gully occurrence patterns across Africa, whereas activity rates are more strongly influenced by recent land use changes and rainfall intensities. These findings suggest that projected changes in climate and land use could result in far greater increases in gully erosion than predicted by models focusing solely on gully occurrence.Drawing on case studies from the Global South, we further explore some of the severe and often unconsidered impacts of gully erosion. Key examples include significant crop yield losses due to altered cropping practices and the emergence of highly destructive gullies in urban environments. Notably, many of these impacts are concentrated in regions that are already highly vulnerable to environmental change.Taken together, these insights suggest that the challenges posed by gully erosion in our changing world may be far greater than previously anticipated. Nonetheless, our findings also highlight that effective land management practices can mitigate or even prevent many of these issues.