University College London
Geography

Healthy soils have many important functions (or ecosystem services) that are critical to human sustenance, such as air and water quality control, temperature regulation, carbon and nutrient cycling, and most importantly, provision of food, fibre and fuel. Soil erosion poses the greatest and the most widespread threat of disrupting one or more of these soil functions. Gully erosion, which is the formation of rapidly eroding networks of incised channels, represents the worst-case scenario as far as soil erosion is concerned. Once formed, gullies remove soil much more rapidly than it forms, and are very hard to manage, primarily because they effect topographic fragmentation of the affected land. Besides causing reduction in crop yields, gully erosion depletes landscape carbon storage, spoils downstream water quality and ecology and sometimes even directly endangers human lives and livelihoods, thwarting efforts to achieve up to nine of the 17 sustainable development goals.

However, despite its pervasive role in global land degradation, soil losses from gullies have so far only been estimated over small areas, likely due to the lack of reliable simulation models able to predict gully erosion rates. As such, no spatial account of global gully erosion exists to date, and even more worryingly, little is known about how (networks of) gullies evolve morphologically. Both these research gaps hinder the development of appropriate land management policy frameworks to mitigate the effects of gully erosion on sustainable development. Therefore, using machine learning and statistical modelling techniques, I aim to provide the very first global spatial quantification of gullying-driven soil losses, and to develop user-friendly novel empirical models capable of predicting gully evolutionary dynamics.

By revealing hotspots of gullying-driven soil loss, the global gully erosion map will help policymakers identify regions in need of land management attention. On the other hand, the developed empirical models will serve as useful tools for land managers by helping them predict gully dynamics and devise management plans accordingly. Furthermore, results of this project will be instrumental in further research on the impact of gully erosion on agricultural productivity and water quality, safeguarding which are central to sustainable development.