Spatial patterns of sediment mobilization and its drivers in the Congo Basin

Soil erosion is a serious environmental issue that is a major threat to global soil resources and substantially contributes to crop yield reduction (1). Moreover, tropical soils are estimated to contain approximately one-third of global soil organic carbon (SOC), which is the largest terrestrial store of OC, bigger than the atmosphere and the vegetation combined (2). Thus, accelerated soil erosion following the degradation of natural habitats, such as the conversion of forests into cropland, has a strong influence on the global carbon cycle. A prime example of these issues and consequences is the Congo Basin (CB), which contains the second-largest tropical forest in the world and is currently experiencing an explosive demographic expansion, leading to drastic land use and land cover changes (LULCC), such as deforestation and cropland expansion. Nevertheless, it is one of the least studied major river basins on Earth (3) and thus the precise impact of these LULCC and other factors on erosion in the CB is not well defined. To address this lack of knowledge, we modeled erosion in 101 watersheds of the CB and used remote sensing techniques in conjunction with field observations and preexisting datasets describing potential drivers such as Worldpop (4), the Hansen global deforestation dataset (5), etc. We analyzed the spatial patterns of sediment mobilization and its drivers within the CB at high spatial resolutions. Five factors have been proven to have a significant impact on erosion in the CB: rainfall erosivity, elevation variation, topographical roughness, NDVI, and population density. In conclusion, anthropogenic activities are definitely accelerating erosion in the CB and should be monitored to avoid losing precious environmental services. REFERENCES 1. Amundson, R. et al. (2015). Soil and human security in the 21st century. Science, 348(6235). https://doi.org/10.1126/SCIENCE.1261071 2. Hunter, B. D., Roering, J. J., Silva, L. C. R., & Moreland, K. C. (2024). Geomorphic controls on the abundance and persistence of soil organic carbon pools in erosional landscapes. Nature Geoscience 2024 17:2, 17(2), 151–157. https://doi.org/10.1038/s41561-023-01365-2 3. Alsdorf, D. et al. (2016). Opportunities for hydrologic research in the Congo Basin. Reviews of Geophysics, 54(2), 378–409. https://doi.org/10.1002/2016RG000517 4. Lloyd, C. T. et al. (2019). Global spatio-temporally harmonised datasets for producing high-resolution gridded population distribution datasets. Big Earth Data, 3(2), 108–139. https://doi.org/10.1080/20964471.2019.1625151 5. Hansen, M. C. et al. (2013). High-Resolution Global Maps of 21st-Century Forest Cover Change. Science, 342(6160), 850–853. https://doi.org/10.1126/science.1244693