Erosion-induced recovery CO2 sink offset the horizontal soil organic carbon removal at the basin scale

To improve soil carbon sequestration capacity, the full soil carbon cycle process needs to be understood and quantified. It is essential to evaluate whether water erosion acts as a net source or sink of atmospheric CO2 at the basin scale, which encompasses the entire hydrological process. This study introduced an approach that combined a spatially distributed sediment delivery model and biogeochemical model to estimate the lateral and vertical carbon fluxes by water erosion at the basin scale. Applying this coupling model to the Dongting Lake Basin, the results showed that the annual average amount of soil erosion during 1980–2020 was 1.33×108 t, displaying a decreasing trend followed by a slight increase. Only 12