Channel erosion dominates sediment sources in an agricultural catchment in the Upper Yangtze basin of China: Evidence from geochemical fingerprints

A sediment fingerprinting approach was applied to identify dominant sources in an area where soil conservation measures (i.e. terracing) had been carried out on steep, intensively cultivated lands but the outcome unknown. The wider purpose provide scientific evidence inform decisions erosion control and mitigation strategies could be further targeted. Geochemical fingerprints were used quantify contributions from three potential sources, i.e. surface under cropland woodland land use, channel banks, a managed small catchment Upper Yangtze River basin southwestern China. In parallel, artificial mixtures with known source proportions evaluated examine effects of grain size selection (<125 µm < 63 µm) accuracy modeled contributions. Source apportionment results suggest that materials originating incised actively eroding banks most important sediment, which contribute over 80% outlet. Sediment inputs (10–20%) (<10%) areas as result less important, since effective have implemented this catchment. Although sampled provided comparable for both coarser fine (<63 fractions, mixture indicated unmixing coarse fraction alone yield poor agreement between actual proportions. mean absolute error (MAE) ranged 8.8% 19.6%, 13.6%, compared values 4.0–7.4%, 5.2% fractions. study highlight bank constitute significant suspended exports heavily agricultural catchment, suggesting future works should focused drivers particular type. Herein, it is surmised reworking legacy valley fill deposits tempering downstream benefits (e.g. reduced siltation) recent upslope conservation, message policy makers. findings work also emphasize methodological need take account uncertainties associate apportionments when using specific particle fractions studies.