Abstract: Background Identifying sediment sources in check-dam–controlled catchments was essential for elucidating soil erosion and sediment transport processes and for informing soil and water conservation measures. Methods This study examined the Wanshenglong check dam in the Ten Tributaries and considered forest, grassland, cropland, and bare land as potential sediment sources. A composite fingerprinting approach was applied to quantify the provenance of deposited sediment. Results The analysis identified Fe₂O₃, P, and χlf as the optimal set of fingerprint tracers. Classification accuracy reached 83.3 %, and the mean goodness-of-fit (GOF) was 0.89, indicating robust model performance. Bare land contributed the largest proportion of the sediment (76.89 %; unit-area yield ratio, 4.05), with cropland second (14.80 %; unit-area yield ratio, 14.51). Forest (5.41 %; unit-area yield ratio, 5.30) and grassland (2.90 %; unit-area yield ratio, 0.04) contributed smaller proportions. Across sedimentary cycles, extreme precipitation increased deposit thickness and coarsened the grain size. The forest contribution rose, suggesting a weakening of its soil-conservation function under extreme rainfall. Conclusion Bare land and cropland were the main sediment sources, with bare land contributing the most overall and cropland having the highest unit-area yield. Forest and grassland contributed to soil and water conservation. These findings underscored the importance of cropland-to-forest conversion and grassland restoration for strengthening catchment-scale conservation. Under a regime of potentially more frequent extreme precipitation, greater attention to forest conservation functions could enhance the system’s resilience to disturbance.