Abstract: Runoff and sediment processes at a basin scale, are an important research focus because of their role in providing regional water and soil resources, reshaping rivers and coastal landforms, and altering ecosystems. Using multivariate time series clustering and erosive rainfall analysis, this study presents a case study of Boluo hydrometric gauge in the Dongjiang River basin to explore variations of flow discharge and sediment load and their potential driving factors. The results indicated that: ① Forest coverage increased by more than 30% in the study area during 1980—2015 owing to large-scale afforestation activities. ② The flow discharge-sediment load relationship at the Boluo hydrometric gauge showed significant changes after 1987, primarily attributed to reservoir construction and operation, as well as afforestation activities. ③ Extreme weather events intensified rainfall erosivity beyond the sediment-yielding threshold, leading to a flow discharge-sediment load relationship that was similar in 2005—2006 to that in 1954—1987. These findings provide a scientific basis for studying the runoff-sediment relationship in the Dongjiang River basin and its response to global changes. They support climate change adaptation and the development of water and soil resources in the basin.