Distinguishing the multiple controls on the decreased sediment flux in the Jialing River basin of the Yangtze River, Southwestern China

Riverine sediment flux is a crucial proxy influencing channel morphology, biogeochemical processes, and riverine ecosystems. However, recent climate change and multiple anthropogenic activities have substantially altered the sediment regimes of the world’s rivers. On a basis of the “multiple double mass curves” method, this study selected the Jialing River (JR) basin as a case study to distinguish the relative impacts of climate change, land-use change, and damming on changes in the runoff and sediment flux over the past 60 years. The results showed that the sediment fluxes in the JR basin drastically decreased by 57–77% from the baseline period (1950s–1984) to the post-change period (1985–2017) mainly due to damming (60–75%), climate change (5–30%), and revegetation (10–20%). The runoff in the JR basin also exhibited a reduction (12–22%) likely because of the joint impacts of a reduction in precipitation and the restoration of vegetation. Although the 2008 Wenchuan Earthquake (M = 7.9) increased the short-term sediment fluxes, its impact on the long-term sediment fluxes in the downstream areas of the JR basin was limited as a result of the buffering effect of the thousands of constructed reservoirs. The decreased sediment fluxes in the JR basin benefit the life expectancy of the Three Gorges Reservoir (the world’s largest hydropower plant), but the reduced runoff can exacerbate water stress. The findings of our study have important implications for better management of water resources, sediment fluxes, and reservoir sedimentation not only for the JR basin, but also for the Three Gorges Reservoir.