Variation of material fluxes in a large heterogenic subtropical river: A combination of climate change and human damming influences

Abstract

Study regionThe West River, the main tributary of the Pearl River, China Study focusA hydrological model of the West River was successfully established and used to quantify the role of basin-wide spatiotemporal change of the impacts of climate change and human damming activities in the variation of material fluxes (water discharge and sediment load) at the river outlet at both interannual and seasonal time scales of the period from 1975 to 2017. New hydrological insights for the regionThe interannual variations of water discharge and sediment load were controlled by a single factor locally: runoff variation was positively correlated with the ENSO index (r = 0.56, p < 0.001) and the dams caused a 75.1% reduction of the annual sediment load in the post-dam period (2009–2017). Seasonally, climate change can alter the monthly water discharge by − 12–23% in the latter half of an abnormal year, while the dams caused a 4.6% reduction and a 12.4% increase in the summer and winter sediment load, respectively. There was a strong interaction between the two influencing factors seasonally, particularly during the wetter summer or drier winter, wherein the dominant driving mechanism in the monthly variation of material fluxes can switch. For the river basin, the impacts of climate change and dams are spatially variable. The basin-wide spatiotemporal change of the impacts of climate change and human damming activities can complicate the hydrological signal at the river outlet.