New discharge regime of the Huanghe (Yellow River): Causes and implications

• Flux, component and seasonality of Huanghe material to the sea have changed.
• Causes and implications of the new discharge regime are analyzed.
• Changes in Huanghe discharge regime are dominantly-driven by human activity.
• Transport and fate of fluvial Huanghe sediments change.
• The salinity, Si:N:P and primary production of Bohai seawater also change.

This research examines changes in the Huanghe discharge regime over the past 60 years, and their multiple implications to the coastal environment. The results reveal that the Huanghe has been reverted from the pristine state of monsoonal nature, to a highly human-regulated hydrologic system. The new discharge regime of the Huanghe is featured with ~70% and ~90% reductions in water and sediment discharges to the sea, altered inter-annual distribution of runoff to the sea, decreasing amplitudes of flood peaks, ~66% loss in SSC (suspended sediment concentration) with coarsening particles, and dam-controlled “flood period”. The altered discharge regime is mainly a consequence of anthropogenic interventions including soil conservation in the Loess Plateau, increasing water consumption and the multiple dam effects. The new discharge regime has a series of geological and ecological implications to the coastal environment, reflected by shrinking delta plain, altered sediment dispersal mechanism, restricted plume extent near the river mouth, less sediment reaching the deeper shelf environment, changing fate of the fluvial sediments, and altered ecological environment in the Bohai sea. This study provides a context for our understanding in changes of riverborne material to the sea for human-altered river system and their impacts on the coastal environment.