Driving forces and their contribution to the recent decrease in sediment flux to ocean of major rivers in China.

Area of Science:

• Earth and Environmental Sciences
• Hydrology
• Riverine Geomorphology

Background:

• Land-ocean sediment transport is vital for managing water and soil resources.
• Understanding sediment flux dynamics is critical for sustainable resource management.

Purpose of the Study:

• Investigate temporal trends and historical phases of sediment flux in nine major Chinese rivers.
• Quantify anthropogenic and natural drivers of sediment flux changes.
• Analyze the impact of reservoirs and soil conservation on sediment delivery.

Main Methods:

• Analysis of sediment flux data over six decades (1954-2016).
• Application of the Sediment Identity approach to determine causes of sediment load reduction.
• Statistical analysis of temporal trends and driving forces.

Main Results:

• Significant decline in sediment flux from 1.92 Gt/yr (1954-1968) to 0.335 Gt/yr (2000-2016).
• ~95% of the decrease attributed to reduced sediment concentration.
• Reservoir construction was the primary driver before 1999; soil conservation became significant (~40% of decrease) after 1999.

Conclusions:

• Intensifying human activities will likely continue to decrease sediment flux.
• Future reductions pose challenges for drainage basin and river delta management.
• Effective management strategies are needed to address altered sediment dynamics.