Advancing river management under dam regulation: Insights from the Yellow River

Yellow River, China River deltas delivering immense economic value and ecosystem services. However, sediment starvation is accelerating land loss and shoreline retreat across worldwide mega-river deltas driven by climate stressors and human interventions. The Yellow River Delta (YRD) exemplifies these challenges. Implementation of the Water–Sediment Regulation Scheme (WSRS) in 2002 initially restored delta progradation, as reservoir releases and channel erosion increased sediment delivery before 2014. The study evaluated the effectiveness of the WSRS over the past two decades from multiple perspectives and explored an optimized regulation using a 3D numerical model. The WSRS has undergone a profound mechanistic shift. A high-efficiency phase (before 2014) has transitioned to a constrained phase (after 2018), marked by severe reservoir siltation, downstream channel armoring and limited delta progradation. The reduced delta progradation rate was controlled by multiple factors: a diminished supply of coarse sediment from the lower channel; intensified tidal currents due to the continuously protruding shoreline; an increased sediment coefficient promoting offshore dispersal; and more frequent typhoon events enhancing sediment redistribution. The river regime has transitioned from a natural to an anthropogenically controlled state, where reservoir operations dictate the water-sediment regime. Optimizing the reservoir regulation based on realistic conditions presents a significant opportunity to enhance the sediment trapping capacity of the delta, thereby promoting the sustainable development of the river-dominated delta. • The Water–Sediment Regulation Scheme impacts exhibited distinct phased variations. • The coupling of water, sediment, ocean and climate regulated delta evolution. • Optimized dam regulation was critical for water utilization and delta conservation.