Phase change in evolution of the modern Huanghe (Yellow River) Delta: Process, pattern, and mechanisms

The modern Huanghe Delta used to be the most rapid land-building delta in the world. Its evolution has become a global concern because the sediment load of the Huanghe has decreased sharply in recent decades. However, few studies have revealed the full picture of Huanghe Delta evolution because of a lack of systematic bathymetric data off the delta. This study used 21 years of bathymetric data off the Huanghe Delta in combination with 34 scenes of Landsat imagery to study spatiotemporal evolution of the delta since 1976. Results indicate that the active lobe had an evolution distinct from the abandoned lobe. The temporal evolution of the active lobe had a four-phase pattern in both subaerial and subaqueous deltas, with different relationships with sediment load. In addition to sediment load, evolution of the active lobe was largely controlled by hydrodynamic-morphologic interactions and grain size of the Huanghe sediment. The abandoned lobe had a three-phase erosion since 1976 when the sediment supply from the river was cut off. A change in sediment dispersals might have dominated the evolution of the abandoned lobe. A newly assessed budget of the Huanghe sediment indicates that similar to 70% of the sediment load accumulated in the Huanghe Delta, which is much more than that estimated based on Pb-210-derived sedimentation rates or numerical studies. The present study comprehensively reveals the evolution of the modern Huanghe Delta and presents a typical example of the evolution of a large-river delta in response to global change.