Changjiang Delta in the Anthropocene: Multi-scale hydro-morphodynamics and management challenges

The Changjiang Delta (CD) is one of well-studied large deltas critical socio-economical and ecological importance regionally global representativeness. Cumulated field data numerical modeling has facilitated scientific understanding its hydro-morphodynamics at multiple spatial time scales, but the changing boundary forcing conditions increasing anthropogenic influences pose management challenges requiring integrated knowledge. Here we provide a comprehensive synthesis multi-scale deltaic hydro-morphodynamics, discuss their relevance perspectives in context, identify knowledge gaps for future study. CD classified as river-tide mixed-energy, muddy highly turbid, fluvio-deltaic composite system involving large-scale land-ocean interacted processes. Its hydro-morphodynamic evolution exhibits profound temporal variations fortnightly, seasonal, inter-annual strong variability between tidal river estuary, different distributary channels. As river-borne sediment declined >70%, morphodynamic adaptation lags behind decline because redistribution within delta emerges to play role sustaining flat accretion. However, channels have become narrower, deepened growingly constrained under cumulated human activities, e.g., extensive embankment construction jetties groins, possibly initiating decrease activities trapping efficiency. Overall, undergoes transitions from net sedimentation naturally slow erosion human-driven radical adjustment. A shift priority development ecosystem conservation provides an opportunity restoring resilience flooding hazards. lessons identified inform study worldwide estuaries undergoing intensified interferences.