River regulation engineering is pivotal for harmonizing flood resilience,
ecological integrity, and navigation efficiency in large alluvial systems,
particularly under intensified hydrological stressors. The Yangtze River, Asia’s
largest fluvial network, has experienced altered hydro-sedimentary regimes and
exacerbated channel instability due to cascade reservoir operations, demanding
adaptive strategies to stabilize dynamic reaches. This study investigates
hydrodynamic and flow distribution responses to integrated regulation measures
in the Chizhou Reach—a vulnerable alluvial segment characterized by severe bank
erosion, sedimentation-induced flow imbalances, and constrained floodplains.
Using a 1:500/1:100 scaled hydraulic model validated under flood and low-flow
conditions, we assess synergistic effects of dredging, submerged dams, and
flow-regulating groynes. Here we show that dredging the Wanchuanzhou right
branch increases its flow diversion ratio by 1.71% (annual average flow) to
4.57% (bankfull flow), redistributing velocities (0.1–0.35 m/s reduction in
dredged zones) and mitigating sedimentation. Submerged dams modulate
cross-sectional flow areas: a –5 m crest dam in the Xinglongzhou right branch
reduces discharge by 23.5%, while a –2 m dam in the Changshazhou left branch
elevates the middle branch’s diversion ratio by 2.01%. Flow-regulating groynes
enhance right-branch inflows by 0.54–0.75% through hydrodynamic redirection,
balancing systemic flow partitioning. Contrasting prior studies focused on
isolated interventions, our results reveal that multi-project integration
addresses both localized instability and basin-scale hydraulic reconfiguration.
These findings underscore the necessity of holistic engineering frameworks to
mitigate cascading impacts in regulated rivers. By linking localized measures to
basin-scale hydraulic stability, this study advances strategies for sustainable
river management in sediment-laden, anthropogenically altered systems.