Systematic investigation of the hydrodynamic adaptive adjustment characteristics in the river network of the Pearl River Delta

The Pearl River Delta （PRD）， one of the world's most complex estuarine systems， serves as the backbone water network of the Guangdong-Hong Kong-Macao Greater Bay Area. While its hydrodynamics exhibit strong adaptive capacity to long-term water-sediment variations and morphological evolution， localized hydrodynamic anomalies emerged in the 1990 s due to intense human activities like sand mining. Previous research primarily focused on key nodal points， lacking a systematic characterization of the hydrodynamic adjustment across the entire network.This study employs an integrated approach combining graph theory-based topological analysis and hydrodynamic numerical modeling to reveal the physical morphological characteristics and dynamic connectivity of the PRD network， elucidating its adaptive adjustment mechanisms. Key findings indicate that the PRD's adaptive physical traits include increasing bifurcation density downstream， expanding cross-sectional flow areas， and enhanced network connectivity resilience. Its dynamic traits feature power-law growth in storage capacity and flow conveyance redundancy. Dynamic flow reversals in lateral branches under runoff restructure the network， while tidal cycles—especially low water levels and steep gradients—significantly amplify tidal channel discharge capacity， representing an adaptive mechanisms to runoff-tide dynamics. This study provides theoretical support for the systematic management and resilience regulation of the Pearl River Delta water network.