Study on the Evolution Trend of Diversion Pattern at the Bifurcated Upper Section of Southern Branch of Yangtze Estuary

In recent years, the trend of “Strong South and Weak North” has been increasingly prominent in the Baimao shoal forks at the entrance of the southern branch of the Yangtze Estuary. This has resulted in erosion in the southern waterway, posing a threat to the stability of the underwater bank slope. This study systematically examines the changes in the “Strong South and Weak North” pattern and its causes by analyzing the evolution and diversion ratio changes of the Baimao shoal forks. The research results suggest that the strengthened trend of the “Strong South and Weak North” pattern in the Baimao shoal forks is a manifesting in a certain stage during the periodic evolution of Baimao shoal inlets. The implementation of the 12.5 m Deep Channel Regulation Project (DCP) in 2014 has effectively controlled the erosion and retreat of the Baimao shoal, altering the periodic evolution mode of the river section and promoting the stability of the river regime. Under the existing water conditions, engineering conditions, and river regime conditions, the pattern change of “Strong South and Weak North” in the Baimao shoal forks is expected to gradually slow down.