Driving Forces and Influences of Flood Diversion on Discharge Fraction and Peak Water Levels at an H-Shaped Compound River Node in the Pearl River Delta, South China

The SiXianJiao (SXJ) is the first-order exchange node of West River and North redistributes water (mass) to downstream river network in Pearl Delta (PRD), South China. lateral SXJ waterway plays a critical role flow diversion between River, forming unique H-shaped compound node. Previous studies mainly focused on Y-shaped bifurcation confluence nodes, there lack research deltaic nodes. This study established Delft3D model investigate driving forces influences flood at results showed that was usually hydraulic equilibrium but often disturbed by large level differences two rivers, due unbalanced asynchronous upstream waves. drove mutual through waterway, which synchronized discharge reduced peak levels (flood hazards), resulting similar or rivers. There exists fraction—about 75.9% (West River)—at incoming from both rivers presents node, little diversion. Above threshold, will divert with maximum rate −11,900 m3/s, accounting for 20% reducing up 1.48 m Makou. Below 11,990 55% 6.63 Sanshui. Meanwhile, fraction Makou (Sanshui) maintained near-constant value during individual floods fluctuated around 76.6% (23.4%). analytical approach are significance flood-risk management engineering design PRD. concept clearly elucidates mechanism via may work other nodes as well.