Abstract: The lower river networks often connect the upstream and downstream of navigation routes,and the river flood discharges have to pass from the upstream to the river networks.This makes the research on the flow in lower river networks one of the most important and necessary researches.In this paper,the authors first review and summarize the methods for the river networks;then,apply the self established 1-D hydrodynamic program,namely hydrodynamic model for river networks,and the 1-D commercial software HEC-RAS...