Structural characteristics of river networks and their relations to basin factors in the Yangtze and Yellow River basins

The integration of rivers and basins highly implies the possible existence of certain relationships between hierarchical characteristics of river networks and primary basin factors. Here we investigated river networks in two large basins, the Yangtze River and the Yellow River, characterized with basic factors such as annual precipitation, slope, soil erodibility and vegetation. Hierarchical analysis demonstrated a fair self-similarity of river networks at the stream-order 1-5 in both rivers, described by the structural parameters including bifurcation ratio, side-branching ratio, drainage density, and length of headwater-river. Besides precipitation, basin slope was essential in shaping river networks in both basins, showing a significant positive correlation (R-2=0.39-0.85) to bifurcation ratio, side-branching ratio, and drainage density. Given the same basin slope (5 degrees-15 degrees), the higher soil erodibility and sparse vegetation would promote greater side-branching ratio and drainage density in the Yellow River, which were estimated 11.97 % and 63.70 % larger, respectively than those in the Yangtze River. This study highlights the importance to formulate basin-specific strategies for water and soil conservation in terms of different structures of river networks.