Technical Note: Drainage Density-Preserving River Network Delineation Algorithm

Accurate representation of drainage density in a river network delineation is crucial for large-domain hydrodynamic simulations, but existing digital elevation model (DEM)-based methods fail to preserve observed drainage density across the entire network. This study introduces a fundamentally improved DEM-based river network delineation method that preserves observed drainage density by incorporating a novel concept of upstream accumulation length, which integrates flow direction and drainage density. A test case demonstrated the method’s compatibility with widely used critical drainage area-based methods; they produced identical results when using the same drainage density. The method was then applied to the Chinese Mainland using the MERIT-Hydro flow direction dataset and a drainage density dataset from the Third National Land Resources Survey of China. The resulting dataset shows superior performance in capturing drainage density variations, particularly in regions with complex topography, compared to existing datasets. The method is promising for delineating more accurate river networks by combining satellite-derived or surveyed drainage density with DEMs, thereby laying a valuable foundation for large-domain hydrodynamic simulations in vast regions of the globe, where there is a lack of manually maintained river geometry datasets.