Global-scale river network extraction based on high-resolution topography and constrained by lithology, climate, slope, and observed drainage density

To improve the representation of surface and groundwater flows, global land surface models rely heavily on high-resolution digital elevation models (DEMs). River pixels are routinely defined as pixels with drainage areas that are greater than a critical drainage area (A(cr)). This parameter is usually uniform across the globe, and the dependence of drainage density on many environmental factors is often overlooked. Using the 15 HydroSHEDS DEM as an example, we propose the calibration of a spatially variable A(cr) as a function of slope, lithology, and climate, to match drainage densities from reference river networks at a 1:50,000 scale in France and Australia. Two variable A(cr) models with varying complexities were derived from the calibration, with satisfactory performances compared to the reference river networks. Intermittency assessment is also proposed. With these simple tools, river networks with natural heterogeneities at the 1:50,000 scale can be extracted from any DEM.