RichDEM is a set of digital elevation model (DEM) hydrologic analysis tools. RichDEM uses parallel processing and state of the art algorithms to quickly process even very large DEMs.
RichDEM offers a variety of flow metrics, such as D8 and D∞. It can flood or breach depressions. It can calculate flow accumulation, slops, curvatures, &c.
RichDEM is available as a performant C++ library, a low-dependency Python package, and a set of command-line tools.
Please cite RichDEM (see below).