To answer geomorphological questions at unprecedented spatial and temporal scales, we need to (a) parse terabyte-scale datasets (DEMs), (b) perform millions of model realizations to pinpoint the parameters which govern landscape evolution, and (c) do so with statistical rigor, which may require thousands of additional realizations. A core set of operations underpin many geomorphic models. These include determination of terrain attributes such as slope and curvature; flow routing; depression flooding and breaching; flat resolution; and flow accumulation. Here, I present RichDEM, a high-performance C++ library and set of wrappers for performing these operations. The library incorporates a number of options for performing each operation and makes full use of modern high-performance capabilities. The library can scale to process DEMs of over one trillion cells and operates effectively on laptops or supercomputers.