What is FaSTMECH?

“FaSTMECH (Flow and Sediment Transport with Morphological Evolution of Channels)” is a quasi-steady two and three-dimensional river flow and morphodynamics solver developed by Dr. Jonathan Nelson of the U.S. Geological Survey (USGS). Because FaSTMECH is developed under the quasi-steady approximation, meaning that discharge varies, but unsteady terms are neglected in the equations of motion, the solver has no Courant condition and can perform spatially detailed calculations over relatively long time scales extremely quickly. The quasi-three-dimensional version also provides explicit estimates of primary and secondary flow vertical structure, so flow solutions are provided throughout the flow for complex habitat or particle tracking problems that require three-dimensional flow without the computational expense of a fully three-dimensional model.