“FaSTMECH (Flow and Sediment Transport with Morphological Evolution of Channels)” is a river flow / riverbed variation analysis solver developed by Dr. Jonathan Nelson of the U.S. Geological Survey (USGS). FaSTMECH employs a cylindrical coordinate system for its lattice system, and because of its flow / riverbed variation calculations under quasi-steady approximation, can perform calculations with extremely long timeframes. Furthermore, FaSTMECH implements a Habitat Calculator, enabling it to evaluate river ecosystems by using the obtained flow / riverbed variation calculation results.