History and Evolution of Watershed Modeling Derived from the Stanford Watershed Model

Watershed Modeling, or hydrologic simulation (sometimes termed rainfallrunoff modeling) began in the 1950s and 1960s with the advent of the digital computer. The Stanford Watershed Model (SWM) was one of the first such programs, developed to replace the tedious manual computations performed by hydrologists of that time, to predict streamflow, given observed precipitation (and other meteorological variables), at short time scales compared to conventional practice. Over the 40-year evolution of the SWM, it was transformed into its current embodiment as the U.S. EPA Hydrological Simulation Program FORTRAN (HSPF) within the U.S. EPA BASINS system.