The Hydrological Simulation Program–FORTRAN (HSPF) is a set of computer codes that can simulate the nonpoint source polluant loads, hydrology, and associated aggreagate water quality, based on describing processes on pervious and impervious land surfaces, streams and well-mixed impoundments. The manual discusses the structure of the modeling system and presents detailed discussion of the algorithms used to simulate various water quantity and quality processes. It also contains all of the information necessary to develop input files for applying the program, including descriptions of program options, parameter definitions, and detailed input formatting data. Version 11 includes documentation of all corrections and enhancements of HSPF through December 1995, including forest nitrogen, yield-based plant uptake, stream bed large increase in the maximum number of operations, and major improvements designed to facilitate software maintenance and enhancement.
Bicknell, B. R., Imhoff, J. C., Kittle Jr, J. L., Donigian Jr, A. S., & Johanson, R. C. (1996). Hydrological simulation program-FORTRAN. User’s manual for release 11. US EPA.