Hydrological simulation program: Fortran. User's manual for release 10

The Hydrological Simulation Program -- FORTRAN (HSPF) is a set of computer codes that can simulate the hydrologic, and associated water quality, processes on pervious and impervious land surfaces and in streams and well-mixed impoundments. The manual discusses the modular structure of the system, and presents a detailed discussion of the algorithms used to simulate various water quantity and quality processes. Data useful to those who need to install, maintain, or alter the system or who wish to examine its structure in greater detail are also presented.