The HELP model (Hydrologic Evaluation of Landfill Performance) is a hydrologic numerical model initially developed by the United States Environmental Protection Agency for landfills. The model uses a water-balance approach to model evapotranspiration and drainage through soil layers.

Versions

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Public domain (free) version:

HELP 3.07 – DOS executable, as well as most of the Fortran source code and user manuals

Commercial versions:

WHI UnSat Suite – based on the HELP version 3.07 codebase, offers a Microsoft Windows GUI to view and edit soil profiles.

HELP 3.80D – Enhanced and "corrected" version by Dr. Klaus Berger at the University of Hamburg; based on HELP 3.07. Uses same DOS interface as the original.