RETC, Retention Curve Program for Unsaturated Soils, is a computer program for describing the hydraulic properties of unsaturated soils. RETC may be used to fit several analytical models to observed water retention and/or unsaturated hydraulic conductivity data. RETC incorporates menu-driven data entry. Features in RETC include: a direct evaluation of the hydraulic functions when the model parameters are known; a more flexible choice of hydraulic parameters to be included in the parameter optimization process; and the possibility of evaluating the model parameters from observed conductivity data rather than only from retention data or simultaneously from measured retention and hydraulic conductivity data.
This model is public domain and can be downloaded for FREE using the link below.
For RETC capability in a Windows-compatible interface, we recommend the SOILPARA software.