Estimating water infiltration and retention characteristics using a computer program in R

Infiltration and water retention functions are widely used soil hydraulic properties in the geosciences. They contain coefficients known as hydraulic parameters that are traditionally obtained through curve-fitting. Computer programs for the curve-fitting process are available for certain infiltration or water retention models. However, these programs are either not freely accessible or do not estimate certain hydraulic parameters. They are also inefficient and prone to errors for applications involving large datasets. This paper discusses the use of a freely accessible HydroMe package for fast, efficient, and accurate estimation of soil hydraulic parameters in some commonly used infiltration and water retention models. The package is executable in the freely downloadable R programming software. It contains a program for estimating the parameters in infiltration models previously proposed. The program is capable of estimating parameters from arrays of grouped data in one single pass without having to enter the data each time for the parameter estimation. It incorporates mixed-effects and covariate modelling techniques for improved estimation accuracy. These techniques are not common in any other computer programs in the geosciences. Through covariate modelling, the package provides opportunity to include environmental correlates in the estimation of soil hydraulic parameters. Therefore, HydroMe not only improves the estimation accuracy and efficiency, but also provides insight into environmental risk factors that influence the management of soil and water resources.