Barry, David AndrewParlange, J.-Y.Haverkamp, R.Ross, P. J.2005-12-092005-12-09199510.1097/00010694-199507000-00002https://infoscience.epfl.ch/handle/20.500.14299/221011An approximation to an implicit infiltration formula presented earlier in this series is developed. At worst, the relative error of the approximation is always less than 1%, and it is much better than that for most cases. The approximation becomes more accurate in both the short- and long-term Limits as it becomes exact in each case. Application of the new formula is demonstrated using both laboratory and numerical experiments.Unsaturated soilsRichards' equationMathematical approximationRelative errorAbsolute errortext::journal::journal article::research article