Peter La Follette, Fred Ogden, and Ahmad Jan authored an innovative research paper that was published in the AGU journal “Water Resources Research” called Layered Green and Ampt Infiltration with Redistribution. Simulating the fraction of precipitation that infiltrates into soil often presents a substantial challenge to hydrologic modelers; results that are both accurate and computationally inexpensive are not guaranteed. The current industry standard for accurate infiltration calculations into layered soils is the Richards equation, which tends to be computationally expensive. Layered Green and Ampt with Redistribution, or LGAR, closely mimics results from the Richards equation, with advantages in terms of runtime and stability. LGAR is designed for arid and semi – arid areas.
Those interested in the most recent version of the model code can check it out here: LGAR