ABSTRACT
Most classical models of soil-water conductivity, K, are based on Poiseuille's law. Early and straightforward approaches, like those of Purcell (1949), Gates and Lietz (1950), and Childs and Collis-George (1950), were later improved with often ad hoc corrections to fit observations, e.g., Burdine (1953), Fatt and Dykstra (1951), Millington and Quirk (1961), Mualem (1976), and Mualem and Dagan (1978).
