Prediction of the absolute hydraulic conductivity function from soil water retention data

For modeling flow and transport processes in the soil-plant-atmosphere system, knowledge of the unsaturated hydraulic properties in functional form is mandatory. While much data are available for the water retention function, the hydraulic conductivity function often needs to be predicted. The classical approach is to predict the relative conductivity from the retention function and scale it with the measured saturated conductivity, K.sub.s . In this paper we highlight the shortcomings of this approach, namely, that measured K.sub.s values are often highly uncertain and biased, resulting in poor predictions of the unsaturated conductivity function.