Evaluation of two soil water retention models for the prediction of hydraulic conductivity of Daisen [Japan] Kuroboku (Volcanic Ash) soil

Abstract

Abstract It is known that soils of volcanic origin are generally well-aggregated. To đescribe their retention characteristics with the unimodal model of van Genuchten (1980), and subsequently predicting the hydraulic conductivity from it can lead to some errors. In this paper both the multi-porosity water retention model of Durner (1992) and the van Genuchten model are used to describe the retention characteristics of some samples of Daisen Kuroboku soil (Andosol). The two types of retention models are then combined separately with the conductivity model of Mualem (1976) to estimate the hydraulic conductivity of the samples. Estimated hydraulic conductivity using the two retention models differed by orders of magnitude. The disagreement between the estimated conductivities may be due to an inadequate description of the retention data by the van Genuchten model.