Field-Scale Water Flow Simulations Using Ensembles of Pedotransfer Functions for Soil Water Retention

Using pedotransfer functions (PTF) to estimate soil hydraulic properties is an alternative to direct laboratory measurement. The accuracy of a PTF outside of its development dataset is generally unknown. Multimodel ensemble prediction techniques (relying on different (PTF) models) can help to cope with this uncertainty. The objective was to estimate the applicability of an ensemble of PTFs for water regime simulations. Measured soil water contents at 60 points in a field transect. Water retention was measured in the laboratory.Contents of soil textural fractions, organic matter content, and bulk density were averaged across the transect and used as input in the ensemble of 22 published PTFs developed from large datasets in different regions. The HYDRUS-1D software was used to simulate water content time series with each of the PTFs from the ensemble and the laboratory-measured water retention data. Simulations with the PTF ensemble had, on average, two times smaller errors those from using laboratory data. A possible explanation for this is that the PTF estimation gave substantially better approximations of field water retention than the laboratory data. The ensemble prediction appears to be a promising source of soil hydraulic properties to simulate soil water dynamics