Analyzing dual porosity in soil hydraulic properties using soil databases for pedotransfer function development

Current databases of soil hydraulic properties (SHPs) have typically been used to develop pedotransfer functions (PTFs) estimate water retention [?(h)] assuming a unimodal pore-size distribution. However, natural soils often show the presence bimodal multimodal distributions. Here, we three widely spread for PTF development: UNsaturated SOil DAtabase (UNSODA) 2.0, Vereecken, and European hydropedological data inventory (EU-HYDI), analyze structural effects in both ?(h) conductivity [K(h)]. Only undisturbed samples were included analysis that contained enough datapoints K(h) properties, especially wet range. One-hundred ninety-two suitable our analysis, which is only 1% total databases. Results showed 65% exhibited distribution, bimodality was not limited fine-textured but also coarser-textured soils. The Mualem–van Genuchten (MvG) expression able predict observed unsaturated K. joint fitting measured provided parameter estimates describe K uni- In addition, negative relationship between ? n case low sand content (<52%) matrix domain contradicting classical notion. ratio macropore positively correlated with fraction macropores content. We anticipate results will contribute deriving structured avoid unrealistic combinations MvG parameters.