Integration of soil hydraulic characteristic parameters for SVAT model in a heterogeneous soil region: A case study

This case study compared two kinds of integrating schematization of soil hydraulic characteristic parameters for a SVAT model?SWAPS in a heterogeneous soil region?Cabauw location in the western plain of the Netherlands. The schematization included aggregating soil parameterization and inverse modeling method, which resulted in two sets of parameters, aggregating soil parameters and effective soil parameters, respectively. The van Genuchten?Mualem model parameters of 4 typical soil profiles in the objective region were determined by direct laboratory method (Wind's Evaporation Method) and two indirect methods (Class PTF and Continuos PTF). Statistical Analysis of the validation and simulation data sets of sensible heat flux and latent heat flux indicated that: (1) for soil hydraulic characteristics from Class PTF, inverse modeling method (effective soil parameterization) could be available to integrate regional soil parameters in modeling partition of available surface energy flux; (2) for individual parameters determined by Wind's method, the schematization by areal averaging van Genuchten-Mualem model parameters (aggregating soil parameterization) could obtain the most accuracy output of partitioning of available surface heat flux; and (3) for soil hydraulic parameters derived from Continuous PTF, both averaging soil component (aggregating soil parameterization) and inverse modeling method (effective soil parameterization) could be available to integrate regional soil parameters, while the former showed better results. Among the studied schematizations for modeling sensible and latent heat flux, areal averaging van Genuchten-Mualem model parameters from Wind's method only horizontally was the best. Meanwhile aggregating soil components in great detail to derive the relevant parameters in the model showed good accuracy nearly as it. It means that the latter schematization could have potential utility to determine regional soil hydraulic parameters for SVAT model due to not only its accuracy but also its little cost both in money and time when available.