Upscaling soil hydraulic properties at locall scale through topography

Estimating effective soil hydraulic properties for largescale is an outstanding challenge in hydrologic modelling. The aim of this study was to provide effective van Genuchten-Mualem hydraulic parameters at localscale through topography-based Upscaling Pedotransfer functions (PTFs) and spectrotransfer functions (STFs, SPTFs). The Zanjanrood sub-watershed with an area about 250 Km2 was selected as the study area for this research.hereby, a topography-based aggregation scheme, the so-called power average operator, PAO, was used to upscale (1Km×1Km) point scale parameters of , , and . With respect to the results, considerable and significant correlations (R>0.50) were obtained between measured and estimated hydraulic parameters. Upscaled STFs showed the largest and significant correlations with upscaled measurements of (0.65), (0.70), (0.86), while upscaled PTFs performed best for (0.55). The PAO performed best in the pixels which have the highest topographic index (CTI). The biggest R values were obtained between shape parameters (i.e., and ) andthe standard deviation CTI as well as between and with the average CTI. The ASAR estimated soil moisture values appeared to be significantly (p