Integration of pedotransfer functions and topographical data to obtain soil hydraulic properties at catchment scale

The emerging importance of large scale distributed-process modeling has generated a pressing need for detailed information on spatial distribution of input data, especially the parameters that describe the hydrologic behavior of soils. Traditional methods to determine soil hydraulic parameters at large scales are time-consuming and very costly. To carry out a soil hydraulic characterization in a cost-effective way, pedotransfer functions (PTFs) are profitable tools to estimate soil hydraulic parameters from easily measurable or already available soil data. Spatial distribution of soil properties can be explained, to a certain extent, in the light of the variability of landscape attributes. Digital terrain analysis can thus provide a quantitative basis for deriving topographic attributes and relating them to soil variables in order to improve the prediction of key soil hydraulic parameters. Topographical data have been used to improve the prediction of soil water retention by PTFs, whereas statistical indicators of goodness-of-fit helped in evaluating the effectiveness of the proposed procedure.