Determination of soil hydraulic properties using pedotransfer functions in a semi-arid basin, Turkey

Abstract

Spatial and temporal variations in soil hydraulic properties such as soil moisture 0(h) and hydraulic conductivity K(theta) or K(h), may affect the performance of hydrological models. Moreover. the cost of determining soil hydraulic properties by field or laboratory methods makes alternative indirect methods desirable. In this paper, various pedotransfer functions (PTFs) arc used to estimate soil hydraulic properties for a small semi-arid basin (Kurukavak) in the north-west of Turkey. The field measurements were a good fit with the retention curve derived using Rosetta SSC-BD for a loamy soil. To predict parameters to describe soil hydraulic characteristics continuous PTFs such as Rosetta SSC-BD (Model H3) and SSC-BD-theta(33)theta(1500)(Model H5) have been applied. Using soil hydraulic properties that vary in time and space, the characteristic curves for three soil types, loam, sandy clay loam and sandy loam have been developed. Spatial and temporal variations in soil moisture have been demonstrated on a plot and catchment scale for loamy soil. It is concluded that accurate site-specific measurements of the soil hydraulic characteristics arc the only and probably the most promising method to progress in the future.