UCLA

The accurate estimation of saturated hydraulic conductivity (Ks) is of high relevance to correctly reproduce water movement in hydrological simulations. Yet, estimation of Ks is challenging particularly in semi-arid regions with particular soil surface characteristics like crusting and sealing. This study presents results of a field campaign in the semi-arid Walnut Gulch Experimental Watershed, Arizona (US), where surface and subsurface Ks measurements were undertaken across the watershed. Results reveal that the following commonly-used assumptions used in estimation of Ks are not plausible in such regions: (i) Ks decreases with increasing soil depth, (ii) soils with coarse-grained texture (sandy loam) have higher surface Ks values compared to relatively fine-grained texture (fine sandy loam), and (iii) pedo-transfer functions are not reliable methods of estimating Ks. Our results also reveal that remote sensing data can provide useful information for estimation of surface and subsurface Ks values.