Evaluation of two methods for measuring saturated hydraulic conductivity of soils under two vegetation covers

The main goal of this work is to determine and to evaluate the saturated hydraulic conductivity for a silt loam soil in field and laboratory conditions. The experimental area was located in the Vallcebre research catchments, in headwaters of the Llobregat River (NE Spain). Hydraulic conductivity was measured in the field using the Guelph permeameter and field saturated hydraulic conductivity (Kfs) based on Elrick equation was calculated. The Guelph permeameter measures were made in two conditions (dry and wet) and in profiles below two vegetation covers (meadows and forest). To determine the saturated hydraulic conductivity at the laboratory (Ks) the constant head permeameter was used. The average Kfs values for the wet period was about 2 cm·h. During the dry period, both soil profiles presented higher values, about 7.5 cm·h. Under laboratory conditions, mean observed Ks values were between 12 and 25 cm·h. The relationship Kfs/Ks was of 0.1 cm·h in wet conditions and about 0.4 cm·h in dry conditions. The results indicated significant differences between both methods and between both seasons. Differences can be explained by the anisotropy of soils as a consequence of vegetation root system that promotes preferential flows paths.