DETERMINING THE SATURATED HYDRAULIC CONDUCTVITY OF A LOAM SOIL WITH DIFFERENT INFILTROMETER TECHNIQUES

The saturated soil hydraulic conductivity, Ks, is one of the most important soil hydraulic properties since it controls many hydrological processes. This hydrodynamic parameter depends on soil texture and structure and it is very difficult to measure. Infiltrometer techniques are becoming very popular to determine Ks in the field but testing alternative approaches is necessary for specific soil types. For a loam soil, the estimated Ks values with six infiltrometer techniques were compared. The so-called BEST procedure of soil hydraulic characterization, the pressure infiltrometer (PI), single head experiments with both the tension infiltrometer (TI) and the mini disk infiltrometer (MDI), the simplified falling head (SFH) technique and the bottomless bucket (BB) method yielded statistically similar estimates of Ks for the sampled area, with mean values differing at the most by a factor of three. The detected differences were attributed to different levels of disturbance of the infiltration surface during the run and to a different duration of the infiltration process. In conclusion, any of the tested infiltration techniques appears usable to obtain the order of magnitude of Ks at the field site. However, the TI, MDI and SFH data seem more representative of a still non-wetted soil whereas the BEST, BB and PI data appear more appropriate to characterize a porous medium at some advanced stage during a rainfall event. Additional investigations carried out on different soils would allow to better establish the relationship between the determination procedure of Ks and the intended use of the data.