Testing a simplified approach to determine field saturated soil hydraulic conductivity

Abstract

Interpreting and simulating hydrological processes need a large number of field saturated soil hydraulic conductivity, Kfs, data that should be collected with simple and rapid field experiments. A Simplified method based on a Beerkan Infiltration run (SBI method) was recently developed and tested successfully on Burundian soils. With the SBI method, a cylinder is inserted to a short depth into the soil and the infiltration time of a few small volumes of water repeatedly applied at the surface of the confined soil is measured. Calculating Kfs needs the slope of the linearized cumulative infiltration vs. time relationship and an estimate of the so called a* parameter. In this investigation, the SBI method was validated with reference to a larger dataset, also including different Sicilian soils. The a* value of first approximation (0.012 mm-1) yielded an estimate of Kfs differing in general by not more than a factor of three from the Kfs values obtained by the more complete and onerous BEST (Beerkan Estimation of Soil Transfer parameters) procedure of soil hydraulic characterization. The Kfs values obtained with SBI method were also very close (means differing by a factor of 1.01) to the one determined with the One Ponding Depth relationship for the single ring pressure infiltrometers technique. Detection of physically plausible relationships between a* and the slope of the linearized infiltration curve indicated that the measured infiltration process contains the necessary information to estimate a*. Different a* predictive relationships for Sicily and Burundi allowed to obtain estimates of Kfs never differing by more than a factor of three from the corresponding values obtained with BEST. The developed method is a good candidate method for intensively sampling an area of interest. Points needing developments include tests with other datasets, comparisons with independent measurements of both a* and Kfs, and maybe development of an improved experimental methodology to obtain the infiltration data.