Comparing Alternative Algorithms to Analyze the Beerkan Infiltration Experiment

Abstract

The increasing interest in the Beerkan Estimation of Soil Transfer parameters (BEST) procedure of soil hydraulic characterization justifies an assessment of alternative methods to analyze infiltration data. The BEST-slope and BEST-intercept algorithms allow estimation of soil sorptivity, S, and saturated soil hydraulic conductivity, Ks, using the transient part of the experimental infiltration curve and the slope and the intercept, respectively, of the linear portion of this curve. With reference to 401 runs performed in Sicily (Italy) and Burundi, this investigation showed that these two algorithms differed by the number of successful runs (positive S and Ks values), with BEST-intercept yielding a higher success percentage (93%) than BEST-slope (66%) at the expense of a poorer performance in terms of data representation by the infiltration model. On average, the two algorithms yielded S values differing by 3.3% and Ks values differing by a factor of 3.1. High discrepancies between two alternative Ks estimates, that is, by even more than two orders of magnitude, were occasionally detected at individual sampling points. The BEST-steady algorithm developed in this investigation, using steady-state cumulative infiltration data, was closer to BEST-intercept (individual S and Ks values differing at the most by 17% and a factor of 1.5, respectively) than to BEST-slope (differences by 22% for S and a factor of 186 for Ks). Data should initially be analyzed with BEST-slope and an attempt to apply BEST-intercept should be made only if the former algorithm fails in giving physically plausible S and Ks values. BEST-steady is an alternative algorithm to be considered in practice for a variety of reasons, including a success percentage of 100%, a simplified calculation of S and Ks, and the possibility to adjust the run duration directly in the field.