An improved method for determining Brooks-Corey model parameters from horizontal absorption

摘要

Low-cost, simple, rapid and accurate approaches for measuring soil hydraulic properties are of great importance in the application of hydrologic models of the vadose zone. A recently proposed method of constant-saturation absorption (MCSA) for determining Brooks-Corey (BC) model parameters is promising. However, this method has not been tested using experimental data. In this paper, measured soil-water diffusivity or soil-water retention curves (SWRCs) of 20 soil samples were used to test the reliability of MCSA. The results indicate that MCSA consistently estimated soil-water diffusivities by the Bruce and Klute method, but it substantially overestimated air-entry suctions (h(d)) and thereby soil suction. A new method (MCPA) is proposed herein to overcome the problems associated with MCSA. Using the improved method, estimated SWRCs are consistent with observation. With the estimated soil hydraulic parameters, HYDRUS-1D generated very accurate simulations of the cumulative absorption curves. Compared with direct or other indirect methods, MCPA is a more accurate, low-cost, and simple method, and it is especially useful for rapid determination of SWRC for soil-water movement simulations. However, if unsaturated soil-water diffusivity is of greater concern, our results also indicate that MCSA more accurately predicts this quantity and thus should be preferred. (C) 2015 Elsevier B.V. All rights reserved,