Assessing saturated hydraulic conductivity from the dielectrically-predicted dry bulk density

Abstract

Direct measurement of saturated hydraulic conductivity (K_s) and dry bulk density (r_b) is often laborious, time consuming, and expensive. Predicted dry bulk density (r_b-ADR) using Amplitude Domain Reflectometry (ADR) probe has been employed to predict saturated hydraulic conductivity (K_{s_ADR}) after a slight modification on the previously available Non-Similar Media Concept (NSMC) model. All the predicted values were validated using the corresponding measured data of 108 undisturbed samples for each of 0-15 and 15-30 cm soil depths observed. The proposed “Dielectric NSMC” model could describe r_{b_ADR} dependencies of K_{s_ADR} better than the other proceeding models for the both ranges of soil depths observed. The proposed model tended to slightly underestimate the measured saturated hydraulic conductivity (K_{s_meas}) as implied from the negative value of mean difference (MD). The scattering pattern of data which was well supported by the small value of Root Mean Square Error (RMSE) and Relative Deviation to Average Measured Data (rRSME), however, suggested a small deviation of the K_{s_ADR} from the K_{s_meas}. Thus, the proposed model was considerably sufficient for characterizing r_{b_ADR} dependencies of K_{s_ADR}. Effectiveness and practical merit of the r_{b_ADR} prediction rather than the conventional direct measurement of r_b, in particular, might promote a certain advantage for smoother fitting parameters.