Adjustment of K s Values of Macroporous Soil Core Samples to K sf Values of a Borehole Permeameter

ABSTRACT Connective macropores dominate the overall saturated hydraulic conductivity ( K s ) of soil samples and should be corrected, when the matrix K sm is required. The K s values of 24 macroporous soil horizons were corrected using individual inverse K factors of the Runoff Generation Research Model (RoGeR) and compared to field‐saturated hydraulic conductivity, K sf , values of borehole permeameter measurements taken in immediate vicinity. When the K sf values of the borehole permeameter were contrasted against the uncorrected K s values of the corresponding soil samples the regression slope amounted to 100.8. By almost two orders of magnitude the regression slope was reduced after RoGeR macropore correction. Remaining deviations were described by a multiple linear regression based on clay content, stone content, anoxic mottles, organic carbon content, and volumetric macropore fraction as explanatory variables. Ninety two percent of the RoGeR corrected K s values of soil samples slightly exceeded the corresponding K sf values of the borehole permeameter. In contrast to the RoGeR correction factors of macroporous soils, which were derived for saturated flow conditions, borehole permeameters usually measure the hydraulic conductivity for field‐saturated conditions, that is, measurements are affected by entrapped air and hysteresis. Despite these inherent differences and the fact that not identical soil material was used in these comparative assessments, K s values of macroporous soil samples could be considerably approximated to nearby borehole permeameter measurements using the RoGeR correction. The RoGeR macropore correction is recommended for issues, where the matrix K sm is required.