On the estimation of hydraulic conductivity of layered vadose zones with limited data availability

Vadose zone acts as a controlling agent for recharge and transport of contaminants into aquifers. Hence, for modelling and quantifying flow and transport processes in subsurface environments, hydraulic conductivity ( K ) of the vadose zone plays an important role. However, given the heterogeneity and anisotropy of subsurface systems, the in-situ measurement of K is a daunting task at a larger scale. The present study was conceived to evaluate the efficacy of salient pedotransfer functions (PTFs) to indirectly estimate the saturated hydraulic conductivity (K_s) of a lateritic vadose zone of eastern India. Also, in-situ hydraulic conductivity along with basic soil physical properties was determined in different vadose-zone layers at three locations (bare plot, cultivated field and orchard). Four PTFs [Campbell, Rawls–Brakensiek/Cronican–Gribb (R–B/C–G), and Models 2 and 3 of Rosetta] were selected to estimate K_s and their performances were evaluated. Based on the statistical indicators, it is concluded that Model 3 of Rosetta is capable of predicting relatively close values of K_s for the lateritic vadose zones to some extent. To generalise the findings of this study, it is recommended that such field-based studies should be carried out at a larger scale in lateritic terrains with varying land use/land cover.