In situ estimation of hydraulic conductivity using simplified methods

Five simplified methods of estimating the relationship between hydraulic conductivity K and water content θ were compared in this study. Redistribution of water following constant rate infiltration (steady state) was monitored for a 10‐day period at 100 locations and seven depths at each location within a 5000‐m 2 fallow sandy loam field. All the methods assumed a unit hydraulic gradient during redistribution and an exponential relationship between k and θ of the form K (θ) = k 0 exp [β(θ − θ 0 )]. The five methods were the θ, flux, and CGA methods (Libardi et al., 1980) and two methods based on a Lax solution of the Richards’ equation (Sisson et al., 1980). Water content data were used to calculate K 0 and β by each method at each depth and location. Soil water flux was estimated for selected depths using appropriate mean and variance values of K 0 and β for the field. Relative differences between the methods are briefly discussed.