Water retention in Australian soils. I. Description and prediction using parametric functions

摘要: The soil water characteristic (SWC) is a fundamental property controlling storage and movement. SWC often described by analytical functions because this convenient in the solution of numerical flow equations as well implementation closed-form methods predicting unsaturated hydraulic conductivity. must adequately describe measured data for these applications to be successful. We used two large sets from Australian soils evaluate five widely on basis how they data. In general, sigmoidal SWCs best, but simpler power-law also gave very good description. Most error with occurred at contents near saturation physically unrealistic equation discontinuity around air entry potential. performance enabled development method predict only points knowledge bulk density. When was together parabolic smoothing parameter values were obtained using just points, then prediction within 0 -150 m matric potential range. This does increase reliance accuracy measurement that are interpolation or extrapolation. 'two-point' significantly reduces cost obtaining data, thus easing an important constraint widespread application simulation models based Richards' equation.