See more from this Session: General Soil Physics: II (Includes Graduate Student Competition)
In contrast, the modeling of the essential hydrodynamic soil characteristic, the unsaturated hydraulic conductivity curve, is in embarrassingly poor shape. The modeling by the Van Genuchten-Mualem method, leading to incomplete beta functions, often requires unrealistic assumptions and sometimes produces unacceptable predictions. The results obtained by the Groenevelt-Grant-Burdine method, leading to incomplete gamma functions, accepting bi-modality as a physical reality, produces excellent predictions. But then, there is the elusive character of the tortuosity. In contrast to the Mualem approach, where the formulation of the tortuosity term is established by pre-curve-fitting, the Burdine approach is based on physical gut-feeling. There, the formulation of the tortuosity term by the relative water content to the power two, is a clever choice, but is otherwise a testimonium paupertatis. This essential hydrodynamic parameter, requires in- depth analysis. For this, the easy access to incomplete gamma functions will be exploited.