A simplified method to determine the first primary drying and wetting curves of water diffusivity of unsaturated soil

Within the framework of a research project examining the spatial variability of hydraulic characteristics of soil intended for irrigation, some of the more frequently used analytical expressions describing the laws linking diffusivity D to the water content of the soil ô€€… were verified. By studying the flow field of soil samples tested in the laboratory, under one-dimensional wetting and drying cycles, it has been found that the laws of hydraulic diffusivity of the exponential types can be ascribed to them. Finally, a simplified laboratory method was proposed which, with the aid of nomographs, allows the definition of the law D(ô€€…) to be easily arrived at.