WATER-RETENTION MODELS FOR FRACTAL SOIL STRUCTURES

A review of water retention functions based upon fractal soil structur es is presented. We consider the modelling approach for a fractal fabr ic, a fractal pore boundary and a fractal pore space, identifying the latter case as one of particular complexity. In each case, the water r etention function is derived from the pore volume distribution arising from the structural model in question. We examine published models an d highlight problems, namely lack of generality and inconsistency with the assumed fractal structure. The models considered in this paper do not account for the effects of pore connectivity, and as such their v alidity as a necessary condition for the existence of fractal structur e is questionable.