Identification of hydro-physical properties causing gravity driven flow in unsaturated porous media

The main goal of the project is to identify conditions inducing the formation of preferential flow path in a porous medium, and to find the threshold height of a fluid body which induces the instability of the fluid distribution in the porous structure. Influence of the following parameters will be tested: effective pore diameter, contact angle between liquid, solid and gas phases, intensity of fluid infiltration, the volume of fluid in a porous material. Experimental methods: visualization of the fluid transfer in a porous medium, measurement of free drainage from a porous medium, the hydrograph separation in two small watersheds under monitored precipitation, tensiometric pressures and soil water content. Computer simulation of fluid flow in a porous medium will be performed on three levels - macroscopic Richards equation based on continuum mechanics approach, microscopic - lattice-gas automata, and mesoscopic - based on network approaches (percolation theory).