HOW TO MEASURE THE UNSATURATED HYDRAULIC PROPERTIES OF ROCKS?

Knowledge of the water retention curve and of the unsaturated hydraulic conductivity are needed to quantify the movement of water in the unsaturated zone. Many methods to determine unsaturated hydraulic properties are available but they are not always adaptable to both rocks and soils. This work presents a summary of a series of laboratory experiments carried out to measure the hydraulic properties of porous rocks, using newly developed methodologies and adapting methods originally used for soil. Attention is given to the difficulties involved in using commercial devices, such as tensiometers and probes to measure water content, designed to be used with soil. In addition, a variety of solutions for overcoming some of these difficulties are explained. Modifications in the sample preparation procedures to be used with various methods are presented. The overview of the experimental tests carried out highlights both similarities and differences between soils and rocks in relation to the measurement of hydraulic properties. Resolving these difficulties is essential in order to treat unsaturated transport phenomena as an integral process involving both soil and rock without artificial boundaries.