This book presents a fundamental study of scaled physical modelling of capillary phenomena at elevated gravity and the basic knowledge of using the geotechnical centrifuge for modelling contaminant migration in unsaturated soils. As contaminant migration in the unsaturated zone depends strongly on capillary forces the basic understanding of capillary phenomena is essential in any attempt to model contaminant behaviour in the geotechnical centrifuge. All models used in the current research were based on a field prototype and for this purpose special electrical equipment was designed in order to monitor contaminant migration during the centrifuge experiments. The current research project was part of the NECER programme (Network of European Centrifuges for Environmental Research) and the research results proved that the geotechnical centrifuge can be used for several environmental projects at different g-levels. The book is intended for all those who come into contact or are concerned with centrifuge modelling applications or projects associated with contaminant migration.