Book excerpt: Vadose Zone Hydrology describes the elements of the physical processes most often encountered by hydrogeologists and ground-water engineers in their vadose zone projects. It illustrates the application of soil physics to practical problems relevant to the characterization and monitoring of the vadose zone. It includes an introduction to physical processes, including basic flow theory, and provides examples of important field-scale processes that must be recognizable by hydrogeologists. Considerable attention is given to the concepts of recharge, including how it is most accurately evaluated in the vadose zone. Field and laboratory methods for characterizing hydraulic properties in the vadose zone are also covered, and case studies illustrating these methods are provided. New and emerging technologies for monitoring the vadose zone, particularly for the purpose of detecting contaminants, are highlighted. In the last section of the book, additional case studies are presented, demonstrating applications related to seepage detection, landfill monitoring, and soil gas investigations. This book is written from the perspective of hydrogeologists and is designed to be directly applicable and to maintain continuity and consistency between chapters. It will be an invaluable primer for environmental or geotechnical consultants, regulators, or students who have no prior formal academic training in unsaturated flow concepts. Because the text contains some of the latest advances in this field, it will be an excellent reference for geologists and engineers currently working on problems of vadose zone hydrology.