This book is intended to provide a diverse overview of important studies on groundwater and ecosystems, including a toolbox for assessing the ecological water requirements for GDEs, and relevant case studies on groundwater/surface-water interactions, as well as the role of nutrients in groundwater for GDEs and ecosystem dependence (vegetation and cave fauna) on groundwater. Case studies are from Australia (nine studies) and Europe (12 studies from nine countries) as well as Argentina, Canada and South Africa. This book is of interest to everybody dealing with groundwater and its relationship with ecosystems. It is highly relevant for researchers, managers and decision-makers in the field of water and environment. It provides up-to-date information on crucial factors and parameters that need to be considered when studying groundwater-ecosystem relationships in different environments worldwide.