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.