Aquatic ecosystems have formed the focus of several UNESCO research projects because of the impact on them of human activities such as intensification of agricultural activity, erosion and sedimentation due to irrigation projects, groundwater pollution and eutrophication. Interfaces, or ecotones, between terrestrial and aquatic ecosystems were found to have an essential role in the movement of water and materials throughout the landscape. Ecotones are zones where ecological processes are more intense and resources more diversified. They are also zones which react quickly to human influences and changes of environmental variables. This volume summarises the results presented at an international conference dedicated to the study of groundwater/surface water ecotones, with contributors of international scientific reputation representing the multidisciplinary viewpoints of hydrologists, biologists and ecologists. It addresses areas of active research in hydrology and biology, and is aimed towards researchers, water resource project managers and policy makers.