Water research in Germany: from the reconstruction of the Roman Rhine to a risk assessment for aquatic neophytes

Germany does not only have a long tradition in water research, but a very active community of scientists and practitioners working on a vast range of "water topics." This thematic issue, which was initiated by four water-related research associations (German Hydrological Society; German Limnological Society; Hydrological Sciences Commission within German Water Association; Working Group Hydrology within German Geographical Society), is a testimony of both the quality and diversity of the water research currently undertaken by Germany's scientific community. Key topics include hydrology and hydromorphology; water quality; aquatic and riparian ecosystems; water in agriculture and forestry; and water management and supply. The manuscripts contained in this thematic issue do not only cover a period of more than two millennia, but also address all types of water resources and a multitude of both established and newly developed methods that help us to better understand the processes governing the hydrological cycle, aquatic ecosystems and the management and operation of various water infrastructures.