Rationale for the “Floodplain Declaration” from environmental conservation toward sustainability science

In the Anthropocene era 73% of the Earth's surface has been changed by Man into various forms of “novel ecosystems” such as agrocenosis, urbanized centers and transport pathways. These are characterized by degradation of the hydrological cycle, emission of nutrients and pollutants, which result in a drastic reduction of biodiversity and ecosystem services for societies. Due to seasonal changes of the hydrological cycle, river floodplains are the most dynamic, resilient and diversified ecosystems. Their role in providing food has been known from the beginning of human civilization. The importance of reducing extreme event impacts, such as floods and droughts, to river purification is well recognized. However, there is still a further need for insights of these and other processes under changing climatic conditions. Therefore, “engineering harmony” between river valley ecosystems and societies (UN MDGs) requires solutions from integrative, transdisciplinary science such as ecohydrology, a sub-discipline of sustainability science focused on ecological aspects of the hydrological cycle, based on:-integration of specific knowledge of various disciplines with special consideration of the economic aspects,-understanding of the past (e.g., cultural heritage, paleohydrology, ecological succession patterns),-considering society's priorities vs. ecosystem carrying capacity, and,-identification of future scenarios applying systemic-approach and “foresight” methodology.The reversal of world wide degradation of floodplains should become an encouraging case for development of sustainability science, fundamental for mutual co-evolution of the ecosphere and anthroposphere.