Green roofs are widely recognized as a viable solution in the context of water-sensitive urbanization, especially with respect to their effects on heat island mitigation and future-proof urban drainage [1, 2, 3, 4, 5]. In order to support their dissemination throughout different regions, comparisons of performance under varying climatic conditions can be very useful. Storm characteristics such as rainfall depth, intensity and duration can be expected to play an important role, as well as the temporal distribution of storm events relative to seasonal patterns of temperature, radiation and wind. This paper summarizes the first of several such data- and model-based comparisons between Germany and China planned in the Sino-German cooperative project “Smart Technologies for Sustainable Water Management in urban Catchments as Key Contribution to Sponge Cities” (KEYS).

Due to rapid economic development and population growth, China is facing severe water problems that include sea-level rise and increasing salinization, floods, water pollution, water shortage, soil erosion and ecosystem deterioration, as well as biodiversity loss. In recent decades, China is progressively more concerned with its water issues that are now at the center of social and political attention. Having to overcome similar challenges, Germany has taken a leading role in the field of water sciences and technology. In particular, China can benefit from the lessons learnt in Germany concerning the rehabilitation of water resources in areas heavily affected by chemical industry and mining after the reunification in 1989. German-Chinese cooperation in water sciences started over 25 years ago and dealt with increasing challenges in the 21st century. Following the open space workshop during the Water Research Horizon Conference in Berlin 2014, this article provides a view of some of the challenges and potential opportunities of German-Chinese cooperation in water science and technology.