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In the search for both immediate solutions and long-term transitions towards sustainability, green infrastructures (GI) are increasingly linked to urban water management. In this study, the GI-based urban water management practices of five cities famous for their progressive approach to water management were investigated. Based on reviews of open-source city plans and strategies, supplemented with information obtained directly from city managers, the purpose was to share best practices for the transition to sustainable urban water management and to gain insight into the role, if any, of GI in urban water management. An analytical frame based on transition theory was adopted. All five cities represented states of transition at the near end of a sustainable urban water management scale. Despite some overlap in challenges concerning water supply, environmental protection, and flood risk management, the development target of each city was unique, as were their solutions. GI has been applied as a way to reduce water footprints in Singapore and Berlin, to protect the environment in Philadelphia, and to help save potable water for consumption in Melbourne and Sino-Singapore Tianjin Eco-city. Despite differences in scale, GI was, in all cases, applied as a supplement to the conventional water infrastructure. All five cities reveal a strong top-down approach towards sustainable urban water management and a strong mindset on GI's role for future development. However, all five cities point to similar challenges for GI implementation, including space and cost constrains as well as barriers for inter-sectorial and stakeholder collaboration, which limit the speed of city-wide upscaling of GI solutions and full realization of GI benefits. The study indicates a need for a simultaneous change in the cognitive, normative, and regulative conditions of the urban water management regime for sustainability transition. Such a change requires a better balance between top-down and bottom-up planning to overcome barriers and foster innovation. The five cities jointly contribute to a noteworthy list of green solutions, city-wide strategies and guidelines, pilot project programs, regulations, and incentive programs, which may serve as inspiration for other cities' transition plans. [ABSTRACT FROM AUTHOR]

China has begun a rapid move towards Sponge City implementation, which will include widespread installation of various Low Impact Development (LID) stormwater infrastructure. Ambitious goals have been set for all Sponge Cities, including a target capture rate of 80–85% of annual precipitation in Beijing. However, there has so far been limited investigation into whether these goals are obtainable at the catchment scale given the physical restrictions of the existing urban landscape. This paper demonstrates the use of long-term continuous hydrologic modelling to evaluate the potential of meeting rainfall capture goals over a long time period for a case study area in Beijing. Detailed land cover classification derived from satellite imagery aided in the parameterization of a SWMM (Stormwater Management Model) model representing a 133 km2 urban study area. The calibrated and validated model demonstrated satisfactory agreement between computed and observed runoff for a variety of precipitation events ranging from 10 to 207 mm. A synthetic high resolution rainfall time series was generated from historic daily observations then used as input to run the model continuously for a 35 year period. Feasible LID model scenarios based on varying degrees of implementation of rain gardens, permeable pavements and green roofs were compared in terms of their potential volume capture of annual rainfall. Modelling results demonstrated that the conversion of 30% of roof area to green roof, 10% of green areas to rain gardens and 35% of paved areas to permeable pavement could increase the baseline volume capture ratio from 59.9% to 82.2%, indicating that Sponge City goals can be met within the case study area with realistic levels of LID implementation. This study provides a decision-making basis for future planning in the study area. • Satellite imagery based hydrologic model shows good agreement with observed flows. • Continuous modelling approach suggested for evaluation of Volume Capture Ratio. • >80% of annual rainfall captured with moderate catchment wide implementation of LID. [ABSTRACT FROM AUTHOR]