Abstract: To address urban flooding and other water issues, a sponge city program (SCP) and its implementation have been promoted across China since 2015. Various SCP measures come into play in different mechanisms, and their overall spatial arrangement influences flooding alleviation effect significantly. This study uses a hydrological-hydrodynamic multi-process coupled model to examine the responses of urban flooding to different SCP measure combinations and different rainfall scenarios in the SCP pilot area of Jinan. We analyze the effect of different overall SCP measure layouts and work out urban flood control schemes from the perspective of watershed hydrological cycling. Results show that implementing low impact development (LID) measures in the upstream area results in a significant decrease in the risk area, while the runoff and inundation are effectively controlled when the measures are implemented downstream. And a comprehensive effect of risk area reduction and inundation control is achieved when a scheme of implementing LID measures in the upstream and upgrading the drainage pipeline network in the downstream is applied. Cities with features similar to Jinan could adopt such schemes or take site-specific schemes through analysis of their runoff generation and concentration processes from a perspective of watershed hydrological cycling. Areas with distinct characteristics should follow the cycling pattern and implement corresponding measures.

Key words: Flood risk management, Flood alleviation, Sponge city, Grey and green facilities, Layout optimization, Jinan City