Blue-Green Infrastructure Planning Based on Flood Risk Assessment: A Case Study of Mentougou New Town, Beijing, China

The rapid urbanization in flood-sensitive areas has exacerbated the need for integrated flood risk management.As a critical junction in the Yongding River Basin, the special topological characteristics of Mentougou New Town, Beijing, surrounded by mountains on three sides, exacerbate the occurrence probability and intensity of rainfall and floods when severe climate events are detected.It underscores the need for Mentougou New Town to optimize urban ecological infrastructure planning and boost the city's adaptation competencies in responding to the pressures of climate change.This paper integrates ecological sensitivity analysis with the InVEST-Urban Flood Risk Mitigation (UFRM) model.The main results comprise the following indicators: (1) Through ecological sensitivity analysis, the research zone could be classified according to high, medium, and low sensitivity regions, with sites along the Yongding River and low-lying Xincheng Park showing the highest ecological sensitivity scores.(2) UFRM model simulation showed that, during the extreme rainstorm situation, the cumulative runoff retention volume in Mentougou New Town reaches 5,826,297m3 (which is equal to 582.63 million cubic meters).According to the flood risk assessment results, we drew up a high-risk flood zone as priority areas to realize a multi-scale "point-line-surface-network" BGI strategy.After these measures, Mentougou New City earned runoff retention capacity of 9.37% and amounted to 6,372,375 cubic meters.The framework discussed here offers a variety of actionable scientific advice to urban planners in optimizing and improving BGI schemes, thereby helping to conquer flood threats and maximizing the ability of urban ecological systems to deal with disasters.It has particularly strong ability in confronting the problems brought by severe weather events and provides valuable support in the sustainable development of the urban world.