Design and Assessment of Integrated Urban Nature‐Based Solutions Under Flow Data Scarcity: Flood Mitigation and Co‐Benefit Analysis in Ipswich, Australia

Abstract This paper assesses the potential of urban Nature‐based Solutions (NbS) to mitigate pluvial flooding in the context of accelerated urbanization and recorded flow data scarcity in Ipswich, Australia. Storm Water Management Model (SWMM) is used to simulate the flood impact of a comprehensive set of NbS (rainwater tanks, green roofs, permeable pavements, increased permeability of residential driveways, bioretention cells, wicking fields, and urban wetlands) in a 26 km 2 catchment within the urban footprint. To overcome absent recorded flow data in the target urban catchment, the SWMM model is calibrated using a Soil and Water Assessment Tool (SWAT) model from the larger Bremer basin, demonstrating an innovative approach to link a catchment hydrological model with an urban hydrological model to addressing hydrometric data scarcity applicable worldwide. The hydrological model reveals tangible reductions in both major and minor flood peaks (19.2% and 19.9% flood peak reduction respectively). The designed strategies also contribute to local government goals including water quality improvement and heat island mitigation efforts. These results suggest that NbS are both scalable and adaptable for urban flood management, providing environmental and social co‐benefits, supporting long‐term urban resilience to both nuisance floods and major storms, and contributing to SDG 11 local disaster risk reduction. Co‐benefits and implementation issues are discussed.