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Integrating Blue-Green Infrastructure with Gray Infrastructure for Climate-Resilient Surface Water Flood Management in the Plain River Networks
Abstract: Along with the progression of globalized climate change, flooding has become a significant challenge in low-lying plain river network regions, where urban areas face increasing vulnerability to extreme climate events. This study explores climate-adaptive land use strategies by coupling blue-green infrastructure with conventional gray infrastructure, forming blue-green-gray infrastructure, to enhance flood resilience at localized and regional scales. By integrating nature-based solutions with engineered systems, this approach focuses on flood mitigation, environmental co-benefits, and adaptive land-use planning. Using the Minhang District in Shanghai as a case study, the research employs geospatial information system analysis, hydrological modeling, and scenario-based assessments to evaluate the performance of blue-green-gray infrastructure systems under projected climate scenarios for the years twenty thirty, twenty fifty, and twenty one hundred. The results highlight that coupled blue-green-gray infrastructure systems significantly improve flood storage and retention capacity, mitigate risks, and provide ecological and social benefits. Water surface-to-catchment area ratios were optimized for primary and secondary catchment areas, with specific increases required in high-risk zones to meet future flood scenarios. Ecological zones exhibited greater adaptability, while urban and industrial areas required targeted interventions. Scenario-based modeling for twenty thirty, twenty fifty, and twenty one hundred demonstrated the scalability, feasibility, and cost-effectiveness of blue-green infrastructure in adapting to climate-induced flooding. The findings contribute to the existing literature on urban flood management, offering a framework for climate-adaptive planning and resilience building with broader implications for sustainable urban development. This research supports the formulation of comprehensive flood management strategies that align with global sustainability objectives and urban resilience frameworks.
One. Introduction
One. Introduction
The frequency and intensity of extreme climate events, driven by global climate change, present serious challenges for urban water management systems worldwide. This is particularly evident in low-lying plain river network regions, where urban flooding has become a recurrent and significant problem. As these areas face increasing pressure from rapid urbanization and climate variability, there is an urgent need for adaptive strategies that enhance resilience and mitigate flood risks. Adopting climate-responsive land use strategies that incorporate resilient infrastructure is crucial for effectively addressing these vulnerabilities.
One promising solution is the integration of blue-green infrastructure with conventional gray infrastructure-a hybrid approach that optimizes urban flood management. Blue-green infrastructure serves as a network of green and blue spaces, providing multiple ecosystem services to create more sustainable urban environments and exemplifying nature-based solutions. Grounded in scientific principles, nature-based solutions incorporate various natural elements and processes to enhance the resilience of urban spaces and improve human well-being. Blue-green infrastructure encompasses features such as green roofs, permeable pavements, rain gardens, and wetlands, which enhance water infiltration, storage, and purification processes. Gray infrastructure, which includes engineered systems such as drainage pipes, levees, and stormwater reservoirs, provides the structural foundation necessary for managing extreme flood events. The integration of these systems into blue-green-gray infrastructure enables an adaptive, scalable, and cost-effective approach to urban flood resilience. By harmonizing natural and engineered systems, blue-green-gray infrastructure offers a comprehensive framework for addressing urban flood challenges, facilitating optimized flood mitigation, enhanced ecological functions, and improved resilience in response to climate uncertainties. Through effective integration, blue-green systems can regulate and absorb excess surface water, while gray infrastructure provides the necessary structural support to direct and control water flow during extreme events.
Additionally, the integration of small- to medium-scale blue-green-gray infrastructure systems has proven effective for targeted flood mitigation, offering cities a scalable, adaptable, and context-specific method to address the unique hydrological needs of their local environments. Small- to medium-scale blue-green-gray infrastructure systems refer to localized interventions implemented at the level of individual buildings, neighborhoods, or specific urban districts. Examples include installing green roofs or rain gardens on buildings or streets, implementing permeable pavements in parking lots or sidewalks, and designing localized wetlands to manage runoff in specific neighborhoods. These systems contrast with large-scale flood management interventions, such as city-wide stormwater management networks or extensive flood barriers along entire riverbanks.
The primary advantage of small- to medium-scale blue-green-gray infrastructure interventions lies in their flexibility. They can be customized to address site-specific challenges, implemented incrementally, and seamlessly integrated into existing urban layouts without requiring extensive infrastructure overhaul. This adaptability makes them particularly suitable for high-density urban environments, where large-scale solutions may be impractical due to space constraints or economic limitations.
Despite the demonstrated benefits of blue-green-gray infrastructure, several gaps remain in the literature regarding its application in densely populated and socioeconomically diverse urban areas. Current research primarily focuses on specific case studies or isolated blue-green infrastructure solutions, with limited emphasis on the effectiveness of small- to medium-scale systems in high-density urban settings. Additionally, while multi-objective frameworks provide useful guidance for decision-making, further research is needed to validate these models across different climates, urban morphologies, and topographical conditions.
This study aims to address these gaps by exploring the coupling of small- to medium-scale blue-green-gray infrastructure systems for flood resilience in plain river network regions, with a particular focus on Shanghai and the surrounding areas. By applying a multi-objective analytical framework and evaluating a range of urban contexts, this research contributes to a more comprehensive understanding of blue-green-gray infrastructure implementation and provides insights into scalable climate-adaptive land use planning strategies.