Assessing the Role of Nature-Based Solutions in Mitigating Cascading Infrastructure Failures in Urban Flood Scenarios

Climate-induced hazards, such as extreme flooding, pose a systemic risk to urban areas by triggering cascading failures across interdependent critical infrastructures. While the direct damages of flooding are well-studied, the indirect consequences from disruptions to power, water, and emergency services can be uncertain and require more research. This study presents a modeling framework to quantify these cascading impacts and to assess the effectiveness of Nature-based Solutions (NBS) in enhancing systemic resilience.

Using the city of Malmö, Sweden, as a case study, we developed an integrated infrastructure model simulating the electricity, water, and emergency service networks. We subjected the city’s infrastructure model to three distinct, high-impact flood scenarios projected for the year 2125: extreme rainfall, extreme sea level, and a combination of mean high water level with heavy rain. The model first quantifies the propagation of failures, identifying critical vulnerabilities and estimating the population affected by service losses. Subsequently, we implemented five large-scale NBS scenarios based on a previous study to measure their potential to mitigate these cascading effects. The solutions include green roofs, street trees, parking area de-sealing, and enhanced park vegetation.

Our local results demonstrate that different flood types trigger unique failure pathways. Extreme rainfall would cause the most severe disruptions to municipal services. The analysis shows that NBS can substantially reduce the number of residents impacted by service disruptions. Comprehensive strategies combining multiple NBS interventions yielded the most significant benefits across all scenarios. This study provides a data-driven framework for policymakers and urban planners that translates the improved hydrological performance of NBS into tangible metrics of urban resilience, supporting the design of climate-resilient landscapes.