Multi-Hazard Interrelationships and Risk Scenarios in Urban Areas: A Case of Nairobi and Istanbul

This paper introduces a methodology for characterizing the breadth of natural hazard types, hazard interrelationships, and risk scenarios in Global South urban areas, focusing on Nairobi, Kenya, and Istanbul, T & uuml;rkiye. Our approach involves (a) a comprehensive characterization of multi-hazards and their interrelationships in an urban setting, (b) collaborative development of relevant multi-hazard scenarios with local disaster risk reduction (DRR) stakeholders, and (c) analysis of the potential for integrating these scenarios into urban DRR efforts. Using a critical review of 135 sources (academic and gray literature, databases, online, and social media), we identify 19 natural hazard types that might influence Nairobi and 23 in Istanbul. We further identified in Nairobi 88 and Istanbul 105 hazard interrelationship pairs (e.g., an earthquake triggering landslides) out of a possible 576 interrelationships. These findings are cataloged in an extensive database, which informs the creation of multi-hazard risk scenario exemplars for each city. These exemplars are refined through stakeholder engagement, involving four workshops (47 participants) and nine semi-structured interviews with local DRR stakeholders. Despite the identified benefits, this engagement reveals a significant gap in integrating multi-hazards into current urban policy and practice. Governance challenges are highlighted as a key barrier, but opportunities for better integration are also identified, including evolving policies and growing awareness among urban actors. Our approach, particularly relevant in data-scarce urban areas of low- and middle-income countries, provides a framework for exploring multi-hazard issues in various urban contexts. Our study sought to understand the breadth of natural hazards an urban area in the Global South might face, how the hazards are interrelated (e.g., an earthquake can trigger landslides), and typical risk scenarios that matter to local experts. We applied our methodology to Nairobi and Istanbul to assess how considering multiple hazards could enhance disaster risk reduction (DRR) efforts. We systematically reviewed 135 information sources, including gray and peer-reviewed literature and online and social media. We found 19 natural hazard types could influence Nairobi, while Istanbul faces 23. These hazards showed numerous interactions, with 88 in Nairobi and 105 in Istanbul. Subsequently, we held workshops and interviews with local DRR stakeholders in both cities to co-designed multi-hazard risk scenarios. Practitioner stakeholders in Nairobi and Istanbul emphasized that considering these interrelationships helped create comprehensive risk scenarios and improved planning for addressing multiple hazards concurrently, a crucial aspect of urban safety and preparedness. They noted that current city policies and practices often overlooked this approach, primarily due to risk management and governance issues; for example, siloed approaches to DRR resulting in disjointed implementation and planning, and a lack of coordination and communication among actors. Our research framework may assist other urban areas, particularly those in developing countries with limited data, in comprehending and preparing for the complex challenges posed by various natural hazards. Using Nairobi and Istanbul, we introduce a framework for analyzing multi-hazard interrelationships in low- and medium-income cities A systematic review of 135 sources finds 19 and 23 hazard types and 88 and 105 hazard interrelationships in Nairobi and Istanbul, respectively Workshops and interviews identify risk scenarios, governance challenges, and opportunities for multi-hazard integration in urban policies