Are Impact Chains too complex? Introducing Layered and Simplified Impact Chains for DRM stakeholders

The co-development of frameworks and tools that address Disaster Risk Reduction/Managemenr (DRR/M) in collaboration with stakeholders has largely been acknowledged as a key advancement in both scientific literature and practitioners’ forums. Despite the increasing availability of frameworks capable of analysing the interplay of factors behind disasters (e.g., Impact Chains, causal loop diagrams, influence diagrams, fuzzy cognitive maps, Impact Webs, etc.), their uptake within DRR/M practice remains limited. The high analytical capacity of these frameworks is double-edged, as they can become too convoluted and therefore difficult to visualise, follow, and further on to validate in participatory settings. This gap between analytical potential and operational use is also motivated by fragmented dialogue between academia and stakeholders and/or a disconnection between the needs and interests of stakeholders and the purpose of the frameworks.

To address this operational gap and promote stakeholder engagement, we developed Layered Impact Chains and Simplified Impact Chains as frameworks designed to streamline stakeholders’ understanding of Impact Chains. Layered Impact Chains divide full Impact Chain models into layers tailored to the interests and professional responsibilities of different stakeholders. Simplified Impact Chains reduce these layers to their essential elements and connections based on a customised statistical metric. Together, these new models improve the transparency and usability of complex Impact Chains, preserving model complexity and enabling clarity.

The proposed models are applied to a case study examining a multi-hazard disaster scenario relevant for Bucharest, Romania. The scenario considers a major earthquake of over 7 M_W as the primary hazard that triggers secondary cascading hazards, including a dam-break flood, post-seismic fires, and soil liquefaction. The full Impact Chain includes 196 elements and 2795 connections, used as a foundation for the development of Layered and Simplified Impact Chains. The full model was developed under a multi-method approach (initially as part of the PARATUS Project), also integrating the inputs from a wide range of stakeholders with DRR/M roles (i.e., first responders, medical professionals, military workforce, policymakers, decision-makers, construction experts, law experts, and representatives of insurance companies). All models were validated in terms of understandability, navigability, and usability through a survey, targeted workshops, and focus groups with the targeted stakeholders.

The case study indicates that the proposed frameworks are accessible and operationally relevant. Layered Impact Chains may be constructed for any stakeholder category of relevance, with the specific configuration of each layer shaped by the roles and responsibilities of the involved actors. A central component of the approach is the collaborative module, which enables the simultaneous activation of multiple stakeholder-dedicated layers. This functionality exposes the elements and connections common to different stakeholder perspectives, thereby facilitating the identification of converging interests, intersecting mandates, and structural or operational disconnections.

We put forward Layered and Simplified Impact Chains as new models that bridge the gap between Impact Chain models and their application in DRR/M. By lowering cognitive load and removing practical barriers to engagement, these new analytical tools enable stakeholders to participate meaningfully in the planning-creation-validation process of the next generation of DRR/M tools for policy and practice.