This document proposes a conceptual framework to enhance the understanding, assessment, and management of natural, environmental, and human-derived risks in urban and metropolitan systems. It aims to standardize the description and assessment of multi-hazard and climate change-related risks by introducing a unified ontology. This is presented through a complete technical documentation for version 1.0 of the RETURN project ontologies, including detailed taxonomies and descriptions of all classes and relationships.

Update version containing version 2.0 of ontological models. This report describes the changes and additions conducted in the second ontology engineering cycle. In this cycle, more emphasis was placed on the representation of soft infrastructure and studying storylines for representing risks and their elements in the urban context. In addition, a series of tests with Vocbench and SKOSMOS were performed to build a controlled vocabulary from the ontologies.

Update version containing version 3.0 of ontological models. This report describes the changes and additions conducted in the third ontology engineering cycle, pointing out the design of taxonomies (e.g., taxonomy of vulnerabilities, taxonomy of hazardous events), the refinement of the risk-driven ontology of urban systems.

Update version containing version 4.0 of ontological models. This report describes the changes and additions conducted in the fourth ontology engineering cycle, pointing out the refinement of the risk-driven ontology of urban systems.

Collection of case studies demonstrating practical applications of the RETURN ontologies in urban risk management. We use the case study called "Casette Inglesi" conducted by the Eurac team to validate the ontological models and taxonomies. The case study established the municipality of Bolzano, Italy, to test integrated approaches for multi-risk assessment, with a specific focus on heatwave-related hazards.

Comprehensive validation report detailing the testing methodology, results, and conclusions from model validation based on the Casette Inglesi case study.

[In progress] Quarterly performance metrics and analytics report showing system performance, usage statistics, and key indicators.