Cees van Westen, University of Twente
Disaster risk is changing dynamically, by accelerating climate change, expanding urbanization, and increasingly interconnected systems. Hazardous events occur more frequent, intensive, and interrelated, interacting with vulnerable societies that become more complex, expanding, and interconnected, and the consequences of extreme events cascade across sectors. Against this backdrop, the European Horizon PARATUS project developed approaches to rethink how multi-hazard risk is assessed, communicated, and managed. One of its central technological pillars is RiskChanges, a web-based Spatial Decision Support System designed to analyse how risk evolves across space and time and to support evidence-based decision-making in complex environments.
RiskChanges was designed to address a fundamental limitation in traditional risk assessment: the tendency to treat hazards, exposure, and vulnerability as static and isolated components rather than dynamic processes. In reality, there are changes that are either long-term (such as urbanisation and population trends, aging infrastructure, and increasing hazards), short-term (such as the impacts of disaster events that modify the risk components), or planned (such as risk reduction and climate adaptation policies). The platform operationalises a risk framework in which these components can be combined, modified, and compared across future scenarios. It integrates hazard layers with spatial data on elements at risk and physical vulnerability functions to quantify exposure, estimate potential losses, and compute risk metrics under different assumptions.
At the technical core, RiskChanges follows a modular architecture consistent with modern Spatial Decision Support System design. Users upload or access hazard maps that describe the spatial distribution and intensity of events such as floods, storms, or other extremes. These hazard datasets are intersected with elements-at-risk layers, which may include buildings, infrastructure, economic assets, or population distributions. Vulnerability information is then applied through damage or loss functions that translate hazard intensity into expected impacts. The system calculates exposure metrics, and loss estimates and synthesizes them into interpretable risk outputs, including spatial risk distributions and aggregated indicators. The result is not merely a visualisation, but a structured analytical workflow that is controlled by the users.
What distinguishes RiskChanges from other tools is its user interface, and its focus on users that are envisaged as disaster risk practitioners with limited technical knowledge on geoinformatics and programming. The user interface is kept relatively simple, with an important map component, visualisation of results in tables and graphs, and adequate import and expert options.
Users are not confined to a single baseline scenario. They can construct alternative scenarios for specific future years with adjusted hazards, exposure, vulnerability and risk assessment. Users can also create alternative risk reduction options by adjusting hazard frequency or intensity, modifying exposure patterns through projected land-use change, or introducing mitigation measures that alter vulnerability. This scenario capability allows planners to ask structured “what-if” questions. What happens to expected annual losses if urban expansion continues into flood-prone zones? How does risk evolve under intensified rainfall projections? What is the comparative effect of implementing structural versus non-structural measures such as relocation or zoning? By enabling side-by-side comparison of these alternatives, the platform supports transparent evaluation of risk reduction strategies under uncertainty.
Within PARATUS, RiskChanges interacts conceptually with complementary tools that address impact chains, rapid hazard assessment, and stakeholder engagement. While other components explore systemic interdependencies or provide rapid hazard modelling, RiskChanges focuses on the quantification and spatialization of losses and risk metrics. This positioning is crucial because decision-makers often require numerical evidence to justify investments in resilience. The platform bridges the gap between scientific hazard modelling and policy-oriented appraisal by translating complex spatial data into indicators that can inform cost–benefit analysis, prioritization of interventions, and long-term adaptation planning.
The documentation underlying the system reflects a commitment to methodological transparency, detailing the structure of hazard inputs, exposure calculations, vulnerability integration, and risk estimation procedures. This transparency strengthens reproducibility and supports informed interpretation of results, and is accompanied by several tutorials. RiskChanges is an Open-Source tool, developed by the University of Twente, the Asian Institute of Technology, and the Nepalese Youth Innovation Lab.
The RiskChanges tool is used within the PARATUS case studies and in training courses by UN-APCICT and UNDRR.
Ongoing developments are in expanding the cost-benefit modules with Cost-effective analysis and multi-criteria evaluation, the use of existing hazard data , elements-at-risk datasets, and vulnerability curves, and the integration of various multi-hazard impact scenarios using impact chains.
For further information, please contact info@riskchanges.org
