Bridging Risk Knowledge and Early Action: using conceptual risk models to advance impact-based early warning for floods and droughts in eastern Africa.

Impact-based early warning (IbEW) is a novel paradigm that aims at improving the efficacy of early warning systems by informing about potential impacts on people, assets and systems, instead of only focusing only forecasting hazards. While applications are emerging, multiple challenges still remain to develop risk-informed, impact-based warnings that are useful for triggering early actions. Conceptual risk models, such as impact chains or impact webs, are tools increasingly used in risk assessments to inform risk management and adaptation, and can provide useful guidance also for IbEW and early action. By identifying the interconnections between drivers of hazards, exposure and vulnerability, they can improve the understanding of possible impacts and risks, thus allowing for a more targeted inclusion of risk information into IbEW. Moreover, through their focus on vulnerability, they can also be used to link the warnings with early actions, highlighting capacities and barriers. Using case studies in Kenya and Ethiopia and the wider IGAD region of Greater Horn of Africa, we have constructed conceptual risk models for different risks connected to droughts and floods: the models provide detailed representations of the interaction of drivers of risk, conducive to specific potential impacts of interest in the context of impact-based early warning (e.g. risk of crop yield loss due to drought). Moreover, in the models we also introduce examples of risk profiles, i.e. characteristics of vulnerability for specific at-risk groups: these can help identifying capacities and barriers of those who need to act on the early actions that are informed by IbEW. This information is essential in order to design warnings that are understandable and actionable by people on the ground. The models were also used to inform the development of an IbEW methodology, currently being implemented at the regional level to cover multiple risks connected to droughts and floods.