Impact perception as driver for extreme event definition, identification and monitoring

The current approach to defining (flash) droughts in climate and hydrology typically relies on standardized indexes like SPI, SMI, and SPEI, combined with specific thresholds to determine the onset and conclusion of these events. However, this methodology often overlooks a crucial aspect – the impacts that communities experience during these events, such as plant mortality, well drying, or heat stress. We propose a novel framework that integrates the community's perception of extreme events, considering both the impact and risk tolerance of these communities. Our approach involves actively engaging with communities and stakeholders to understand their perception of extreme events, their associated impacts, and their levels of resilience and risk acceptance. By leveraging hydrological and crop models alongside historical and projected climate data, we can analyse conditions associated with specific impacts and the severity of these impacts for each community or user group. Additionally, we can develop local definitions of droughts and other related extreme events that align more closely with community perceptions and relevant impacts. This tailored approach aims to enhance communication and resilience within these communities. We tested this new framework in the farming communities of Illinois (USA), Brandenburg (Germany) and Ceará (Brazil), where we identified varying perceptions of drought impacts. Using these insights, we formulated distinct definitions of flash droughts for different regions, considering local climate conditions and community perspectives. This approach resulted in improved event identification and definition, facilitating more effective communication and empowering community actions.