Flash Droughts in the Southern United States: A Driver-Impact-Response (DRI) Framework

Flash droughts are rapidly evolving drought events, primarily affecting agriculture, with an onset ranging from 5 days to 8 weeks. Previous research has highlighted the significant impact of flash droughts on agriculture and ecosystems, posing unique challenges for drought monitoring and mitigation. Various indicators have been used to identify the regions and occurrences of flash droughts. However, studies indicate that a single unique indicator does not serve the purpose of identifying/monitoring flash droughts in the United States. This study aims to identify flash droughts using indicators, including the Evaporative Stress Index (ESI), Soil Moisture (SM), and Normalized Difference Vegetation Index (NDVI), complemented by data from the United States Drought Monitor (USDM), which is used as a reference. The research examines flash droughts across Florida, Georgia, and Louisiana from 2000 to 2023, incorporating case studies of recent events. The findings indicate that the SM indicator demonstrates the highest consistency (91%) with the USDM, followed by SESI (64%) and NDVI (52%). Seasonally, flash droughts were most frequent in Florida and Georgia during May and October, whereas Louisiana experienced the highest occurrences between June and October. These indicators effectively reflect flash drought impacts, as documented by crop progress and condition reports from the United States Department of Agriculture (USDA). Finally, to enhance understanding and management of flash droughts, the study proposes a Driver-Impact-Response (DRI) conceptual framework is proposed to connect the drivers, impacts, and responses. The DRI framework identifies the drivers initiating flash droughts, evaluates their impacts, and develops mitigation strategies. The DRI framework is specifically of support and management use for planners to summarize the information for decision-making.