Observational analysis of long-term streamflow response to flash drought in the Mississippi River Basin

Flash droughts, characterized by rapid onset and severe intensity, pose significant challenges to water resource management. This study investigates the relationship between meteorological conditions and streamflow dynamics during flash drought events within the Mississippi River Basin (MRB) over the period 1980–2022. The MRB has been a hot spot for flash drought events in recent years with significant ecological, agricultural, and economic damages. Existing literature has predominantly focused on studying the meteorological conditions preceding and during flash drought events. However, the media attention on low flows during flash drought events in 2022 and 2023 in the MRB has highlighted the adverse impact of flash droughts on streamflow levels, emphasizing the need to study the connection between flash drought conditions and streamflow dynamics. This study employs the Standardized Antecedent Precipitation Evapotranspiration Index (SAPEI), a daily drought index, to identify flash droughts at the catchment scale and assess the response of streamflow to the identified events across the MRB. Over 1000 flash drought events were identified at the catchment scale. The analysis of these events reveals spatial variations in the frequency, intensity, and duration of flash droughts. The eastern MRB experiences frequent but shorter flash droughts, while the northwest experiences lengthier but less frequent events. The southern region grapples with the most severe drought conditions and is heavily influenced by upstream water management practices. The analysis between SAPEI and streamflow anomalies showed a strong positive correlation in 221 of the 258 catchments with an average ρ of 0.64. The SAPEI-based method for identifying flash droughts and the subsequent comparison with streamflow anomalies is highly transferable, providing a valuable framework for assessing the impacts of flash drought on streamflow and informing water management strategies in other regions. This research significantly contributes to advancing our understanding of flash droughts, offering critical insights for informed water resource management, and bolstering resilience against the impacts of flash droughts.