Research Projects

Flash drought leads to rapid intensification of soil moisture deficit that has a potential to affect multiple sectors such as agriculture yield decline, ecological degradation, enhanced forest fire risk, and others (Rippey, 2015; Otkin et al., 2018; Hoell et al., 2020; Parker et al., 2021; Wang & Yuan, 2021). Flash droughts are also becoming more intense and frequent due to increasing evaporation demand and higher changes of heatwave occurrence under warming Earth (Otkin et al., 2021). In contrast, drought is a slow-moving and long-duration water deficit phenomenon in different hydrological cycle components (Maity et al., 2016). Hydro-climatic factors and driving physical mechanism leading to flash drought differ from drought. Additionally, these driving mechanisms work on a finer temporal scale due to rapid onset, which adds uncertainty to prediction of flash drought (DeAngelis et al., 2020; Pendergrass et al., 2020). Hence, conventional early warning system for drought does not apply to flash drought (Otkin et al., 2018; 2022). Primarily, flash droughts are driven by either heatwave or water deficit caused by less precipitation/high evaporation demand (Mo and Lettenmaier, 2015, 2016;Wang and Yuan, 2018). These conditions may exist together and lead to fast soil moisture depletion in top soil. Some of driving forces behind these conditions have been identified in different regions of world. For instance, Feedback between land surface and atmosphere can play a role in development of flash drought (Koster et al. 2010; PaiMazumder and Done 2016). Similarly, large-scale climatic oscillations such as El Niño–Southern Oscillation (ENSO; Trenberth, 1997) and Indian Ocean dipole (IOD; Saji et al. 1999) are found to affect flash droughts in the United States (Chen et al. 2019) and Australia (Nguyen et al. 2020, 2021). India is being considered a hotspot (Christian et al., 2021). Most large-scale flash drought in India (about 80%) is reported to occur in monsoon season primarily due to precipitation deficit, which is aggravated by delayed monsoon onset and warm temperature anomalies (Mahto and Mishra, 2020). Large-scale flash drought in India is also linked to El Niño–Southern Oscillation (Mahto and Mishra, 2023b). Moreover, soil moisture-atmospheric vapor pressure deficit, delayed summer monsoon onset, air temperature gradients in Arabian Sea during spring-summer and stationary anticyclonic system in Indian Ocean during spring-summer transition season, etc. have been recognized as factors affecting monsoon flash drought in India (Mishra et al., 2021; Mahto and Mishra, 2023a; Ullah et al., 2024). However, the investigation of dynamics and hydro-climatic precursors or drivers for local or basin-scale flash drought is still lacking in Indian context. Such an investigation can also help in targeted mitigation and adaptation measures, and the nation can build resilience to future flash drought risks and ensure food and water safety in a changing climate.