Increasing footprints of flash drought over the Indus River Basin

Flash drought with the characteristics of sudden onset and rapid intensification poses adverse effects on the agriculture and ecological health of a region. So far, no study has examined the dynamics of flash drought over the Indus River Basin, which has been experiencing rapid hydroclimatic changes from past decades. This study aims to assess the susceptibility of the Indus River Basin to the flash drought and asses its characteristics (i.e., intensity, frequency, extent) between 1970 and 2022. For this purpose, the weekly averaged soil moisture data set of the Global Land Data Assimilation System (GLDAS) was used to identify the events with respect to the different soil moisture layers (0-10cm, 10-40cm, 0-40cm, and 100cm). In this way, the role of most contributing soil layer in the development of flash drought in a particular climatic zone of this basin can be assessed. The study period was sliced into two halves to understand the relationship of flash drought with climatic changes. Based on these results, we conclude that the frequency of flash drought events has increased over the past two decades, which may be related to climatic changes in this region. The intensification rate and severity of flash drought show a positive correlation. Moreover, the spatial extent indicates the signals of flash drought events from Upper to Middle Indus basin. This study offers a baseline understanding for identifying the flash drought standards across the Indus basin.