Assessment of drought vulnerability in the Nile River basin using satellite remote sensing, Africa

ABSTRACT The variation in water storage leads to frequent recurrence of droughts in the world, which causes societal, economic, and environmental impacts. In this research, the gravity recovery and climate experiments (GRACE) terrestrial water storage variation (TWS) was used to suggest drought events and compared with commonly used drought indices. The cross-wavelet coherence analysis was applied to further identify the possible multiscale relationships between TWS and chamite variables. From the perspective of drought events, 12 were observed based on estimated water storage deficit between 2002 and 2023 in the Nile River basin, and out of the 12 confirmed drought events, the periods between October 2003 and July 2007 and between September 2008 and September 2012 were the most extensive drought periods in the study region, with durations of 45 and 49 months, respectively. The multiscale relationship between the GRACE-based drought index (GDI) and the corresponding drought indices was detected using a cross-wavelet spectrum to understand its correlations. The evaluated GDI significantly correlated with meteorological drought. Finally, this study verified the importance of utilizing GRACE data for drought quantification and characterization.