Global study

In 2010-12 and 2020 long-term drought conditions have been followed by extensive riverine flooding and flash floods across large parts of the UK, with impacts on urban and energy infrastructure and severe damage on properties and business to the amount of 600 million pounds (Chan et al., 2021; Environment Agency, 2013; Marsh et al., 2013; The Guardian, 2013; The week UK, 2022). Similar events have occurred in Afghanistan, Syria, the Horn of Africa, Peru, California and Italy. These events have developed from arid to wet basins, impacting both vulnerable and non-vulnerable societies and ecosystems. However, it is still unclear where and when these events most often occur? What are the hydrological mechanisms underlying the abrupt transition from drought to flood? And why in some areas do the benefits of heavy rain after drought outpace the impacts of floods, while in other areas the impacts of drought and flood accumulate and cascade?

To answer these questions, we investigate the interplay between droughts and floods on a global scale, using both qualitative and quantitative methods. Our analysis encompasses the hydrological and social systems, allowing us to gain a deeper understanding of how consecutive drought-flood events develop and affect different regions and communities. Our multi-faceted approach combines data-driven methods, text-mining, and expert elicitation. We use data-driven approaches to analyze hydrological and biophysical variables from global satellite and observation datasets, identifying past drought-flood hazards. Additionally, we use text-mining techniques to collect data on hazard types, impacts, and responses from peer-reviewed articles, reports, and newspapers. Finally, through expert elicitation, we investigate potential interactions between hydrological and societal systems during drought-flood events.

This mixed approach allows us to shed lights on the socio-hydrological processes behind consecutive drought-flood events, developing quantitative and qualitative storylines of the past. Understanding how past events unfolded is critical to gaining insight into future storylines and coherently develop effective preparedness and mitigation strategies.