Future climate projections show a strengthening of the hydrological cycle with more droughts and floods expected. This means a higher likelihood of cascading drought-to-flood disasters. This year (2023) flashfloods occurred in many parts of Europe after a dry winter and a heatwave summer, including Spain, Italy, England and Turkey. Elsewhere, in Somalia, Chile and California (USA) record rainfall and flooding occurred also during or after an extreme drought. Other recent examples are the the 2012-16 California drought – 2017 Oroville spillway collapse in the US, the 2017-18 drought in East Africa followed by floods that caused hundreds of deaths, and the Millennium Drought – Brisbane flooding in Australia (2000-2010). These events resulted in large economic losses, casualties and displacements.
Studies on future risks analyse drought and floods separately. However, droughts allow ample time for impacts and adaptation, which influence hazard, exposure, and vulnerability of a subsequent flood. Drought and floods are caused by extremes of the same hydrological cycle and hence are correlated by dynamic feedback, strongly interlinked with human processes. Treating droughts and floods as independent phenomena, while ignoring their interaction with societal forces, leads to incomplete/inaccurate understanding of the processes that lead to the impacts experienced, and hence to possible underestimations of future risks.
In the PerfectSTORM (STOrylines of FutuRe ExtreMes) project, a group of researchers studies the risk of cascading hazards of flooding after drought, focusing on hydro-social feedbacks. The project aims to provide guidance on future management of drought-to-flood events to boost the positive impacts of above-average rainfall on drought effects while reducing its impacts.
A mixed-methods approach based on theory from data science, hydrological modelling, sociology, behavioural and cognitive sciences is used to develop quantitative and qualitative storylines in selected case areas in Kenya and Peru. Qualitative storylines are collected through storytelling and scenario development workshops and will be edited and analysed. Quantitative storylines are constructed through time series of hydrological and social data that will be analysed and modelled following socio-ecological systems, network theory and system dynamic modelling. These storylines will then be combined in an iterative way using innovative data visualisation.
The context-specific features of the developed storylines are also being compared and extrapolated on a global scale by exploring a range of global datasets through novel data analyses techniques. Contextual information on past drought-to-flood events is extracted through a grey literature review, which will provide insight on impacts and response strategies. This will result in the identification of global types and hotspots of drought-to-flood events. Positive pathways for future management of drought-to-flood events in different parts of the world will then be explored.
