Compound Drought-Flood Events in Fragile Contexts: Examples from the Horn of Africa

Humanitarian crises often result from a combination of multiple physical and societal processes, rather than independently from a single driver. The combination of processes leads to “compound events”, whose socio-economic impacts could be larger than those expected by analysing each driver individually. In recent years, the Horn of Africa has been increasingly exposed to compound events. Frequent extreme wet and dry conditions often compound with its fragile context characterized by internal ethnic conflicts, unstable governments, and high levels of poverty, resulting in impacts usually larger than anticipated. An improved understanding of the drivers and their interactions can help to reduce future risks associated with compound events.

Here, we conducted a retrospective analysis of the humanitarian crises that occurred in Kenya and Ethiopia in 2017-2018. In this period, a severe drought that occurred over the span of around 18/24 months, was followed by extensive flooding during the 2018 March-May rainy season. The impacts and their related drivers were explored, first through a review of the literature, and then through a survey and semi-structured interviews with several stakeholders from national agencies, civil societies, and NGOs. The approach resulted in a participatory co-creation of causal loop diagrams used as qualitative mental maps of the perceived drivers and interactions. These were then used as a basis for the semi-quantitative analysis of driver-interactions, modelling the impacts of immediate and long-term effects of the compound events.

The analysis disentangles the spatial-temporal feedback of drought and flood events, and their interconnections with societal forces. We found both negative and positive feedback on the food security level of the Kenyan and Ethiopian population. For instance, the flood initially exacerbated food insecurity caused by the long drought, but in the long term, it helped alleviate related water shortages. The results show the importance of taking drought response actions that first do not increase the risk related to subsequent floods (e.g., encouraging the allocation of people in lowland areas), but also that can boost the positive impacts of above-average rainfall on drought effects. Moreover, we investigated potential early warning signs and explored the impacts of several measures, identifying windows of opportunity for interventions.