Impact attribution of compound flooding from Tropical Cyclone Idai: Assessing the influence of land cover change and underlying socio-economic drivers using a mixed-methods approach

Abstract. In this study, we investigate the influence of socio-economic drivers on the impacts of compound flooding induced by tropical cyclone (TC) Idai. Making landfall close to the city of Beira in Mozambique in 2019, TC Idai was one of the most devastating TC’s to have hit the Southern Hemisphere. Attribution studies generally quantify the contribution of climate change to extreme events and their societal impacts; however, few studies assess how socio-economic drivers amplify or attenuate those impacts. We develop a mixed-methods approach, combining qualitative data from Key Informant Interviews (KIIs) and Causal Loop Diagrams (CLDs) with quantitative data from a physics-based modelling chain to assess how land use and land cover (LULC) changes over 20 years prior to TC Idai plausibly influenced the compound flooding impacts from TC Idai. Results from the quantitative approach show that land use changes (irrespective of climate change) potentially worsened the flood hazard from TC Idai. Results from the qualitative approach explain the underlying drivers of these land use changes such as deforestation driven by charcoal production and informal urban expansion. By integrating two methodologies, we find that the impacts of TC Idai were not only the result of intense climatic hazards but were amplified by complex, deeply rooted socio-economic processes that create reinforcing cycles of vulnerability and exposure. This research demonstrates the value of an interdisciplinary, mixed-methods approach, using localised contextual information to advance impact attribution in data-scarce settings.