Storylines for compound flood impacts and adaptation: a case study of cyclone Idai in Beira

As climate change intensifies, coastal communities face growing threats from tropical cyclones and rising seas. These communities need practical ways to plan their adaptation strategies. Our study presents a new approach that integrates storyline analysis with local adaptation planning. For that, we combine different climate and adaptation scenarios with a modelling framework that allows cascading hydrometeorological conditions to flood hazards and to socio-economic impacts (including exposure and vulnerability information). We adopt as case study cyclone Idai's (2019) flood impacts on the coastal city of Beira, Mozambique.

The storylines of Idai are based on different scenarios of climate change and tidal cycles, but also on testing potential different adaptation responses to coastal protection. Our findings show that when climate change combines with high tides, the flood impacts grow considerably, affecting more people and causing more economical damage. Among the different adaptation strategies considered, building only seawalls offer limited protection against very extreme events, while strategies that mix different adaptation measures significantly reduce potential damage across all scenarios.

By offering localized, detailed information on compound climate hazards and adaptation, storylines can be used to measure the effectiveness of adaptation strategies against extreme events. This approach allows us to evaluate the robustness of different strategies across scenarios and quantify residual impacts, complementing traditional climate risk assessments. Our framework helps bridge the gap between climate projections and practical adaptation planning, supporting more informed decision-making at the local level.