Advancing Human Displacement Modeling: A Case Study of the 2022 Summer Floods in Pakistan

The devastating 2022 summer flood in Pakistan displaced about 7 million people in the Sindh province alone. Up to one-third of the country's area, mostly the country's south, was flooded. Effective response to intensifying and compounding hazards requires a better understanding of these processes. We can gain insights if impact assessments include socio-economic components and uncertainties arising from the interactions between impacts. However, the quantitative evidence from impact assessments remains limited and fragmented, due to methodological challenges and data limitations. Using the open-source impact assessment platform CLIMADA, we study to what extent flood-related hazards can be used to quantify displacement outcomes in a data-limited region. Using flood depth, exposed population, and impact functions, we link flood vulnerability to displaced people. This allows us to estimate internal displacement resulting from the flood event, and to further assess how displacement varies across the region. We find that a flood depth threshold of 0.67 m, with a confidence interval (CI) from 0.35 to 1.10 m, provides a best fit to all data from Sindh province. We find a negative correlation between displacement and the degree of urbanization. By testing the performance of our model in explaining differing displacement estimates reported across Pakistan, we show the limitations of existing impact assessment frameworks. We emphasize the importance of estimating potential displacement alongside other impacts to better characterize, communicate, and ultimately mitigate the impacts of flooding hazards.