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The human consequences of flood and drought disasters are widespread and detrimental. Large-scale studies, drawing on global geodata products and international databases, can systematically examine how anthropogenic megatrends shape disaster risk and test the generalisability of findings from other scientific methodologies. However, the top-down lens of these global studies often misses the pivotal role that human societies play in shaping disaster risk, including how water management influences physical hazards and how political factors shape social vulnerability. It is precisely this tension – characterised by the need for global perspectives alongside the need to incorporate human influences in the study of disaster risk – that motivates my research.

This thesis specifically examines how observations from global data can leverage our understanding of how humans shape hydrological disaster risk, in terms of the hazard, human exposure and social vulnerability. To this end, the thesis draws on multiple methodologies across four individual studies, including one scoping review and three quantitative geospatial studies. The findings of this thesis provide insights into 1) how the landscape of global data shapes disaster studies and 2) how human societies shape disaster risk.

For the former, my thesis shows that key data opportunities and challenges vary across disaster types and risk dimensions. Addressing each of these limitations is important because of the interrelated nature of disaster risk. The thesis also underlines how the pursuit of transforming fragmented disaster knowledge into holistic and useful information would encounter fewer obstacles if the global datasets were more integrated or, at the very least, more compatible. Databases recording past disaster losses serve as a natural place for such an integration.

For the latter, this thesis brings to light the heterogeneous impact that large-scale infrastructure projects can have on disaster risk, by showing that river regulation does not serve as a universal solution for reducing long-term drought risk. The thesis also highlights the central role of human exposure and economic inequality in shaping human losses during severe flood disasters. Taken together, this underlines the importance of addressing root causes of vulnerability to reduce fatalities during disasters.