Mapping world’s coastal population facing water-related risks

Abstract

Endowed with opportunities from both land and ocean, coastal areas attract expanding human populations and economic activities. At the same time, they face growing societal and environmental pressures from both the above river catchments and the bordering sea due to climate change, ecosystem degradation, and expansion of built-up areas. Despite the accumulation of human population, economic activities, and environmental impacts, we lack social-ecological systems analysis on water-related risks to world’s coastal human population. To address this research gap, we analyze the spatial extent of six globally important water stressors to people within the world’s coastal zone (100 km from the coastal line) and classify this zone globally into 12 groups by distance from the coastline and elevation from the mean sea level. Adopting the approaches of the UN Sendai Framework and IPCC, we produce risk maps from the stressor maps by multiplying them with population exposure and vulnerability. For most risks, geographical hotspots are the Chinese coast, Bay of Bengal, Gujarat, and the Island of Java. The analysis reveals fundamental differences between water stressors and related risks, often mixed in scholarly literature. Both manifest specific geographic patterns and latitudinal profiles. Our study highlights the importance of high-resolution spatial analysis of vulnerability, exposure, and risks posed by water related stressors in the world’s coastal zone, in a manner prompted by key policy bodies to promote policy design and shared responsibility for managing stress-prone areas.

Keywords

Coastal zone / Population / Risk / Social-ecological systems / Spatial analysis / Water

Declaration of generative AI in scientific writing

Authors have not used generative AI in any part of this research.

CRediT authorship contribution statement

Olli Varis: Writing - review & editing, Writing - original draft, Visualization, Validation, Supervision, Software, Project administration, Methodology, Investigation, Funding acquisition, Formal analysis, Data curation, Conceptualization. Maija Taka: Writing - review & editing, Validation, Investigation. Matti Kummu: Writing - review & editing, Validation, Software, Methodology, Investigation, Funding acquisition.

Declaration of competing interests

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Olli Varis is an Editorial Board Member for this journal and was not involved in the editorial review or the decision to publish this article.

Acknowledgements

MK got financial support from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (Grant agreement No. 819202), the Research Council of Finland’s Flagship Programme and Doctoral Education Pilot under project Digital Waters (Grant No. 359248) funded by the Research Council of Finland's Flagship Programme, and Strategic Research Council (SRC) through project ‘Water & Food’ (Grant No. 365512).

Supplementary materials

Supplementary material associated with this article can be found, in the online version, at doi:10.1016/j.geosus.2026.100411.

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