07 Jun 2021

07 Jun 2021

Review status: this preprint is currently under review for the journal ESSD.

Estimating Population and Urban Areas at Risk of Coastal Hazards, 1990–2015: How data choices matter

Kytt MacManus1, Deborah Balk2,3, Hasim Engin2, Gordon McGranahan4, and Rya Inman1 Kytt MacManus et al.
  • 1CIESIN, Columbia University
  • 2CUNY Institute for Demographic Research (CIDR), City University of New York
  • 3Marxe School of Public and International Affairs, Baruch College, City University of New York
  • 4Independent Researcher, Lewes, United Kingdom

Abstract. The accurate estimation of population living in the Low Elevation Coastal Zone (LECZ), and at heightened risk from sea level rise, is critically important for policy makers and risk managers worldwide. This characterization of potential exposure depends not only on robust representations of coastal elevation and spatial population data, but also of settlements along the urban-rural continuum. The empirical basis for LECZ estimation has improved considerably in the 13 years since it was first estimated that 10 % of the world’s population, and an even greater share of the urban population, lived in the LECZ (McGranahan et al., 2007). Those estimates were constrained in several ways, most notably by a single 10-meter LECZ, but also by a dichotomous urban-rural proxy and population from a single source. This paper updates those initial estimates with newer, improved inputs and provides a range of estimates, along with sensitivity analyses that reveal the importance of understanding the strengths and weaknesses of the underlying data. We estimate that between 750 million to nearly 1.1 billion persons globally, in 2015, live in the ≤ 10 m LECZ, with the variation depending on the elevation and population data sources used. The variations are considerably greater at more disaggregated levels, when finer elevation bands (e.g. the ≤ 5 m LECZ) or differing delineations between urban, quasi-urban and rural populations are considered. Despite these variations, there is general agreement that the LECZ is disproportionately home to urban dwellers, and that the urban population in the LECZ has grown more than urban areas outside the LECZ since 1990. We describe the main results across these new elevation, population, and urban proxy data sources in order to guide future research and improvements to characterizing risk in low elevation coastal zones. DOI: assigned upon completion of data peer-review.

Kytt MacManus et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • CC1: 'Comment on essd-2021-165', Alexander Kmoch, 17 Jun 2021
    • AC1: 'Reply on CC1', Kytt MacManus, 22 Jun 2021
  • RC1: 'Comment on essd-2021-165', Anonymous Referee #1, 01 Aug 2021
  • RC2: 'Comment on essd-2021-165', Anonymous Referee #2, 26 Aug 2021

Kytt MacManus et al.

Data sets

Low Elevation Coastal Zone Urban-Rural Population and Land Area Estimates (1990, 2000, 2015) Version 3 Center for International Earth Science Information Network - CIESIN - Columbia University, and CUNY Institute for Demographic Research - CIDR - City University of New York

Model code and software

Python Code for Low Elevation Coastal Zone (LECZ) Urban-Rural Population and Land Area Estimates, Version 3. Center for International Earth Science Information Network - CIESIN - Columbia University

Kytt MacManus et al.


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Short summary
New estimates of population and land area by settlement types within Low Elevation Coastal Zones (LECZs) based on 4 sources of population data, 4 sources of settlement data, and 4 sources of elevation data for the years 1990, 2000, and 2015. The paper describes the sensitivity of these estimates and discusses the fitness of use which could guide user decisions. Data choices impact the number of people estimated within LECZs, but across all sources the LECZs are predominantly Urban and growing.