Exploring Data-Related Uncertainties in Analyses of Land Area and Population in the "Low-Elevation Coastal Zone" (LECZ)

Analyses of land area and population distribution in the Low Elevation Coastal Zone (LECZ) and their potential susceptibility to future sea level rise have been used to derive first-order assessments of areas and populations at risk. Variations in results are shown to be highly dependent on the input datasets. In this paper we explore differences in land and population distribution estimates in the LECZ resulting from the use of three digital elevation models and two population datasets at global, continent, and country levels. Results at the global scale show differences of up to 150% in area estimates, depending on the elevation model used. The differences are most extreme below 1 m elevation and diminish at higher elevation increments. On the continent level, the use of different elevation models produced area estimate differences ranging from more than 1200% at an elevation of 1 m to 160% in the LECZ. Country-level differences are even higher. Similarly, substantial differences in population distribution can arise with the use of different population datasets. Population counts below 1 m elevation range from 1% to 2.3% of the total global population. In the LECZ, estimates vary from 9.2% to 10.9% of the total global population. Differences at continental and country levels are also significant depending on the elevation model and the population dataset used. These large differences indicate that results of such analyses should be regarded with caution and within the context of the methods and materials used.