Populations in Coastal Zones

Percentage of total population living within 100 km of the coastline

  • Source: CIESIN/UNEP GPA Coordination Office

The percentage of the total population living within 100 km of the coastline, created by CIESIN, also includes population living at or below 50 m above sea level. This indicator serves 2 purposes. It quantifies an important driver of coastal ecosystem pressure, and it also quantifies an important component of vulnerability to sea-level rise and other coastal hazards. Because of the economic benefits that accrue from access to ocean navigation, coastal fisheries, tourism, and recreation, human settlements are often more concentrated in the coastal zone than elsewhere. Presently about 40% of the world’s population lives within 100 km of the coast. As population density and economic activity in the coastal zone increases, pressures on coastal ecosystems increase. Among the most important pressures are habitat conversion, land cover change, pollutant loads, and introduction of invasive species. These pressures can lead to loss of biodiversity, coral reef bleaching, new diseases among organisms, hypoxia, harmful algal blooms, siltation, reduced water quality, and a threat to human health through toxins in fish and shellfish and pathogens such as cholera and hepatitis A residing in polluted water. Finally, it is important to recognize that a high population concentration in the low elevation coastal zone (defined as less than 10 m elevation) increases a country’s vulnerability to sea-level rise and other coastal hazards such as storm surges. To calculate the percentage of the population within those boundaries requires a disaggregated population data set so that the population within the zone can be distinguished from the rest of the country. Censuses usually offer population data disaggregated subnationally by administrative units, such as regions and districts. These smaller administrative units can be gridded and converted to a raster file, each cell having an equal population. A 100 m buffer can be created from an equidistant map projection of coasts and a low elevation mask from a gridded elevation set. The population within that zone can then be divided by the total country's population and multiplied by 100 to find the percentage. Resource Watch shows only a subset of the data set. For access to the full data set and additional information, see the Learn More link.

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Formal name

Population, Landscape, And Climate Estimates (PLACE III), v3 (1990, 2000, 2010)

Cautions

Users should be cautioned that because land cover and elevation are among the parameters that drive the population allocation model, Landscan (the global population distribution data set used) may be less appropriate as a monitoring tool than population data sets that do not assume a particular relationship between population and these factors. The spatial detail of census data varied greatly between countries, and 1 km resolution was considered the highest resolution that could be supported globally. The SRTM data utilized was at a resolution of 1 km to facilitate a 1 to 1 spatial match with the population data. By degrading the resolution of the SRTM data to 1 km, the estimates shown likely underestimate the population counts in the zone. A 10 m elevation ceiling was chosen in part because of the error documented in SRTM data precision globally. The country land area calculations in the "country_lecz" worksheet have been adjusted for the overestimation of urban extents by the nighttime lights data. Globally, the coastal lights were reduced in size by an average of 6% when clipped to the coast. The noncoastal lights were also reduced by 6% for consistency. The remaining land area was included in the rural land area calculations. Some areas may be at similar risk to those in coastal zones but are above 50 m in elevation or further than 100 km from the coast. Some population density data are not provided by governments and are sourced elsewhere. These data may not be as accurate or detailed as data from national governments. Values of -9999 indicate data are missing.

Suggested citation

Center for International Earth Science Information Network - CIESIN - Columbia University. 2012. "National Aggregates of Geospatial Data Collection: Population, Landscape, And Climate Estimates, Version 3 (PLACE III)." Palisades, NY: NASA Socioeconomic Data and Applications Center (SEDAC).http://dx.doi.org/10.7927/H4F769GP. Accessed Dec 1 2017. Accessed through Resource Watch, (date). www.resourcewatch.org.

Sources

Columbia University Earth Institute Center for International Earth Science Information Network (CIESIN)
United Nations Environment Programme Global Programme of Action for the Protection of the Marine Environment From Land-based Activities Coordination Office (UNEP GPA Coordination Office)

Geographic coverage

Global

Spatial resolution

National

Date of content

1990, 1995, 2000

Published language

en

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