Low Elevation Coastal Zone (LECZ)

Introduction

The Low Elevation Coastal Zone collection includes four data sets: Urban-Rural Population Estimates, v1 (1990, 1995, 2000), Urban-Rural Population and Land Area Estimates, v2 (1990, 2000, 2010, 2100), Urban-Rural Population and Land Area Estimates, v3 (1990, 2000, 2015), and the Sea Level Rise Impacts on Ramsar Wetlands of International Importance, v1 (2000 – 2010). Users are encouraged to review the methodologies used for constructing these data sets and to acknowledge uncertainties and limitations.

Country-level estimates of population and land area by settlement type in LECZ’s were generated globally. The Urban-Rural Population Estimates, v1 (1990, 1995, 2000) data set uses Global Rural-Urban Mapping Project (GRUMP) alpha data and was estimated at a 1km (30 arc-second) grid resolution.  The Urban-Rural Population and Land Area Estimates, v2 (1990, 2000, 2010, 2100) data set used GRUMPv1 population inputs and urban-rural data, and is estimated at a ~90m (3 arc-second) grid resolution to conform with the native resolution of the elevation data, and at a 1km (30 arc-second) grid resolution in order to reflect uncertainty levels in the product resulting from the interplay of input population data resolutions (based on census units) and the elevation data. The Urban-Rural Population and Land Area Estimates, v3 (1990, 2000, 2015) data set  is estimated at ~300m (9 arc-second) resolution and uses population, settlement, and elevation data from multiple sources (4 sources for each factor) in order to characterize the range of estimates which might result from the use of different input data. All three data sets include a Digital Elevation Model (DEM) derived from NASA Shuttle Radar Topographic Mission (SRTM) data, but the v3 data set also considers DEMs from the Multi-Error-Removed Improved-Terrain DEM (MERIT-DEM), TanDEM-X, and Coastal DEM respectively. The low elevation coastal zones were derived from a DEM by selecting all land areas contiguous to the coast below each respective zones elevation (eg <10m, <5m, etc...). Estimates of population (head counts) and land areas (square kilometers) were generated for locations by settlement type for each country as a whole and within the LECZs.

Sea Level Rise Impacts on Ramsar Wetlands of International Importance, v1 (2000- 2010) provides estimates of the area and percent area of coastal Ramsar wetland sites that would become inundated under 1 and 2 meter sea level rise scenarios.