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Please note that most of the time, these population distribution datasets are usually not available. In this case, one may use data sets based on census data such as those shared through projects like WorldPop (http://www.worldpop.org.uk/) or the Gridded Population of the World (GPW, http://sedac.ciesin.columbia.edu/data/collection/gpw-v3).
These grids might nevertheless need to be adjusted before being used in AccessMod. Appendix 1 provides details on the process to be applied when using the WorldPop dataset.
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In AccessMod, "No data" areas (e.g. water bodies) should be considered as unpopulated. Therefore, population distribution grid needs to be consistent with the "No data" areas reported in the merged land cover distribution grid (see next section 3.3.1.4). If population remains in “No Data” cells, a warning message will appear in AccessMod. The user can either decide to launch the analysis anyway (thereby missing some population that will virtually “escape” the analysis) or to use the tool “Correct for population on barriers” (see section 5.7). The geographic coverage analysis generates a raster showing those population cells that are located on top of barriers. This allows users to more easily pinpoint these cells and correct them in their GIS software if necessary. |
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