This tool is found in the Toolbox and allows one to adjust the population distribution raster so that the population found in barrier pixels (as specified in the merged landcover) is redistributed outside of these barriers. The redistribution is done uniformly over all non-barrier pixels found within each of the user-specified sub-administrative units. The correction of the population on barriers is important when you want to ensure that your statistics (e.g. percentage of coverage, number of populations found in each catchment, etc.) accountsaccount for it.
The underlying hypothesis when using this tool is that the methodology used to obtain the population density raster has wrongly distributed some population in places where there should not be any population (e.g. on some rivers, airport, wetlands, etc.).
Please see Appendix 1 for the details of the algorithm implemented in this tool.
There are two correction modes available (since version 5.6.25):
- Population value known: for this, it is assumed the attribute table of the administrative unit shapefile has a column informing about the official number of population in each administrative unit. AccessMod will therefore ensure, in each administrative unit, that the population redistributed outside barriers sum up to the official population number of that unit.
- Population value not known: for this, it is assumed you do not know the official total distribution of each administrative unit. AccessMod therefore assumes that the sum of population in each administrative unit is the correct one and redistribute this total population outside barriers.
Before running the tool, it is assumed that the following three layers are already uploaded into AccessMod and that all of them have the same projection system, extent and resolution than the DEM :
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