Source Population Data Base: Center for International Earth Science Information Network - CIESIN - Columbia University. 2017. Gridded Population of the World, Version 4 (GPWv4): Population Count, Revision 10. Palisades, NY: NASA Socioeconomic Data and Applications Center (SEDAC) Accessed 23 Feb 2018. These data were treated afterwards by Rivers Network to fit with river basin limits and formated for web maps purposes. The density ranking is based on the DN values from SEDAC data base.