Exquisitely low tech on the ground, and a fun, engaging, global exercise. May not be perfect for total population figures, but may identify where undercounting is occurring (and overcounts). A nice image: hundreds of millions of lights at the same time, each representing a single human life, spanning large portions of the globe. The spy satellite folks would get a kick out of it.
perrygeo•8mo ago
Given that these regions were clearly valuable real estate - valleys with waterways near urban centers - it's very hard to make the case that these 307 flooded valleys represent all rural areas on earth. It seems like the authors conveniently skip the bias they themselves introduced. A few hundred dam sites are not representative of rural land on earth, and this paper is sketchy AF for trying to make that claim without supporting their assumption.
Furthermore, and this might be more a chip on my personal shoulder, they fail to outline their methods or do adequate sensitivity analysis. The vector footprint of the reservoirs and the raster population grid are disparate data models and there are many different approaches for determining their overlap. Do you include the center of the cell? Only 50% coverage? Any coverage? 100% coverage only? How are the data reprojected to align spatially? And given the coarse resolution and spatial arrangement (fractal coastlines, high perimeter:area), those details are not just GIS nerdery, they have massive impacts on the results. At least the code is available so it could potentially be reviewed.