Hello. In OSM there seems to be concurrent 2 tagging systems for flood tagging. And each of them seems to be incomplete.
Just to remember: There are several types of flood. I think the most common types are: – case 1: caused by heavy rainfall: “on flat or low-lying areas when the ground is saturated and water either cannot run off or cannot run off quickly enough to stop accumulating” (from Wikipedia article “flood”). Typically various times during one year – and quite common in some African countries during the rain season. – case 2: caused by overflow of water of a riverbed: not directly related to rainfall at this spot (rainfall can be hundrids of kilometers upstream, causing a river overflow hundrids of kilometers downstream). Typically maybe one per year or maybe each two or three years… In OSM we have flood_prone. The wiki descript fits most with “case 1”: “ this is mostly applicable to roads that go under water after heavy rains”; so combining it with highway=* on OSM ways (alternatively on nodes within a highway) would be the typical use case. We have currently 204 nodes and 10 582 ways. In OSM we have also hazard_type=flood. The wiki description fits mostly (but not exclusivly) with “case 2”. Tagging areas as independent OSM elements seems to be the typical use case (no combining with other objects). We have currently 1 node and 56 ways. hazard_type=flood comes from OpenHazardMap – but OpenHazardMap wiki page hasn’t been updated since one year. OpenHazardMap seems to focus on landslide (hazard_type=landslide has 3 169 comparing with only 57 elements for hazard_type=flood). Questions: – Shouldn’t we deprecate one of these tagging? If so, which one? – Shouldn’t we introduce a possiblility to distinguish river overflowing floods and directly rainfall related floods? – Only supplementary tagging of highway=*? Or independent OSM elements (areas)? Or both? Probably both makes sense. Suggestions? Lukas Sommer _______________________________________________ Tagging mailing list Tagging@openstreetmap.org https://lists.openstreetmap.org/listinfo/tagging
