I am aware of the underground basins that are dedicated to the task, but I am wondering how to map above-ground basins that are used as regular land 360+ days of the year - something you don't have to deal with when mapping the underground tanks.
~~~~~ The rest is not important, but read on if you Want. Yea, Thats in Tokyo on the Arakawa/Edo rivers, the the Tokyo metro area. The start of the Edo river is a lock-controlled flow from the Tone - as the larger Tone goes off to the Pacific 70 Km north of Tokyo (it doesn't discharge into Tokyo Bay). As I understand it, those tanks manage the water going into the system in Tokyo itself, absorbing the flow from the smaller channels/rivers in Tokyo (Tokyo is big and flat) and buffering it before it gets discharged into the rivers, absorbing what would normally be trapped behind the River levees. The Tokyo tank system couldn't handle the river flow directly (it's immense) - The rivers channeling water down through the region just use extra-wide and tall 8-10m levees to provide ~ 10-15x normal flow volume to the sea. (The river goes from 1-2m deep to 8-9m deep, and doubles in width) Small towns in my area (pictured) were flooded not by a levee breach, but by water trapped outside the levee that couldn't get into the river through the normal gates. The Tokyo system prevents that from happening - though I wonder if it could absorb even a quarter of what the Usuichi trapped. The Usuichi is gigantic. Javbw > On Oct 24, 2019, at 9:08 PM, Paul Allen <pla16...@gmail.com> wrote: > > >> On Thu, 24 Oct 2019 at 10:56, John Willis via Tagging >> <tagging@openstreetmap.org> wrote: >> > >> Inside, there are three “retarding basins” (numbered 1, 2 & 3), with #1 >> having with a large traditional reservoir, parks, golf course, and sports >> grounds inside. > > There is more to the system than that. There are also underground holding > tanks and > tunnels: https://www.youtube.com/watch?v=cfJOW2PtrGk > > -- > Paul >
_______________________________________________ Tagging mailing list Tagging@openstreetmap.org https://lists.openstreetmap.org/listinfo/tagging
