[Tagging] tagging extremely large flood control features.

John Willis johnw at mac.com
Wed Nov 6 23:48:22 UTC 2019

the government released photos of the water control features I’ve mentioned being filled by the recent typhoon. The “flooding” pictured is by design, controlled by short inner and large, tall outer levees. 

This should give people a better idea of the scale of the water features I am talking about. 

it also gives you an idea of how much stuff that is regularly used is (rarely) flooded in these events. it is very irregular. 

~ What it looks like normally, 360+ days a year. the brighter yellow reed grass shows the extent of the basins:

http://www.ktr.mlit.go.jp/ktr_content/content/000708028.pdf <http://www.ktr.mlit.go.jp/ktr_content/content/000708028.pdf>

~ 2 years ago, when the rivers and canals filled, but the larger basins were not really used:

http://www.ktr.mlit.go.jp/ktr_content/content/000708025.pdf <http://www.ktr.mlit.go.jp/ktr_content/content/000708025.pdf>

~The recent typhoon that completely filled the basins & rivers to become one giant lake (as designed) controlled by the outer levees:

http://www.ktr.mlit.go.jp/ktr_content/content/000759027.pdf <http://www.ktr.mlit.go.jp/ktr_content/content/000759027.pdf>

~ Where this river meets the larger river just below (Watarase meets Tone). This flood control system is merely meant to delay a surge into this larger river. 
Localized flooding (rain that can’t drain away) can be seen as clear shiny water in the adjacent fields and villages. it is 1-2m deep. The river is ~9m higher than normal.

http://www.ktr.mlit.go.jp/ktr_content/content/000759029.pdf <http://www.ktr.mlit.go.jp/ktr_content/content/000759029.pdf>

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