[Tagging] Irrigation: usage=irrigation vs irrigation=yes [Was Irrigation: ditches, canals and drains]

John Willis johnw at mac.com
Wed Jun 5 06:00:43 UTC 2019

> On May 30, 2019, at 9:03 AM, Joseph Eisenberg <joseph.eisenberg at gmail.com <mailto:joseph.eisenberg at gmail.com>> wrote:
> Thank you for the information about Japan.
> How are the small drainage/irrigation channels tagged currently in Japan?

I uploaded some pictures of drains I see in Japan.

a vast majority are between 20-50CM wide precast concrete segments. 
https://wiki.openstreetmap.org/wiki/File:Drain_50cm.jpg <https://wiki.openstreetmap.org/wiki/File:Drain_50cm.jpg>

old ones are made out of concrete and river stones.  
https://wiki.openstreetmap.org/wiki/File:Drain_old_40cm.jpg <https://wiki.openstreetmap.org/wiki/File:Drain_old_40cm.jpg>
https://wiki.openstreetmap.org/wiki/File:Drain_old_180cm.jpg <https://wiki.openstreetmap.org/wiki/File:Drain_old_180cm.jpg> 

Larger ones are usually 90cm that provide (upstream) and collect water (downstream) from the smaller ones. they often serve multiple sets of fields before returning to the river or stream the water was diverted from. 
https://wiki.openstreetmap.org/wiki/File:Drain_90cm.jpg <https://wiki.openstreetmap.org/wiki/File:Drain_90cm.jpg>
https://wiki.openstreetmap.org/wiki/File:Drain_90cm_covered.jpg <https://wiki.openstreetmap.org/wiki/File:Drain_90cm_covered.jpg>

plastic pipes and earthen ditches are used to provide water from the drain to the fields. 
flow is controlled via movable doors, rocks, or small sluice gates the size of a sheet of paper (or smaller). 
https://wiki.openstreetmap.org/wiki/File:Drain_large_and_small.jpg <https://wiki.openstreetmap.org/wiki/File:Drain_large_and_small.jpg>

small concrete weir boxes (40x40cm up to 2x4M) control flow and overflow from supply into irrigation channels. 
https://wiki.openstreetmap.org/wiki/File:Drain_weir_box.jpg <https://wiki.openstreetmap.org/wiki/File:Drain_weir_box.jpg>

There are also very small reservoirs used to water specific sets of fields. 
https://wiki.openstreetmap.org/wiki/File:Resivoir_box.jpg <https://wiki.openstreetmap.org/wiki/File:Resivoir_box.jpg>

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