<html><head><meta http-equiv="Content-Type" content="text/html; charset=us-ascii"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><br class=""><div><br class=""><blockquote type="cite" class=""><div class="">On May 30, 2019, at 9:03 AM, Joseph Eisenberg <<a href="mailto:joseph.eisenberg@gmail.com" class="">joseph.eisenberg@gmail.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><span style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; float: none; display: inline !important;" class="">How are the small drainage/irrigation channels tagged currently in Japan?</span><br style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><br style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><span style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; float: none; display: inline !important;" class="">Are most tagged as waterway=drain, waterway=canal or waterway=ditch?</span></div></blockquote></div><br class=""><div class=""><br class=""></div><div class="">they are used for different purposes. based on purpose and construction. I use all three when mapping. (along with many many weirs & sluice_gates). </div><div class=""><br class=""></div><div class=""><br class=""></div><div class=""><div><br class=""></div><div>people tag them as streams, drains, and ditches. many streams are re-routed into new (straight) channelized systems, removing them from the old path. </div><div><br class=""></div><div>aqueducts are usually tagged as waterway=canal canal=irrigation. </div><br class=""><div class="">Here is a drain that pulls off of a stream and supplies water to some rice fields and then dumps back into the river less than 1 KM downstream. </div><div class=""><br class=""></div><div class="">you can see how stuff is commonly tagged. I assume there are some errors. </div><div class=""><br class=""></div><div class=""><a href="https://www.openstreetmap.org/way/621898960#map=15/36.3124/139.3520" class="">https://www.openstreetmap.org/way/621898960#map=15/36.3124/139.3520</a></div><div class=""><br class=""></div><div class="">most rice fields are divided into long rectangles, and nominally are separated alternately by access road (alley) and a ditch. </div><div class=""><br class=""></div><div class="">here is a picture of the 30-40cm drains that run along most roads to supply and collect water for the fields. </div><div class=""><br class=""></div><div class=""><a href="https://www.flickr.com/photos/javbw/11091110715/in/album-72157638113676925/" class="">https://www.flickr.com/photos/javbw/11091110715/in/album-72157638113676925/</a></div><div class=""><br class=""></div><div class=""><br class=""></div><div class=""><br class=""></div><div class="">These are almost all prefabricated concrete, from 1m2 to 30cm2. </div><div class=""><br class=""></div><div class="">the drains have small little plastic doors (metal wood, or a plastic soda bottle jammed in there) that feed fields directly or feed the old ditch system (1m- 50cm ditches) </div><div class=""><br class=""></div><div class=""><br class=""></div><div class=""><div class="">here is a large ditch that enters from the right, goes in a culvert under the road and into a concrete distribution box with a wooden weir board inside to control the water height.</div><div class=""><br class=""></div><div class=""> The yellow bag is controlling the flow from the box into that field set. It then continues on as a ditch towards camera. </div><div class=""><br class=""></div><div class=""><a href="https://www.flickr.com/photos/javbw/11091115355/in/album-72157638113676925/" class="">https://www.flickr.com/photos/javbw/11091115355/in/album-72157638113676925/</a></div></div><div class=""><br class=""></div><div class=""><br class=""></div><div class="">the lower fields then feed their water back into the ditches and drains and the drains continue on to the next set and eventually back to the source they were pulled out of (from the weir) </div><div class=""><br class=""></div><div class="">it might seem unnecessary to have them re-connect to the river further downstream (often with a sluice gate through a levee), but this system absorbs all of the rain and acts as a flooding buffer, and has to empty back out into the river eventually. </div><div class=""><br class=""></div><div class="">they can divert some water into holding ponds for the three weeks in summer when it is really hot and doesn't rain. </div><div class=""><br class=""></div><div class=""> here is a small one <a href="https://www.openstreetmap.org/way/243411132" class="">https://www.openstreetmap.org/way/243411132</a> </div><div class=""><br class=""></div><div class="">These same drains, in suburban areas, pass through neighborhoods to go from field to field. </div><div class=""><br class=""></div><div class="">aqueducts move water from river to river to keep the supply equalized or to supply water treatment plants. </div><div class=""><br class=""></div><div class="">One aqaduct pulls water from a giant river about 20KM from my house to a holding lake just above my house. it then feeds water into this stream to take care of farmers down stream. </div><div class=""><br class=""></div><div class=""> here is quick look at one of these aqueducts (it goes above and underground). </div><div class=""><br class=""></div><div class=""><a href="https://www.openstreetmap.org/node/3123867846" class="">https://www.openstreetmap.org/node/3123867846</a> node where disappears underground in the below pictures. </div><div class=""> <a href="https://blogs.yahoo.co.jp/shsyc511/9073548.html" class="">https://blogs.yahoo.co.jp/shsyc511/9073548.html</a></div><div class=""><br class=""></div><div class=""><br class=""></div><div class=""><br class=""></div><div class="">here is the beginning to an (old) aquaduct near Nikko </div><div class=""><br class=""></div><div class=""><a href="https://www.openstreetmap.org/way/685540122" class="">https://www.openstreetmap.org/way/685540122</a></div><div class=""><br class=""></div><div class=""><br class=""></div><div class="">here is an aquaduct that goes under a huge river in Nagano. </div><div class=""><a href="https://www.openstreetmap.org/way/684097406" class="">https://www.openstreetmap.org/way/684097406</a></div><div class="">it has bridges over rivers and water control gates and flow control waterways it crosses.</div><div class=""><a href="https://www.openstreetmap.org/way/401319150" class="">https://www.openstreetmap.org/way/401319150</a></div><div class="">it feeds agricultural water to Wasabi farms, which need very clean and controlled water. </div><div class="">it grows in ditches that feed water into the riverbed gravel it grows in. </div><div class=""><a href="https://www.openstreetmap.org/way/684097406" class="">https://www.openstreetmap.org/way/684097406</a> </div><div class=""><br class=""></div><div class=""><br class=""></div><div class="">Javbw</div><div class=""><br class=""></div></div></body></html>