As i am mapping in Bangkok there are many khlongs (คลอง) i want to map correctly. I see the word khlong on many maps. And there are many signs on bridges in Bangkok, stating the name of “Klong XY”. In Thailand many things seem to be named a khlong. Only a few of them are used for transportation purpose. There are big canals, 15 meter and more wide. And there are very small waterways, sometimes not more than 1 or 2 meters wide. Maybe the question shouldn’t be “How to tag khlongs”? Maybe it should be “How to tag waterways (correctly)”? Or “How to identify the type of a waterway (in Thailand)”?
In my opinion most khlongs i see in Bangkok would be “canal”, “ditch” or “drain”. But maybe some are even “river” or “stream”, if they are naturally formed? But how to find out easily if something is formed naturally? I do not know very much about the history of khlongs.
I am starting this thread hoping that i can collect some ideas from the community. I would than take this ideas and try to add a guidance to the wiki, so beginners would have an easier start with “mapping khlongs”
Unfotunately I’ve never been to Bankok yet (is on my ToDo-List ).
While reading your post I took a look at some more familiar to me: Venice. I don’t know, if you can compare thier waterway-infrastructure with Bankok.
The translation of Khlong (คลอง) is “canal” and clearly indicates the waterway is artificial (artificial, made by man). Thus in OSM terms “canal”, “ditch” or “drain” according to the definitions OpenStreetMap-Wiki: Map_Features#Waterway. In OSM terms “river” or “stream” are for natural waterways (made by nature), in Thai called “Mae Nam” (แม่น้ำ), “Lam Nam” (ลำน้ำ) or “Huai Nam” (ห้วยน้ำ).
I think the name of a waterway is more important and correct than its appearance. The name reflects what people think. The appearance changes, sometimes rather fast. Due to human actions some rivers might look more like canals: more concrete than earth. Due to lacking maintenance some canals might look more like rivers.
This is similar to highways. E.g. some “unclassified” highways in Bangkok are wider and in much better shape than the “trunk” highway 2 when you go to Nong Khai. In my opinion classification of highways is related to their relevance for the traffic. The actual appearance varies also with the location. There are additional tags to cover this like width, lanes, boat.
Imho it does not matter for a map if a waterway is natural or artificial. It is a blue line in both cases. A map is not an encyclopedia. Sometimes I get the impression that some OSM mappers are going in this direction. But that is another story.
I wrote down some notices. Maybe it is a start for a short wiki guidance for tagging khlongs or waterways in general. E.g. i am not sure about the use of “drain”, so i would like to hear your opinions.
Naturally formed waterways
Some names and descriptions for naturally formed waterways in Thailand:
Thai: แม่น้ำ (Mae Nam)
English: big river
Thai: ลำน้ำ (Lam Nam)
English: watercourse; river trunk
Thai: น้ำห้วย (Nam Huai) (แอ่งที่ขังน้ำซึ่งไหลมาจากภูเขา) (stream from the mountains with deep water)
Thai: ลำธาร (Lam Tarn) (ทางน้ำเล็กที่ไหลจากเขา) (slowly flowing stream from the mountains)
English: stream; brook; creek
The tagging for all of these naturally formed waterways depends only on the average width of the waterway:
Some names and descriptions for man made waterways in Thailand:
Thai: คลอง (Khlong)
If the waterway is named something like “Khlong XY”, we know it is a khlong for sure and we should tag it as “waterway=canal”. If the (man made) waterway has no name or the name is not known, it is up to the user to choose the proper tag from “canal”, “ditch” or “drain”.
waterway = ditch
If the waterway is significant smaller than a typical canal (less than 2 meters), chances are good that it is a “ditch”.
Links: Wikipedia: Ditch
waterway = drain
If it is made out of concrete (คอนกรีต; Beton) or build from other hard materials, it is maybe a “drain”. A drain must not nessessarily contain water all the time. In dry seasons it could be dry and only be filled while it is raining!
Links: OpenStreetMap-Wiki: Tag:waterway=drain
Examples of useful additional keys
name - the name of the waterway in thai (e.g. “คลองปลัดเฟรียง”)
name:th - again, the name of the waterway in thai (e.g. “คลองปลัดเฟรียง”)
name:en - the name of the waterway in english (e.g. “Klong Palat Priang”)
width - the width of the waterway (e.g. “8” meaning 8 meter)
tunnel - if the water flows underground (e.g. “yes”)
boat - this could state the access conditions for boats (e.g. “yes” or “permissive”)
Rendering of waterways
Some renderers (e.g. Osmarender) already support rendering of the attribute “width”, so it is a good idea to add this information to the waterway. This will make sure that the waterways will appear on the maps with a proper thickness.
Of course, we should stick to the tagging scheme. And I think it makes sense to distinguish between canal and river.
Following my opinions to your notices which I greatly appreciate for the Wiki.
General: We should not repeat definitions from other Wiki pages. We should only add specific additions or clarifications for Thailand. I like kiss (keep it small and simple).
“Naturally formed waterways” can be interpreted as describing the appearance and not the origin.
I suggest to replace it by “Nature-made waterways”. But I’m not sure if this is good English.
I propose to replace “Some names and descriptions for naturally formed waterways in Thailand” by “Some terms used in Thailand”. As we are not native Thai we should be careful with the meaning Thai words. The current usage might be different from the book we look into.
waterway=stream: To jump over a 5 m wide waterway is rather ambitious. I think 2 m is already too much, 1 m is OK. I would avoid “stream” completely and use “river” together with “width”. “average width” is more to define and measure: over time, from source to mouth? See also below.
“Man made waterways”: I think there should be a hyphen “Man-made waterways”.
"If the waterway is named something like “Khlong XY” … ":
I propose to delete this paragraph and replace the sentence “If it is officially named …” by "if the name of the waterway contains the word “Khlong” (Thai: คลอง).
I would avoid “ditch” and “drain”. I looked up some definitions and translation. They differ quiet a bit. E.g. “A long narrow trench or furrow dug in the ground, as for irrigation, drainage, or a boundary line” and “A pipe or channel by which liquid is drawn off”. Or in German “Straßengraben” und “Entwässerungsgraben”. In my opinion it is better to use only “canal” together with “with”. No misunderstanding, no discussions about what is what, which tend to be lengthy and coming up again and again. It is easier but still not easy because the width may change significantly from dry to rainy season. I think it’s worth to map “real” canals. May be when there’s nothing else left to map I might start to think about mapping ditches and drains which are not canals ;).
I like the KISS principle too. This is the reason why i want to write a short guide on how to tag waterways. Yes, it should be as simple as it can be. But it should be mostly complete too
This is why i want to create a schema that is easy and can not fail. And for this i have to repeat some definitions and add own notices. Do not forget that at the moment there is almost nothing written down in thai language in the OSM wiki. For thai beginners it is very hard to find answers because all is written in foreign languages. A short and simple guide giving answers to the FAQ would be a good help for beginners i guess. Than maybe some thai people can translate this into thai language. It will be a long way and need some time to get all important wiki pages translated into thai. We have to start somewhere to transfer our knowledge.
Yes, good point. You are totally right. Maybe “waterways that are made by nature (not made by humans)”?
Again, you are right. Maybe “Some terms used in Thailand for waterways that are made by nature”.
5 meters maybe is too much. A stream is described as “a naturally-forming waterway that is too thin to be classed as a river. Maybe you can just jump over it.”. If we limit streams to be not wider than 2 meters, than every “naturally-forming waterway” wider than 2 meters would be a river. I do not know rivers that are only 3 meters wide but i know streams that are. I just want to make a failsafe guide, so there has to be a width we can use as limit.
And we should not forget the name and the “local knowledge of the people” as indicator. I know many streams in Germany ending with “-bach”. So nobody would say it is a river, even if it is wider than 2 meters.
As we mainly are mapping streets at the moment, at least everything that affect streets is also worth to be mapped. And small bridges for “small waterways” are worth to be mapped, imho. So i would map the corresponding waterway too, if i have the possibility (e.g. Yahoo sattelite images for Bangkok). And because some of this waterways are not real canals i started to think about what they are. And i am looking for a simple way to identify the type.
Completely ignoring “stream”, “ditch” and “drain” is not good in my opinion. To help people make the right choice we need to explain all possibilities.
I try to list all indicators for identifying the type of waterways, that we found untill now:
appearance; shape; …
width (and sometimes even deepness)
material the waterway is made off (for human build waterways)
We should carefully think how to address this. OSM is moving rather fast. Even the English Wiki does not follow. And despite the many German users the German Wiki is even more behind. I think updating is more easy when the pages are translated and additional stuff in the other language is either on another page or clearly marked. E.g. the English and German page about multipolygon are quite different: Relation:multipolygon and DE:Relation:multipolygon
Currently I’m mapping bridges only when really necessary. In my opinion bridges over waterways are not necessary. Each editor, renderer, mapper and map user assumes that per default a highway crossing a waterway is a bridge. In addition I think it is no good idea to add a bridge without knowing the end points. There are many other things missing in Thailand which I will map before bridges.
I mapped several rivers in Thailand based on “LandSat” and later crossed them to get the name. None of them was smaller than 2 m, they were more than 4 m wide. Thus I think from “LandSat” you can’t draw “streams”. Same with “ditch” and “drain”. So I’m wondering how you will draw them at all.
But of course in OSM each mapper can map what he wants. I don’t object. I give only my 2 cents.
This is true. And this inconsistency causes a lot of confusion, not only with the tagging of waterways. I just want to create a small guide for tagging waterways in thailand. It is just a first try to create basic definitions, so people in thailand can easily start to work, without first getting involved into endless discussions e.g. about “How is the perfect definition of a drain?”.
If some thai people start to translate the “main definition pages for waterways” i would be happy about it. But how could someone translate these pages, when the content is different in every language. And there are also much pages with conflictive content in englisch.
I always collect the data where a bridge starts and where it ends, if you mean this. I find bridges very useful as points for orientation, thats all. I do not think bridges are a must to map for everyone everywhere
Maybe i will walk them, maybe i put my GPS on a remote controlled toy boat
No, i will not draw them all. I have never drawn a small waterway until now. And of course its difficult to draw things that are smaller then 5 meters with nothing more than satellite images. But who has said that a stream, a drain or a ditch can not be 5 meters wide? This is something i am still trying to find out.
To define definitions for tagging waterways for myself, i have now created an OSM wiki page: OpenStreetMap-Wiki: User:WanTan/Howto_tagging_of_waterways_in_Thailand
I placed the page in my own wiki namespace, so hopefully nobody gets confused about this. At the moment this is just a collection of personal thoughts i got with help of the discussion in this forum thread.
Maybe you and some other people will have a look at it. I would be happy about suggestions how to make it better, how to simplify it and how to make it more failsafe. If some other people find it useful we can maybe link it or make it part of the Thailand project pages sometime. Or maybe someone wants to take this as a base for further discussions about how to simplify the definitions for waterways in general.
Good idea adding a short version to the main page. Thanks for this, its looking really nice. Maybe i find some time for collecting more info and more pictures as examples and then create an extra page for issues of tagging waterways.
But isn’t it a bit strange to use waterway=drain together with barrier=ditch? This sounds wrong (contradictorily) to me, even if its written down like this on the page http://wiki.openstreetmap.org/wiki/Key:barrier at the moment. Then better make a new proposal for barrier=drain, if somone really needs this information. My suggestion was to use barrier=ditch instead of waterway=ditch when the ditch does not contain water most of the time.
In case someone wonders: I replaces the pictures showing waterways with some showing waterways in Thailand, resp. showing a Klong.
That should help in recognizing them.
I agree we can get rid of some specialty tagging explanation like the barrier tag or fuel types. In case a mapper considers them important, they can be added. But on that introduction page we should focus on the most important things, especially when there is a special usage of them in Thailand.