User:Jeisenbe/Irrigation
| Tag:usage=irrigation | |
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| Proposal status: | Draft (under way) |
| Proposed by: | jeisenbe |
| Tagging: | irrigation=yes |
| Applies to: | Waterways |
| Definition: | Specifies that a waterway carries water intended for agriculture |
| Statistics: |
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| Draft started: | 2019-06-03 |
 irrigation = yes
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| Description |
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Specifies that a waterway carries water intended for agriculture  
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| Group: waterways |
| Used on these elements |
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| Requires |
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| Useful combination |
Status: in use
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| Tools for this tag |
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Specifies that an artificial waterway is used to transport water to agriculture fields or facilities
Should the tag be: irrigation=yes or usage=irrigation?
Proposal
Artificial waterways which bring water to agriculture fields or facilities may be tagged with usage=irrigation - or perhaps irrigation=yes. The key/value needs to be decided.
Rationale
A number of tags have been used to specify that a waterway is used for irrigation, but none has been formally proposed or discussed:
irrigation=yes was the first tag used, starting it 2011. As of May 2019, it has been used 200 times with canals and 2000 times with ditches. Currently there are 2645 ways tagged with waterway and irrigation=yes. Most of the increase in tags was added between 2011 and 2014.
- The key irrigation=* is also used a few thousand times to specify the that a field is irrigated with a central pivot system, with the tag irrigation=pivot. And there are under 200 uses of irrigation=ditch with landuse=* to specify the type of irrigation for a field.
- However, these minor uses of the key do not conflict with the clear meaning of irrigation=yes as specifying that a waterway is used for irrigation.
- Mappers can verify the usage of a waterway by observing characteristics such as flow direction, direction of sluice gates, and seasonal presence of water, which show that the water is directed into agricultural areas, rather than flowing away as drainage water.
- For example, in a climate with a dry season, an intermittent waterway used for irrigation will be full of water during the growing season for crops or throughout the dry season, while an drainage channel will only flow with water during storms or during the dry season.
- Drainage channels are designed for water to flow away from fields and developed areas and towards streams and rivers, while irrigation channels flow toward fields and other agricultural areas. Any weirs or sluice gates along the waterway will be designed to direct water towards the field
- In some areas there are waterways which are used to provide water to fields in the dry season but remove excess water during the wet season. These waterways will be designed so that water may flow in either direction, and may be tagged with both irrigation=yes and drainage=yes.
Alternatives
- A couple hundred canals are tagged canal=irrigation. Even fewer ditches are tagged {Tag|ditch|irrigation}}. However, the key canal=* is also to used to specify the type of canal construction, for example a canal=qanat or canal=leat and this key should be reserved for such subtags which are related to the type of canal, rather than used to define how the water is used. Since irrigation canals can have a variety of sizes and construction methods, they cannot be verifiably determined to be a type of canal based on local characteristics only;
- service=irrigation was used starting in 2012, as as of May 2019 is used 12,000 times, twice as often as usage=irrigation, however, usage=irrigation is increasing more quickly. The key service=* is mainly used for railways and highways, to specify the type of service road (such as a driveway) or the type of railway service, but also used with "=tyres" and similar for motor vehicle service locations and "=irrigation" for waterways. Therefore, using this key to specify the usage of an artificial waterway is confusing.
The key usage=* has already been used for waterways and pipelines, and railways. The current values used frequently with pipelines (including oil, gas and water pipelines) and waterways are:
The values "penstock" and "headrace" were recently approved for use with waterway=pressurised
While this key is also used for railways (in addition to the key service=*), the list of values is entirely different. I've debated whether usage=irrigation or irrigation=yes is superior:
Tagging
- Add usage=irrigation to a way which is also tagged as a waterway=canal feature
- Some mappers have also used this tag with waterway=ditch. Many irrigation ditches in are indistinguishable from drainage ditches in construction. This proposal suggests that such usage is acceptable
- usage=irrigation could also be used with the new waterway tag waterway=pressurised for certain sections of irrigation waterways where the water passes through a pressurized pipeline, siphon or tunnel.
- Sometimes this tag can be used with man_made=pipeline + substance=water - but consider if a waterway=pressurised tag is appropriate as well.
Applies to
Way features tagged waterway=canal or waterway=pressurised, and sometimes waterway=ditch or man_made=pipeline
Possible Errors
- irrigation=yes should 'not be used with waterway=drain - these are specifically defined as drainage features, rather than irrigation features.
- irrigation=yes should not be used with waterway=stream or waterway=river since these are natural features. If a waterway which was originally a natural stream or river has been heavily modified, channelised and used for irrigation, considering using waterway=canal with irrigation=yes for that portion of the waterway which has become and irrigation canal.
Features/Pages Affected
This proposal will deprecate service=irrigation, and either irrigation=yes or usage=irrigation