[Tagging] waterway=wadi problem

Eugene Alvin Villar seav80 at gmail.com
Fri Jan 16 00:27:10 UTC 2015


Given the current discussion, I wonder if roads that are usually flooded
during heavy rainfall should be also be tagged as waterway=river/stream and
intermittent=yes. ;-)

On Fri, Jan 16, 2015 at 7:27 AM, John F. Eldredge <john at jfeldredge.com>
wrote:

> I would recommend expanding the definition of "intermittent streams" to
> include not only streams that have a regular, seasonal water flow but also
> streams in desert areas that exist only when a rare storm comes along. The
> topography is the same, the tendency of water to run downhill is the same,
> only the frequency of rainfall is different.
>
> --
> John F. Eldredge -- john at jfeldredge.com
> "Darkness cannot drive out darkness; only light can do that. Hate cannot
> drive out hate; only love can do that." -- Martin Luther King, Jr.
>
>
>
>
> On January 15, 2015 3:13:38 AM Christoph Hormann <chris_hormann at gmx.de>
> wrote:
>
>  On Thursday 15 January 2015, johnw wrote:
>> >
>> > A wadi is a place where flash floods occur. It is not an intermittent
>> > river - it isn’t really seasonally wet, and doesn’t provide any real
>> > expectation that water will be present (except deep underground) -
>> > because they are located in places where rain itself is unexpected
>> > for most of the year.
>>
>> Well - that would be a useful concept of a wadi but it has two problems:
>>
>> * current use of the tag is very different from that, you can see that
>> quite well when you look at the taginfo map:
>>
>> https://taginfo.openstreetmap.org/tags/waterway=wadi#map
>>
>> the uses in Europe for example are probably almost always seasonal.
>>
>> * sporadic waterflow is very difficult to determine for the mapper.
>> This is especially true for northern Africa where climate got a lot
>> drier in the last few thousand years and as a result there are many
>> permanently dry valleys that still look like being formed by waterflow
>> but that have not seen significant waterflow in the last hundred years.
>>
>> My suggestion would probably be to stop rendering waterway=wadi in a way
>> implying waterflow, encourage mappers to use intermittent/seasonal
>> where this is known and reserve waterway=wadi - despite the then
>> misleading key - for valleys where waterflow is unknown.
>>
>> --
>> Christoph Hormann
>> http://www.imagico.de/
>>
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>
>
>
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