[Imports] Tenerife streams import

[Christoph Hormann]

On Monday 20 March 2017, Frederik Ramm wrote:
>
> 1. You propose to map all streams with "intermittent=yes". I am not
> familiar with Tenerify hydrography but is it really correct that they
> are all subject to drying out?

The vast majority of natural waterways on the Canary islands are dry for 
at least part of the year.  Even in the wettest parts in the cloud 
forests small streams will usually dry up duing periods of warm and dry 
weather and the larger ones are largely diverted for irrigation anyway.

In other words:  There are far more waterways on the Canaries that miss 
intermittent=yes (in particula on La Gomera and Gran Canaria) than 
there are ones with it being incorrectly applied (possibly a few 
sections on La Palma).

Many Barrancos there are in fact fossile waterways, they have formed and 
carried water during former, more humid times but are permanently dry 
today.  It will likely be difficult to reliably map additional streams 
not currently in OSM based on imagery alone without on-the-ground 
inspection because of that.  This won't affect adding missing names to 
existing streams of course.

-- 
Christoph Hormann
http://www.imagico.de/