OpenStreetMap
The Barragem de Alqueva/Embalse de Alqueva (Relation Number 1.464.895):
With a surface of 250 km2, a lakeside of 1.200 km (about 1.000 km on Portuguese territory, the rest in Spain) and a length of about 85 km the "Barragem de Alqueva" is today the biggest artificial lake in Europe.
It would have been impossible to map this object without the help of aerial imagery in the detail that BING gives us. The only other way to have mapped this for OSM would have been by using official data from some other source. It took 4 months to complete.
I do not know how many nodes and ways (and islets) it contains, as I cannot download it in JOSM as a single entity as it is too large. I think I mapped about 100-200 islets and over 10.000 nodes but it is just a guess.
View it in OSM:
http://www.openstreetmap.org/?lat=38.4006500244141&lon=-7.27157592773438&zoom=10
Pictorial Map
http://www.alqueva.de/alquevakarte.html
Website in Portugies, German, English
http://www.alqueva.eu/
Discussion
Comment from c2r on 14 May 2011 at 13:02
Good going - well done!
Comment from olejorgenb on 14 May 2011 at 16:26
Well done :) You should make some before/after shots. Not sure if there is an easy way though. (ought to be!)
Comment from Roman Fischer on 14 May 2011 at 16:26
Simply impressive work! :)
Comment from kerosin on 14 May 2011 at 22:03
Really impressive! But maybe it is a bit too detailed;) Bing Imagery is always just a snapshot in time and edges of lakes are not steady. They are subjected to natural changes like aridity or rising water level because of lasting rain.
Anyway, thank you for your great work!
Comment from malenki on 15 May 2011 at 18:21
Awful impressive work indeed! Yes, it is a big relief to have a lot of good aerial imagery.
I assume working four (!) months on it you drew all of it by hand?
To complete your stats a bit:
The relation contains 275 islets, all objects have 48.996 nodes.
Its outer ways have a total length of 1.124 km (1.124.139,19 m)
Although it maybe discourages you a bit I want to mention scanaerial¹ which can trace coasts, riverbanks and such.
With its predecessor in spirit Lakewalker I traced Lake Nasser.² Though I had this great tool I needed one week (seemed much to me) to complete my work.
¹http://wiki.openstreetmap.org/wiki/Scanaerial
²http://osm.org/go/xijygc--
Comment from dcp on 16 May 2011 at 20:03
Thank-you user malenki for the statistics. I am amazed at the numbers; maybe I should not have started. When I say 4 months it was not continous of course: I stoped for 5 weeks while in Portugal in March.
I looked at Scanaerial using your link. I don't think that I have the know-how to use it though.
Once again thanks
Comment from malenki on 17 May 2011 at 14:18
So 3 months of work remain - still an unbelievable effort.
Regarding scanaerial: I have enhanced the wiki page so setup should be easier. After all, you already mastered JOSM! ;)
Comment from jamesks on 11 February 2013 at 17:34
IMpressive. I think I sketched this in a few years ago, and wondered how it would ever get drawn in detail!