To Hamragarðaheidi, the plateau where Seljalandsá that flows down at Seljalandsfoss has its origin. Namely this place:
No wait. That is one of the origins of Gljúfrafoss. The water that flows from this hydrant then runs into the marshlands Tröllamyri, and is there joined by others streams before falling down at Gljúfrafoss.
The water in Seljalandsá comes from places like these:
Apparently the water runs in the lava fields before emerging from the ground here at Hamragarðaheidi. Surface water are probably mixed with melt water from Akstaðajökull, and depending on the time of year there are more or less water in the streams.
The map indicates that a lot of water is flowing through Tröllagil. But during my visit here in the autumn 2013 there was no water at all in the canyon.
Finally an picture of Hamragarðaheidi with Storhöfdi to the left and Seljalandsá flowing at its base.
