It seems to me that "rebosadero" here refers to a rainfall waterfall, or "cloud waterfall", rather than a spring, as the text mentions the water going into the Caldera, "hacia el interior". The trade winds cause a spectacular phenomenum in the area:

"The cloud waterfall is caused by those same, star-perfect Atlantic trade winds hitting the tall, steep island. If this island was located anywhere else, and if it wasn’t a massive volcano, the cloud waterfall, the microclimates, the clear sky – none of it would exist."
http://www.huffingtonpost.com/michael-schuermann/seeing-gran...

Degollada de Becerra - La Culata - Tejeda - Guía de Senderos de las ...
www.medianias.org › Inicio › Tejeda
Ya desde la época prehispánica, esta zona de la Caldera de Tejeda .... Canarias se halla bajo los efectos casi constantes de los alisios, vientos que tienen su ... es la cascada de nubes que hace visible la línea divisoria entre barlovento y ...


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Note added at 1 hr (2017-03-16 12:16:10 GMT)
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Phenomenon, not phenomenum, I meant to say.

Little Continent Gran Canaria - Walking Festival #gcwalkingfestival
www.easyhiker.co.uk/little-continent-gran-canaria/
Oct 13, 2013 - "Above the clouds in the little continent Gran Canaria" From here, you get a stunning view across the Caldera de Tejeda, possibly ... This is not quite a waterfall, more of a “cloudfall”, and if nature has a more ...