Horizontal wells!

Next stop on recent vacation, Tenerife which is famous for its 'horizontal wells' or galleries to access ground water - which because of the particular geology of this volcanic island can be accessed by tunnelling horizontally above a harder rock layer and therefore achieving a gravity flow of water supply. Much of this being used for irrigation water originally, some for drinking water.

The map below is courtesy of the website of water supplier CIATF - detailing all the galleries on the island, the green lines indicating the tunnels, the red dots the access points and the blue dots conventional wells at a lower level.

My visit took me to the north west of the island where there are far fewer of the galleries - though I spent time on a coach tour trying to see if I could spot any galleries.

I guess this shed in the middle of this picture is nothing to do with a gallery ...

And I suspect this doesn't mean anything either.

More usefully http://www.secrettenerife.co.uk/2006/10/water-in-canary-islands.shtml- tells the story: "Most of the galleries in Tenerife were opened during the 20th Century and are horizontal tunnels, orientated to extract what has always been a scarce and precious resource. The galleries vary in length, between 1,000 and 2,000 meters, which were excavated - with dynamite and hand tools - 3/4 of a meter, or a meter at most with an experienced worker, during the 8 to 12 hour working day. It wasn't until the 1950's, when any sort of mechanization was introduced. For many young men in this area, working in these water mines was the only employment available to complement working the land for subsistence. It was an unknown world worked, in blood and sweat, in deplorable conditions, by these authentic hombres-topos (mole-men) down in the dark tunnels. In those days, the water was not a matter for the local council either. Once it was excavated, it was channelled to a "trusted source" who then saw to distributing it, via private "shareholders", to the enclaves they considered convenient. These labour conditions explain why throughout the history of the galleries, quite unsurprisingly, there have been numerous grave accidents: loss of limbs, loss of partial or total hearing from the blasts and even the death of some miners."

The website pagosylugaresdetenerife/blogspot.com/galerias-de-agua_has this picture of an old miners wagon in a gallery ...

And also a photo of a working gallery:

If you want to know more about the recent history of the management of the private galleries there is a fascinating article online from Sophie Tremolet from back in 2001 - Financial Times Global Water Report, Issue 122 | 28/05/2001 - where she explains "As for any private good, allocation is carried out through markets. Water can either be sold on an annual basis or on a temporary basis (particularly in times of drought). The price on the temporary market can fetch up to 75 times more than on the annual market, depending on weather conditions. It is also possible to transfer shares in water communities. Buyers are either farmers needing to complement their own allocation, hotel owners or municipal water companies. The latter have very few resources of their own, and need to purchase water from up to 50 different suppliers through bi-annual tendering processes. Some (especially privatised municipal companies) buy shares in water communities to increase their security of supply." Worth reading the whole article where she also estimates "the the current cost of accumulated investment in galleries in Tenerife alone (which has 1,700km of galleries) can be estimated at US$884m" and explains that "Following the passing of the 1985 water law in continental Spain, the socialist government tried to bring private waters into the public domain following a transition period of 15 years. But the Canarios were so attached to private water management that this threat of nationalisation led to the largest social unrest ever experienced in the archipelago and contributed to the fall of the government."

With the increased demand from tourism and population growth "The public sector has also started to invest massively in the water sector to find alternative sources of supply, as they do not believe that groundwater resources, even if managed in a sustainable fashion, will be sufficient to meet increases in demand."

Finally a couple of my photos showing more normal collection of rain/spring water for irrigation in the north west of the island:

and