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Isbert's Folly

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Offline Big Vern

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« on: August 09, 2008, 15:29 PM »
I thought I'd start a separate thread on this one, as it will probably attract a different set of experts to the last question about rock formations in this valley.

In the Vall de Leguart is a dam know as Isbert's Folly. It was built at the beginning of this century I believe and the location chosen seems very sensible - physically - in that it was built at the narrowest point in the ravine (see photo). However, it appears that due to the porous nature of the surrounding rock, any water that the dam did accumulate, very quickly drained away; the Barranco del Infierno across which the dam was built is dry for 99% of the year anyway as far as I can see.   

It must have been something of a feat of engineering in it's time. Does anyone know of any historical material on the Folly or explanation as to why research prior to its building failed to foresee the problem?

Offline Clive

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« Reply #1 on: August 09, 2008, 18:04 PM »
I had a quick search on Google and found very little information.... Looks like you get the job of research Vern ;)

Maybe a trip to a local museum or the nearest village council....

I would be interested to know more as we too have a failed dam for similar reasons over here in Grazalema.
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Offline nick

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« Reply #2 on: August 10, 2008, 12:08 PM »
Looks like limestone to me
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Offline steveT

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« Reply #3 on: August 30, 2008, 00:13 AM »
Hi everyone ......

We are looking at the down river end of the dam.

I agree it looks like limestone ...... and this type of rock generally very porous.

There could be geological scenarios where I guess where you might be able to have a viable dam in a porous valley....ie if the valley was in a syncline and there was under lying non porous rock and the dam end was also folded up or provided a non porous floor at the dam end  or through an unconformity......I need to draw it really!!

There is the another scenario why you would build a dam in a limestone area....a river runs through expanses of limestone ....you have little geological technology .....water is a scarce resource ...... you decide to build a small dam and hope that you can store some for a few months hoping that eventhough it will drain away it will provide some water in the dry months .......or you do nothing.

Clive do you have any information on the dam you refer too.

Interesting stuff!!!!!

steveT


Offline Technopat

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« Reply #4 on: February 03, 2009, 23:11 PM »
Fascinating stuff!
The phrase "Man's folly knows no bounds" springs to mind - can't remember where I first heard it, but it's too good to be my own  :dancing:

A quick google produced the following:
http://riuadagirona.blogspot.com/2008/10/presa-de-isbert-se-desborda.html - which if nothing else, gives us the Plataforma Ciutadana "Riu Girona" and/or the Confedaración Hidrográfica del Júcar as the folks to check out for further info.

Sweeping aside the passing thought that it was the brainwave of the local cementera (En. anyone?) to boost business, could it be a sort of Thames Barrier built to give the locals time to evacuate the flood areas and mitigate the damage?

Regs.,
Technopat
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